2885 lines
99 KiB
Go
2885 lines
99 KiB
Go
// Copyright 2013 The LevelDB-Go and Pebble Authors. All rights reserved. Use
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// of this source code is governed by a BSD-style license that can be found in
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// the LICENSE file.
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package pebble
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import (
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"bytes"
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"context"
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"fmt"
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"io"
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"math"
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"runtime/pprof"
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"sort"
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"strings"
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"sync/atomic"
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"time"
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"github.com/cockroachdb/errors"
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"github.com/cockroachdb/errors/oserror"
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"github.com/cockroachdb/pebble/internal/base"
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"github.com/cockroachdb/pebble/internal/keyspan"
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"github.com/cockroachdb/pebble/internal/manifest"
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"github.com/cockroachdb/pebble/internal/private"
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"github.com/cockroachdb/pebble/internal/rangedel"
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"github.com/cockroachdb/pebble/sstable"
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"github.com/cockroachdb/pebble/vfs"
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)
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var errEmptyTable = errors.New("pebble: empty table")
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var errFlushInvariant = errors.New("pebble: flush next log number is unset")
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var compactLabels = pprof.Labels("pebble", "compact")
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var flushLabels = pprof.Labels("pebble", "flush")
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var gcLabels = pprof.Labels("pebble", "gc")
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// expandedCompactionByteSizeLimit is the maximum number of bytes in all
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// compacted files. We avoid expanding the lower level file set of a compaction
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// if it would make the total compaction cover more than this many bytes.
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func expandedCompactionByteSizeLimit(opts *Options, level int, availBytes uint64) uint64 {
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v := uint64(25 * opts.Level(level).TargetFileSize)
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// Never expand a compaction beyond half the available capacity, divided
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// by the maximum number of concurrent compactions. Each of the concurrent
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// compactions may expand up to this limit, so this attempts to limit
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// compactions to half of available disk space. Note that this will not
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// prevent compaction picking from pursuing compactions that are larger
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// than this threshold before expansion.
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diskMax := (availBytes / 2) / uint64(opts.MaxConcurrentCompactions)
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if v > diskMax {
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v = diskMax
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}
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return v
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}
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// maxGrandparentOverlapBytes is the maximum bytes of overlap with level+1
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// before we stop building a single file in a level-1 to level compaction.
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func maxGrandparentOverlapBytes(opts *Options, level int) uint64 {
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return uint64(10 * opts.Level(level).TargetFileSize)
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}
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// maxReadCompactionBytes is used to prevent read compactions which
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// are too wide.
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func maxReadCompactionBytes(opts *Options, level int) uint64 {
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return uint64(10 * opts.Level(level).TargetFileSize)
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}
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// noCloseIter wraps around a FragmentIterator, intercepting and eliding
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// calls to Close. It is used during compaction to ensure that rangeDelIters
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// are not closed prematurely.
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type noCloseIter struct {
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keyspan.FragmentIterator
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}
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func (i noCloseIter) Close() error {
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return nil
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}
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type compactionLevel struct {
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level int
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files manifest.LevelSlice
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}
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// Return output from compactionOutputSplitters. See comment on
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// compactionOutputSplitter.shouldSplitBefore() on how this value is used.
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type compactionSplitSuggestion int
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const (
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noSplit compactionSplitSuggestion = iota
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splitNow
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)
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// String implements the Stringer interface.
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func (c compactionSplitSuggestion) String() string {
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if c == noSplit {
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return "no-split"
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}
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return "split-now"
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}
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// compactionOutputSplitter is an interface for encapsulating logic around
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// switching the output of a compaction to a new output file. Additional
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// constraints around switching compaction outputs that are specific to that
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// compaction type (eg. flush splits) are implemented in
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// compactionOutputSplitters that compose other child compactionOutputSplitters.
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type compactionOutputSplitter interface {
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// shouldSplitBefore returns whether we should split outputs before the
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// specified "current key". The return value is splitNow or noSplit.
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// splitNow means a split is advised before the specified key, and noSplit
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// means no split is advised. If shouldSplitBefore(a) advises a split then
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// shouldSplitBefore(b) should also advise a split given b >= a, until
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// onNewOutput is called.
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shouldSplitBefore(key *InternalKey, tw *sstable.Writer) compactionSplitSuggestion
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// onNewOutput updates internal splitter state when the compaction switches
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// to a new sstable, and returns the next limit for the new output which
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// would get used to truncate range tombstones if the compaction iterator
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// runs out of keys. The limit returned MUST be > key according to the
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// compaction's comparator. The specified key is the first key in the new
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// output, or nil if this sstable will only contain range tombstones already
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// in the fragmenter.
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onNewOutput(key *InternalKey) []byte
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}
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// fileSizeSplitter is a compactionOutputSplitter that makes a determination
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// to split outputs based on the estimated file size of the current output.
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// Note that, unlike most other splitters, this splitter does not guarantee
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// that it will advise splits only at user key change boundaries.
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type fileSizeSplitter struct {
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maxFileSize uint64
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}
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func (f *fileSizeSplitter) shouldSplitBefore(
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key *InternalKey, tw *sstable.Writer,
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) compactionSplitSuggestion {
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// The Kind != RangeDelete part exists because EstimatedSize doesn't grow
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// rightaway when a range tombstone is added to the fragmenter. It's always
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// better to make a sequence of range tombstones visible to the fragmenter.
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if key.Kind() != InternalKeyKindRangeDelete && tw != nil &&
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tw.EstimatedSize() >= f.maxFileSize {
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return splitNow
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}
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return noSplit
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}
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func (f *fileSizeSplitter) onNewOutput(key *InternalKey) []byte {
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return nil
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}
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type limitFuncSplitter struct {
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c *compaction
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limitFunc func(userKey []byte) []byte
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limit []byte
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}
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func (lf *limitFuncSplitter) shouldSplitBefore(
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key *InternalKey, tw *sstable.Writer,
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) compactionSplitSuggestion {
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// NB: The limit must be applied using >= since lf.limit may be used as the
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// `splitterSuggestion` ultimately passed to `compactionIter.Tombstones` to
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// serve as an *exclusive* end boundary truncation point. If we used > then,
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// we may have already added a key with the user key `lf.limit` to the
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// previous sstable.
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if lf.limit != nil && lf.c.cmp(key.UserKey, lf.limit) >= 0 {
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return splitNow
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}
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return noSplit
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}
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func (lf *limitFuncSplitter) onNewOutput(key *InternalKey) []byte {
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lf.limit = nil
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if key != nil {
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lf.limit = lf.limitFunc(key.UserKey)
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} else {
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// Use the start key of the first pending tombstone to find the
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// next limit. All pending tombstones have the same start key.
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// We use this as opposed to the end key of the
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// last written sstable to effectively handle cases like these:
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//
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// a.SET.3
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// (lf.limit at b)
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// d.RANGEDEL.4:f
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//
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// In this case, the partition after b has only range deletions,
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// so if we were to find the limit after the last written key at
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// the split point (key a), we'd get the limit b again, and
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// finishOutput() would not advance any further because the next
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// range tombstone to write does not start until after the L0
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// split point.
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if startKey := lf.c.rangeDelFrag.Start(); startKey != nil {
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lf.limit = lf.limitFunc(startKey)
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}
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}
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return lf.limit
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}
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// splitterGroup is a compactionOutputSplitter that splits whenever one of its
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// child splitters advises a compaction split.
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type splitterGroup struct {
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cmp Compare
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splitters []compactionOutputSplitter
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}
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func (a *splitterGroup) shouldSplitBefore(
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key *InternalKey, tw *sstable.Writer,
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) (suggestion compactionSplitSuggestion) {
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for _, splitter := range a.splitters {
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if splitter.shouldSplitBefore(key, tw) == splitNow {
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return splitNow
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}
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}
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return noSplit
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}
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func (a *splitterGroup) onNewOutput(key *InternalKey) []byte {
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var earliestLimit []byte
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for _, splitter := range a.splitters {
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limit := splitter.onNewOutput(key)
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if limit == nil {
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continue
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}
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if earliestLimit == nil || a.cmp(limit, earliestLimit) < 0 {
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earliestLimit = limit
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}
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}
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return earliestLimit
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}
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// userKeyChangeSplitter is a compactionOutputSplitter that takes in a child
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// splitter, and splits when 1) that child splitter has advised a split, and 2)
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// the compaction output is at the boundary between two user keys (also
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// the boundary between atomic compaction units). Use this splitter to wrap
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// any splitters that don't guarantee user key splits (i.e. splitters that make
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// their determination in ways other than comparing the current key against a
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// limit key.) If a wrapped splitter advises a split, it must continue
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// to advise a split until a new output.
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type userKeyChangeSplitter struct {
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cmp Compare
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splitter compactionOutputSplitter
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unsafePrevUserKey func() []byte
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}
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func (u *userKeyChangeSplitter) shouldSplitBefore(
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key *InternalKey, tw *sstable.Writer,
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) compactionSplitSuggestion {
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if split := u.splitter.shouldSplitBefore(key, tw); split != splitNow {
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return split
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}
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if u.cmp(key.UserKey, u.unsafePrevUserKey()) > 0 {
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return splitNow
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}
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return noSplit
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}
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func (u *userKeyChangeSplitter) onNewOutput(key *InternalKey) []byte {
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return u.splitter.onNewOutput(key)
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}
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// compactionFile is a vfs.File wrapper that, on every write, updates a metric
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// in `versions` on bytes written by in-progress compactions so far. It also
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// increments a per-compaction `written` int.
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type compactionFile struct {
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vfs.File
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versions *versionSet
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written *int64
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}
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// Write implements the io.Writer interface.
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func (c *compactionFile) Write(p []byte) (n int, err error) {
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n, err = c.File.Write(p)
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if err != nil {
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return n, err
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}
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*c.written += int64(n)
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c.versions.incrementCompactionBytes(int64(n))
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return n, err
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}
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type compactionKind int
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const (
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compactionKindDefault compactionKind = iota
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compactionKindFlush
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compactionKindMove
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compactionKindDeleteOnly
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compactionKindElisionOnly
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compactionKindRead
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compactionKindRewrite
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)
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func (k compactionKind) String() string {
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switch k {
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case compactionKindDefault:
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return "default"
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case compactionKindFlush:
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return "flush"
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case compactionKindMove:
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return "move"
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case compactionKindDeleteOnly:
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return "delete-only"
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case compactionKindElisionOnly:
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return "elision-only"
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case compactionKindRead:
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return "read"
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case compactionKindRewrite:
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return "rewrite"
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}
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return "?"
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}
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// compaction is a table compaction from one level to the next, starting from a
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// given version.
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type compaction struct {
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kind compactionKind
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cmp Compare
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equal Equal
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formatKey base.FormatKey
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logger Logger
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version *version
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score float64
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// startLevel is the level that is being compacted. Inputs from startLevel
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// and outputLevel will be merged to produce a set of outputLevel files.
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startLevel *compactionLevel
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// outputLevel is the level that files are being produced in. For default
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// compactions, outputLevel is equal to startLevel+1 except when startLevel
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// is 0 in which case it is equal to compactionPicker.baseLevel().
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outputLevel *compactionLevel
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inputs []compactionLevel
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// maxOutputFileSize is the maximum size of an individual table created
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// during compaction.
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maxOutputFileSize uint64
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// maxOverlapBytes is the maximum number of bytes of overlap allowed for a
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// single output table with the tables in the grandparent level.
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maxOverlapBytes uint64
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// disableRangeTombstoneElision disables elision of range tombstones. Used by
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// tests to allow range tombstones to be added to tables where they would
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// otherwise be elided.
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disableRangeTombstoneElision bool
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// flushing contains the flushables (aka memtables) that are being flushed.
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flushing flushableList
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// bytesIterated contains the number of bytes that have been flushed/compacted.
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bytesIterated uint64
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// bytesWritten contains the number of bytes that have been written to outputs.
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bytesWritten int64
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// atomicBytesIterated points to the variable to increment during iteration.
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// atomicBytesIterated must be read/written atomically. Flushing will increment
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// the shared variable which compaction will read. This allows for the
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// compaction routine to know how many bytes have been flushed before the flush
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// is applied.
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atomicBytesIterated *uint64
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// The boundaries of the input data.
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smallest InternalKey
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largest InternalKey
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// The range deletion tombstone fragmenter. Adds range tombstones as they are
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// returned from `compactionIter` and fragments them for output to files.
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// Referenced by `compactionIter` which uses it to check whether keys are deleted.
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rangeDelFrag keyspan.Fragmenter
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// The range deletion tombstone iterator, that merges and fragments
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// tombstones across levels. This iterator is included within the compaction
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// input iterator as a single level.
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// TODO(jackson): Remove this when the refactor of FragmentIterator,
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// InterleavingIterator, etc is complete.
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rangeDelIter keyspan.InternalIteratorShim
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// A list of objects to close when the compaction finishes. Used by input
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// iteration to keep rangeDelIters open for the lifetime of the compaction,
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// and only close them when the compaction finishes.
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closers []io.Closer
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// grandparents are the tables in level+2 that overlap with the files being
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// compacted. Used to determine output table boundaries. Do not assume that the actual files
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// in the grandparent when this compaction finishes will be the same.
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grandparents manifest.LevelSlice
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// Boundaries at which flushes to L0 should be split. Determined by
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// L0Sublevels. If nil, flushes aren't split.
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l0Limits [][]byte
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// L0 sublevel info is used for compactions out of L0. It is nil for all
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// other compactions.
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l0SublevelInfo []sublevelInfo
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// List of disjoint inuse key ranges the compaction overlaps with in
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// grandparent and lower levels. See setupInuseKeyRanges() for the
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// construction. Used by elideTombstone() and elideRangeTombstone() to
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// determine if keys affected by a tombstone possibly exist at a lower level.
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inuseKeyRanges []manifest.UserKeyRange
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elideTombstoneIndex int
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// allowedZeroSeqNum is true if seqnums can be zeroed if there are no
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// snapshots requiring them to be kept. This determination is made by
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// looking for an sstable which overlaps the bounds of the compaction at a
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// lower level in the LSM during runCompaction.
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allowedZeroSeqNum bool
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metrics map[int]*LevelMetrics
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}
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func (c *compaction) makeInfo(jobID int) CompactionInfo {
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info := CompactionInfo{
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JobID: jobID,
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Reason: c.kind.String(),
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Input: make([]LevelInfo, 0, len(c.inputs)),
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}
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for _, cl := range c.inputs {
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inputInfo := LevelInfo{Level: cl.level, Tables: nil}
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iter := cl.files.Iter()
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for m := iter.First(); m != nil; m = iter.Next() {
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inputInfo.Tables = append(inputInfo.Tables, m.TableInfo())
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}
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info.Input = append(info.Input, inputInfo)
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}
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if c.outputLevel != nil {
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info.Output.Level = c.outputLevel.level
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// If there are no inputs from the output level (eg, a move
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// compaction), add an empty LevelInfo to info.Input.
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if len(c.inputs) > 0 && c.inputs[len(c.inputs)-1].level != c.outputLevel.level {
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info.Input = append(info.Input, LevelInfo{Level: c.outputLevel.level})
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}
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} else {
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// For a delete-only compaction, set the output level to L6. The
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// output level is not meaningful here, but complicating the
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// info.Output interface with a pointer doesn't seem worth the
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// semantic distinction.
