1241 lines
41 KiB
Go
1241 lines
41 KiB
Go
// Copyright 2018 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 sstable
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import (
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"encoding/binary"
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"unsafe"
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"github.com/cockroachdb/pebble/internal/base"
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"github.com/cockroachdb/pebble/internal/cache"
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"github.com/cockroachdb/pebble/internal/invariants"
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"github.com/cockroachdb/pebble/internal/keyspan"
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"github.com/cockroachdb/pebble/internal/rangedel"
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"github.com/cockroachdb/pebble/internal/rangekey"
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)
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func uvarintLen(v uint32) int {
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i := 0
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for v >= 0x80 {
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v >>= 7
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i++
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}
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return i + 1
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}
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type blockWriter struct {
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restartInterval int
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nEntries int
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nextRestart int
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buf []byte
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restarts []uint32
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curKey []byte
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curValue []byte
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prevKey []byte
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tmp [4]byte
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}
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func (w *blockWriter) clear() {
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*w = blockWriter{
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buf: w.buf[:0],
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restarts: w.restarts[:0],
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curKey: w.curKey[:0],
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curValue: w.curValue[:0],
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prevKey: w.prevKey[:0],
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}
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}
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func (w *blockWriter) store(keySize int, value []byte) {
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shared := 0
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if w.nEntries == w.nextRestart {
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w.nextRestart = w.nEntries + w.restartInterval
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w.restarts = append(w.restarts, uint32(len(w.buf)))
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} else {
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// TODO(peter): Manually inlined version of base.SharedPrefixLen(). This
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// is 3% faster on BenchmarkWriter on go1.16. Remove if future versions
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// show this to not be a performance win. For now, functions that use of
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// unsafe cannot be inlined.
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n := len(w.curKey)
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if n > len(w.prevKey) {
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n = len(w.prevKey)
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}
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asUint64 := func(b []byte, i int) uint64 {
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return binary.LittleEndian.Uint64(b[i:])
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}
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for shared < n-7 && asUint64(w.curKey, shared) == asUint64(w.prevKey, shared) {
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shared += 8
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}
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for shared < n && w.curKey[shared] == w.prevKey[shared] {
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shared++
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}
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}
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needed := 3*binary.MaxVarintLen32 + len(w.curKey[shared:]) + len(value)
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n := len(w.buf)
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if cap(w.buf) < n+needed {
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newCap := 2 * cap(w.buf)
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if newCap == 0 {
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newCap = 1024
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}
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for newCap < n+needed {
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newCap *= 2
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}
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newBuf := make([]byte, n, newCap)
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copy(newBuf, w.buf)
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w.buf = newBuf
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}
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w.buf = w.buf[:n+needed]
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// TODO(peter): Manually inlined versions of binary.PutUvarint(). This is 15%
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// faster on BenchmarkWriter on go1.13. Remove if go1.14 or future versions
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// show this to not be a performance win.
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{
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x := uint32(shared)
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for x >= 0x80 {
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w.buf[n] = byte(x) | 0x80
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x >>= 7
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n++
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}
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w.buf[n] = byte(x)
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n++
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}
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{
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x := uint32(keySize - shared)
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for x >= 0x80 {
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w.buf[n] = byte(x) | 0x80
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x >>= 7
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n++
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}
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w.buf[n] = byte(x)
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n++
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}
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{
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x := uint32(len(value))
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for x >= 0x80 {
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w.buf[n] = byte(x) | 0x80
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x >>= 7
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n++
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}
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w.buf[n] = byte(x)
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n++
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}
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n += copy(w.buf[n:], w.curKey[shared:])
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n += copy(w.buf[n:], value)
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w.buf = w.buf[:n]
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w.curValue = w.buf[n-len(value):]
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w.nEntries++
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}
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func (w *blockWriter) add(key InternalKey, value []byte) {
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w.curKey, w.prevKey = w.prevKey, w.curKey
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size := key.Size()
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if cap(w.curKey) < size {
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w.curKey = make([]byte, 0, size*2)
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}
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w.curKey = w.curKey[:size]
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key.Encode(w.curKey)
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w.store(size, value)
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}
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func (w *blockWriter) finish() []byte {
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// Write the restart points to the buffer.
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if w.nEntries == 0 {
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// Every block must have at least one restart point.
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if cap(w.restarts) > 0 {
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w.restarts = w.restarts[:1]
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w.restarts[0] = 0
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} else {
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w.restarts = append(w.restarts, 0)
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}
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}
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tmp4 := w.tmp[:4]
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for _, x := range w.restarts {
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binary.LittleEndian.PutUint32(tmp4, x)
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w.buf = append(w.buf, tmp4...)
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}
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binary.LittleEndian.PutUint32(tmp4, uint32(len(w.restarts)))
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w.buf = append(w.buf, tmp4...)
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result := w.buf
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// Reset the block state.
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w.nEntries = 0
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w.nextRestart = 0
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w.buf = w.buf[:0]
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w.restarts = w.restarts[:0]
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return result
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}
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// emptyBlockSize holds the size of an empty block. Every block ends
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// in a uint32 trailer encoding the number of restart points within the
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// block.
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const emptyBlockSize = 4
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func (w *blockWriter) estimatedSize() int {
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return len(w.buf) + 4*len(w.restarts) + emptyBlockSize
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}
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type blockEntry struct {
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offset int32
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keyStart int32
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keyEnd int32
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valStart int32
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valSize int32
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}
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// blockIter is an iterator over a single block of data.
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//
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// A blockIter provides an additional guarantee around key stability when a
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// block has a restart interval of 1 (i.e. when there is no prefix
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// compression). Key stability refers to whether the InternalKey.UserKey bytes
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// returned by a positioning call will remain stable after a subsequent
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// positioning call. The normal case is that a positioning call will invalidate
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// any previously returned InternalKey.UserKey. If a block has a restart
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// interval of 1 (no prefix compression), blockIter guarantees that
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// InternalKey.UserKey will point to the key as stored in the block itself
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// which will remain valid until the blockIter is closed. The key stability
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// guarantee is used by the range tombstone and range key code, which knows that
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// the respective blocks are always encoded with a restart interval of 1. This
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// per-block key stability guarantee is sufficient for range tombstones and
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// range deletes as they are always encoded in a single block.
