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Upgrade versions of vendored libs

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This commit is contained in:
eleksir
2022-11-04 16:29:14 +03:00
parent fba732cc24
commit a7ae372459
941 changed files with 219674 additions and 23611 deletions
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38
vendor/github.com/cockroachdb/pebble/internal/base/comparer.go generated vendored
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@@ -66,6 +66,23 @@ type Separator func(dst, a, b []byte) []byte
// key must be valid to pass to Compare.
type Successor func(dst, a []byte) []byte
// ImmediateSuccessor is invoked with a prefix key ([Split(a) == len(a)]) and
// returns the smallest key that is larger than the given prefix a.
// ImmediateSuccessor must return a prefix key k such that:
//
// Split(k) == len(k) and Compare(k, a) > 0
//
// and there exists no representable k2 such that:
//
// Split(k2) == len(k2) and Compare(k2, a) > 0 and Compare(k2, k) < 0
//
// As an example, an implementation built on the natural byte ordering using
// bytes.Compare could append a `\0` to `a`.
//
// The dst parameter may be used to store the returned key, though it is valid
// to pass nil. The returned key must be valid to pass to Compare.
type ImmediateSuccessor func(dst, a []byte) []byte
// Split returns the length of the prefix of the user key that corresponds to
// the key portion of an MVCC encoding scheme to enable the use of prefix bloom
// filters.
@@ -104,14 +121,15 @@ type Split func(a []byte) int
// Comparer defines a total ordering over the space of []byte keys: a 'less
// than' relationship.
type Comparer struct {
Compare Compare
Equal Equal
AbbreviatedKey AbbreviatedKey
FormatKey FormatKey
FormatValue FormatValue
Separator Separator
Split Split
Successor Successor
Compare Compare
Equal Equal
AbbreviatedKey AbbreviatedKey
FormatKey FormatKey
FormatValue FormatValue
Separator Separator
Split Split
Successor Successor
ImmediateSuccessor ImmediateSuccessor
// Name is the name of the comparer.
//
@@ -193,6 +211,10 @@ var DefaultComparer = &Comparer{
return append(dst, a...)
},
ImmediateSuccessor: func(dst, a []byte) (ret []byte) {
return append(append(dst, a...), 0x00)
},
// This name is part of the C++ Level-DB implementation's default file
// format, and should not be changed.
Name: "leveldb.BytewiseComparator",

28
vendor/github.com/cockroachdb/pebble/internal/base/internal.go generated vendored
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@@ -71,6 +71,10 @@ const (
// seqNum.
InternalKeyKindMax InternalKeyKind = 21
// InternalKeyZeroSeqnumMaxTrailer is the largest trailer with a
// zero sequence number.
InternalKeyZeroSeqnumMaxTrailer = uint64(InternalKeyKindInvalid)
// A marker for an invalid key.
InternalKeyKindInvalid InternalKeyKind = 255
@@ -329,14 +333,28 @@ func (k InternalKey) SeqNum() uint64 {
// Visible returns true if the key is visible at the specified snapshot
// sequence number.
func (k InternalKey) Visible(snapshot uint64) bool {
return Visible(k.SeqNum(), snapshot)
func (k InternalKey) Visible(snapshot, batchSnapshot uint64) bool {
return Visible(k.SeqNum(), snapshot, batchSnapshot)
}
// Visible returns true if a key with the provided sequence number is visible at
// the specified snapshot sequence number.
func Visible(seqNum uint64, snapshot uint64) bool {
return seqNum < snapshot || (seqNum&InternalKeySeqNumBatch) != 0
// the specified snapshot sequence numbers.
func Visible(seqNum uint64, snapshot, batchSnapshot uint64) bool {
// There are two snapshot sequence numbers, one for committed keys and one
// for batch keys. If a seqNum is less than `snapshot`, then seqNum
// corresponds to a committed key that is visible. If seqNum has its batch
// bit set, then seqNum corresponds to an uncommitted batch key. Its
// visible if its snapshot is less than batchSnapshot.