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info.Output.Level = numLevels - 1
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}
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return info
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}
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func newCompaction(pc *pickedCompaction, opts *Options, bytesCompacted *uint64) *compaction {
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c := &compaction{
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kind: compactionKindDefault,
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cmp: pc.cmp,
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equal: opts.equal(),
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formatKey: opts.Comparer.FormatKey,
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score: pc.score,
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inputs: pc.inputs,
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smallest: pc.smallest,
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largest: pc.largest,
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logger: opts.Logger,
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version: pc.version,
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maxOutputFileSize: pc.maxOutputFileSize,
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maxOverlapBytes: pc.maxOverlapBytes,
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atomicBytesIterated: bytesCompacted,
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l0SublevelInfo: pc.l0SublevelInfo,
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}
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c.startLevel = &c.inputs[0]
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c.outputLevel = &c.inputs[1]
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// Compute the set of outputLevel+1 files that overlap this compaction (these
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// are the grandparent sstables).
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if c.outputLevel.level+1 < numLevels {
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c.grandparents = c.version.Overlaps(c.outputLevel.level+1, c.cmp,
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c.smallest.UserKey, c.largest.UserKey, c.largest.IsExclusiveSentinel())
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}
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c.setupInuseKeyRanges()
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c.kind = pc.kind
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if c.kind == compactionKindDefault && c.outputLevel.files.Empty() &&
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c.startLevel.files.Len() == 1 && c.grandparents.SizeSum() <= c.maxOverlapBytes {
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// This compaction can be converted into a trivial move from one level
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// to the next. We avoid such a move if there is lots of overlapping
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// grandparent data. Otherwise, the move could create a parent file
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// that will require a very expensive merge later on.
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c.kind = compactionKindMove
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}
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return c
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}
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func newDeleteOnlyCompaction(opts *Options, cur *version, inputs []compactionLevel) *compaction {
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c := &compaction{
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kind: compactionKindDeleteOnly,
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cmp: opts.Comparer.Compare,
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equal: opts.equal(),
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formatKey: opts.Comparer.FormatKey,
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logger: opts.Logger,
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version: cur,
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inputs: inputs,
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}
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// Set c.smallest, c.largest.
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files := make([]manifest.LevelIterator, 0, len(inputs))
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for _, in := range inputs {
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files = append(files, in.files.Iter())
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}
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c.smallest, c.largest = manifest.KeyRange(opts.Comparer.Compare, files...)
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return c
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}
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func adjustGrandparentOverlapBytesForFlush(c *compaction, flushingBytes uint64) {
|
|
// Heuristic to place a lower bound on compaction output file size
|
|
// caused by Lbase. Prior to this heuristic we have observed an L0 in
|
|
// production with 310K files of which 290K files were < 10KB in size.
|
|
// Our hypothesis is that it was caused by L1 having 2600 files and
|
|
// ~10GB, such that each flush got split into many tiny files due to
|
|
// overlapping with most of the files in Lbase.
|
|
//
|
|
// The computation below is general in that it accounts
|
|
// for flushing different volumes of data (e.g. we may be flushing
|
|
// many memtables). For illustration, we consider the typical
|
|
// example of flushing a 64MB memtable. So 12.8MB output,
|
|
// based on the compression guess below. If the compressed bytes
|
|
// guess is an over-estimate we will end up with smaller files,
|
|
// and if an under-estimate we will end up with larger files.
|
|
// With a 2MB target file size, 7 files. We are willing to accept
|
|
// 4x the number of files, if it results in better write amplification
|
|
// when later compacting to Lbase, i.e., ~450KB files (target file
|
|
// size / 4).
|
|
//
|
|
// Note that this is a pessimistic heuristic in that
|
|
// fileCountUpperBoundDueToGrandparents could be far from the actual
|
|
// number of files produced due to the grandparent limits. For
|
|
// example, in the extreme, consider a flush that overlaps with 1000
|
|
// files in Lbase f0...f999, and the initially calculated value of
|
|
// maxOverlapBytes will cause splits at f10, f20,..., f990, which
|
|
// means an upper bound file count of 100 files. Say the input bytes
|
|
// in the flush are such that acceptableFileCount=10. We will fatten
|
|
// up maxOverlapBytes by 10x to ensure that the upper bound file count
|
|
// drops to 10. However, it is possible that in practice, even without
|
|
// this change, we would have produced no more than 10 files, and that
|
|
// this change makes the files unnecessarily wide. Say the input bytes
|
|
// are distributed such that 10% are in f0...f9, 10% in f10...f19, ...
|
|
// 10% in f80...f89 and 10% in f990...f999. The original value of
|
|
// maxOverlapBytes would have actually produced only 10 sstables. But
|
|
// by increasing maxOverlapBytes by 10x, we may produce 1 sstable that
|
|
// spans f0...f89, i.e., a much wider sstable than necessary.
|
|
//
|
|
// We could produce a tighter estimate of
|
|
// fileCountUpperBoundDueToGrandparents if we had knowledge of the key
|
|
// distribution of the flush. The 4x multiplier mentioned earlier is
|
|
// a way to try to compensate for this pessimism.
|
|
//
|
|
// TODO(sumeer): we don't have compression info for the data being
|
|
// flushed, but it is likely that existing files that overlap with
|
|
// this flush in Lbase are representative wrt compression ratio. We
|
|
// could store the uncompressed size in FileMetadata and estimate
|
|
// the compression ratio.
|
|
const approxCompressionRatio = 0.2
|
|
approxOutputBytes := approxCompressionRatio * float64(flushingBytes)
|
|
approxNumFilesBasedOnTargetSize :=
|
|
int(math.Ceil(approxOutputBytes / float64(c.maxOutputFileSize)))
|
|
acceptableFileCount := float64(4 * approxNumFilesBasedOnTargetSize)
|
|
// The byte calculation is linear in numGrandparentFiles, but we will
|
|
// incur this linear cost in findGrandparentLimit too, so we are also
|
|
// willing to pay it now. We could approximate this cheaply by using
|
|
// the mean file size of Lbase.
|
|
grandparentFileBytes := c.grandparents.SizeSum()
|
|
fileCountUpperBoundDueToGrandparents :=
|
|
float64(grandparentFileBytes) / float64(c.maxOverlapBytes)
|
|
if fileCountUpperBoundDueToGrandparents > acceptableFileCount {
|
|
c.maxOverlapBytes = uint64(
|
|
float64(c.maxOverlapBytes) *
|
|
(fileCountUpperBoundDueToGrandparents / acceptableFileCount))
|
|
}
|
|
}
|
|
|
|
func newFlush(
|
|
opts *Options, cur *version, baseLevel int, flushing flushableList, bytesFlushed *uint64,
|
|
) *compaction {
|
|
c := &compaction{
|
|
kind: compactionKindFlush,
|
|
cmp: opts.Comparer.Compare,
|
|
equal: opts.equal(),
|
|
formatKey: opts.Comparer.FormatKey,
|
|
logger: opts.Logger,
|
|
version: cur,
|
|
inputs: []compactionLevel{{level: -1}, {level: 0}},
|
|
maxOutputFileSize: math.MaxUint64,
|
|
maxOverlapBytes: math.MaxUint64,
|
|
flushing: flushing,
|
|
atomicBytesIterated: bytesFlushed,
|
|
}
|
|
c.startLevel = &c.inputs[0]
|
|
c.outputLevel = &c.inputs[1]
|
|
if cur.L0Sublevels != nil {
|
|
c.l0Limits = cur.L0Sublevels.FlushSplitKeys()
|
|
}
|
|
|
|
smallestSet, largestSet := false, false
|
|
updatePointBounds := func(iter internalIterator) {
|
|
if key, _ := iter.First(); key != nil {
|
|
if !smallestSet ||
|
|
base.InternalCompare(c.cmp, c.smallest, *key) > 0 {
|
|
smallestSet = true
|
|
c.smallest = key.Clone()
|
|
}
|
|
}
|
|
if key, _ := iter.Last(); key != nil {
|
|
if !largestSet ||
|
|
base.InternalCompare(c.cmp, c.largest, *key) < 0 {
|
|
largestSet = true
|
|
c.largest = key.Clone()
|
|
}
|
|
}
|
|
}
|
|
|
|
updateRangeBounds := func(iter keyspan.FragmentIterator) {
|
|
if s := iter.First(); s.Valid() {
|
|
if key := s.SmallestKey(); !smallestSet ||
|
|
base.InternalCompare(c.cmp, c.smallest, key) > 0 {
|
|
smallestSet = true
|
|
c.smallest = key.Clone()
|
|
}
|
|
}
|
|
if s := iter.Last(); s.Valid() {
|
|
if key := s.LargestKey(); !largestSet ||
|
|
base.InternalCompare(c.cmp, c.largest, key) < 0 {
|
|
largestSet = true
|
|
c.largest = key.Clone()
|
|
}
|
|
}
|
|
}
|
|
|
|
var flushingBytes uint64
|
|
for i := range flushing {
|
|
f := flushing[i]
|
|
updatePointBounds(f.newIter(nil))
|
|
if rangeDelIter := f.newRangeDelIter(nil); rangeDelIter != nil {
|
|
updateRangeBounds(rangeDelIter)
|
|
}
|
|
flushingBytes += f.inuseBytes()
|
|
}
|
|
|
|
if opts.FlushSplitBytes > 0 {
|
|
c.maxOutputFileSize = uint64(opts.Level(0).TargetFileSize)
|
|
c.maxOverlapBytes = maxGrandparentOverlapBytes(opts, 0)
|
|
c.grandparents = c.version.Overlaps(baseLevel, c.cmp, c.smallest.UserKey,
|
|
c.largest.UserKey, c.largest.IsExclusiveSentinel())
|
|
adjustGrandparentOverlapBytesForFlush(c, flushingBytes)
|
|
}
|
|
|
|
c.setupInuseKeyRanges()
|
|
return c
|
|
}
|
|
|
|
func (c *compaction) setupInuseKeyRanges() {
|
|
level := c.outputLevel.level + 1
|
|
if c.outputLevel.level == 0 {
|
|
level = 0
|
|
}
|
|
c.inuseKeyRanges = calculateInuseKeyRanges(
|
|
c.version, c.cmp, level, numLevels-1, c.smallest.UserKey, c.largest.UserKey,
|
|
)
|
|
}
|
|
|
|
func calculateInuseKeyRanges(
|
|
v *version, cmp base.Compare, level, maxLevel int, smallest, largest []byte,
|
|
) []manifest.UserKeyRange {
|
|
// Use two slices, alternating which one is input and which one is output
|
|
// as we descend the LSM.
|
|
var input, output []manifest.UserKeyRange
|
|
|
|
// L0 requires special treatment, since sstables within L0 may overlap.
|
|
// We use the L0 Sublevels structure to efficiently calculate the merged
|
|
// in-use key ranges.
|
|
if level == 0 {
|
|
output = v.L0Sublevels.InUseKeyRanges(smallest, largest)
|
|
level++
|
|
}
|
|
|
|
for ; level <= maxLevel; level++ {
|
|
// NB: We always treat `largest` as inclusive for simplicity, because
|
|
// there's little consequence to calculating slightly broader in-use key
|
|
// ranges.
|
|
overlaps := v.Overlaps(level, cmp, smallest, largest, false /* exclusiveEnd */)
|
|
iter := overlaps.Iter()
|
|
|
|
// We may already have in-use key ranges from higher levels. Iterate
|
|
// through both our accumulated in-use key ranges and this level's
|
|
// files, merging the two.
|
|
//
|
|
// Tables higher within the LSM have broader key spaces. We use this
|
|
// when possible to seek past a level's files that are contained by
|
|
// our current accumulated in-use key ranges. This helps avoid
|
|
// per-sstable work during flushes or compactions in high levels which
|
|
// overlap the majority of the LSM's sstables.
|
|
input, output = output, input
|
|
output = output[:0]
|
|
|
|
var currFile *fileMetadata
|
|
var currAccum *manifest.UserKeyRange
|
|
if len(input) > 0 {
|
|
currAccum, input = &input[0], input[1:]
|
|
}
|
|
|
|
// If we have an accumulated key range and its start is ≤ smallest,
|
|
// we can seek to the accumulated range's end. Otherwise, we need to
|
|
// start at the first overlapping file within the level.
|
|
if currAccum != nil && cmp(currAccum.Start, smallest) <= 0 {
|
|
currFile = seekGT(&iter, cmp, currAccum.End)
|
|
} else {
|
|
currFile = iter.First()
|
|
}
|
|
|
|
for currFile != nil || currAccum != nil {
|
|
// If we've exhausted either the files in the level or the
|
|
// accumulated key ranges, we just need to append the one we have.
|
|
// If we have both a currFile and a currAccum, they either overlap
|
|
// or they're disjoint. If they're disjoint, we append whichever
|
|
// one sorts first and move on to the next file or range. If they
|
|
// overlap, we merge them into currAccum and proceed to the next
|
|
// file.
|
|
switch {
|
|
case currAccum == nil || (currFile != nil && cmp(currFile.Largest.UserKey, currAccum.Start) < 0):
|
|
// This file is strictly before the current accumulated range,
|
|
// or there are no more accumulated ranges.
|
|
output = append(output, manifest.UserKeyRange{
|
|
Start: currFile.Smallest.UserKey,
|
|
End: currFile.Largest.UserKey,
|
|
})
|
|
currFile = iter.Next()
|
|
case currFile == nil || (currAccum != nil && cmp(currAccum.End, currFile.Smallest.UserKey) < 0):
|
|
// The current accumulated key range is strictly before the
|
|
// current file, or there are no more files.
|
|
output = append(output, *currAccum)
|
|
currAccum = nil
|
|
if len(input) > 0 {
|
|
currAccum, input = &input[0], input[1:]
|
|
}
|
|
default:
|
|
// The current accumulated range and the current file overlap.
|
|
// Adjust the accumulated range to be the union.
|
|
if cmp(currFile.Smallest.UserKey, currAccum.Start) < 0 {
|
|
currAccum.Start = currFile.Smallest.UserKey
|
|
}
|
|
if cmp(currFile.Largest.UserKey, currAccum.End) > 0 {
|
|
currAccum.End = currFile.Largest.UserKey
|
|
}
|
|
|
|
// Extending `currAccum`'s end boundary may have caused it to
|
|
// overlap with `input` key ranges that we haven't processed
|
|
// yet. Merge any such key ranges.
|
|
for len(input) > 0 && cmp(input[0].Start, currAccum.End) <= 0 {
|
|
if cmp(input[0].End, currAccum.End) > 0 {
|
|
currAccum.End = input[0].End
|
|
}
|
|
input = input[1:]
|
|
}
|
|
// Seek the level iterator past our current accumulated end.
|
|
currFile = seekGT(&iter, cmp, currAccum.End)
|
|
}
|
|
}
|
|
}
|
|
return output
|
|
}
|
|
|
|
func seekGT(iter *manifest.LevelIterator, cmp base.Compare, key []byte) *manifest.FileMetadata {
|
|
f := iter.SeekGE(cmp, key)
|
|
for f != nil && cmp(f.Largest.UserKey, key) == 0 {
|
|
f = iter.Next()
|
|
}
|
|
return f
|
|
}
|
|
|
|
// findGrandparentLimit takes the start user key for a table and returns the
|
|
// user key to which that table can extend without excessively overlapping
|
|
// the grandparent level. If no limit is needed considering the grandparent
|
|
// files, this function returns nil. This is done in order to prevent a table
|
|
// at level N from overlapping too much data at level N+1. We want to avoid
|
|
// such large overlaps because they translate into large compactions. The
|
|
// current heuristic stops output of a table if the addition of another key
|
|
// would cause the table to overlap more than 10x the target file size at
|
|
// level N. See maxGrandparentOverlapBytes.
|
|
func (c *compaction) findGrandparentLimit(start []byte) []byte {
|
|
iter := c.grandparents.Iter()
|
|
var overlappedBytes uint64
|
|
var greater bool
|
|
for f := iter.SeekGE(c.cmp, start); f != nil; f = iter.Next() {
|
|
overlappedBytes += f.Size
|
|
// To ensure forward progress we always return a larger user
|
|
// key than where we started. See comments above clients of
|
|
// this function for how this is used.