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//
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// A blockIter also provides a value stability guarantee for range deletions and
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// range keys since there is only a single range deletion and range key block
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// per sstable and the blockIter will not release the bytes for the block until
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// it is closed.
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type blockIter struct {
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cmp Compare
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// offset is the byte index that marks where the current key/value is
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// encoded in the block.
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offset int32
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// nextOffset is the byte index where the next key/value is encoded in the
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// block.
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nextOffset int32
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// A "restart point" in a block is a point where the full key is encoded,
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// instead of just having a suffix of the key encoded. See readEntry() for
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// how prefix compression of keys works. Keys in between two restart points
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// only have a suffix encoded in the block. When restart interval is 1, no
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// prefix compression of keys happens. This is the case with range tombstone
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// blocks.
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//
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// All restart offsets are listed in increasing order in
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// i.ptr[i.restarts:len(block)-4], while numRestarts is encoded in the last
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// 4 bytes of the block as a uint32 (i.ptr[len(block)-4:]). i.restarts can
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// therefore be seen as the point where data in the block ends, and a list
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// of offsets of all restart points begins.
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restarts int32
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// Number of restart points in this block. Encoded at the end of the block
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// as a uint32.
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numRestarts int32
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globalSeqNum uint64
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ptr unsafe.Pointer
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data []byte
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// key contains the raw key the iterator is currently pointed at. This may
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// point directly to data stored in the block (for a key which has no prefix
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// compression), to fullKey (for a prefix compressed key), or to a slice of
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// data stored in cachedBuf (during reverse iteration).
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key []byte
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// fullKey is a buffer used for key prefix decompression.
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fullKey []byte
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// val contains the value the iterator is currently pointed at. If non-nil,
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// this points to a slice of the block data.
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val []byte
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// ikey contains the decoded InternalKey the iterator is currently pointed
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// at. Note that the memory backing ikey.UserKey is either data stored
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// directly in the block, fullKey, or cachedBuf. The key stability guarantee
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// for blocks built with a restart interval of 1 is achieved by having
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// ikey.UserKey always point to data stored directly in the block.
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ikey InternalKey
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// cached and cachedBuf are used during reverse iteration. They are needed
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// because we can't perform prefix decoding in reverse, only in the forward
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// direction. In order to iterate in reverse, we decode and cache the entries
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// between two restart points.
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//
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// Note that cached[len(cached)-1] contains the previous entry to the one the
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// blockIter is currently pointed at. As usual, nextOffset will contain the
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// offset of the next entry. During reverse iteration, nextOffset will be
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// updated to point to offset, and we'll set the blockIter to point at the
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// entry cached[len(cached)-1]. See Prev() for more details.
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//
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// For a block encoded with a restart interval of 1, cached and cachedBuf
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// will not be used as there are no prefix compressed entries between the
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// restart points.
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cached []blockEntry
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cachedBuf []byte
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cacheHandle cache.Handle
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// The first key in the block. This is used by the caller to set bounds
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// for block iteration for already loaded blocks.
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firstKey InternalKey
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}
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// blockIter implements the base.InternalIterator interface.
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var _ base.InternalIterator = (*blockIter)(nil)
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func newBlockIter(cmp Compare, block block) (*blockIter, error) {
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i := &blockIter{}
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return i, i.init(cmp, block, 0)
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}
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func (i *blockIter) String() string {
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return "block"
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}
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func (i *blockIter) init(cmp Compare, block block, globalSeqNum uint64) error {
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numRestarts := int32(binary.LittleEndian.Uint32(block[len(block)-4:]))
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if numRestarts == 0 {
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return base.CorruptionErrorf("pebble/table: invalid table (block has no restart points)")
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}
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i.cmp = cmp
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i.restarts = int32(len(block)) - 4*(1+numRestarts)
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i.numRestarts = numRestarts
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i.globalSeqNum = globalSeqNum
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i.ptr = unsafe.Pointer(&block[0])
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i.data = block
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i.fullKey = i.fullKey[:0]
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i.val = nil
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i.clearCache()
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if i.restarts > 0 {
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if err := i.readFirstKey(); err != nil {
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return err
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}
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} else {
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// Block is empty.
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i.firstKey = InternalKey{}
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}
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return nil
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}
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func (i *blockIter) initHandle(cmp Compare, block cache.Handle, globalSeqNum uint64) error {
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i.cacheHandle.Release()
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i.cacheHandle = block
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return i.init(cmp, block.Get(), globalSeqNum)
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}
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func (i *blockIter) invalidate() {
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i.clearCache()
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i.offset = 0
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i.nextOffset = 0
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i.restarts = 0
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i.numRestarts = 0
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i.data = nil
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}
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// isDataInvalidated returns true when the blockIter has been invalidated
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// using an invalidate call. NB: this is different from blockIter.Valid
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// which is part of the InternalIterator implementation.
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func (i *blockIter) isDataInvalidated() bool {
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return i.data == nil
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}
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func (i *blockIter) resetForReuse() blockIter {
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return blockIter{
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fullKey: i.fullKey[:0],
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cached: i.cached[:0],
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cachedBuf: i.cachedBuf[:0],
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data: nil,
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}
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}
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func (i *blockIter) readEntry() {
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ptr := unsafe.Pointer(uintptr(i.ptr) + uintptr(i.offset))
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// This is an ugly performance hack. Reading entries from blocks is one of
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// the inner-most routines and decoding the 3 varints per-entry takes
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// significant time. Neither go1.11 or go1.12 will inline decodeVarint for
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// us, so we do it manually. This provides a 10-15% performance improvement
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// on blockIter benchmarks on both go1.11 and go1.12.
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//
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// TODO(peter): remove this hack if go:inline is ever supported.