//
// There's one complication. The maximal sequence number
// (`InternalKeySeqNumMax`) is used across Pebble for exclusive sentinel
// keys and other purposes. The maximal sequence number has its batch bit
// set, but it can never be < `batchSnapshot`, since there is no expressible
// larger snapshot. We dictate that the maximal sequence number is always
// visible.
return seqNum < snapshot ||
((seqNum&InternalKeySeqNumBatch) != 0 && seqNum < batchSnapshot) ||
seqNum == InternalKeySeqNumMax
}
// SetKind sets the kind component of the key.

252
vendor/github.com/cockroachdb/pebble/internal/base/iterator.go generated vendored
View File

@@ -85,33 +85,19 @@ import "fmt"
// them through the Error method. All of the absolute positioning methods
// reset any accumulated error before positioning. Relative positioning
// methods return without advancing if the iterator has accumulated an error.
//
// nilv == shorthand for LazyValue{}, which represents a nil value.
type InternalIterator interface {
// SeekGE moves the iterator to the first key/value pair whose key is greater
// than or equal to the given key. Returns the key and value if the iterator
// is pointing at a valid entry, and (nil, nil) otherwise. Note that SeekGE
// is pointing at a valid entry, and (nil, nilv) otherwise. Note that SeekGE
// only checks the upper bound. It is up to the caller to ensure that key
// is greater than or equal to the lower bound.
//
// trySeekUsingNext is a performance optimization that callers can use to
// indicate that they have not done any action to move this iterator beyond
// the first key that would be found if this iterator were to honestly do
// the intended seek. For example, say the caller did a
// SeekGE(k1...), followed by SeekGE(k2...) where k1 <= k2, without any
// intermediate positioning calls. The caller can safely specify true for this
// parameter in the second call. As another example, say the caller did do one
// call to Next between the two Seek calls, and k1 < k2. Again, the caller can
// safely specify a true value for this parameter. Note that a false value is
// always safe. The callee is free to ignore the true value if its
// implementation does not permit this optimization.
// - We make the caller do this determination since a string comparison of
// k1, k2 is not necessarily cheap, and there may be many iterators in
// the iterator stack. Doing it once at the root of the iterator stack
// is cheaper.
SeekGE(key []byte, trySeekUsingNext bool) (*InternalKey, []byte)
SeekGE(key []byte, flags SeekGEFlags) (*InternalKey, LazyValue)
// SeekPrefixGE moves the iterator to the first key/value pair whose key is
// greater than or equal to the given key. Returns the key and value if the
// iterator is pointing at a valid entry, and (nil, nil) otherwise. Note that
// iterator is pointing at a valid entry, and (nil, nilv) otherwise. Note that
// SeekPrefixGE only checks the upper bound. It is up to the caller to ensure
// that key is greater than or equal to the lower bound.
//
@@ -120,7 +106,7 @@ type InternalIterator interface {
// function must be supplied to the Comparer for the DB. The supplied prefix
// will be the prefix of the given key returned by that Split function. If
// the iterator is able to determine that no key with the prefix exists, it
// can return (nil,nil). Unlike SeekGE, this is not an indication that
// can return (nil,nilv). Unlike SeekGE, this is not an indication that
// iteration is exhausted.
//
// Note that the iterator may return keys not matching the prefix. It is up
@@ -132,78 +118,53 @@ type InternalIterator interface {
// not supporting reverse iteration in prefix iteration mode until a
// different positioning routine (SeekGE, SeekLT, First or Last) switches the
// iterator out of prefix iteration.
//
// trySeekUsingNext is a performance optimization that callers can use to
// indicate that they have not done any action to move this iterator
// beyond the first key that would be found if this iterator were to
// honestly do the indicated seek. For example, say the caller did a
// SeekPrefixGE(k1...), followed by SeekPrefixGE(k2...) where k1 <= k2,
// without any intermediate positioning calls. The caller can safely
// specify true for this parameter in the second call. As another example,
// say the caller did do one call to Next between the two SeekPrefixGE
// calls, and k1 < k2. Again, the caller can safely specify a true value
// for this parameter. Note that a false value is always safe. The callee
// is free to ignore the true value if its implementation does not permit
// this optimization.