|
|
greater = greater || c.cmp(f.Smallest.UserKey, start) > 0
|
|
if !greater {
|
|
continue
|
|
}
|
|
|
|
// We return the smallest bound of a sstable rather than the
|
|
// largest because the smallest is always inclusive, and limits
|
|
// are used exlusively when truncating range tombstones. If we
|
|
// truncated an output to the largest key while there's a
|
|
// pending tombstone, the next output file would also overlap
|
|
// the same grandparent f.
|
|
if overlappedBytes > c.maxOverlapBytes {
|
|
return f.Smallest.UserKey
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// findL0Limit takes the start key for a table and returns the user key to which
|
|
// that table can be extended without hitting the next l0Limit. Having flushed
|
|
// sstables "bridging across" an l0Limit could lead to increased L0 -> LBase
|
|
// compaction sizes as well as elevated read amplification.
|
|
func (c *compaction) findL0Limit(start []byte) []byte {
|
|
if c.startLevel.level > -1 || c.outputLevel.level != 0 || len(c.l0Limits) == 0 {
|
|
return nil
|
|
}
|
|
index := sort.Search(len(c.l0Limits), func(i int) bool {
|
|
return c.cmp(c.l0Limits[i], start) > 0
|
|
})
|
|
if index < len(c.l0Limits) {
|
|
return c.l0Limits[index]
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// errorOnUserKeyOverlap returns an error if the last two written sstables in
|
|
// this compaction have revisions of the same user key present in both sstables,
|
|
// when it shouldn't (eg. when splitting flushes).
|
|
func (c *compaction) errorOnUserKeyOverlap(ve *versionEdit) error {
|
|
if n := len(ve.NewFiles); n > 1 {
|
|
meta := ve.NewFiles[n-1].Meta
|
|
prevMeta := ve.NewFiles[n-2].Meta
|
|
if !prevMeta.Largest.IsExclusiveSentinel() &&
|
|
c.cmp(prevMeta.Largest.UserKey, meta.Smallest.UserKey) >= 0 {
|
|
return errors.Errorf("pebble: compaction split user key across two sstables: %s in %s and %s",
|
|
prevMeta.Largest.Pretty(c.formatKey),
|
|
prevMeta.FileNum,
|
|
meta.FileNum)
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// allowZeroSeqNum returns true if seqnum's can be zeroed if there are no
|
|
// snapshots requiring them to be kept. It performs this determination by
|
|
// looking for an sstable which overlaps the bounds of the compaction at a
|
|
// lower level in the LSM.
|
|
func (c *compaction) allowZeroSeqNum() bool {
|
|
return c.elideRangeTombstone(c.smallest.UserKey, c.largest.UserKey)
|
|
}
|
|
|
|
// elideTombstone returns true if it is ok to elide a tombstone for the
|
|
// specified key. A return value of true guarantees that there are no key/value
|
|
// pairs at c.level+2 or higher that possibly contain the specified user
|
|
// key. The keys in multiple invocations to elideTombstone must be supplied in
|
|
// order.
|
|
func (c *compaction) elideTombstone(key []byte) bool {
|
|
if len(c.flushing) != 0 {
|
|
return false
|
|
}
|
|
|
|
for ; c.elideTombstoneIndex < len(c.inuseKeyRanges); c.elideTombstoneIndex++ {
|
|
r := &c.inuseKeyRanges[c.elideTombstoneIndex]
|
|
if c.cmp(key, r.End) <= 0 {
|
|
if c.cmp(key, r.Start) >= 0 {
|
|
return false
|
|
}
|
|
break
|
|
}
|
|
}
|
|
return true
|
|
}
|
|
|
|
// elideRangeTombstone returns true if it is ok to elide the specified range
|
|
// tombstone. A return value of true guarantees that there are no key/value
|
|
// pairs at c.outputLevel.level+1 or higher that possibly overlap the specified
|
|
// tombstone.
|
|
func (c *compaction) elideRangeTombstone(start, end []byte) bool {
|
|
// Disable range tombstone elision if the testing knob for that is enabled,
|
|
// or if we are flushing memtables. The latter requirement is due to
|
|
// inuseKeyRanges not accounting for key ranges in other memtables that are
|
|
// being flushed in the same compaction. It's possible for a range tombstone
|
|
// in one memtable to overlap keys in a preceding memtable in c.flushing.
|
|
//
|
|
// This function is also used in setting allowZeroSeqNum, so disabling
|
|
// elision of range tombstones also disables zeroing of SeqNums.
|
|
//
|
|
// TODO(peter): we disable zeroing of seqnums during flushing to match
|
|
// RocksDB behavior and to avoid generating overlapping sstables during
|
|
// DB.replayWAL. When replaying WAL files at startup, we flush after each
|
|
// WAL is replayed building up a single version edit that is
|
|
// applied. Because we don't apply the version edit after each flush, this
|
|
// code doesn't know that L0 contains files and zeroing of seqnums should
|
|
// be disabled. That is fixable, but it seems safer to just match the
|
|
// RocksDB behavior for now.
|
|
if c.disableRangeTombstoneElision || len(c.flushing) != 0 {
|
|
return false
|
|
}
|
|
|
|
lower := sort.Search(len(c.inuseKeyRanges), func(i int) bool {
|
|
return c.cmp(c.inuseKeyRanges[i].End, start) >= 0
|
|
})
|
|
upper := sort.Search(len(c.inuseKeyRanges), func(i int) bool {
|
|
return c.cmp(c.inuseKeyRanges[i].Start, end) > 0
|
|
})
|
|
return lower >= upper
|
|
}
|
|
|
|
// newInputIter returns an iterator over all the input tables in a compaction.
|
|
func (c *compaction) newInputIter(newIters tableNewIters) (_ internalIterator, retErr error) {
|
|
var rangeDelIters []keyspan.FragmentIterator
|
|
|
|
if len(c.flushing) != 0 {
|
|
if len(c.flushing) == 1 {
|
|
f := c.flushing[0]
|
|
iter := f.newFlushIter(nil, &c.bytesIterated)
|
|
if rangeDelIter := f.newRangeDelIter(nil); rangeDelIter != nil {
|
|
c.rangeDelIter.Init(c.cmp, rangeDelIter)
|
|
return newMergingIter(c.logger, c.cmp, nil, iter, &c.rangeDelIter), nil
|
|
}
|
|
return iter, nil
|
|
}
|
|
iters := make([]internalIterator, 0, len(c.flushing)+1)
|
|
rangeDelIters = make([]keyspan.FragmentIterator, 0, len(c.flushing))
|
|
for i := range c.flushing {
|
|
f := c.flushing[i]
|
|
iters = append(iters, f.newFlushIter(nil, &c.bytesIterated))
|
|
rangeDelIter := f.newRangeDelIter(nil)
|
|
if rangeDelIter != nil {
|
|
rangeDelIters = append(rangeDelIters, rangeDelIter)
|
|
}
|
|
}
|
|
if len(rangeDelIters) > 0 {
|
|
c.rangeDelIter.Init(c.cmp, rangeDelIters...)
|
|
iters = append(iters, &c.rangeDelIter)
|
|
}
|
|
return newMergingIter(c.logger, c.cmp, nil, iters...), nil
|
|
}
|
|
|
|
if c.startLevel.level >= 0 {
|
|
err := manifest.CheckOrdering(c.cmp, c.formatKey,
|
|
manifest.Level(c.startLevel.level), c.startLevel.files.Iter())
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
err := manifest.CheckOrdering(c.cmp, c.formatKey,
|
|
manifest.Level(c.outputLevel.level), c.outputLevel.files.Iter())
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
if c.startLevel.level == 0 {
|
|
if c.l0SublevelInfo == nil {
|
|
panic("l0SublevelInfo not created for compaction out of L0")
|
|
}
|
|
|
|
for _, info := range c.l0SublevelInfo {
|
|
err := manifest.CheckOrdering(c.cmp, c.formatKey,
|
|
info.sublevel, info.Iter())
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
}
|
|
|
|
iters := make([]internalIterator, 0, 2*c.startLevel.files.Len()+1)
|
|
defer func() {
|
|
if retErr != nil {
|
|
for _, iter := range iters {
|
|
if iter != nil {
|
|
iter.Close()
|
|
}
|
|
}
|
|
for _, rangeDelIter := range rangeDelIters {
|
|
rangeDelIter.Close()
|
|
}
|
|
}
|
|
}()
|
|
|
|
// In normal operation, levelIter iterates over the point operations in a
|
|
// level, and initializes a rangeDelIter pointer for the range deletions in
|
|
// each table. During compaction, we want to iterate over the merged view of
|
|
// point operations and range deletions. In order to do this we create one
|
|
// levelIter per level to iterate over the point operations, and collect up
|
|
// all the range deletion files.
|
|
//
|
|
// The range deletion levels are first combined with a keyspan.MergingIter
|
|
// (currently wrapped by a keyspan.InternalIteratorShim to satisfy the
|
|
// internal iterator interface). The resulting merged rangedel iterator is
|
|
// then included with the point levels in a single mergingIter.
|
|
newRangeDelIter := func(
|
|
f *manifest.FileMetadata, slice manifest.LevelSlice, _ *IterOptions, bytesIterated *uint64,
|
|
) (keyspan.FragmentIterator, error) {
|
|
iter, rangeDelIter, err := newIters(f, nil /* iter options */, &c.bytesIterated)
|
|
if err == nil {
|
|
// TODO(peter): It is mildly wasteful to open the point iterator only to
|
|
// immediately close it. One way to solve this would be to add new
|
|
// methods to tableCache for creating point and range-deletion iterators
|
|
// independently. We'd only want to use those methods here,
|
|
// though. Doesn't seem worth the hassle in the near term.
|
|
if err = iter.Close(); err != nil {
|
|
rangeDelIter.Close()
|
|
rangeDelIter = nil
|
|
}
|
|
}
|
|
if rangeDelIter != nil {
|
|
// Ensure that rangeDelIter is not closed until the compaction is
|
|
// finished. This is necessary because range tombstone processing
|
|
// requires the range tombstones to be held in memory for up to the
|
|
// lifetime of the compaction.
|
|
c.closers = append(c.closers, rangeDelIter)
|
|
rangeDelIter = noCloseIter{rangeDelIter}
|
|
|
|
// Truncate the range tombstones returned by the iterator to the
|
|
// upper bound of the atomic compaction unit. Note that we need do
|
|
// this truncation at read time in order to handle sstables
|
|
// generated by RocksDB and earlier versions of Pebble which do not
|
|
// truncate range tombstones to atomic compaction unit boundaries at
|
|
// write time.
|
|
//
|
|
// The current Pebble compaction logic DOES truncate tombstones to
|
|
// atomic unit boundaries at compaction time too.
|
|
atomicUnit, _ := expandToAtomicUnit(c.cmp, slice, true /* disableIsCompacting */)
|
|
lowerBound, upperBound := manifest.KeyRange(c.cmp, atomicUnit.Iter())
|
|
// Range deletion tombstones are often written to sstables
|
|
// untruncated on the end key side. However, they are still only
|
|
// valid within a given file's bounds. The logic for writing range
|
|
// tombstones to an output file sometimes has an incomplete view
|
|
// of range tombstones outside the file's internal key bounds. Skip
|
|
// any range tombstones completely outside file bounds.
|
|
rangeDelIter = keyspan.Truncate(
|
|
c.cmp, rangeDelIter, lowerBound.UserKey, upperBound.UserKey, &f.Smallest, &f.Largest)
|
|
}
|
|
if rangeDelIter == nil {
|
|
rangeDelIter = emptyKeyspanIter
|
|
}
|
|
return rangeDelIter, err
|
|
}
|
|
|
|
iterOpts := IterOptions{logger: c.logger}
|
|
// TODO(bananabrick): Get rid of the extra manifest.Level parameter and fold it into
|
|
// compactionLevel.
|
|
addItersForLevel := func(level *compactionLevel, l manifest.Level) error {
|
|
iters = append(iters, newLevelIter(iterOpts, c.cmp, nil /* split */, newIters,
|
|
level.files.Iter(), l, &c.bytesIterated))
|
|
// Create a wrapping closure to turn newRangeDelIter into a
|
|
// keyspan.TableNewSpanIter, and return a LevelIter that lazily creates
|
|
// rangedel iterators. This is safe now that range deletions are truncated
|
|
// at file bounds; the merging iterator no longer needs to see all range
|
|
// deletes for correctness.
|
|
wrapper := func(file *manifest.FileMetadata, iterOptions *keyspan.SpanIterOptions) (keyspan.FragmentIterator, error) {
|
|
return newRangeDelIter(file, level.files, nil, &c.bytesIterated)
|
|
}
|
|
li := &keyspan.LevelIter{}
|
|
li.Init(keyspan.SpanIterOptions{}, c.cmp, wrapper, level.files.Iter(), l, c.logger, manifest.KeyTypePoint)
|
|
rangeDelIters = append(rangeDelIters, li)
|
|
return nil
|
|
}
|
|
|
|
if c.startLevel.level != 0 {
|
|
if err = addItersForLevel(c.startLevel, manifest.Level(c.startLevel.level)); err != nil {
|
|
return nil, err
|
|
}
|
|
} else {
|
|
for _, info := range c.l0SublevelInfo {
|
|
if err = addItersForLevel(
|
|
&compactionLevel{0, info.LevelSlice}, info.sublevel); err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
}
|
|
|
|
if err = addItersForLevel(c.outputLevel, manifest.Level(c.outputLevel.level)); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Combine all the rangedel iterators using a keyspan.MergingIterator and a
|
|
// InternalIteratorShim so that the range deletions may be interleaved in
|
|
// the compaction input.
|
|
// TODO(jackson): Replace the InternalIteratorShim with an interleaving
|
|
// iterator.
|
|
if len(rangeDelIters) > 0 {
|
|
c.rangeDelIter.Init(c.cmp, rangeDelIters...)
|
|
iters = append(iters, &c.rangeDelIter)
|
|
}
|
|
return newMergingIter(c.logger, c.cmp, nil, iters...), nil
|
|
}
|
|
|
|
func (c *compaction) String() string {
|
|
if len(c.flushing) != 0 {
|
|
return "flush\n"
|
|
}
|
|
|
|
var buf bytes.Buffer
|
|
for i := range c.inputs {
|
|
level := c.startLevel.level
|
|
if i == 1 {
|
|
level = c.outputLevel.level
|
|
}
|
|
fmt.Fprintf(&buf, "%d:", level)
|
|
iter := c.inputs[i].files.Iter()
|
|
for f := iter.First(); f != nil; f = iter.Next() {
|
|
fmt.Fprintf(&buf, " %s:%s-%s", f.FileNum, f.Smallest, f.Largest)
|
|
}
|
|
fmt.Fprintf(&buf, "\n")
|
|
}
|
|
return buf.String()
|
|
}
|
|
|
|
type manualCompaction struct {
|
|
// Count of the retries either due to too many concurrent compactions, or a
|
|
// concurrent compaction to overlapping levels.
|
|
retries int
|
|
level int
|
|
outputLevel int
|
|
done chan error
|
|
start []byte
|
|
end []byte
|
|
split bool
|
|
}
|
|
|
|
type readCompaction struct {
|
|
level int
|
|
// [start, end] key ranges are used for de-duping.
|
|
start []byte
|
|
end []byte
|
|
|
|
// The file associated with the compaction.
|
|
// If the file no longer belongs in the same
|
|
// level, then we skip the compaction.