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var shared uint32
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if a := *((*uint8)(ptr)); a < 128 {
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shared = uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 1)
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} else if a, b := a&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 1))); b < 128 {
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shared = uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 2)
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} else if b, c := b&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 2))); c < 128 {
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shared = uint32(c)<<14 | uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 3)
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} else if c, d := c&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 3))); d < 128 {
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shared = uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 4)
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} else {
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d, e := d&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 4)))
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shared = uint32(e)<<28 | uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 5)
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}
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var unshared uint32
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if a := *((*uint8)(ptr)); a < 128 {
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unshared = uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 1)
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} else if a, b := a&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 1))); b < 128 {
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unshared = uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 2)
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} else if b, c := b&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 2))); c < 128 {
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unshared = uint32(c)<<14 | uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 3)
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} else if c, d := c&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 3))); d < 128 {
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unshared = uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 4)
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} else {
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d, e := d&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 4)))
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unshared = uint32(e)<<28 | uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 5)
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}
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var value uint32
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if a := *((*uint8)(ptr)); a < 128 {
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value = uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 1)
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} else if a, b := a&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 1))); b < 128 {
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value = uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 2)
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} else if b, c := b&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 2))); c < 128 {
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value = uint32(c)<<14 | uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 3)
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} else if c, d := c&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 3))); d < 128 {
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value = uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 4)
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} else {
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d, e := d&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 4)))
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value = uint32(e)<<28 | uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 5)
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}
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unsharedKey := getBytes(ptr, int(unshared))
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i.fullKey = append(i.fullKey[:shared], unsharedKey...)
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if shared == 0 {
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// Provide stability for the key across positioning calls if the key
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// doesn't share a prefix with the previous key. This removes requiring the
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// key to be copied if the caller knows the block has a restart interval of
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// 1. An important example of this is range-del blocks.
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i.key = unsharedKey
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} else {
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i.key = i.fullKey
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}
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ptr = unsafe.Pointer(uintptr(ptr) + uintptr(unshared))
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i.val = getBytes(ptr, int(value))
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i.nextOffset = int32(uintptr(ptr)-uintptr(i.ptr)) + int32(value)
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}
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func (i *blockIter) readFirstKey() error {
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ptr := i.ptr
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|
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// This is an ugly performance hack. Reading entries from blocks is one of
|
|
// the inner-most routines and decoding the 3 varints per-entry takes
|
|
// significant time. Neither go1.11 or go1.12 will inline decodeVarint for
|
|
// us, so we do it manually. This provides a 10-15% performance improvement
|
|
// on blockIter benchmarks on both go1.11 and go1.12.
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//
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// TODO(peter): remove this hack if go:inline is ever supported.
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if shared := *((*uint8)(ptr)); shared == 0 {
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ptr = unsafe.Pointer(uintptr(ptr) + 1)
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} else {
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// The shared length is != 0, which is invalid.
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panic("first key in block must have zero shared length")
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}
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var unshared uint32
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if a := *((*uint8)(ptr)); a < 128 {
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unshared = uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 1)
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} else if a, b := a&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 1))); b < 128 {
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unshared = uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 2)
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} else if b, c := b&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 2))); c < 128 {
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unshared = uint32(c)<<14 | uint32(b)<<7 | uint32(a)
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ptr = unsafe.Pointer(uintptr(ptr) + 3)
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|
} else if c, d := c&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 3))); d < 128 {
|
|
unshared = uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 4)
|
|
} else {
|
|
d, e := d&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 4)))
|
|
unshared = uint32(e)<<28 | uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 5)
|
|
}
|
|
|
|
// Skip the value length.
|
|
if a := *((*uint8)(ptr)); a < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 1)
|
|
} else if a := *((*uint8)(unsafe.Pointer(uintptr(ptr) + 1))); a < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 2)
|
|
} else if a := *((*uint8)(unsafe.Pointer(uintptr(ptr) + 2))); a < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 3)
|
|
} else if a := *((*uint8)(unsafe.Pointer(uintptr(ptr) + 3))); a < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 4)
|
|
} else {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 5)
|
|
}
|
|
|
|
firstKey := getBytes(ptr, int(unshared))
|
|
// Manually inlining base.DecodeInternalKey provides a 5-10% speedup on
|
|
// BlockIter benchmarks.
|
|
if n := len(firstKey) - 8; n >= 0 {
|
|
i.firstKey.Trailer = binary.LittleEndian.Uint64(firstKey[n:])
|
|
i.firstKey.UserKey = firstKey[:n:n]
|
|
if i.globalSeqNum != 0 {
|
|
i.firstKey.SetSeqNum(i.globalSeqNum)
|
|
}
|
|
} else {
|
|
i.firstKey.Trailer = uint64(InternalKeyKindInvalid)
|
|
i.firstKey.UserKey = nil
|
|
return base.CorruptionErrorf("pebble/table: invalid firstKey in block")
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (i *blockIter) decodeInternalKey(key []byte) {
|
|
// Manually inlining base.DecodeInternalKey provides a 5-10% speedup on
|
|
// BlockIter benchmarks.
|
|
if n := len(key) - 8; n >= 0 {
|
|
i.ikey.Trailer = binary.LittleEndian.Uint64(key[n:])
|
|
i.ikey.UserKey = key[:n:n]
|
|
if i.globalSeqNum != 0 {
|
|
i.ikey.SetSeqNum(i.globalSeqNum)
|
|
}
|
|
} else {
|
|
i.ikey.Trailer = uint64(InternalKeyKindInvalid)
|
|
i.ikey.UserKey = nil
|
|
}
|
|
}
|
|
|
|
func (i *blockIter) clearCache() {
|
|
i.cached = i.cached[:0]
|
|
i.cachedBuf = i.cachedBuf[:0]
|
|
}
|
|
|
|
func (i *blockIter) cacheEntry() {
|
|
var valStart int32
|
|
valSize := int32(len(i.val))
|
|
if valSize > 0 {
|
|
valStart = int32(uintptr(unsafe.Pointer(&i.val[0])) - uintptr(i.ptr))
|
|
}
|
|
|
|
i.cached = append(i.cached, blockEntry{
|
|
offset: i.offset,
|
|
keyStart: int32(len(i.cachedBuf)),
|
|
keyEnd: int32(len(i.cachedBuf) + len(i.key)),
|
|
valStart: valStart,
|
|
valSize: valSize,
|
|
})
|
|
i.cachedBuf = append(i.cachedBuf, i.key...)
|
|
}
|
|
|
|
// SeekGE implements internalIterator.SeekGE, as documented in the pebble
|
|
// package.
|
|
func (i *blockIter) SeekGE(key []byte, flags base.SeekGEFlags) (*InternalKey, base.LazyValue) {
|
|
i.clearCache()
|
|
|
|
ikey := base.MakeSearchKey(key)
|
|
|
|
// Find the index of the smallest restart point whose key is > the key
|
|
// sought; index will be numRestarts if there is no such restart point.