// - We make the caller do this determination since a string comparison of
// k1, k2 is not necessarily cheap, and there may be many iterators in
// the iterator stack. Doing it once at the root of the iterator stack
// is cheaper.
// - This optimization could also be applied to SeekLT (where it would be
// trySeekUsingPrev). We currently only do it for SeekPrefixGE and SeekGE
// because this is where this optimization helps the performance of
// CockroachDB. The SeekLT cases in CockroachDB are typically accompanied
// with bounds that change between seek calls, and is optimized inside
// certain iterator implementations, like singleLevelIterator, without any
// extra parameter passing (though the same amortization of string
// comparisons could be done to improve that optimization, by making the
// root of the iterator stack do it).
SeekPrefixGE(prefix, key []byte, trySeekUsingNext bool) (*InternalKey, []byte)
SeekPrefixGE(prefix, key []byte, flags SeekGEFlags) (*InternalKey, LazyValue)
// SeekLT moves the iterator to the last key/value pair whose key is less
// than the given key. Returns the key and value if the iterator is pointing
// at a valid entry, and (nil, nil) otherwise. Note that SeekLT only checks
// at a valid entry, and (nil, nilv) otherwise. Note that SeekLT only checks
// the lower bound. It is up to the caller to ensure that key is less than
// the upper bound.
SeekLT(key []byte) (*InternalKey, []byte)
SeekLT(key []byte, flags SeekLTFlags) (*InternalKey, LazyValue)
// First moves the iterator the the first key/value pair. Returns the key and
// value if the iterator is pointing at a valid entry, and (nil, nil)
// value if the iterator is pointing at a valid entry, and (nil, nilv)
// otherwise. Note that First only checks the upper bound. It is up to the
// caller to ensure that First() is not called when there is a lower bound,
// and instead call SeekGE(lower).
First() (*InternalKey, []byte)
First() (*InternalKey, LazyValue)
// Last moves the iterator the the last key/value pair. Returns the key and
// value if the iterator is pointing at a valid entry, and (nil, nil)
// value if the iterator is pointing at a valid entry, and (nil, nilv)
// otherwise. Note that Last only checks the lower bound. It is up to the
// caller to ensure that Last() is not called when there is an upper bound,
// and instead call SeekLT(upper).
Last() (*InternalKey, []byte)
Last() (*InternalKey, LazyValue)
// Next moves the iterator to the next key/value pair. Returns the key and
// value if the iterator is pointing at a valid entry, and (nil, nil)
// value if the iterator is pointing at a valid entry, and (nil, nilv)
// otherwise. Note that Next only checks the upper bound. It is up to the
// caller to ensure that key is greater than or equal to the lower bound.
//
// It is valid to call Next when the iterator is positioned before the first
// key/value pair due to either a prior call to SeekLT or Prev which returned
// (nil, nil). It is not allowed to call Next when the previous call to SeekGE,
// SeekPrefixGE or Next returned (nil, nil).
Next() (*InternalKey, []byte)
// (nil, nilv). It is not allowed to call Next when the previous call to SeekGE,
// SeekPrefixGE or Next returned (nil, nilv).
Next() (*InternalKey, LazyValue)
// Prev moves the iterator to the previous key/value pair. Returns the key
// and value if the iterator is pointing at a valid entry, and (nil, nil)
// and value if the iterator is pointing at a valid entry, and (nil, nilv)
// otherwise. Note that Prev only checks the lower bound. It is up to the
// caller to ensure that key is less than the upper bound.
//
// It is valid to call Prev when the iterator is positioned after the last
// key/value pair due to either a prior call to SeekGE or Next which returned
// (nil, nil). It is not allowed to call Prev when the previous call to SeekLT
// or Prev returned (nil, nil).