|
|
fileNum base.FileNum
|
|
}
|
|
|
|
func (d *DB) addInProgressCompaction(c *compaction) {
|
|
d.mu.compact.inProgress[c] = struct{}{}
|
|
var isBase, isIntraL0 bool
|
|
for _, cl := range c.inputs {
|
|
iter := cl.files.Iter()
|
|
for f := iter.First(); f != nil; f = iter.Next() {
|
|
if f.Compacting {
|
|
d.opts.Logger.Fatalf("L%d->L%d: %s already being compacted", c.startLevel.level, c.outputLevel.level, f.FileNum)
|
|
}
|
|
f.Compacting = true
|
|
if c.startLevel != nil && c.outputLevel != nil && c.startLevel.level == 0 {
|
|
if c.outputLevel.level == 0 {
|
|
f.IsIntraL0Compacting = true
|
|
isIntraL0 = true
|
|
} else {
|
|
isBase = true
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
if (isIntraL0 || isBase) && c.version.L0Sublevels != nil {
|
|
l0Inputs := []manifest.LevelSlice{c.startLevel.files}
|
|
if isIntraL0 {
|
|
l0Inputs = append(l0Inputs, c.outputLevel.files)
|
|
}
|
|
if err := c.version.L0Sublevels.UpdateStateForStartedCompaction(l0Inputs, isBase); err != nil {
|
|
d.opts.Logger.Fatalf("could not update state for compaction: %s", err)
|
|
}
|
|
}
|
|
|
|
if false {
|
|
// TODO(peter): Do we want to keep this? It is useful for seeing the
|
|
// concurrent compactions/flushes that are taking place. Right now, this
|
|
// spams the logs and output to tests. Figure out a way to useful expose
|
|
// it.
|
|
strs := make([]string, 0, len(d.mu.compact.inProgress))
|
|
for c := range d.mu.compact.inProgress {
|
|
var s string
|
|
if c.startLevel.level == -1 {
|
|
s = fmt.Sprintf("mem->L%d", c.outputLevel.level)
|
|
} else {
|
|
s = fmt.Sprintf("L%d->L%d:%.1f", c.startLevel.level, c.outputLevel.level, c.score)
|
|
}
|
|
strs = append(strs, s)
|
|
}
|
|
// This odd sorting function is intended to sort "mem" before "L*".
|
|
sort.Slice(strs, func(i, j int) bool {
|
|
if strs[i][0] == strs[j][0] {
|
|
return strs[i] < strs[j]
|
|
}
|
|
return strs[i] > strs[j]
|
|
})
|
|
d.opts.Logger.Infof("compactions: %s", strings.Join(strs, " "))
|
|
}
|
|
}
|
|
|
|
// Removes compaction markers from files in a compaction.
|
|
//
|
|
// DB.mu must be held when calling this method. All writes to the manifest
|
|
// for this compaction should have completed by this point.
|
|
func (d *DB) removeInProgressCompaction(c *compaction) {
|
|
for _, cl := range c.inputs {
|
|
iter := cl.files.Iter()
|
|
for f := iter.First(); f != nil; f = iter.Next() {
|
|
if !f.Compacting {
|
|
d.opts.Logger.Fatalf("L%d->L%d: %s not being compacted", c.startLevel.level, c.outputLevel.level, f.FileNum)
|
|
}
|
|
f.Compacting = false
|
|
f.IsIntraL0Compacting = false
|
|
}
|
|
}
|
|
delete(d.mu.compact.inProgress, c)
|
|
|
|
l0InProgress := inProgressL0Compactions(d.getInProgressCompactionInfoLocked(c))
|
|
d.mu.versions.currentVersion().L0Sublevels.InitCompactingFileInfo(l0InProgress)
|
|
}
|
|
|
|
func (d *DB) getCompactionPacerInfo() compactionPacerInfo {
|
|
bytesFlushed := atomic.LoadUint64(&d.atomic.bytesFlushed)
|
|
|
|
d.mu.Lock()
|
|
estimatedMaxWAmp := d.mu.versions.picker.getEstimatedMaxWAmp()
|
|
pacerInfo := compactionPacerInfo{
|
|
slowdownThreshold: uint64(estimatedMaxWAmp * float64(d.opts.MemTableSize)),
|
|
totalCompactionDebt: d.mu.versions.picker.estimatedCompactionDebt(bytesFlushed),
|
|
}
|
|
for _, m := range d.mu.mem.queue {
|
|
pacerInfo.totalDirtyBytes += m.inuseBytes()
|
|
}
|
|
d.mu.Unlock()
|
|
|
|
return pacerInfo
|
|
}
|
|
|
|
func (d *DB) getFlushPacerInfo() flushPacerInfo {
|
|
var pacerInfo flushPacerInfo
|
|
d.mu.Lock()
|
|
for _, m := range d.mu.mem.queue {
|
|
pacerInfo.inuseBytes += m.inuseBytes()
|
|
}
|
|
d.mu.Unlock()
|
|
return pacerInfo
|
|
}
|
|
|
|
func (d *DB) calculateDiskAvailableBytes() uint64 {
|
|
if space, err := d.opts.FS.GetDiskUsage(d.dirname); err == nil {
|
|
atomic.StoreUint64(&d.atomic.diskAvailBytes, space.AvailBytes)
|
|
return space.AvailBytes
|
|
} else if !errors.Is(err, vfs.ErrUnsupported) {
|
|
d.opts.EventListener.BackgroundError(err)
|
|
}
|
|
return atomic.LoadUint64(&d.atomic.diskAvailBytes)
|
|
}
|
|
|
|
func (d *DB) getDiskAvailableBytesCached() uint64 {
|
|
return atomic.LoadUint64(&d.atomic.diskAvailBytes)
|
|
}
|
|
|
|
func (d *DB) getDeletionPacerInfo() deletionPacerInfo {
|
|
var pacerInfo deletionPacerInfo
|
|
// Call GetDiskUsage after every file deletion. This may seem inefficient,
|
|
// but in practice this was observed to take constant time, regardless of
|
|
// volume size used, at least on linux with ext4 and zfs. All invocations
|
|
// take 10 microseconds or less.
|
|
pacerInfo.freeBytes = d.calculateDiskAvailableBytes()
|
|
d.mu.Lock()
|
|
pacerInfo.obsoleteBytes = d.mu.versions.metrics.Table.ObsoleteSize
|
|
pacerInfo.liveBytes = uint64(d.mu.versions.metrics.Total().Size)
|
|
d.mu.Unlock()
|
|
return pacerInfo
|
|
}
|
|
|
|
// maybeScheduleFlush schedules a flush if necessary.
|
|
//
|
|
// d.mu must be held when calling this.
|
|
func (d *DB) maybeScheduleFlush() {
|
|
if d.mu.compact.flushing || d.closed.Load() != nil || d.opts.ReadOnly {
|
|
return
|
|
}
|
|
if len(d.mu.mem.queue) <= 1 {
|
|
return
|
|
}
|
|
|
|
if !d.passedFlushThreshold() {
|
|
return
|
|
}
|
|
|
|
d.mu.compact.flushing = true
|
|
go d.flush()
|
|
}
|
|
|
|
func (d *DB) passedFlushThreshold() bool {
|
|
var n int
|
|
var size uint64
|
|
for ; n < len(d.mu.mem.queue)-1; n++ {
|
|
if !d.mu.mem.queue[n].readyForFlush() {
|
|
break
|
|
}
|
|
if d.mu.mem.queue[n].flushForced {
|
|
// A flush was forced. Pretend the memtable size is the configured
|
|
// size. See minFlushSize below.
|
|
size += uint64(d.opts.MemTableSize)
|
|
} else {
|
|
size += d.mu.mem.queue[n].totalBytes()
|
|
}
|
|
}
|
|
if n == 0 {
|
|
// None of the immutable memtables are ready for flushing.
|
|
return false
|
|
}
|
|
|
|
// Only flush once the sum of the queued memtable sizes exceeds half the
|
|
// configured memtable size. This prevents flushing of memtables at startup
|
|
// while we're undergoing the ramp period on the memtable size. See
|
|
// DB.newMemTable().
|
|
minFlushSize := uint64(d.opts.MemTableSize) / 2
|
|
return size >= minFlushSize
|
|
}
|
|
|
|
func (d *DB) maybeScheduleDelayedFlush(tbl *memTable) {
|
|
var mem *flushableEntry
|
|
for _, m := range d.mu.mem.queue {
|
|
if m.flushable == tbl {
|
|
mem = m
|
|
break
|
|
}
|
|
}
|
|
if mem == nil || mem.flushForced || mem.delayedFlushForced {
|
|
return
|
|
}
|
|
mem.delayedFlushForced = true
|
|
go func() {
|
|
timer := time.NewTimer(d.opts.Experimental.DeleteRangeFlushDelay)
|
|
defer timer.Stop()
|
|
|
|
select {
|
|
case <-d.closedCh:
|
|
return
|
|
case <-mem.flushed:
|
|
return
|
|
case <-timer.C:
|
|
d.commit.mu.Lock()
|
|
defer d.commit.mu.Unlock()
|
|
d.mu.Lock()
|
|
defer d.mu.Unlock()
|
|
|
|
// NB: The timer may fire concurrently with a call to Close. If a
|
|
// Close call beat us to acquiring d.mu, d.closed is 1, and it's
|
|
// too late to flush anything. Otherwise, the Close call will
|
|
// block on locking d.mu until we've finished scheduling the flush
|
|
// and set `d.mu.compact.flushing` to true. Close will wait for
|
|
// the current flush to complete.
|
|
if d.closed.Load() != nil {
|
|
return
|
|
}
|
|
|
|
if d.mu.mem.mutable == tbl {
|
|
d.makeRoomForWrite(nil)
|
|
} else {
|
|
mem.flushForced = true
|
|
d.maybeScheduleFlush()
|
|
}
|
|
}
|
|
}()
|
|
}
|
|
|
|
func (d *DB) flush() {
|
|
pprof.Do(context.Background(), flushLabels, func(context.Context) {
|
|
flushingWorkStart := time.Now()
|
|
d.mu.Lock()
|
|
defer d.mu.Unlock()
|
|
idleDuration := flushingWorkStart.Sub(d.mu.compact.noOngoingFlushStartTime)
|
|
var bytesFlushed uint64
|
|
var err error
|
|
if bytesFlushed, err = d.flush1(); err != nil {
|
|
// TODO(peter): count consecutive flush errors and backoff.
|
|
d.opts.EventListener.BackgroundError(err)
|
|
}
|
|
d.mu.compact.flushing = false
|
|
d.mu.compact.noOngoingFlushStartTime = time.Now()
|
|
workDuration := d.mu.compact.noOngoingFlushStartTime.Sub(flushingWorkStart)
|
|
d.mu.compact.flushWriteThroughput.Bytes += int64(bytesFlushed)
|
|
d.mu.compact.flushWriteThroughput.WorkDuration += workDuration
|
|
d.mu.compact.flushWriteThroughput.IdleDuration += idleDuration
|
|
// More flush work may have arrived while we were flushing, so schedule
|
|
// another flush if needed.
|
|
d.maybeScheduleFlush()
|
|
// The flush may have produced too many files in a level, so schedule a
|
|
// compaction if needed.
|
|
d.maybeScheduleCompaction()
|
|
d.mu.compact.cond.Broadcast()
|
|
})
|
|
}
|
|
|
|
// flush runs a compaction that copies the immutable memtables from memory to
|
|
// disk.
|
|
//
|
|
// d.mu must be held when calling this, but the mutex may be dropped and
|
|
// re-acquired during the course of this method.
|
|
func (d *DB) flush1() (bytesFlushed uint64, err error) {
|
|
var n int
|
|
for ; n < len(d.mu.mem.queue)-1; n++ {
|
|
if !d.mu.mem.queue[n].readyForFlush() {
|
|
break
|
|
}
|
|
}
|
|
if n == 0 {
|
|
// None of the immutable memtables are ready for flushing.
|
|
return 0, nil
|
|
}
|
|
|
|
// Require that every memtable being flushed has a log number less than the
|
|
// new minimum unflushed log number.
|
|
minUnflushedLogNum := d.mu.mem.queue[n].logNum
|
|
if !d.opts.DisableWAL {
|
|
for i := 0; i < n; i++ {
|
|
logNum := d.mu.mem.queue[i].logNum
|
|
if logNum >= minUnflushedLogNum {
|
|
return 0, errFlushInvariant
|
|
}
|
|
}
|
|
}
|
|
|
|
c := newFlush(d.opts, d.mu.versions.currentVersion(),
|
|
d.mu.versions.picker.getBaseLevel(), d.mu.mem.queue[:n], &d.atomic.bytesFlushed)
|
|
d.addInProgressCompaction(c)
|
|
|
|
jobID := d.mu.nextJobID
|
|
d.mu.nextJobID++
|
|
d.opts.EventListener.FlushBegin(FlushInfo{
|
|
JobID: jobID,
|
|
Input: n,
|
|
})
|
|
startTime := d.timeNow()
|
|
|
|
flushPacer := (pacer)(nilPacer)
|
|
if d.opts.private.enablePacing {
|
|
// TODO(peter): Flush pacing is disabled until we figure out why it impacts
|
|
// throughput.
|
|
flushPacer = newFlushPacer(flushPacerEnv{
|
|
limiter: d.flushLimiter,
|
|
memTableSize: uint64(d.opts.MemTableSize),
|
|
getInfo: d.getFlushPacerInfo,
|
|
})
|
|
}
|
|
ve, pendingOutputs, err := d.runCompaction(jobID, c, flushPacer)
|
|
|
|
info := FlushInfo{
|
|
JobID: jobID,
|
|
Input: n,
|
|
Duration: d.timeNow().Sub(startTime),
|
|
Done: true,
|
|
Err: err,
|
|
}
|
|
if err == nil {
|
|
for i := range ve.NewFiles {
|
|
e := &ve.NewFiles[i]
|
|
info.Output = append(info.Output, e.Meta.TableInfo())
|
|
}
|
|
if len(ve.NewFiles) == 0 {
|
|
info.Err = errEmptyTable
|
|
}
|
|
|
|
// The flush succeeded or it produced an empty sstable. In either case we
|
|
// want to bump the minimum unflushed log number to the log number of the
|
|
// oldest unflushed memtable.
|
|
ve.MinUnflushedLogNum = minUnflushedLogNum
|
|
metrics := c.metrics[0]
|
|
for i := 0; i < n; i++ {
|
|
metrics.BytesIn += d.mu.mem.queue[i].logSize
|
|
}
|
|
|
|
d.mu.versions.logLock()
|
|
err = d.mu.versions.logAndApply(jobID, ve, c.metrics, false, /* forceRotation */
|
|
func() []compactionInfo { return d.getInProgressCompactionInfoLocked(c) })
|
|
if err != nil {
|
|
// TODO(peter): untested.
|
|
d.mu.versions.obsoleteTables = append(d.mu.versions.obsoleteTables, pendingOutputs...)
|
|
d.mu.versions.incrementObsoleteTablesLocked(pendingOutputs)
|
|
}
|
|
}
|
|
|
|
d.maybeUpdateDeleteCompactionHints(c)
|
|
d.removeInProgressCompaction(c)
|
|
d.mu.versions.incrementCompactions(c.kind)
|
|
d.mu.versions.incrementCompactionBytes(-c.bytesWritten)
|
|
|
|
// Refresh bytes flushed count.
|
|
bytesFlushed = atomic.LoadUint64(&d.atomic.bytesFlushed)
|
|
atomic.StoreUint64(&d.atomic.bytesFlushed, 0)
|
|
|
|
var flushed flushableList
|
|
if err == nil {
|
|
flushed = d.mu.mem.queue[:n]
|
|
d.mu.mem.queue = d.mu.mem.queue[n:]
|
|
d.updateReadStateLocked(d.opts.DebugCheck, func() {
|
|
// TODO(jackson): Remove this, plus this updateReadStateLocked
|
|
// parameter when range keys are persisted to sstables.