|
|
i.offset = 0
|
|
var index int32
|
|
|
|
{
|
|
// NB: manually inlined sort.Seach is ~5% faster.
|
|
//
|
|
// Define f(-1) == false and f(n) == true.
|
|
// Invariant: f(index-1) == false, f(upper) == true.
|
|
upper := i.numRestarts
|
|
for index < upper {
|
|
h := int32(uint(index+upper) >> 1) // avoid overflow when computing h
|
|
// index ≤ h < upper
|
|
offset := int32(binary.LittleEndian.Uint32(i.data[i.restarts+4*h:]))
|
|
// For a restart point, there are 0 bytes shared with the previous key.
|
|
// The varint encoding of 0 occupies 1 byte.
|
|
ptr := unsafe.Pointer(uintptr(i.ptr) + uintptr(offset+1))
|
|
|
|
// Decode the key at that restart point, and compare it to the key
|
|
// sought. See the comment in readEntry for why we manually inline the
|
|
// varint decoding.
|
|
var v1 uint32
|
|
if a := *((*uint8)(ptr)); a < 128 {
|
|
v1 = uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 1)
|
|
} else if a, b := a&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 1))); b < 128 {
|
|
v1 = uint32(b)<<7 | uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 2)
|
|
} else if b, c := b&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 2))); c < 128 {
|
|
v1 = uint32(c)<<14 | uint32(b)<<7 | uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 3)
|
|
} else if c, d := c&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 3))); d < 128 {
|
|
v1 = uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 4)
|
|
} else {
|
|
d, e := d&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 4)))
|
|
v1 = uint32(e)<<28 | uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 5)
|
|
}
|
|
|
|
if *((*uint8)(ptr)) < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 1)
|
|
} else if *((*uint8)(unsafe.Pointer(uintptr(ptr) + 1))) < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 2)
|
|
} else if *((*uint8)(unsafe.Pointer(uintptr(ptr) + 2))) < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 3)
|
|
} else if *((*uint8)(unsafe.Pointer(uintptr(ptr) + 3))) < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 4)
|
|
} else {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 5)
|
|
}
|
|
|
|
// Manually inlining base.DecodeInternalKey provides a 5-10% speedup on
|
|
// BlockIter benchmarks.
|
|
s := getBytes(ptr, int(v1))
|
|
var k InternalKey
|
|
if n := len(s) - 8; n >= 0 {
|
|
k.Trailer = binary.LittleEndian.Uint64(s[n:])
|
|
k.UserKey = s[:n:n]
|
|
// NB: We can't have duplicate keys if the globalSeqNum != 0, so we
|
|
// leave the seqnum on this key as 0 as it won't affect our search
|
|
// since ikey has the maximum seqnum.
|
|
} else {
|
|
k.Trailer = uint64(InternalKeyKindInvalid)
|
|
}
|
|
|
|
if base.InternalCompare(i.cmp, ikey, k) >= 0 {
|
|
index = h + 1 // preserves f(i-1) == false
|
|
} else {
|
|
upper = h // preserves f(j) == true
|
|
}
|
|
}
|
|
// index == upper, f(index-1) == false, and f(upper) (= f(index)) == true
|
|
// => answer is index.
|
|
}
|
|
|
|
// Since keys are strictly increasing, if index > 0 then the restart point at
|
|
// index-1 will be the largest whose key is <= the key sought. If index ==
|
|
// 0, then all keys in this block are larger than the key sought, and offset
|
|
// remains at zero.
|
|
if index > 0 {
|
|
i.offset = int32(binary.LittleEndian.Uint32(i.data[i.restarts+4*(index-1):]))
|
|
}
|
|
i.readEntry()
|
|
i.decodeInternalKey(i.key)
|
|
|
|
// Iterate from that restart point to somewhere >= the key sought.
|
|
for ; i.valid(); i.Next() {
|
|
if base.InternalCompare(i.cmp, i.ikey, ikey) >= 0 {
|
|
return &i.ikey, base.MakeInPlaceValue(i.val)
|
|
}
|
|
}
|
|
|
|
return nil, base.LazyValue{}
|
|
}
|
|
|
|
// SeekPrefixGE implements internalIterator.SeekPrefixGE, as documented in the
|
|
// pebble package.
|
|
func (i *blockIter) SeekPrefixGE(
|
|
prefix, key []byte, flags base.SeekGEFlags,
|
|
) (*base.InternalKey, base.LazyValue) {
|
|
// This should never be called as prefix iteration is handled by sstable.Iterator.
|
|
panic("pebble: SeekPrefixGE unimplemented")
|
|
}
|
|
|
|
// SeekLT implements internalIterator.SeekLT, as documented in the pebble
|
|
// package.
|
|
func (i *blockIter) SeekLT(key []byte, flags base.SeekLTFlags) (*InternalKey, base.LazyValue) {
|
|
i.clearCache()
|
|
|
|
ikey := base.MakeSearchKey(key)
|
|
|
|
// Find the index of the smallest restart point whose key is >= the key
|
|
// sought; index will be numRestarts if there is no such restart point.
|
|
i.offset = 0
|
|
var index int32
|
|
|
|
{
|
|
// NB: manually inlined sort.Search is ~5% faster.
|
|
//
|
|
// Define f(-1) == false and f(n) == true.
|
|
// Invariant: f(index-1) == false, f(upper) == true.
|
|
upper := i.numRestarts
|
|
for index < upper {
|
|
h := int32(uint(index+upper) >> 1) // avoid overflow when computing h
|
|
// index ≤ h < upper
|
|
offset := int32(binary.LittleEndian.Uint32(i.data[i.restarts+4*h:]))
|
|
// For a restart point, there are 0 bytes shared with the previous key.
|
|
// The varint encoding of 0 occupies 1 byte.
|
|
ptr := unsafe.Pointer(uintptr(i.ptr) + uintptr(offset+1))
|
|
|
|
// Decode the key at that restart point, and compare it to the key
|
|
// sought. See the comment in readEntry for why we manually inline the
|
|
// varint decoding.