Prev() (*InternalKey, []byte)
// (nil, nilv). It is not allowed to call Prev when the previous call to SeekLT
// or Prev returned (nil, nilv).
Prev() (*InternalKey, LazyValue)
// Error returns any accumulated error.
// Error returns any accumulated error. It may not include errors returned
// to the client when calling LazyValue.Value().
Error() error
// Close closes the iterator and returns any accumulated error. Exhausting
@@ -225,11 +186,137 @@ type InternalIterator interface {
fmt.Stringer
}
// InternalIteratorWithStats extends InternalIterator to expose stats.
type InternalIteratorWithStats interface {
InternalIterator
Stats() InternalIteratorStats
ResetStats()
// SeekGEFlags holds flags that may configure the behavior of a forward seek.
// Not all flags are relevant to all iterators.
type SeekGEFlags uint8
const (
seekGEFlagTrySeekUsingNext uint8 = iota
seekGEFlagRelativeSeek
seekGEFlagBatchJustRefreshed
)
// SeekGEFlagsNone is the default value of SeekGEFlags, with all flags disabled.
const SeekGEFlagsNone = SeekGEFlags(0)
// TrySeekUsingNext indicates whether a performance optimization was enabled
// by a caller, indicating the caller has not done any action to move this
// iterator beyond the first key that would be found if this iterator were to
// honestly do the intended seek. For example, say the caller did a
// SeekGE(k1...), followed by SeekGE(k2...) where k1 <= k2, without any
// intermediate positioning calls. The caller can safely specify true for this
// parameter in the second call. As another example, say the caller did do one
// call to Next between the two Seek calls, and k1 < k2. Again, the caller can
// safely specify a true value for this parameter. Note that a false value is
// always safe. The callee is free to ignore the true value if its
// implementation does not permit this optimization.
//
// We make the caller do this determination since a string comparison of k1, k2
// is not necessarily cheap, and there may be many iterators in the iterator
// stack. Doing it once at the root of the iterator stack is cheaper.
//
// This optimization could also be applied to SeekLT (where it would be
// trySeekUsingPrev). We currently only do it for SeekPrefixGE and SeekGE
// because this is where this optimization helps the performance of CockroachDB.
// The SeekLT cases in CockroachDB are typically accompanied with bounds that
// change between seek calls, and is optimized inside certain iterator
// implementations, like singleLevelIterator, without any extra parameter
// passing (though the same amortization of string comparisons could be done to
// improve that optimization, by making the root of the iterator stack do it).
func (s SeekGEFlags) TrySeekUsingNext() bool { return (s & (1 << seekGEFlagTrySeekUsingNext)) != 0 }
// RelativeSeek is set when in the course of a forward positioning operation, a
// higher-level iterator seeks a lower-level iterator to a larger key than the
// one at the current iterator position.
//
// Concretely, this occurs when the merging iterator observes a range deletion
// covering the key at a level's current position, and the merging iterator
// seeks the level to the range deletion's end key. During lazy-combined
// iteration, this flag signals to the level iterator that the seek is NOT an
// absolute-positioning operation from the perspective of the pebble.Iterator,
// and the level iterator must look for range keys in tables between the current
// iterator position and the new seeked position.
func (s SeekGEFlags) RelativeSeek() bool { return (s & (1 << seekGEFlagRelativeSeek)) != 0 }
// BatchJustRefreshed is set by Seek[Prefix]GE when an iterator's view of an
// indexed batch was just refreshed. It serves as a signal to the batch iterator
// to ignore the TrySeekUsingNext optimization, because the external knowledge
// imparted by the TrySeekUsingNext flag does not apply to the batch iterator's
// position. See (pebble.Iterator).batchJustRefreshed.
func (s SeekGEFlags) BatchJustRefreshed() bool { return (s & (1 << seekGEFlagBatchJustRefreshed)) != 0 }
// EnableTrySeekUsingNext returns the provided flags with the
// try-seek-using-next optimization enabled. See TrySeekUsingNext for an
// explanation of this optimization.