|
|
err = d.applyFlushedRangeKeys(flushed)
|
|
})
|
|
d.updateTableStatsLocked(ve.NewFiles)
|
|
}
|
|
// Signal FlushEnd after installing the new readState. This helps for unit
|
|
// tests that use the callback to trigger a read using an iterator with
|
|
// IterOptions.OnlyReadGuaranteedDurable.
|
|
info.TotalDuration = d.timeNow().Sub(startTime)
|
|
d.opts.EventListener.FlushEnd(info)
|
|
|
|
d.deleteObsoleteFiles(jobID, false /* waitForOngoing */)
|
|
|
|
// Mark all the memtables we flushed as flushed. Note that we do this last so
|
|
// that a synchronous call to DB.Flush() will not return until the deletion
|
|
// of obsolete files from this job have completed. This makes testing easier
|
|
// and provides similar behavior to manual compactions where the compaction
|
|
// is not marked as completed until the deletion of obsolete files job has
|
|
// completed.
|
|
for i := range flushed {
|
|
// The order of these operations matters here for ease of testing. Removing
|
|
// the reader reference first allows tests to be guaranteed that the
|
|
// memtable reservation has been released by the time a synchronous flush
|
|
// returns.
|
|
flushed[i].readerUnref()
|
|
close(flushed[i].flushed)
|
|
}
|
|
return bytesFlushed, err
|
|
}
|
|
|
|
// maybeScheduleCompactionAsync should be used when
|
|
// we want to possibly schedule a compaction, but don't
|
|
// want to eat the cost of running maybeScheduleCompaction.
|
|
// This method should be launched in a separate goroutine.
|
|
// d.mu must not be held when this is called.
|
|
func (d *DB) maybeScheduleCompactionAsync() {
|
|
defer d.compactionSchedulers.Done()
|
|
|
|
d.mu.Lock()
|
|
d.maybeScheduleCompaction()
|
|
d.mu.Unlock()
|
|
}
|
|
|
|
// maybeScheduleCompaction schedules a compaction if necessary.
|
|
//
|
|
// d.mu must be held when calling this.
|
|
func (d *DB) maybeScheduleCompaction() {
|
|
d.maybeScheduleCompactionPicker(pickAuto)
|
|
}
|
|
|
|
func pickAuto(picker compactionPicker, env compactionEnv) *pickedCompaction {
|
|
return picker.pickAuto(env)
|
|
}
|
|
|
|
func pickElisionOnly(picker compactionPicker, env compactionEnv) *pickedCompaction {
|
|
return picker.pickElisionOnlyCompaction(env)
|
|
}
|
|
|
|
// maybeScheduleCompactionPicker schedules a compaction if necessary,
|
|
// calling `pickFunc` to pick automatic compactions.
|
|
//
|
|
// d.mu must be held when calling this.
|
|
func (d *DB) maybeScheduleCompactionPicker(
|
|
pickFunc func(compactionPicker, compactionEnv) *pickedCompaction,
|
|
) {
|
|
if d.closed.Load() != nil || d.opts.ReadOnly {
|
|
return
|
|
}
|
|
if d.mu.compact.compactingCount >= d.opts.MaxConcurrentCompactions {
|
|
if len(d.mu.compact.manual) > 0 {
|
|
// Inability to run head blocks later manual compactions.
|
|
d.mu.compact.manual[0].retries++
|
|
}
|
|
return
|
|
}
|
|
|
|
// Compaction picking needs a coherent view of a Version. In particular, we
|
|
// need to exlude concurrent ingestions from making a decision on which level
|
|
// to ingest into that conflicts with our compaction
|
|
// decision. versionSet.logLock provides the necessary mutual exclusion.
|
|
d.mu.versions.logLock()
|
|
defer d.mu.versions.logUnlock()
|
|
|
|
// Check for the closed flag again, in case the DB was closed while we were
|
|
// waiting for logLock().
|
|
if d.closed.Load() != nil {
|
|
return
|
|
}
|
|
|
|
env := compactionEnv{
|
|
bytesCompacted: &d.atomic.bytesCompacted,
|
|
earliestSnapshotSeqNum: d.mu.snapshots.earliest(),
|
|
earliestUnflushedSeqNum: d.getEarliestUnflushedSeqNumLocked(),
|
|
}
|
|
|
|
// Check for delete-only compactions first, because they're expected to be
|
|
// cheap and reduce future compaction work.
|
|
if len(d.mu.compact.deletionHints) > 0 &&
|
|
d.mu.compact.compactingCount < d.opts.MaxConcurrentCompactions &&
|
|
!d.opts.DisableAutomaticCompactions {
|
|
v := d.mu.versions.currentVersion()
|
|
snapshots := d.mu.snapshots.toSlice()
|
|
inputs, unresolvedHints := checkDeleteCompactionHints(d.cmp, v, d.mu.compact.deletionHints, snapshots)
|
|
d.mu.compact.deletionHints = unresolvedHints
|
|
|
|
if len(inputs) > 0 {
|
|
c := newDeleteOnlyCompaction(d.opts, v, inputs)
|
|
d.mu.compact.compactingCount++
|
|
d.addInProgressCompaction(c)
|
|
go d.compact(c, nil)
|
|
}
|
|
}
|
|
|
|
for len(d.mu.compact.manual) > 0 && d.mu.compact.compactingCount < d.opts.MaxConcurrentCompactions {
|
|
manual := d.mu.compact.manual[0]
|
|
env.inProgressCompactions = d.getInProgressCompactionInfoLocked(nil)
|
|
pc, retryLater := d.mu.versions.picker.pickManual(env, manual)
|
|
if pc != nil {
|
|
c := newCompaction(pc, d.opts, env.bytesCompacted)
|
|
d.mu.compact.manual = d.mu.compact.manual[1:]
|
|
d.mu.compact.compactingCount++
|
|
d.addInProgressCompaction(c)
|
|
go d.compact(c, manual.done)
|
|
} else if !retryLater {
|
|
// Noop
|
|
d.mu.compact.manual = d.mu.compact.manual[1:]
|
|
manual.done <- nil
|
|
} else {
|
|
// Inability to run head blocks later manual compactions.
|
|
manual.retries++
|
|
break
|
|
}
|
|
}
|
|
|
|
for !d.opts.DisableAutomaticCompactions && d.mu.compact.compactingCount < d.opts.MaxConcurrentCompactions {
|
|
env.inProgressCompactions = d.getInProgressCompactionInfoLocked(nil)
|
|
env.readCompactionEnv = readCompactionEnv{
|
|
readCompactions: &d.mu.compact.readCompactions,
|
|
flushing: d.mu.compact.flushing || d.passedFlushThreshold(),
|
|
rescheduleReadCompaction: &d.mu.compact.rescheduleReadCompaction,
|
|
}
|
|
pc := pickFunc(d.mu.versions.picker, env)
|
|
if pc == nil {
|
|
break
|
|
}
|
|
c := newCompaction(pc, d.opts, env.bytesCompacted)
|
|
d.mu.compact.compactingCount++
|
|
d.addInProgressCompaction(c)
|
|
go d.compact(c, nil)
|
|
}
|
|
}
|
|
|
|
// A deleteCompactionHint records a user key and sequence number span that has been
|
|
// deleted by a range tombstone. A hint is recorded if at least one sstable
|
|
// falls completely within both the user key and sequence number spans.
|
|
// Once the tombstones and the observed completely-contained sstables fall
|
|
// into the same snapshot stripe, a delete-only compaction may delete any
|
|
// sstables within the range.
|
|
type deleteCompactionHint struct {
|
|
// start and end are user keys specifying a key range [start, end) of
|
|
// deleted keys.
|
|
start []byte
|
|
end []byte
|
|
// The level of the file containing the range tombstone(s) when the hint
|
|
// was created. Only lower levels need to be searched for files that may
|
|
// be deleted.
|
|
tombstoneLevel int
|
|
// The file containing the range tombstone(s) that created the hint.
|
|
tombstoneFile *fileMetadata
|
|
// The smallest and largest sequence numbers of the abutting tombstones
|
|
// merged to form this hint. All of a tables' keys must be less than the
|
|
// tombstone smallest sequence number to be deleted. All of a tables'
|
|
// sequence numbers must fall into the same snapshot stripe as the
|
|
// tombstone largest sequence number to be deleted.
|
|
tombstoneLargestSeqNum uint64
|
|
tombstoneSmallestSeqNum uint64
|
|
// The smallest sequence number of a sstable that was found to be covered
|
|
// by this hint. The hint cannot be resolved until this sequence number is
|
|
// in the same snapshot stripe as the largest tombstone sequence number.
|
|
// This is set when a hint is created, so the LSM may look different and
|
|
// notably no longer contain the sstable that contained the key at this
|
|
// sequence number.
|
|
fileSmallestSeqNum uint64
|
|
}
|
|
|
|
func (h deleteCompactionHint) String() string {
|
|
return fmt.Sprintf("L%d.%s %s-%s seqnums(tombstone=%d-%d, file-smallest=%d)",
|
|
h.tombstoneLevel, h.tombstoneFile.FileNum, h.start, h.end,
|
|
h.tombstoneSmallestSeqNum, h.tombstoneLargestSeqNum, h.fileSmallestSeqNum)
|
|
}
|
|
|
|
func (h *deleteCompactionHint) canDelete(cmp Compare, m *fileMetadata, snapshots []uint64) bool {
|
|
// The file can only be deleted if all of its keys are older than the
|
|
// earliest tombstone aggregated into the hint.
|
|
if m.LargestSeqNum >= h.tombstoneSmallestSeqNum || m.SmallestSeqNum < h.fileSmallestSeqNum {
|
|
return false
|
|
}
|
|
|
|
// The file's oldest key must be in the same snapshot stripe as the
|
|
// newest tombstone. NB: We already checked the hint's sequence numbers,
|
|
// but this file's oldest sequence number might be lower than the hint's
|
|
// smallest sequence number despite the file falling within the key range
|
|
// if this file was constructed after the hint by a compaction.
|
|
ti, _ := snapshotIndex(h.tombstoneLargestSeqNum, snapshots)
|
|
fi, _ := snapshotIndex(m.SmallestSeqNum, snapshots)
|
|
if ti != fi {
|
|
return false
|
|
}
|
|
|
|
// The file's keys must be completely contained within the hint range.
|
|
return cmp(h.start, m.Smallest.UserKey) <= 0 && cmp(m.Largest.UserKey, h.end) < 0
|
|
}
|
|
|
|
func (d *DB) maybeUpdateDeleteCompactionHints(c *compaction) {
|
|
// Compactions that zero sequence numbers can interfere with compaction
|
|
// deletion hints. Deletion hints apply to tables containing keys older
|
|
// than a threshold. If a key more recent than the threshold is zeroed in
|
|
// a compaction, a delete-only compaction may mistake it as meeting the
|
|
// threshold and drop a table containing live data.
|
|
//
|
|
// To avoid this scenario, compactions that zero sequence numbers remove
|
|
// any conflicting deletion hints. A deletion hint is conflicting if both
|
|
// of the following conditions apply:
|
|
// * its key space overlaps with the compaction
|
|
// * at least one of its inputs contains a key as recent as one of the
|
|
// hint's tombstones.
|
|
//
|
|
if !c.allowedZeroSeqNum {
|
|
return
|
|
}
|
|
|
|
updatedHints := d.mu.compact.deletionHints[:0]
|
|
for _, h := range d.mu.compact.deletionHints {
|
|
// If the compaction's key space is disjoint from the hint's key
|
|
// space, the zeroing of sequence numbers won't affect the hint. Keep
|
|
// the hint.
|
|
keysDisjoint := d.cmp(h.end, c.smallest.UserKey) < 0 || d.cmp(h.start, c.largest.UserKey) > 0
|
|
if keysDisjoint {
|
|
updatedHints = append(updatedHints, h)
|
|
continue
|
|
}
|
|
|
|
// All of the compaction's inputs must be older than the hint's
|
|
// tombstones.
|
|
inputsOlder := true
|
|
for _, in := range c.inputs {
|
|
iter := in.files.Iter()
|
|
for f := iter.First(); f != nil; f = iter.Next() {
|
|
inputsOlder = inputsOlder && f.LargestSeqNum < h.tombstoneSmallestSeqNum
|
|
}
|
|
}
|
|
if inputsOlder {
|
|
updatedHints = append(updatedHints, h)
|
|
continue
|
|
}
|
|
|
|
// Drop h, because the compaction c may have zeroed sequence numbers
|
|
// of keys more recent than some of h's tombstones.
|
|
}
|
|
d.mu.compact.deletionHints = updatedHints
|
|
}
|
|
|
|
func checkDeleteCompactionHints(
|
|
cmp Compare, v *version, hints []deleteCompactionHint, snapshots []uint64,
|
|
) ([]compactionLevel, []deleteCompactionHint) {
|
|
var files map[*fileMetadata]bool
|
|
var byLevel [numLevels][]*fileMetadata
|
|
|
|
unresolvedHints := hints[:0]
|
|
for _, h := range hints {
|
|
// Check each compaction hint to see if it's resolvable. Resolvable
|
|
// hints are removed and trigger a delete-only compaction if any files
|
|
// in the current LSM still meet their criteria. Unresolvable hints
|
|
// are saved and don't trigger a delete-only compaction.
|
|
//
|
|
// When a compaction hint is created, the sequence numbers of the
|
|
// range tombstones and the covered file with the oldest key are
|
|
// recorded. The largest tombstone sequence number and the smallest
|
|
// file sequence number must be in the same snapshot stripe for the
|
|
// hint to be resolved. The below graphic models a compaction hint
|
|
// covering the keyspace [b, r). The hint completely contains two
|
|
// files, 000002 and 000003. The file 000003 contains the lowest
|
|
// covered sequence number at #90. The tombstone b.RANGEDEL.230:h has
|
|
// the highest tombstone sequence number incorporated into the hint.
|
|
// The hint may be resolved only once the snapshots at #100, #180 and
|
|
// #210 are all closed. File 000001 is not included within the hint
|
|
// because it extends beyond the range tombstones in user key space.
|
|
//
|
|
// 250
|
|
//
|
|
// |-b...230:h-|
|
|
// _____________________________________________________ snapshot #210
|
|
// 200 |--h.RANGEDEL.200:r--|
|
|
//
|
|
// _____________________________________________________ snapshot #180
|
|
//
|
|
// 150 +--------+
|
|
// +---------+ | 000003 |
|
|
// | 000002 | | |
|
|
// +_________+ | |
|
|
// 100_____________________|________|___________________ snapshot #100
|
|
// +--------+
|
|
// _____________________________________________________ snapshot #70
|
|
// +---------------+
|
|
// 50 | 000001 |
|
|
// | |
|
|
// +---------------+
|
|
// ______________________________________________________________
|
|
// a b c d e f g h i j k l m n o p q r s t u v w x y z
|
|
|
|
ti, _ := snapshotIndex(h.tombstoneLargestSeqNum, snapshots)
|
|
fi, _ := snapshotIndex(h.fileSmallestSeqNum, snapshots)
|
|
if ti != fi {
|
|
// Cannot resolve yet.
|
|
unresolvedHints = append(unresolvedHints, h)
|
|
continue
|
|
}
|
|
|
|
// The hint h will be resolved and dropped, regardless of whether
|
|
// there are any tables that can be deleted.
|
|
for l := h.tombstoneLevel + 1; l < numLevels; l++ {
|
|
overlaps := v.Overlaps(l, cmp, h.start, h.end, true /* exclusiveEnd */)
|
|
iter := overlaps.Iter()
|
|
for m := iter.First(); m != nil; m = iter.Next() {
|
|
if m.Compacting || !h.canDelete(cmp, m, snapshots) || files[m] {
|
|
continue
|
|
}
|
|
|
|
if files == nil {
|
|
// Construct files lazily, assuming most calls will not
|
|
// produce delete-only compactions.