|
|
var v1 uint32
|
|
if a := *((*uint8)(ptr)); a < 128 {
|
|
v1 = uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 1)
|
|
} else if a, b := a&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 1))); b < 128 {
|
|
v1 = uint32(b)<<7 | uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 2)
|
|
} else if b, c := b&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 2))); c < 128 {
|
|
v1 = uint32(c)<<14 | uint32(b)<<7 | uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 3)
|
|
} else if c, d := c&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 3))); d < 128 {
|
|
v1 = uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 4)
|
|
} else {
|
|
d, e := d&0x7f, *((*uint8)(unsafe.Pointer(uintptr(ptr) + 4)))
|
|
v1 = uint32(e)<<28 | uint32(d)<<21 | uint32(c)<<14 | uint32(b)<<7 | uint32(a)
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 5)
|
|
}
|
|
|
|
if *((*uint8)(ptr)) < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 1)
|
|
} else if *((*uint8)(unsafe.Pointer(uintptr(ptr) + 1))) < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 2)
|
|
} else if *((*uint8)(unsafe.Pointer(uintptr(ptr) + 2))) < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 3)
|
|
} else if *((*uint8)(unsafe.Pointer(uintptr(ptr) + 3))) < 128 {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 4)
|
|
} else {
|
|
ptr = unsafe.Pointer(uintptr(ptr) + 5)
|
|
}
|
|
|
|
// Manually inlining base.DecodeInternalKey provides a 5-10% speedup on
|
|
// BlockIter benchmarks.
|
|
s := getBytes(ptr, int(v1))
|
|
var k InternalKey
|
|
if n := len(s) - 8; n >= 0 {
|
|
k.Trailer = binary.LittleEndian.Uint64(s[n:])
|
|
k.UserKey = s[:n:n]
|
|
// NB: We can't have duplicate keys if the globalSeqNum != 0, so we
|
|
// leave the seqnum on this key as 0 as it won't affect our search
|
|
// since ikey has the maximum seqnum.
|
|
} else {
|
|
k.Trailer = uint64(InternalKeyKindInvalid)
|
|
}
|
|
|
|
if base.InternalCompare(i.cmp, ikey, k) > 0 {
|
|
index = h + 1 // preserves f(i-1) == false
|
|
} else {
|
|
upper = h // preserves f(j) == true
|
|
}
|
|
}
|
|
// index == upper, f(index-1) == false, and f(upper) (= f(index)) == true
|
|
// => answer is index.
|
|
}
|
|
|
|
// Since keys are strictly increasing, if index > 0 then the restart point at
|
|
// index-1 will be the largest whose key is < the key sought.
|
|
targetOffset := i.restarts
|
|
if index > 0 {
|
|
i.offset = int32(binary.LittleEndian.Uint32(i.data[i.restarts+4*(index-1):]))
|
|
if index < i.numRestarts {
|
|
targetOffset = int32(binary.LittleEndian.Uint32(i.data[i.restarts+4*(index):]))
|
|
}
|
|
} else if index == 0 {
|
|
// If index == 0 then all keys in this block are larger than the key
|
|
// sought.
|
|
i.offset = -1
|
|
i.nextOffset = 0
|
|
return nil, base.LazyValue{}
|
|
}
|
|
|
|
// Iterate from that restart point to somewhere >= the key sought, then back
|
|
// up to the previous entry. The expectation is that we'll be performing
|
|
// reverse iteration, so we cache the entries as we advance forward.
|
|
i.nextOffset = i.offset
|
|
|
|
for {
|
|
i.offset = i.nextOffset
|
|
i.readEntry()
|
|
i.decodeInternalKey(i.key)
|
|
|
|
if i.cmp(i.ikey.UserKey, ikey.UserKey) >= 0 {
|
|
// The current key is greater than or equal to our search key. Back up to
|
|
// the previous key which was less than our search key. Note that his for
|
|
// loop will execute at least once with this if-block not being true, so
|
|
// the key we are backing up to is the last one this loop cached.
|
|
i.Prev()
|
|
return &i.ikey, base.MakeInPlaceValue(i.val)
|
|
}
|
|
|
|
if i.nextOffset >= targetOffset {
|
|
// We've reached the end of the current restart block. Return the current
|
|
// key. When the restart interval is 1, the first iteration of the for
|
|
// loop will bring us here. In that case ikey is backed by the block so
|
|
// we get the desired key stability guarantee for the lifetime of the
|
|
// blockIter.
|
|
break
|
|
}
|
|
|
|
i.cacheEntry()
|
|
}
|
|
|
|
if !i.valid() {
|
|
return nil, base.LazyValue{}
|
|
}
|
|
return &i.ikey, base.MakeInPlaceValue(i.val)
|
|
}
|
|
|
|
// First implements internalIterator.First, as documented in the pebble
|
|
// package.
|
|
func (i *blockIter) First() (*InternalKey, base.LazyValue) {
|
|
i.offset = 0
|
|
if !i.valid() {
|
|
return nil, base.LazyValue{}
|
|
}
|
|
i.clearCache()
|
|
i.readEntry()
|
|
i.decodeInternalKey(i.key)
|
|
return &i.ikey, base.MakeInPlaceValue(i.val)
|
|
}
|
|
|
|
// Last implements internalIterator.Last, as documented in the pebble package.
|
|
func (i *blockIter) Last() (*InternalKey, base.LazyValue) {
|
|
// Seek forward from the last restart point.
|
|
i.offset = int32(binary.LittleEndian.Uint32(i.data[i.restarts+4*(i.numRestarts-1):]))
|
|
if !i.valid() {
|
|
return nil, base.LazyValue{}
|
|
}
|
|
|
|
i.readEntry()
|
|
i.clearCache()
|
|
|
|
for i.nextOffset < i.restarts {
|
|
i.cacheEntry()
|
|
i.offset = i.nextOffset
|
|
i.readEntry()
|
|
}
|
|
|
|
i.decodeInternalKey(i.key)
|
|
return &i.ikey, base.MakeInPlaceValue(i.val)
|
|
}
|
|
|
|
// Next implements internalIterator.Next, as documented in the pebble
|
|
// package.
|
|
func (i *blockIter) Next() (*InternalKey, base.LazyValue) {
|
|
if len(i.cachedBuf) > 0 {
|
|
// We're switching from reverse iteration to forward iteration. We need to
|
|
// populate i.fullKey with the current key we're positioned at so that
|
|
// readEntry() can use i.fullKey for key prefix decompression. Note that we
|
|
// don't know whether i.key is backed by i.cachedBuf or i.fullKey (if
|
|
// SeekLT was the previous call, i.key may be backed by i.fullKey), but
|
|
// copying into i.fullKey works for both cases.