func (s SeekGEFlags) EnableTrySeekUsingNext() SeekGEFlags {
return s | (1 << seekGEFlagTrySeekUsingNext)
}
// DisableTrySeekUsingNext returns the provided flags with the
// try-seek-using-next optimization disabled.
func (s SeekGEFlags) DisableTrySeekUsingNext() SeekGEFlags {
return s &^ (1 << seekGEFlagTrySeekUsingNext)
}
// EnableRelativeSeek returns the provided flags with the relative-seek flag
// enabled. See RelativeSeek for an explanation of this flag's use.
func (s SeekGEFlags) EnableRelativeSeek() SeekGEFlags {
return s | (1 << seekGEFlagRelativeSeek)
}
// DisableRelativeSeek returns the provided flags with the relative-seek flag
// disabled.
func (s SeekGEFlags) DisableRelativeSeek() SeekGEFlags {
return s &^ (1 << seekGEFlagRelativeSeek)
}
// EnableBatchJustRefreshed returns the provided flags with the
// batch-just-refreshed bit set. See BatchJustRefreshed for an explanation of
// this flag.
func (s SeekGEFlags) EnableBatchJustRefreshed() SeekGEFlags {
return s | (1 << seekGEFlagBatchJustRefreshed)
}
// DisableBatchJustRefreshed returns the provided flags with the
// batch-just-refreshed bit unset.
func (s SeekGEFlags) DisableBatchJustRefreshed() SeekGEFlags {
return s &^ (1 << seekGEFlagBatchJustRefreshed)
}
// SeekLTFlags holds flags that may configure the behavior of a reverse seek.
// Not all flags are relevant to all iterators.
type SeekLTFlags uint8
const (
seekLTFlagRelativeSeek uint8 = iota
)
// SeekLTFlagsNone is the default value of SeekLTFlags, with all flags disabled.
const SeekLTFlagsNone = SeekLTFlags(0)
// RelativeSeek is set when in the course of a reverse positioning operation, a
// higher-level iterator seeks a lower-level iterator to a smaller key than the
// one at the current iterator position.
//
// Concretely, this occurs when the merging iterator observes a range deletion
// covering the key at a level's current position, and the merging iterator
// seeks the level to the range deletion's start key. During lazy-combined
// iteration, this flag signals to the level iterator that the seek is NOT an
// absolute-positioning operation from the perspective of the pebble.Iterator,
// and the level iterator must look for range keys in tables between the current
// iterator position and the new seeked position.
func (s SeekLTFlags) RelativeSeek() bool { return s&(1<<seekLTFlagRelativeSeek) != 0 }
// EnableRelativeSeek returns the provided flags with the relative-seek flag
// enabled. See RelativeSeek for an explanation of this flag's use.
func (s SeekLTFlags) EnableRelativeSeek() SeekLTFlags {
return s | (1 << seekLTFlagRelativeSeek)
}
// DisableRelativeSeek returns the provided flags with the relative-seek flag
// disabled.
func (s SeekLTFlags) DisableRelativeSeek() SeekLTFlags {
return s &^ (1 << seekLTFlagRelativeSeek)
}
// InternalIteratorStats contains miscellaneous stats produced by
@@ -238,8 +325,8 @@ type InternalIteratorWithStats interface {
// are aggregated as one goes up the InternalIterator tree.
type InternalIteratorStats struct {
// Bytes in the loaded blocks. If the block was compressed, this is the
// compressed bytes. Currently, only the second-level index and data blocks
// containing points are included.
// compressed bytes. Currently, only the index blocks, data blocks
// containing points, and filter blocks are included.
BlockBytes uint64
// Subset of BlockBytes that were in the block cache.