|
|
files = make(map[*fileMetadata]bool)
|
|
}
|
|
files[m] = true
|
|
byLevel[l] = append(byLevel[l], m)
|
|
}
|
|
}
|
|
}
|
|
|
|
var compactLevels []compactionLevel
|
|
for l, files := range byLevel {
|
|
if len(files) == 0 {
|
|
continue
|
|
}
|
|
compactLevels = append(compactLevels, compactionLevel{
|
|
level: l,
|
|
files: manifest.NewLevelSliceKeySorted(cmp, files),
|
|
})
|
|
}
|
|
return compactLevels, unresolvedHints
|
|
}
|
|
|
|
// compact runs one compaction and maybe schedules another call to compact.
|
|
func (d *DB) compact(c *compaction, errChannel chan error) {
|
|
pprof.Do(context.Background(), compactLabels, func(context.Context) {
|
|
d.mu.Lock()
|
|
defer d.mu.Unlock()
|
|
if err := d.compact1(c, errChannel); err != nil {
|
|
// TODO(peter): count consecutive compaction errors and backoff.
|
|
d.opts.EventListener.BackgroundError(err)
|
|
}
|
|
d.mu.compact.compactingCount--
|
|
// The previous compaction may have produced too many files in a
|
|
// level, so reschedule another compaction if needed.
|
|
d.maybeScheduleCompaction()
|
|
d.mu.compact.cond.Broadcast()
|
|
})
|
|
}
|
|
|
|
// compact1 runs one compaction.
|
|
//
|
|
// d.mu must be held when calling this, but the mutex may be dropped and
|
|
// re-acquired during the course of this method.
|
|
func (d *DB) compact1(c *compaction, errChannel chan error) (err error) {
|
|
if errChannel != nil {
|
|
defer func() {
|
|
errChannel <- err
|
|
}()
|
|
}
|
|
|
|
jobID := d.mu.nextJobID
|
|
d.mu.nextJobID++
|
|
info := c.makeInfo(jobID)
|
|
d.opts.EventListener.CompactionBegin(info)
|
|
startTime := d.timeNow()
|
|
|
|
compactionPacer := (pacer)(nilPacer)
|
|
if d.opts.private.enablePacing {
|
|
// TODO(peter): Compaction pacing is disabled until we figure out why it
|
|
// impacts throughput.
|
|
compactionPacer = newCompactionPacer(compactionPacerEnv{
|
|
limiter: d.compactionLimiter,
|
|
memTableSize: uint64(d.opts.MemTableSize),
|
|
getInfo: d.getCompactionPacerInfo,
|
|
})
|
|
}
|
|
ve, pendingOutputs, err := d.runCompaction(jobID, c, compactionPacer)
|
|
|
|
info.Duration = d.timeNow().Sub(startTime)
|
|
if err == nil {
|
|
d.mu.versions.logLock()
|
|
err = d.mu.versions.logAndApply(jobID, ve, c.metrics, false /* forceRotation */, func() []compactionInfo {
|
|
return d.getInProgressCompactionInfoLocked(c)
|
|
})
|
|
if err != nil {
|
|
// TODO(peter): untested.
|
|
d.mu.versions.obsoleteTables = append(d.mu.versions.obsoleteTables, pendingOutputs...)
|
|
d.mu.versions.incrementObsoleteTablesLocked(pendingOutputs)
|
|
}
|
|
}
|
|
|
|
info.Done = true
|
|
info.Err = err
|
|
if err == nil {
|
|
for i := range ve.NewFiles {
|
|
e := &ve.NewFiles[i]
|
|
info.Output.Tables = append(info.Output.Tables, e.Meta.TableInfo())
|
|
}
|
|
}
|
|
|
|
d.maybeUpdateDeleteCompactionHints(c)
|
|
d.removeInProgressCompaction(c)
|
|
d.mu.versions.incrementCompactions(c.kind)
|
|
d.mu.versions.incrementCompactionBytes(-c.bytesWritten)
|
|
|
|
info.TotalDuration = d.timeNow().Sub(startTime)
|
|
d.opts.EventListener.CompactionEnd(info)
|
|
|
|
// Update the read state before deleting obsolete files because the
|
|
// read-state update will cause the previous version to be unref'd and if
|
|
// there are no references obsolete tables will be added to the obsolete
|
|
// table list.
|
|
if err == nil {
|
|
d.updateReadStateLocked(d.opts.DebugCheck, nil)
|
|
d.updateTableStatsLocked(ve.NewFiles)
|
|
}
|
|
d.deleteObsoleteFiles(jobID, true /* waitForOngoing */)
|
|
|
|
return err
|
|
}
|
|
|
|
// runCompactions runs a compaction that produces new on-disk tables from
|
|
// memtables or old on-disk tables.
|
|
//
|
|
// d.mu must be held when calling this, but the mutex may be dropped and
|
|
// re-acquired during the course of this method.
|
|
func (d *DB) runCompaction(
|
|
jobID int, c *compaction, pacer pacer,
|
|
) (ve *versionEdit, pendingOutputs []*fileMetadata, retErr error) {
|
|
// As a sanity check, confirm that the smallest / largest keys for new and
|
|
// deleted files in the new versionEdit pass a validation function before
|
|
// returning the edit.
|
|
defer func() {
|
|
if ve != nil {
|
|
err := validateVersionEdit(ve, d.opts.Experimental.KeyValidationFunc, d.opts.Comparer.FormatKey)
|
|
if err != nil {
|
|
d.opts.Logger.Fatalf("pebble: version edit validation failed: %s", err)
|
|
}
|
|
}
|
|
}()
|
|
|
|
// Check for a delete-only compaction. This can occur when wide range
|
|
// tombstones completely contain sstables.
|
|
if c.kind == compactionKindDeleteOnly {
|
|
c.metrics = make(map[int]*LevelMetrics, len(c.inputs))
|
|
ve := &versionEdit{
|
|
DeletedFiles: map[deletedFileEntry]*fileMetadata{},
|
|
}
|
|
for _, cl := range c.inputs {
|
|
levelMetrics := &LevelMetrics{}
|
|
iter := cl.files.Iter()
|
|
for f := iter.First(); f != nil; f = iter.Next() {
|
|
levelMetrics.NumFiles--
|
|
levelMetrics.Size -= int64(f.Size)
|
|
ve.DeletedFiles[deletedFileEntry{
|
|
Level: cl.level,
|
|
FileNum: f.FileNum,
|
|
}] = f
|
|
}
|
|
c.metrics[cl.level] = levelMetrics
|
|
}
|
|
return ve, nil, nil
|
|
}
|
|
|
|
// Check for a trivial move of one table from one level to the next. We avoid
|
|
// such a move if there is lots of overlapping grandparent data. Otherwise,
|
|
// the move could create a parent file that will require a very expensive
|
|
// merge later on.
|
|
if c.kind == compactionKindMove {
|
|
iter := c.startLevel.files.Iter()
|
|
meta := iter.First()
|
|
c.metrics = map[int]*LevelMetrics{
|
|
c.startLevel.level: {
|
|
NumFiles: -1,
|
|
Size: -int64(meta.Size),
|
|
},
|
|
c.outputLevel.level: {
|
|
NumFiles: 1,
|
|
Size: int64(meta.Size),
|
|
BytesMoved: meta.Size,
|
|
TablesMoved: 1,
|
|
},
|
|
}
|
|
ve := &versionEdit{
|
|
DeletedFiles: map[deletedFileEntry]*fileMetadata{
|
|
{Level: c.startLevel.level, FileNum: meta.FileNum}: meta,
|
|
},
|
|
NewFiles: []newFileEntry{
|
|
{Level: c.outputLevel.level, Meta: meta},
|
|
},
|
|
}
|
|
return ve, nil, nil
|
|
}
|
|
|
|
defer func() {
|
|
if retErr != nil {
|
|
pendingOutputs = nil
|
|
}
|
|
}()
|
|
|
|
snapshots := d.mu.snapshots.toSlice()
|
|
formatVers := d.mu.formatVers.vers
|
|
// The table is written at the maximum allowable format implied by the current
|
|
// format major version of the DB.
|
|
tableFormat := formatVers.MaxTableFormat()
|
|
|
|
// Release the d.mu lock while doing I/O.
|
|
// Note the unusual order: Unlock and then Lock.
|
|
d.mu.Unlock()
|
|
defer d.mu.Lock()
|
|
|
|
iiter, err := c.newInputIter(d.newIters)
|
|
if err != nil {
|
|
return nil, pendingOutputs, err
|
|
}
|
|
c.allowedZeroSeqNum = c.allowZeroSeqNum()
|
|
iter := newCompactionIter(c.cmp, c.equal, c.formatKey, d.merge, iiter, snapshots,
|
|
&c.rangeDelFrag, c.allowedZeroSeqNum, c.elideTombstone,
|
|
c.elideRangeTombstone, d.FormatMajorVersion())
|
|
|
|
var (
|
|
filenames []string
|
|
tw *sstable.Writer
|
|
)
|
|
defer func() {
|
|
if iter != nil {
|
|
retErr = firstError(retErr, iter.Close())
|
|
}
|
|
if tw != nil {
|
|
retErr = firstError(retErr, tw.Close())
|
|
}
|
|
if retErr != nil {
|
|
for _, filename := range filenames {
|
|
d.opts.FS.Remove(filename)
|
|
}
|
|
}
|
|
for _, closer := range c.closers {
|
|
retErr = firstError(retErr, closer.Close())
|
|
}
|
|
}()
|
|
|
|
ve = &versionEdit{
|
|
DeletedFiles: map[deletedFileEntry]*fileMetadata{},
|
|
}
|
|
|
|
outputMetrics := &LevelMetrics{
|
|
BytesIn: c.startLevel.files.SizeSum(),
|
|
BytesRead: c.outputLevel.files.SizeSum(),
|
|
}
|
|
outputMetrics.BytesRead += outputMetrics.BytesIn
|
|
c.metrics = map[int]*LevelMetrics{
|
|
c.outputLevel.level: outputMetrics,
|
|
}
|
|
if len(c.flushing) == 0 && c.metrics[c.startLevel.level] == nil {
|
|
c.metrics[c.startLevel.level] = &LevelMetrics{}
|
|
}
|
|
|
|
writerOpts := d.opts.MakeWriterOptions(c.outputLevel.level, tableFormat)
|
|
if formatVers < FormatBlockPropertyCollector {
|
|
// Cannot yet write block properties.
|
|
writerOpts.BlockPropertyCollectors = nil
|
|
}
|
|
|
|
// prevPointKey is a sstable.WriterOption that provides access to
|
|
// the last point key written to a writer's sstable. When a new
|
|
// output begins in newOutput, prevPointKey is updated to point to
|
|
// the new output's sstable.Writer. This allows the compaction loop
|
|
// to access the last written point key without requiring the
|
|
// compaction loop to make a copy of each key ahead of time. Users
|
|
// must be careful, because the byte slice returned by UnsafeKey
|
|
// points directly into the Writer's block buffer.
|
|
var prevPointKey sstable.PreviousPointKeyOpt
|
|
|
|
newOutput := func() error {
|
|
fileMeta := &fileMetadata{}
|
|
d.mu.Lock()
|
|
fileNum := d.mu.versions.getNextFileNum()
|
|
fileMeta.FileNum = fileNum
|
|
pendingOutputs = append(pendingOutputs, fileMeta)
|
|
d.mu.Unlock()
|
|
|
|
filename := base.MakeFilepath(d.opts.FS, d.dirname, fileTypeTable, fileNum)
|
|
file, err := d.opts.FS.Create(filename)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
reason := "flushing"
|
|
if c.flushing == nil {
|
|
reason = "compacting"
|
|
}
|
|
d.opts.EventListener.TableCreated(TableCreateInfo{
|
|
JobID: jobID,
|
|
Reason: reason,
|
|
Path: filename,
|
|
FileNum: fileNum,
|
|
})
|
|
file = vfs.NewSyncingFile(file, vfs.SyncingFileOptions{
|
|
BytesPerSync: d.opts.BytesPerSync,
|
|
})
|
|
file = &compactionFile{
|
|
File: file,
|
|
versions: d.mu.versions,
|
|
written: &c.bytesWritten,
|
|
}
|
|
filenames = append(filenames, filename)
|
|
cacheOpts := private.SSTableCacheOpts(d.cacheID, fileNum).(sstable.WriterOption)
|
|
internalTableOpt := private.SSTableInternalTableOpt.(sstable.WriterOption)
|
|
tw = sstable.NewWriter(file, writerOpts, cacheOpts, internalTableOpt, &prevPointKey)
|
|
|
|
fileMeta.CreationTime = time.Now().Unix()
|
|
ve.NewFiles = append(ve.NewFiles, newFileEntry{
|
|
Level: c.outputLevel.level,
|
|
Meta: fileMeta,
|
|
})
|
|
return nil
|
|
}
|
|
|
|
// splitL0Outputs is true during flushes and intra-L0 compactions with flush
|
|
// splits enabled.
|
|
splitL0Outputs := c.outputLevel.level == 0 && d.opts.FlushSplitBytes > 0
|
|
|
|
// finishOutput is called with the a user key up to which all tombstones
|
|
// should be flushed. Typically, this is the first key of the next
|
|
// sstable or an empty key if this output is the final sstable.
|
|
finishOutput := func(splitKey []byte) error {
|
|
// If we haven't output any point records to the sstable (tw == nil)
|
|
// then the sstable will only contain range tombstones. The smallest
|
|
// key in the sstable will be the start key of the first range
|
|
// tombstone added. We need to ensure that this start key is distinct
|
|
// from the splitKey passed to finishOutput (if set), otherwise we
|
|
// would generate an sstable where the largest key is smaller than the
|
|
// smallest key due to how the largest key boundary is set below.
|
|
// NB: It is permissible for the range tombstone start key to be the
|
|
// empty string.
|
|
// TODO: It is unfortunate that we have to do this check here rather
|
|
// than when we decide to finish the sstable in the runCompaction
|
|
// loop. A better structure currently eludes us.
|
|
if tw == nil {
|
|
startKey := c.rangeDelFrag.Start()
|
|
if len(iter.tombstones) > 0 {
|
|
startKey = iter.tombstones[0].Start
|
|
}
|
|
if splitKey != nil && d.cmp(startKey, splitKey) == 0 {
|
|
return nil
|
|
}
|
|
}
|
|
|
|
// NB: clone the key because the data can be held on to by the call to
|
|
// compactionIter.Tombstones via keyspan.Fragmenter.FlushTo, and by the
|
|
// WriterMetadata.LargestRangeDel.UserKey.
|
|
splitKey = append([]byte(nil), splitKey...)
|
|
for _, v := range iter.Tombstones(splitKey) {
|
|
if tw == nil {
|
|
if err := newOutput(); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
// The tombstone being added could be completely outside the
|
|
// eventual bounds of the sstable. Consider this example (bounds
|
|
// in square brackets next to table filename):
|
|
//
|
|
// ./000240.sst [tmgc#391,MERGE-tmgc#391,MERGE]
|
|
// tmgc#391,MERGE [786e627a]
|
|
// tmgc-udkatvs#331,RANGEDEL
|
|
//
|
|
// ./000241.sst [tmgc#384,MERGE-tmgc#384,MERGE]
|
|
// tmgc#384,MERGE [666c7070]
|
|
// tmgc-tvsalezade#383,RANGEDEL
|
|
// tmgc-tvsalezade#331,RANGEDEL
|
|
//
|
|
// ./000242.sst [tmgc#383,RANGEDEL-tvsalezade#72057594037927935,RANGEDEL]
|
|
// tmgc-tvsalezade#383,RANGEDEL
|
|
// tmgc#375,SET [72646c78766965616c72776865676e79]
|
|
// tmgc-tvsalezade#356,RANGEDEL
|
|
//
|
|
// Note that both of the top two SSTables have range tombstones
|
|
// that start after the file's end keys. Since the file bound
|
|
// computation happens well after all range tombstones have been
|
|
// added to the writer, eliding out-of-file range tombstones based
|
|
// on sequence number at this stage is difficult, and necessitates
|
|
// read-time logic to ignore range tombstones outside file bounds.