|
|
//
|
|
// TODO(peter): Rather than clearing the cache, we could instead use the
|
|
// cache until it is exhausted. This would likely be faster than falling
|
|
// through to the normal forward iteration code below.
|
|
i.fullKey = append(i.fullKey[:0], i.key...)
|
|
i.clearCache()
|
|
}
|
|
|
|
i.offset = i.nextOffset
|
|
if !i.valid() {
|
|
return nil, base.LazyValue{}
|
|
}
|
|
i.readEntry()
|
|
// Manually inlined version of i.decodeInternalKey(i.key).
|
|
if n := len(i.key) - 8; n >= 0 {
|
|
i.ikey.Trailer = binary.LittleEndian.Uint64(i.key[n:])
|
|
i.ikey.UserKey = i.key[:n:n]
|
|
if i.globalSeqNum != 0 {
|
|
i.ikey.SetSeqNum(i.globalSeqNum)
|
|
}
|
|
} else {
|
|
i.ikey.Trailer = uint64(InternalKeyKindInvalid)
|
|
i.ikey.UserKey = nil
|
|
}
|
|
return &i.ikey, base.MakeInPlaceValue(i.val)
|
|
}
|
|
|
|
// Prev implements internalIterator.Prev, as documented in the pebble
|
|
// package.
|
|
func (i *blockIter) Prev() (*InternalKey, base.LazyValue) {
|
|
if n := len(i.cached) - 1; n >= 0 {
|
|
i.nextOffset = i.offset
|
|
e := &i.cached[n]
|
|
i.offset = e.offset
|
|
i.val = getBytes(unsafe.Pointer(uintptr(i.ptr)+uintptr(e.valStart)), int(e.valSize))
|
|
// Manually inlined version of i.decodeInternalKey(i.key).
|
|
i.key = i.cachedBuf[e.keyStart:e.keyEnd]
|
|
if n := len(i.key) - 8; n >= 0 {
|
|
i.ikey.Trailer = binary.LittleEndian.Uint64(i.key[n:])
|
|
i.ikey.UserKey = i.key[:n:n]
|
|
if i.globalSeqNum != 0 {
|
|
i.ikey.SetSeqNum(i.globalSeqNum)
|
|
}
|
|
} else {
|
|
i.ikey.Trailer = uint64(InternalKeyKindInvalid)
|
|
i.ikey.UserKey = nil
|
|
}
|
|
i.cached = i.cached[:n]
|
|
return &i.ikey, base.MakeInPlaceValue(i.val)
|
|
}
|
|
|
|
i.clearCache()
|
|
if i.offset <= 0 {
|
|
i.offset = -1
|
|
i.nextOffset = 0
|
|
return nil, base.LazyValue{}
|
|
}
|
|
|
|
targetOffset := i.offset
|
|
var index int32
|
|
|
|
{
|
|
// NB: manually inlined sort.Sort is ~5% faster.
|
|
//
|
|
// Define f(-1) == false and f(n) == true.
|
|
// Invariant: f(index-1) == false, f(upper) == true.
|
|
upper := i.numRestarts
|
|
for index < upper {
|
|
h := int32(uint(index+upper) >> 1) // avoid overflow when computing h
|
|
// index ≤ h < upper
|
|
offset := int32(binary.LittleEndian.Uint32(i.data[i.restarts+4*h:]))
|
|
if offset < targetOffset {
|
|
index = h + 1 // preserves f(i-1) == false
|
|
} else {
|
|
upper = h // preserves f(j) == true
|
|
}
|
|
}
|
|
// index == upper, f(index-1) == false, and f(upper) (= f(index)) == true
|
|
// => answer is index.
|
|
}
|
|
|
|
i.offset = 0
|
|
if index > 0 {
|
|
i.offset = int32(binary.LittleEndian.Uint32(i.data[i.restarts+4*(index-1):]))
|
|
}
|
|
|
|
i.readEntry()
|
|
|
|
for i.nextOffset < targetOffset {
|
|
i.cacheEntry()
|
|
i.offset = i.nextOffset
|
|
i.readEntry()
|
|
}
|
|
|
|
i.decodeInternalKey(i.key)
|
|
return &i.ikey, base.MakeInPlaceValue(i.val)
|
|
}
|
|
|
|
// Key implements internalIterator.Key, as documented in the pebble package.
|
|
func (i *blockIter) Key() *InternalKey {
|
|
return &i.ikey
|
|
}
|
|
|
|
func (i *blockIter) value() base.LazyValue {
|
|
return base.MakeInPlaceValue(i.val)
|
|
}
|
|
|
|
// Error implements internalIterator.Error, as documented in the pebble
|
|
// package.
|
|
func (i *blockIter) Error() error {
|
|
return nil // infallible
|
|
}
|
|
|
|
// Close implements internalIterator.Close, as documented in the pebble
|
|
// package.
|
|
func (i *blockIter) Close() error {
|
|
i.cacheHandle.Release()
|
|
i.cacheHandle = cache.Handle{}
|
|
i.val = nil
|
|
return nil
|
|
}
|
|
|
|
func (i *blockIter) SetBounds(lower, upper []byte) {
|
|
// This should never be called as bounds are handled by sstable.Iterator.
|
|
panic("pebble: SetBounds unimplemented")
|
|
}
|
|
|
|
func (i *blockIter) valid() bool {
|
|
return i.offset >= 0 && i.offset < i.restarts
|
|
}
|
|
|
|
// fragmentBlockIter wraps a blockIter, implementing the
|
|
// keyspan.FragmentIterator interface. It's used for reading range deletion and
|
|
// range key blocks.
|
|
//
|
|
// Range deletions and range keys are fragmented before they're persisted to the
|
|
// block. Overlapping fragments have identical bounds. The fragmentBlockIter
|
|
// gathers all the fragments with identical bounds within a block and returns a
|
|
// single keyspan.Span describing all the keys defined over the span.
|
|
//
|
|
// Memory lifetime
|
|
//
|
|
// A Span returned by fragmentBlockIter is only guaranteed to be stable until
|
|
// the next fragmentBlockIter iteration positioning method. A Span's Keys slice
|
|
// may be reused, so the user must not assume it's stable.