BlockBytesInCache uint64
@@ -271,30 +358,3 @@ func (s *InternalIteratorStats) Merge(from InternalIteratorStats) {
s.PointCount += from.PointCount
s.PointsCoveredByRangeTombstones += from.PointsCoveredByRangeTombstones
}
type internalIteratorWithEmptyStats struct {
InternalIterator
}
var _ InternalIteratorWithStats = internalIteratorWithEmptyStats{}
// Stats implements InternalIteratorWithStats.
func (i internalIteratorWithEmptyStats) Stats() InternalIteratorStats {
return InternalIteratorStats{}
}
// ResetStats implements InternalIteratorWithStats.
func (i internalIteratorWithEmptyStats) ResetStats() {}
// WrapIterWithStats ensures that either iter implements the stats methods or
// wraps it, such that the return value implements InternalIteratorWithStats.
func WrapIterWithStats(iter InternalIterator) InternalIteratorWithStats {
if iter == nil {
return nil
}
i, ok := iter.(InternalIteratorWithStats)
if ok {
return i
}
return internalIteratorWithEmptyStats{InternalIterator: iter}
}

256
vendor/github.com/cockroachdb/pebble/internal/base/lazy_value.go generated vendored Normal file
View File

@@ -0,0 +1,256 @@
// Copyright 2022 The LevelDB-Go and Pebble Authors. All rights reserved. Use
// of this source code is governed by a BSD-style license that can be found in
// the LICENSE file.
package base
import "github.com/cockroachdb/pebble/internal/invariants"
// A value can have user-defined attributes that are a function of the value
// byte slice. For now, we only support "short attributes", which can be
// encoded in 3 bits. We will likely extend this to "long attributes" later
// for values that are even more expensive to access than those in value
// blocks in the same sstable.
//
// When a sstable writer chooses not to store a value together with the key,
// it can call the ShortAttributeExtractor to extract the attribute and store
// it together with the key. This allows for cheap retrieval of
// AttributeAndLen on the read-path, without doing a more expensive retrieval
// of the value.
//
// In general, the extraction code may want to also look at the key to decide
// how to treat the value. Our current needs can be satisfied by configuring a
// keyspan for which the ShortAttributeExtractor should be used, so we do not
// expose the key to the extractor.
//
// Write path performance: The ShortAttributeExtractor func cannot be inlined,
// so we will pay the cost of this function call. However, we will only pay
// this when (a) the value is not being stored together with the key, and (b)
// the key-value pair is being initially written to the DB, or a compaction is
// transitioning the key-value pair from being stored together to being stored
// separately.
// ShortAttribute encodes a user-specified attribute of the value.
type ShortAttribute uint8
// MaxShortAttribute is the maximum value of the short attribute (3 bits).
const MaxShortAttribute = 7
// ShortAttributeExtractor is an extractor that given the value, will return
// the ShortAttribute.
type ShortAttributeExtractor func(value []byte) (ShortAttribute, error)
// AttributeAndLen represents the pair of value length and the short
// attribute.
type AttributeAndLen struct {
ValueLen int32
ShortAttribute ShortAttribute
}
// LazyValue represents a value that may not already have been extracted.
// Currently, it can represent either an in-place value (stored with the key)
// or a value stored in the value section. However, the interface is general
// enough to support values that are stored in separate files.
//
// LazyValue is used in the InternalIterator interface, such that all
// positioning calls return (*InternalKey, LazyValue). It is also exposed via
// the public Iterator for callers that need to remember a recent but not
// necessarily latest LazyValue, in case they need the actual value in the
// future. An example is a caller that is iterating in reverse and looking for
// the latest MVCC version for a key -- it cannot identify the latest MVCC
// version without stepping to the previous key-value pair e.g.
// storage.pebbleMVCCScanner in CockroachDB.
//
// Performance note: It is important for this struct to not exceed a sizeof 32
// bytes, for optimizing the common case of the in-place value. Prior to
// introducing LazyValue, we were passing around a []byte which is 24 bytes.
// Passing a 40 byte or larger struct causes performance to drop by 75% on
// some benchmarks that do tight iteration loops.
//
// Memory management:
// This is subtle, but important for performance.