|
|
if rangedel.Encode(v, tw.Add); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
|
|
if tw == nil {
|
|
return nil
|
|
}
|
|
|
|
if err := tw.Close(); err != nil {
|
|
tw = nil
|
|
return err
|
|
}
|
|
writerMeta, err := tw.Metadata()
|
|
if err != nil {
|
|
tw = nil
|
|
return err
|
|
}
|
|
tw = nil
|
|
meta := ve.NewFiles[len(ve.NewFiles)-1].Meta
|
|
meta.Size = writerMeta.Size
|
|
meta.SmallestSeqNum = writerMeta.SmallestSeqNum
|
|
meta.LargestSeqNum = writerMeta.LargestSeqNum
|
|
// If the file didn't contain any range deletions, we can fill its
|
|
// table stats now, avoiding unnecessarily loading the table later.
|
|
maybeSetStatsFromProperties(meta, &writerMeta.Properties)
|
|
|
|
if c.flushing == nil {
|
|
outputMetrics.TablesCompacted++
|
|
outputMetrics.BytesCompacted += meta.Size
|
|
} else {
|
|
outputMetrics.TablesFlushed++
|
|
outputMetrics.BytesFlushed += meta.Size
|
|
}
|
|
outputMetrics.Size += int64(meta.Size)
|
|
outputMetrics.NumFiles++
|
|
|
|
if n := len(ve.NewFiles); n > 1 {
|
|
// This is not the first output file. Ensure the sstable boundaries
|
|
// are nonoverlapping.
|
|
prevMeta := ve.NewFiles[n-2].Meta
|
|
if writerMeta.SmallestRangeDel.UserKey != nil {
|
|
c := d.cmp(writerMeta.SmallestRangeDel.UserKey, prevMeta.Largest.UserKey)
|
|
if c < 0 {
|
|
return errors.Errorf(
|
|
"pebble: smallest range tombstone start key is less than previous sstable largest key: %s < %s",
|
|
writerMeta.SmallestRangeDel.Pretty(d.opts.Comparer.FormatKey),
|
|
prevMeta.Largest.Pretty(d.opts.Comparer.FormatKey))
|
|
} else if c == 0 && !prevMeta.Largest.IsExclusiveSentinel() {
|
|
// The user key portion of the range boundary start key is
|
|
// equal to the previous table's largest key user key, and
|
|
// the previous table's largest key is not exclusive. This
|
|
// violates the invariant that tables are key-space
|
|
// partitioned.
|
|
return errors.Errorf(
|
|
"pebble: invariant violation: previous sstable largest key %s, current sstable smallest rangedel: %s",
|
|
prevMeta.Largest.Pretty(d.opts.Comparer.FormatKey),
|
|
writerMeta.SmallestRangeDel.Pretty(d.opts.Comparer.FormatKey),
|
|
)
|
|
}
|
|
}
|
|
}
|
|
|
|
// Verify that all range deletions outputted to the sstable are
|
|
// truncated to split key.
|
|
if splitKey != nil && writerMeta.LargestRangeDel.UserKey != nil &&
|
|
d.cmp(writerMeta.LargestRangeDel.UserKey, splitKey) > 0 {
|
|
return errors.Errorf(
|
|
"pebble: invariant violation: rangedel largest key %q extends beyond split key %q",
|
|
writerMeta.LargestRangeDel.Pretty(d.opts.Comparer.FormatKey),
|
|
d.opts.Comparer.FormatKey(splitKey),
|
|
)
|
|
}
|
|
|
|
if writerMeta.HasPointKeys {
|
|
meta.ExtendPointKeyBounds(d.cmp, writerMeta.SmallestPoint, writerMeta.LargestPoint)
|
|
}
|
|
if writerMeta.HasRangeDelKeys {
|
|
meta.ExtendPointKeyBounds(d.cmp, writerMeta.SmallestRangeDel, writerMeta.LargestRangeDel)
|
|
}
|
|
if writerMeta.HasRangeKeys {
|
|
meta.ExtendRangeKeyBounds(d.cmp, writerMeta.SmallestRangeKey, writerMeta.LargestRangeKey)
|
|
}
|
|
|
|
// Verify that the sstable bounds fall within the compaction input
|
|
// bounds. This is a sanity check that we don't have a logic error
|
|
// elsewhere that causes the sstable bounds to accidentally expand past the
|
|
// compaction input bounds as doing so could lead to various badness such
|
|
// as keys being deleted by a range tombstone incorrectly.
|
|
if c.smallest.UserKey != nil {
|
|
switch v := d.cmp(meta.Smallest.UserKey, c.smallest.UserKey); {
|
|
case v >= 0:
|
|
// Nothing to do.
|
|
case v < 0:
|
|
return errors.Errorf("pebble: compaction output grew beyond bounds of input: %s < %s",
|
|
meta.Smallest.Pretty(d.opts.Comparer.FormatKey),
|
|
c.smallest.Pretty(d.opts.Comparer.FormatKey))
|
|
}
|
|
}
|
|
if c.largest.UserKey != nil {
|
|
switch v := d.cmp(meta.Largest.UserKey, c.largest.UserKey); {
|
|
case v <= 0:
|
|
// Nothing to do.
|
|
case v > 0:
|
|
return errors.Errorf("pebble: compaction output grew beyond bounds of input: %s > %s",
|
|
meta.Largest.Pretty(d.opts.Comparer.FormatKey),
|
|
c.largest.Pretty(d.opts.Comparer.FormatKey))
|
|
}
|
|
}
|
|
// Verify that we never split different revisions of the same user key
|
|
// across two different sstables.
|
|
if err := c.errorOnUserKeyOverlap(ve); err != nil {
|
|
return err
|
|
}
|
|
if err := meta.Validate(d.cmp, d.opts.Comparer.FormatKey); err != nil {
|
|
return err
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// compactionOutputSplitters contain all logic to determine whether the
|
|
// compaction loop should stop writing to one output sstable and switch to
|
|
// a new one. Some splitters can wrap other splitters, and
|
|
// the splitterGroup can be composed of multiple splitters. In this case,
|
|
// we start off with splitters for file sizes, grandparent limits, and (for
|
|
// L0 splits) L0 limits, before wrapping them in an splitterGroup.
|
|
outputSplitters := []compactionOutputSplitter{
|
|
// We do not split the same user key across different sstables within
|
|
// one flush or compaction. The fileSizeSplitter may request a split in
|
|
// the middle of a user key, so the userKeyChangeSplitter ensures we are
|
|
// at a user key change boundary when doing a split.
|
|
&userKeyChangeSplitter{
|
|
cmp: c.cmp,
|
|
splitter: &fileSizeSplitter{maxFileSize: c.maxOutputFileSize},
|
|
unsafePrevUserKey: func() []byte {
|
|
// Return the largest point key written to tw or the start of
|
|
// the current range deletion in the fragmenter, whichever is
|
|
// greater.
|
|
prevPoint := prevPointKey.UnsafeKey()
|
|
if c.cmp(prevPoint.UserKey, c.rangeDelFrag.Start()) > 0 {
|
|
return prevPoint.UserKey
|
|
}
|
|
return c.rangeDelFrag.Start()
|
|
},
|
|
},
|
|
&limitFuncSplitter{c: c, limitFunc: c.findGrandparentLimit},
|
|
}
|
|
if splitL0Outputs {
|
|
outputSplitters = append(outputSplitters, &limitFuncSplitter{c: c, limitFunc: c.findL0Limit})
|
|
}
|
|
splitter := &splitterGroup{cmp: c.cmp, splitters: outputSplitters}
|
|
|
|
// NB: we avoid calling maybeThrottle on a nilPacer because the cost of
|
|
// dynamic dispatch in the hot loop below is pronounced in CPU profiles (see
|
|
// #1030). Additionally, even the cost of this interface comparison is
|
|
// pronounced in CPU profiles, so we hoist the entire thing out of the hot
|
|
// loop. This allows the branch predictor to do its job and make the pacer
|
|
// interactions ~free when a nilPacer is used.
|
|
isNilPacer := pacer == nilPacer
|
|
|
|
// Each outer loop iteration produces one output file. An iteration that
|
|
// produces a file containing point keys (and optionally range tombstones)
|
|
// guarantees that the input iterator advanced. An iteration that produces
|
|
// a file containing only range tombstones guarantees the limit passed to
|
|
// `finishOutput()` advanced to a strictly greater user key corresponding
|
|
// to a grandparent file largest key, or nil. Taken together, these
|
|
// progress guarantees ensure that eventually the input iterator will be
|
|
// exhausted and the range tombstone fragments will all be flushed.
|
|
for key, val := iter.First(); key != nil || !c.rangeDelFrag.Empty(); {
|
|
splitterSuggestion := splitter.onNewOutput(key)
|
|
|
|
// Each inner loop iteration processes one key from the input iterator.
|
|
for ; key != nil; key, val = iter.Next() {
|
|
if split := splitter.shouldSplitBefore(key, tw); split == splitNow {
|
|
break
|
|
}
|
|
|
|
atomic.StoreUint64(c.atomicBytesIterated, c.bytesIterated)
|
|
if !isNilPacer {
|
|
if err := pacer.maybeThrottle(c.bytesIterated); err != nil {
|
|
return nil, pendingOutputs, err
|
|
}
|
|
}
|
|
if key.Kind() == InternalKeyKindRangeDelete {
|
|
// Range tombstones are handled specially. They are fragmented,
|
|
// and they're not written until later during `finishOutput()`.
|
|
// We add them to the `Fragmenter` now to make them visible to
|
|
// `compactionIter` so covered keys in the same snapshot stripe
|
|
// can be elided.
|
|
|
|
// The interleaved range deletion might only be one of many with
|
|
// these bounds. Some fragmenting is performed ahead of time by
|
|
// keyspan.MergingIter.
|
|
if s := c.rangeDelIter.Span(); !s.Empty() {
|
|
// The memory management here is subtle. Range deletions
|
|
// blocks do NOT use prefix compression, which ensures that
|
|
// range deletion spans' memory is available as long we keep
|
|
// the iterator open. However, the keyspan.MergingIter that
|
|
// merges spans across levels only guarantees the lifetime
|
|
// of the [start, end) bounds until the next positioning
|
|
// method is called.
|
|
//
|
|
// Additionally, the Span.Keys slice is owned by the the
|
|
// range deletion iterator stack, and it may be overwritten
|
|
// when we advance.
|
|
//
|
|
// Clone the Keys slice and the start and end keys.
|
|
//
|
|
// TODO(jackson): Avoid the clone by removing c.rangeDelFrag
|
|
// and performing explicit truncation of the pending
|
|
// rangedel span as necessary.
|
|
clone := keyspan.Span{
|
|
Start: iter.cloneKey(s.Start),
|
|
End: iter.cloneKey(s.End),
|
|
Keys: make([]keyspan.Key, len(s.Keys)),
|
|
}
|
|
copy(clone.Keys, s.Keys)
|
|
c.rangeDelFrag.Add(clone)
|
|
}
|
|
continue
|
|
}
|
|
if tw == nil {
|
|
if err := newOutput(); err != nil {
|
|
return nil, pendingOutputs, err
|
|
}
|
|
}
|
|
if err := tw.Add(*key, val); err != nil {
|
|
return nil, pendingOutputs, err
|
|
}
|
|
}
|
|
|
|
// A splitter requested a split, and we're ready to finish the output.
|
|
// We need to choose the key at which to split any pending range
|
|
// tombstones. There are two options:
|
|
// 1. splitterSuggestion — The key suggested by the splitter. This key
|
|
// is guaranteed to be greater than the last key written to the
|
|
// current output.
|
|
// 2. key.UserKey — the first key of the next sstable output. This user
|
|
// key is also guaranteed to be greater than the last user key
|
|
// written to the current output (see userKeyChangeSplitter).
|
|
//
|
|
// Use whichever is smaller. Using the smaller of the two limits
|
|
// overlap with grandparents. Consider the case where the
|
|
// grandparent limit is calculated to be 'b', key is 'x', and
|
|
// there exist many sstables between 'b' and 'x'. If the range
|
|
// deletion fragmenter has a pending tombstone [a,x), splitting
|
|
// at 'x' would cause the output table to overlap many
|
|
// grandparents well beyond the calculated grandparent limit
|
|
// 'b'. Splitting at the smaller `splitterSuggestion` avoids
|
|
// this unbounded overlap with grandparent tables.
|
|
splitKey := splitterSuggestion
|
|
if key != nil && (splitKey == nil || c.cmp(splitKey, key.UserKey) > 0) {
|
|
splitKey = key.UserKey
|
|
}
|
|
if err := finishOutput(splitKey); err != nil {
|
|
return nil, pendingOutputs, err
|
|
}
|
|
}
|
|
|
|
for _, cl := range c.inputs {
|
|
iter := cl.files.Iter()
|
|
for f := iter.First(); f != nil; f = iter.Next() {
|
|
c.metrics[cl.level].NumFiles--
|
|
c.metrics[cl.level].Size -= int64(f.Size)
|
|
ve.DeletedFiles[deletedFileEntry{
|
|
Level: cl.level,
|
|
FileNum: f.FileNum,
|
|
}] = f
|
|
}
|
|
}
|
|
|
|
if err := d.dataDir.Sync(); err != nil {
|
|
return nil, pendingOutputs, err
|
|
}
|
|
|
|
// Refresh the disk available statistic whenever a compaction/flush
|
|
// completes, before re-acquiring the mutex.
|
|
_ = d.calculateDiskAvailableBytes()
|
|
|
|
return ve, pendingOutputs, nil
|
|
}
|
|
|
|
// validateVersionEdit validates that start and end keys across new and deleted
|
|
// files in a versionEdit pass the given validation function.
|
|
func validateVersionEdit(
|
|
ve *versionEdit, validateFn func([]byte) error, format base.FormatKey,
|
|
) error {
|
|
validateMetaFn := func(f *manifest.FileMetadata) error {
|
|
for _, key := range []InternalKey{f.Smallest, f.Largest} {
|
|
if err := validateFn(key.UserKey); err != nil {
|
|
return errors.Wrapf(err, "key=%q; file=%s", format(key.UserKey), f)
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Validate both new and deleted files.
|
|
for _, f := range ve.NewFiles {
|
|
if err := validateMetaFn(f.Meta); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
for _, m := range ve.DeletedFiles {
|
|
if err := validateMetaFn(m); err != nil {
|
|
return err
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// scanObsoleteFiles scans the filesystem for files that are no longer needed
|
|
// and adds those to the internal lists of obsolete files. Note that the files
|
|
// are not actually deleted by this method. A subsequent call to
|
|
// deleteObsoleteFiles must be performed. Must be not be called concurrently
|
|
// with compactions and flushes. db.mu must be held when calling this function,
|
|
// however as this function is expected to only be called during Open(), no
|
|
// other operations should be contending on it just yet.