|
|
//
|
|
// Blocks holding range deletions and range keys are configured to use a restart
|
|
// interval of 1. This provides key stability. The caller may treat the various
|
|
// byte slices (start, end, suffix, value) as stable for the lifetime of the
|
|
// iterator.
|
|
type fragmentBlockIter struct {
|
|
blockIter blockIter
|
|
keyBuf [2]keyspan.Key
|
|
span keyspan.Span
|
|
err error
|
|
dir int8
|
|
closeHook func(i keyspan.FragmentIterator) error
|
|
}
|
|
|
|
func (i *fragmentBlockIter) resetForReuse() fragmentBlockIter {
|
|
return fragmentBlockIter{blockIter: i.blockIter.resetForReuse()}
|
|
}
|
|
|
|
func (i *fragmentBlockIter) decodeSpanKeys(k *InternalKey, internalValue []byte) {
|
|
// TODO(jackson): The use of i.span.Keys to accumulate keys across multiple
|
|
// calls to Decode is too confusing and subtle. Refactor to make it
|
|
// explicit.
|
|
|
|
// decode the contents of the fragment's value. This always includes at
|
|
// least the end key: RANGEDELs store the end key directly as the value,
|
|
// whereas the various range key kinds store are more complicated. The
|
|
// details of the range key internal value format are documented within the
|
|
// internal/rangekey package.
|
|
switch k.Kind() {
|
|
case base.InternalKeyKindRangeDelete:
|
|
i.span = rangedel.Decode(*k, internalValue, i.span.Keys)
|
|
i.err = nil
|
|
case base.InternalKeyKindRangeKeySet, base.InternalKeyKindRangeKeyUnset, base.InternalKeyKindRangeKeyDelete:
|
|
i.span, i.err = rangekey.Decode(*k, internalValue, i.span.Keys)
|
|
default:
|
|
i.span = keyspan.Span{}
|
|
i.err = base.CorruptionErrorf("pebble: corrupt keyspan fragment of kind %d", k.Kind())
|
|
}
|
|
}
|
|
|
|
// gatherForward gathers internal keys with identical bounds. Keys defined over
|
|
// spans of the keyspace are fragmented such that any overlapping key spans have
|
|
// identical bounds. When these spans are persisted to a range deletion or range
|
|
// key block, they may be persisted as multiple internal keys in order to encode
|
|
// multiple sequence numbers or key kinds.
|
|
//
|
|
// gatherForward iterates forward, re-combining the fragmented internal keys to
|
|
// reconstruct a keyspan.Span that holds all the keys defined over the span.
|
|
func (i *fragmentBlockIter) gatherForward(k *InternalKey, lazyValue base.LazyValue) *keyspan.Span {
|
|
i.span = keyspan.Span{}
|
|
if k == nil || !i.blockIter.valid() {
|
|
return nil
|
|
}
|
|
i.err = nil
|
|
// Use the i.keyBuf array to back the Keys slice to prevent an allocation
|
|
// when a span contains few keys.
|
|
i.span.Keys = i.keyBuf[:0]
|
|
|
|
// Decode the span's end key and individual keys from the value.
|
|
internalValue := lazyValue.InPlaceValue()
|
|
i.decodeSpanKeys(k, internalValue)
|
|
if i.err != nil {
|
|
return nil
|
|
}
|
|
prevEnd := i.span.End
|
|
|
|
// There might exist additional internal keys with identical bounds encoded
|
|
// within the block. Iterate forward, accumulating all the keys with
|
|
// identical bounds to s.
|
|
k, lazyValue = i.blockIter.Next()
|
|
internalValue = lazyValue.InPlaceValue()
|
|
for k != nil && i.blockIter.cmp(k.UserKey, i.span.Start) == 0 {
|
|
i.decodeSpanKeys(k, internalValue)
|
|
if i.err != nil {
|
|
return nil
|
|
}
|
|
|
|
// Since k indicates an equal start key, the encoded end key must
|
|
// exactly equal the original end key from the first internal key.
|
|
// Overlapping fragments are required to have exactly equal start and
|
|
// end bounds.
|
|
if i.blockIter.cmp(prevEnd, i.span.End) != 0 {
|
|
i.err = base.CorruptionErrorf("pebble: corrupt keyspan fragmentation")
|
|
i.span = keyspan.Span{}
|
|
return nil
|
|
}
|
|
k, lazyValue = i.blockIter.Next()
|
|
internalValue = lazyValue.InPlaceValue()
|
|
}
|
|
// i.blockIter is positioned over the first internal key for the next span.
|
|
return &i.span
|
|
}
|
|
|
|
// gatherBackward gathers internal keys with identical bounds. Keys defined over
|
|
// spans of the keyspace are fragmented such that any overlapping key spans have
|
|
// identical bounds. When these spans are persisted to a range deletion or range
|
|
// key block, they may be persisted as multiple internal keys in order to encode
|
|
// multiple sequence numbers or key kinds.
|
|
//
|
|
// gatherBackward iterates backwards, re-combining the fragmented internal keys
|
|
// to reconstruct a keyspan.Span that holds all the keys defined over the span.
|
|
func (i *fragmentBlockIter) gatherBackward(k *InternalKey, lazyValue base.LazyValue) *keyspan.Span {
|
|
i.span = keyspan.Span{}
|
|
if k == nil || !i.blockIter.valid() {
|
|
return nil
|
|
}
|
|
i.err = nil
|
|
// Use the i.keyBuf array to back the Keys slice to prevent an allocation
|
|
// when a span contains few keys.
|
|
i.span.Keys = i.keyBuf[:0]
|
|
|
|
// Decode the span's end key and individual keys from the value.
|
|
internalValue := lazyValue.InPlaceValue()
|
|
i.decodeSpanKeys(k, internalValue)
|
|
if i.err != nil {
|
|
return nil
|
|
}
|
|
prevEnd := i.span.End
|
|
|
|
// There might exist additional internal keys with identical bounds encoded
|
|
// within the block. Iterate backward, accumulating all the keys with
|
|
// identical bounds to s.
|
|
k, lazyValue = i.blockIter.Prev()
|
|
internalValue = lazyValue.InPlaceValue()
|
|
for k != nil && i.blockIter.cmp(k.UserKey, i.span.Start) == 0 {
|
|
i.decodeSpanKeys(k, internalValue)
|
|
if i.err != nil {
|
|
return nil
|
|
}
|
|
|
|
// Since k indicates an equal start key, the encoded end key must
|
|
// exactly equal the original end key from the first internal key.