//
// - A LazyValue returned by an InternalIterator or Iterator is unstable in
// that repositioning the iterator will invalidate the memory inside it. A
// caller wishing to maintain that LazyValue needs to call
// LazyValue.Clone(). Note that this does not fetch the value if it is not
// in-place. Additionally, Clone() *must* only be called if
// LazyValue.Value() has *not* been called, since (a) it only makes a
// promise about stability of LazyValue and not the underlying value, (b) if
// LazyValue.Value() has been called already, the caller has the value
// []byte slice so it is unnecessary to fiddle around with LazyValue.
//
// - A user of an iterator that calls LazyValue.Value() wants as much as
// possible for the returned value []byte to point to iterator owned memory.
// - [P1] The underlying iterator that owns that memory also needs a promise
// from that user that at any time there is at most one value []byte slice
// that the caller is expecting it to maintain. Otherwise, the underlying
// iterator has to maintain multiple such []byte slices which results in
// more complicated and inefficient code.
// - [P2] The underlying iterator, in order to make the promise that it is
// maintaining the one value []byte slice, also needs a way to know when
// it is relieved of that promise. One way it is relieved of that promise
// is by being told that it is being repositioned. Typically, the owner of
// the value []byte slice is a sstable iterator, and it will know that it
// is relieved of the promise when it is repositioned. However, consider
// the case where the caller has used LazyValue.Clone() and repositioned
// the iterator (which is actually a tree of iterators). In this case the
// underlying sstable iterator may not even be open. LazyValue.Value()
// will still work (at a higher cost), but since the sstable iterator is
// not open, it does not have a mechanism to know when the retrieved value
// is no longer in use. We refer to this situation as "not satisfying P2".
// To handle this situation, the LazyValue.Value() method accepts a caller
// owned buffer, that the callee will use if needed. The callee explicitly
// tells the caller whether the []byte slice for the value is now owned by
// the caller. This will be true if the callee attempted to use buf and
// either successfully used it or allocated a new []byte slice.
//
// To ground the above in reality, we consider three examples of callers of
// LazyValue.Value():
// - Iterator: it calls LazyValue.Value for its own use when merging values.
// When merging during reverse iteration, it may have cloned the LazyValue.
// In this case it calls LazyValue.Value() on the cloned value, merges it,
// and then calls LazyValue.Value() on the current iterator position and
// merges it. So it is honoring P1.
// - Iterator on behalf of Iterator clients: The Iterator.Value() method
// needs to call LazyValue.Value(). The client of Iterator is satisfying P1
// because of the inherent Iterator interface constraint, i.e., it is calling
// Iterator.Value() on the current Iterator position. It is possible that
// the Iterator has cloned this LazyValue (for the reverse iteration case),
// which the client is unaware of, so the underlying sstable iterator may
// not be able to satisfy P2. This is ok because Iterator will call
// LazyValue.Value with its (reusable) owned buffer.
// - CockroachDB's pebbleMVCCScanner: This will use LazyValues from Iterator
// since during reverse iteration in order to find the highest version that
// satisfies a read it needs to clone the LazyValue, step back the iterator
// and then decide whether it needs the value from the previously cloned
// LazyValue. The pebbleMVCCScanner will satisfy P1. The P2 story is
// similar to the previous case in that it will call LazyValue.Value with
// its (reusable) owned buffer.
//
// Corollary: callers that directly use InternalIterator can know that they
// have done nothing to interfere with promise P2 can pass in a nil buf and be
// sure that it will not trigger an allocation.
//
// Repeated calling of LazyValue.Value:
// This is ok as long as the caller continues to satisfy P1. The previously
// fetched value will be remembered inside LazyValue to avoid fetching again.
// So if the caller's buffer is used the first time the value was fetched, it
// is still in use.
//
// LazyValue fields are visible outside the package for use in
// InternalIterator implementations and in Iterator, but not meant for direct
// use by users of Pebble.
type LazyValue struct {
// ValueOrHandle represents a value, or a handle to be passed to ValueFetcher.
// - Fetcher == nil: ValueOrHandle is a value.
// - Fetcher != nil: ValueOrHandle is a handle and Fetcher.Attribute is
// initialized.