|
|
func (d *DB) scanObsoleteFiles(list []string) {
|
|
if d.mu.compact.compactingCount > 0 || d.mu.compact.flushing {
|
|
panic("pebble: cannot scan obsolete files concurrently with compaction/flushing")
|
|
}
|
|
|
|
liveFileNums := make(map[FileNum]struct{})
|
|
d.mu.versions.addLiveFileNums(liveFileNums)
|
|
minUnflushedLogNum := d.mu.versions.minUnflushedLogNum
|
|
manifestFileNum := d.mu.versions.manifestFileNum
|
|
|
|
var obsoleteLogs []fileInfo
|
|
var obsoleteTables []*fileMetadata
|
|
var obsoleteManifests []fileInfo
|
|
var obsoleteOptions []fileInfo
|
|
|
|
for _, filename := range list {
|
|
fileType, fileNum, ok := base.ParseFilename(d.opts.FS, filename)
|
|
if !ok {
|
|
continue
|
|
}
|
|
switch fileType {
|
|
case fileTypeLog:
|
|
if fileNum >= minUnflushedLogNum {
|
|
continue
|
|
}
|
|
fi := fileInfo{fileNum: fileNum}
|
|
if stat, err := d.opts.FS.Stat(filename); err == nil {
|
|
fi.fileSize = uint64(stat.Size())
|
|
}
|
|
obsoleteLogs = append(obsoleteLogs, fi)
|
|
case fileTypeManifest:
|
|
if fileNum >= manifestFileNum {
|
|
continue
|
|
}
|
|
fi := fileInfo{fileNum: fileNum}
|
|
if stat, err := d.opts.FS.Stat(filename); err == nil {
|
|
fi.fileSize = uint64(stat.Size())
|
|
}
|
|
obsoleteManifests = append(obsoleteManifests, fi)
|
|
case fileTypeOptions:
|
|
if fileNum >= d.optionsFileNum {
|
|
continue
|
|
}
|
|
fi := fileInfo{fileNum: fileNum}
|
|
if stat, err := d.opts.FS.Stat(filename); err == nil {
|
|
fi.fileSize = uint64(stat.Size())
|
|
}
|
|
obsoleteOptions = append(obsoleteOptions, fi)
|
|
case fileTypeTable:
|
|
if _, ok := liveFileNums[fileNum]; ok {
|
|
continue
|
|
}
|
|
fileMeta := &fileMetadata{
|
|
FileNum: fileNum,
|
|
}
|
|
if stat, err := d.opts.FS.Stat(filename); err == nil {
|
|
fileMeta.Size = uint64(stat.Size())
|
|
}
|
|
obsoleteTables = append(obsoleteTables, fileMeta)
|
|
default:
|
|
// Don't delete files we don't know about.
|
|
continue
|
|
}
|
|
}
|
|
|
|
d.mu.log.queue = merge(d.mu.log.queue, obsoleteLogs)
|
|
d.mu.versions.metrics.WAL.Files += int64(len(obsoleteLogs))
|
|
d.mu.versions.obsoleteTables = mergeFileMetas(d.mu.versions.obsoleteTables, obsoleteTables)
|
|
d.mu.versions.incrementObsoleteTablesLocked(obsoleteTables)
|
|
d.mu.versions.obsoleteManifests = merge(d.mu.versions.obsoleteManifests, obsoleteManifests)
|
|
d.mu.versions.obsoleteOptions = merge(d.mu.versions.obsoleteOptions, obsoleteOptions)
|
|
}
|
|
|
|
// disableFileDeletions disables file deletions and then waits for any
|
|
// in-progress deletion to finish. The caller is required to call
|
|
// enableFileDeletions in order to enable file deletions again. It is ok for
|
|
// multiple callers to disable file deletions simultaneously, though they must
|
|
// all invoke enableFileDeletions in order for file deletions to be re-enabled
|
|
// (there is an internal reference count on file deletion disablement).
|
|
//
|
|
// d.mu must be held when calling this method.
|
|
func (d *DB) disableFileDeletions() {
|
|
d.mu.cleaner.disabled++
|
|
for d.mu.cleaner.cleaning {
|
|
d.mu.cleaner.cond.Wait()
|
|
}
|
|
d.mu.cleaner.cond.Broadcast()
|
|
}
|
|
|
|
// enableFileDeletions enables previously disabled file deletions. Note that if
|
|
// file deletions have been re-enabled, the current goroutine will be used to
|
|
// perform the queued up deletions.
|
|
//
|
|
// d.mu must be held when calling this method.
|
|
func (d *DB) enableFileDeletions() {
|
|
if d.mu.cleaner.disabled <= 0 || d.mu.cleaner.cleaning {
|
|
panic("pebble: file deletion disablement invariant violated")
|
|
}
|
|
d.mu.cleaner.disabled--
|
|
if d.mu.cleaner.disabled > 0 {
|
|
return
|
|
}
|
|
jobID := d.mu.nextJobID
|
|
d.mu.nextJobID++
|
|
d.deleteObsoleteFiles(jobID, true /* waitForOngoing */)
|
|
}
|
|
|
|
// d.mu must be held when calling this.
|
|
func (d *DB) acquireCleaningTurn(waitForOngoing bool) bool {
|
|
// Only allow a single delete obsolete files job to run at a time.
|
|
for d.mu.cleaner.cleaning && d.mu.cleaner.disabled == 0 && waitForOngoing {
|
|
d.mu.cleaner.cond.Wait()
|
|
}
|
|
if d.mu.cleaner.cleaning {
|
|
return false
|
|
}
|
|
if d.mu.cleaner.disabled > 0 {
|
|
// File deletions are currently disabled. When they are re-enabled a new
|
|
// job will be created to catch up on file deletions.
|
|
return false
|
|
}
|
|
d.mu.cleaner.cleaning = true
|
|
return true
|
|
}
|
|
|
|
// d.mu must be held when calling this.
|
|
func (d *DB) releaseCleaningTurn() {
|
|
d.mu.cleaner.cleaning = false
|
|
d.mu.cleaner.cond.Broadcast()
|
|
}
|
|
|
|
// deleteObsoleteFiles deletes those files that are no longer needed. If
|
|
// waitForOngoing is true, it waits for any ongoing cleaning turns to complete,
|
|
// and if false, it returns rightaway if a cleaning turn is ongoing.
|
|
//
|
|
// d.mu must be held when calling this, but the mutex may be dropped and
|
|
// re-acquired during the course of this method.
|
|
func (d *DB) deleteObsoleteFiles(jobID int, waitForOngoing bool) {
|
|
if !d.acquireCleaningTurn(waitForOngoing) {
|
|
return
|
|
}
|
|
d.doDeleteObsoleteFiles(jobID)
|
|
d.releaseCleaningTurn()
|
|
}
|
|
|
|
// obsoleteFile holds information about a file that needs to be deleted soon.
|
|
type obsoleteFile struct {
|
|
dir string
|
|
fileNum base.FileNum
|
|
fileType fileType
|
|
fileSize uint64
|
|
}
|
|
|
|
type fileInfo struct {
|
|
fileNum FileNum
|
|
fileSize uint64
|
|
}
|
|
|
|
// d.mu must be held when calling this, but the mutex may be dropped and
|
|
// re-acquired during the course of this method.
|
|
func (d *DB) doDeleteObsoleteFiles(jobID int) {
|
|
var obsoleteTables []fileInfo
|
|
|
|
defer func() {
|
|
for _, tbl := range obsoleteTables {
|
|
delete(d.mu.versions.zombieTables, tbl.fileNum)
|
|
}
|
|
}()
|
|
|
|
var obsoleteLogs []fileInfo
|
|
for i := range d.mu.log.queue {
|
|
// NB: d.mu.versions.minUnflushedLogNum is the log number of the earliest
|
|
// log that has not had its contents flushed to an sstable. We can recycle
|
|
// the prefix of d.mu.log.queue with log numbers less than
|
|
// minUnflushedLogNum.
|
|
if d.mu.log.queue[i].fileNum >= d.mu.versions.minUnflushedLogNum {
|
|
obsoleteLogs = d.mu.log.queue[:i]
|
|
d.mu.log.queue = d.mu.log.queue[i:]
|
|
d.mu.versions.metrics.WAL.Files -= int64(len(obsoleteLogs))
|
|
break
|
|
}
|
|
}
|
|
|
|
for _, table := range d.mu.versions.obsoleteTables {
|
|
obsoleteTables = append(obsoleteTables, fileInfo{
|
|
fileNum: table.FileNum,
|
|
fileSize: table.Size,
|
|
})
|
|
}
|
|
d.mu.versions.obsoleteTables = nil
|
|
|
|
// Sort the manifests cause we want to delete some contiguous prefix
|
|
// of the older manifests.
|
|
sort.Slice(d.mu.versions.obsoleteManifests, func(i, j int) bool {
|
|
return d.mu.versions.obsoleteManifests[i].fileNum <
|
|
d.mu.versions.obsoleteManifests[j].fileNum
|
|
})
|
|
|
|
var obsoleteManifests []fileInfo
|
|
manifestsToDelete := len(d.mu.versions.obsoleteManifests) - d.opts.NumPrevManifest
|
|
if manifestsToDelete > 0 {
|
|
obsoleteManifests = d.mu.versions.obsoleteManifests[:manifestsToDelete]
|
|
d.mu.versions.obsoleteManifests = d.mu.versions.obsoleteManifests[manifestsToDelete:]
|
|
if len(d.mu.versions.obsoleteManifests) == 0 {
|
|
d.mu.versions.obsoleteManifests = nil
|
|
}
|
|
}
|
|
|
|
obsoleteOptions := d.mu.versions.obsoleteOptions
|
|
d.mu.versions.obsoleteOptions = nil
|
|
|
|
// Release d.mu while doing I/O
|
|
// Note the unusual order: Unlock and then Lock.
|
|
d.mu.Unlock()
|
|
defer d.mu.Lock()
|
|
|
|
files := [4]struct {
|
|
fileType fileType
|
|
obsolete []fileInfo
|
|
}{
|
|
{fileTypeLog, obsoleteLogs},
|
|
{fileTypeTable, obsoleteTables},
|
|
{fileTypeManifest, obsoleteManifests},
|
|
{fileTypeOptions, obsoleteOptions},
|
|
}
|
|
_, noRecycle := d.opts.Cleaner.(base.NeedsFileContents)
|
|
filesToDelete := make([]obsoleteFile, 0, len(files))
|
|
for _, f := range files {
|
|
// We sort to make the order of deletions deterministic, which is nice for
|
|
// tests.
|
|
sort.Slice(f.obsolete, func(i, j int) bool {
|
|
return f.obsolete[i].fileNum < f.obsolete[j].fileNum
|
|
})
|
|
for _, fi := range f.obsolete {
|
|
dir := d.dirname
|
|
switch f.fileType {
|
|
case fileTypeLog:
|
|
if !noRecycle && d.logRecycler.add(fi) {
|
|
continue
|
|
}
|
|
dir = d.walDirname
|
|
case fileTypeTable:
|
|
d.tableCache.evict(fi.fileNum)
|
|
}
|
|
|
|
filesToDelete = append(filesToDelete, obsoleteFile{
|
|
dir: dir,
|
|
fileNum: fi.fileNum,
|
|
fileType: f.fileType,
|
|
fileSize: fi.fileSize,
|
|
})
|
|
}
|
|
}
|
|
if len(filesToDelete) > 0 {
|
|
d.deleters.Add(1)
|
|
// Delete asynchronously if that could get held up in the pacer.
|
|
if d.opts.Experimental.MinDeletionRate > 0 {
|
|
go d.paceAndDeleteObsoleteFiles(jobID, filesToDelete)
|
|
} else {
|
|
d.paceAndDeleteObsoleteFiles(jobID, filesToDelete)
|
|
}
|
|
}
|
|
}
|
|
|
|
// Paces and eventually deletes the list of obsolete files passed in. db.mu
|
|
// must NOT be held when calling this method.
|
|
func (d *DB) paceAndDeleteObsoleteFiles(jobID int, files []obsoleteFile) {
|
|
defer d.deleters.Done()
|
|
pacer := (pacer)(nilPacer)
|
|
if d.opts.Experimental.MinDeletionRate > 0 {
|
|
pacer = newDeletionPacer(d.deletionLimiter, d.getDeletionPacerInfo)
|
|
}
|
|
|
|
for _, of := range files {
|
|
path := base.MakeFilepath(d.opts.FS, of.dir, of.fileType, of.fileNum)
|
|
if of.fileType == fileTypeTable {
|
|
_ = pacer.maybeThrottle(of.fileSize)
|
|
d.mu.Lock()
|
|
d.mu.versions.metrics.Table.ObsoleteCount--
|
|
d.mu.versions.metrics.Table.ObsoleteSize -= of.fileSize
|
|
d.mu.Unlock()
|
|
}
|
|
d.deleteObsoleteFile(of.fileType, jobID, path, of.fileNum)
|
|
}
|
|
}
|
|
|
|
func (d *DB) maybeScheduleObsoleteTableDeletion() {
|
|
d.mu.Lock()
|
|
defer d.mu.Unlock()
|
|
|
|
if len(d.mu.versions.obsoleteTables) == 0 {
|
|
return
|
|
}
|
|
if !d.acquireCleaningTurn(false) {
|
|
return
|
|
}
|
|
|
|
go func() {
|
|
pprof.Do(context.Background(), gcLabels, func(context.Context) {
|
|
d.mu.Lock()
|
|
defer d.mu.Unlock()
|
|
|
|
jobID := d.mu.nextJobID
|
|
d.mu.nextJobID++
|
|
d.doDeleteObsoleteFiles(jobID)
|
|
d.releaseCleaningTurn()
|
|
})
|
|
}()
|
|
}
|
|
|
|
// deleteObsoleteFile deletes file that is no longer needed.
|
|
func (d *DB) deleteObsoleteFile(fileType fileType, jobID int, path string, fileNum FileNum) {
|
|
// TODO(peter): need to handle this error, probably by re-adding the
|
|
// file that couldn't be deleted to one of the obsolete slices map.
|
|
err := d.opts.Cleaner.Clean(d.opts.FS, fileType, path)
|
|
if oserror.IsNotExist(err) {
|
|
return
|
|
}
|
|
|
|
switch fileType {
|
|
case fileTypeLog:
|
|
d.opts.EventListener.WALDeleted(WALDeleteInfo{
|
|
JobID: jobID,
|
|
Path: path,
|
|
FileNum: fileNum,
|
|
Err: err,
|
|
})
|
|
case fileTypeManifest:
|
|
d.opts.EventListener.ManifestDeleted(ManifestDeleteInfo{
|
|
JobID: jobID,
|
|
Path: path,
|
|
FileNum: fileNum,
|
|
Err: err,
|
|
})
|
|
case fileTypeTable:
|
|
d.opts.EventListener.TableDeleted(TableDeleteInfo{
|
|
JobID: jobID,
|
|
Path: path,
|
|
FileNum: fileNum,
|
|
Err: err,
|
|
})
|
|
}
|
|
}
|
|
|
|
func merge(a, b []fileInfo) []fileInfo {
|
|
if len(b) == 0 {
|
|
return a
|
|
}
|
|
|
|
a = append(a, b...)
|
|
sort.Slice(a, func(i, j int) bool {
|
|
return a[i].fileNum < a[j].fileNum
|
|
})
|
|
|
|
n := 0
|
|
for i := 0; i < len(a); i++ {
|
|
if n == 0 || a[i].fileNum != a[n-1].fileNum {
|
|
a[n] = a[i]
|
|
n++
|
|
}
|
|
}
|
|
return a[:n]
|
|
}
|
|
|
|
func mergeFileMetas(a, b []*fileMetadata) []*fileMetadata {
|
|
if len(b) == 0 {
|
|
return a
|
|
}
|
|
|
|
a = append(a, b...)
|
|
sort.Slice(a, func(i, j int) bool {
|
|
return a[i].FileNum < a[j].FileNum
|
|
})
|
|
|
|
n := 0
|
|
for i := 0; i < len(a); i++ {
|
|
if n == 0 || a[i].FileNum != a[n-1].FileNum {
|
|
a[n] = a[i]
|
|
n++
|
|
}
|
|
}
|
|
return a[:n]
|
|
}
|