|
|
// Overlapping fragments are required to have exactly equal start and
|
|
// end bounds.
|
|
if i.blockIter.cmp(prevEnd, i.span.End) != 0 {
|
|
i.err = base.CorruptionErrorf("pebble: corrupt keyspan fragmentation")
|
|
i.span = keyspan.Span{}
|
|
return nil
|
|
}
|
|
k, lazyValue = i.blockIter.Prev()
|
|
internalValue = lazyValue.InPlaceValue()
|
|
}
|
|
// i.blockIter is positioned over the last internal key for the previous
|
|
// span.
|
|
|
|
// Backwards iteration encounters internal keys in the wrong order.
|
|
keyspan.SortKeysByTrailer(&i.span.Keys)
|
|
|
|
return &i.span
|
|
}
|
|
|
|
// Error implements (keyspan.FragmentIterator).Error.
|
|
func (i *fragmentBlockIter) Error() error {
|
|
return i.err
|
|
}
|
|
|
|
// Close implements (keyspan.FragmentIterator).Close.
|
|
func (i *fragmentBlockIter) Close() error {
|
|
var err error
|
|
if i.closeHook != nil {
|
|
err = i.closeHook(i)
|
|
}
|
|
err = firstError(err, i.blockIter.Close())
|
|
return err
|
|
}
|
|
|
|
// First implements (keyspan.FragmentIterator).First
|
|
func (i *fragmentBlockIter) First() *keyspan.Span {
|
|
i.dir = +1
|
|
return i.gatherForward(i.blockIter.First())
|
|
}
|
|
|
|
// Last implements (keyspan.FragmentIterator).Last.
|
|
func (i *fragmentBlockIter) Last() *keyspan.Span {
|
|
i.dir = -1
|
|
return i.gatherBackward(i.blockIter.Last())
|
|
}
|
|
|
|
// Next implements (keyspan.FragmentIterator).Next.
|
|
func (i *fragmentBlockIter) Next() *keyspan.Span {
|
|
switch {
|
|
case i.dir == -1 && !i.span.Valid():
|
|
// Switching directions.
|
|
//
|
|
// i.blockIter is exhausted, before the first key. Move onto the first.
|
|
i.blockIter.First()
|
|
i.dir = +1
|
|
case i.dir == -1 && i.span.Valid():
|
|
// Switching directions.
|
|
//
|
|
// i.blockIter is currently positioned over the last internal key for
|
|
// the previous span. Next it once to move to the first internal key
|
|
// that makes up the current span, and gatherForwaad to land on the
|
|
// first internal key making up the next span.
|
|
//
|
|
// In the diagram below, if the last span returned to the user during
|
|
// reverse iteration was [b,c), i.blockIter is currently positioned at
|
|
// [a,b). The block iter must be positioned over [d,e) to gather the
|
|
// next span's fragments.
|
|
//
|
|
// ... [a,b) [b,c) [b,c) [b,c) [d,e) ...
|
|
// ^ ^
|
|
// i.blockIter want
|
|
if x := i.gatherForward(i.blockIter.Next()); invariants.Enabled && !x.Valid() {
|
|
panic("pebble: invariant violation: next entry unexpectedly invalid")
|
|
}
|
|
i.dir = +1
|
|
}
|
|
// We know that this blockIter has in-place values.
|
|
return i.gatherForward(&i.blockIter.ikey, base.MakeInPlaceValue(i.blockIter.val))
|
|
}
|
|
|
|
// Prev implements (keyspan.FragmentIterator).Prev.
|
|
func (i *fragmentBlockIter) Prev() *keyspan.Span {
|
|
switch {
|
|
case i.dir == +1 && !i.span.Valid():
|
|
// Switching directions.
|
|
//
|
|
// i.blockIter is exhausted, after the last key. Move onto the last.
|
|
i.blockIter.Last()
|
|
i.dir = -1
|
|
case i.dir == +1 && i.span.Valid():
|
|
// Switching directions.
|
|
//
|
|
// i.blockIter is currently positioned over the first internal key for
|
|
// the next span. Prev it once to move to the last internal key that
|
|
// makes up the current span, and gatherBackward to land on the last
|
|
// internal key making up the previous span.
|
|
//
|
|
// In the diagram below, if the last span returned to the user during
|
|
// forward iteration was [b,c), i.blockIter is currently positioned at
|
|
// [d,e). The block iter must be positioned over [a,b) to gather the
|
|
// previous span's fragments.
|
|
//
|
|
// ... [a,b) [b,c) [b,c) [b,c) [d,e) ...
|
|
// ^ ^
|
|
// want i.blockIter
|
|
if x := i.gatherBackward(i.blockIter.Prev()); invariants.Enabled && !x.Valid() {
|
|
panic("pebble: invariant violation: previous entry unexpectedly invalid")
|
|
}
|
|
i.dir = -1
|
|
}
|
|
// We know that this blockIter has in-place values.
|
|
return i.gatherBackward(&i.blockIter.ikey, base.MakeInPlaceValue(i.blockIter.val))
|
|
}
|
|
|
|
// SeekGE implements (keyspan.FragmentIterator).SeekGE.
|
|
func (i *fragmentBlockIter) SeekGE(k []byte) *keyspan.Span {
|
|
i.dir = +1
|
|
return i.gatherForward(i.blockIter.SeekGE(k, base.SeekGEFlags(0)))
|
|
}
|
|
|
|
// SeekLT implements (keyspan.FragmentIterator).SeekLT.
|
|
func (i *fragmentBlockIter) SeekLT(k []byte) *keyspan.Span {
|
|
i.dir = -1
|
|
return i.gatherBackward(i.blockIter.SeekLT(k, base.SeekLTFlagsNone))
|
|
}
|
|
|
|
// String implements fmt.Stringer.
|
|
func (i *fragmentBlockIter) String() string {
|
|
return "fragment-block-iter"
|
|
}
|
|
|
|
// SetCloseHook implements sstable.FragmentIterator.
|
|
func (i *fragmentBlockIter) SetCloseHook(fn func(i keyspan.FragmentIterator) error) {
|
|
i.closeHook = fn
|
|
}
|