// The ValueOrHandle exposed by InternalIterator or Iterator may not be stable
// if the iterator is stepped. To make it stable, make a copy using Clone.
ValueOrHandle []byte
// Fetcher provides support for fetching an actually lazy value.
Fetcher *LazyFetcher
}
// LazyFetcher supports fetching a lazy value.
type LazyFetcher struct {
// ValueFetcher, given a handle, returns the value. It is acceptable to call
// the ValueFetcher as long as the DB is open. However, one should assume
// there is a fast-path when the iterator tree has not moved off the sstable
// iterator that initially provided this LazyValue. Hence, to utilize this
// fast-path the caller should try to decide whether it needs the value or
// not as soon as possible, with minimal possible stepping of the iterator.
//
// buf will be used if the fetcher cannot satisfy P2 (see earlier comment).
// If the fetcher attempted to use buf *and* len(buf) was insufficient, it
// will allocate a new slice for the value. In either case it will set
// callerOwned to true.
ValueFetcher func(handle []byte, buf []byte) (val []byte, callerOwned bool, err error)
// Attribute includes the short attribute and value length.
Attribute AttributeAndLen
fetched bool
value []byte
callerOwned bool
err error
}
// Value returns the underlying value.
func (lv *LazyValue) Value(buf []byte) (val []byte, callerOwned bool, err error) {
if lv.Fetcher == nil {
return lv.ValueOrHandle, false, nil
}
// Do the rest of the work in a separate method to attempt mid-stack
// inlining of Value(). Unfortunately, this still does not inline since the
// cost of 85 exceeds the budget of 80.
//
// TODO(sumeer): Packing the return values into a struct{[]byte error bool}
// causes it to be below the budget. Consider this if we need to recover
// more performance. I suspect that inlining this only matters in
// micro-benchmarks, and in actual use cases in CockroachDB it will not
// matter because there is substantial work done with a fetched value.
return lv.fetchValue(buf)
}
// INVARIANT: lv.Fetcher != nil
func (lv *LazyValue) fetchValue(buf []byte) (val []byte, callerOwned bool, err error) {
f := lv.Fetcher
if !f.fetched {
f.fetched = true
f.value, f.callerOwned, f.err = lv.Fetcher.ValueFetcher(lv.ValueOrHandle, buf)
}
return f.value, f.callerOwned, f.err
}
// InPlaceValue returns the value under the assumption that it is in-place.
// This is for Pebble-internal code.
func (lv *LazyValue) InPlaceValue() []byte {
if invariants.Enabled && lv.Fetcher != nil {
panic("value must be in-place")
}
return lv.ValueOrHandle
}
// Len returns the length of the value.
func (lv *LazyValue) Len() int {
if lv.Fetcher == nil {
return len(lv.ValueOrHandle)
}
return int(lv.Fetcher.Attribute.ValueLen)
}
// Clone creates a stable copy of the LazyValue, by appending bytes to buf.
// REQUIRES: LazyValue.Value() has not been called.
// Ensure that this is only called before LazyValue.Value is called. We don't
// actually care if it was in-place but we don't want confusing things about whether
// we need to clone the value inside the fetcher.
func (lv *LazyValue) Clone(buf []byte) (LazyValue, []byte) {
if invariants.Enabled && lv.Fetcher != nil && lv.Fetcher.fetched {
panic("value has already been fetched")
}
// INVARIANT: LazyFetcher.value is nil, so there is nothing to copy there.
vLen := len(lv.ValueOrHandle)
lvCopy := LazyValue{Fetcher: lv.Fetcher}
if vLen == 0 {
return lvCopy, buf
}
bufLen := len(buf)
buf = append(buf, lv.ValueOrHandle...)
lvCopy.ValueOrHandle = buf[bufLen : bufLen+vLen]
return lvCopy, buf
}
// MakeInPlaceValue constructs an in-place value.
func MakeInPlaceValue(val []byte) LazyValue {
return LazyValue{ValueOrHandle: val}
}
// TODO(sumeer): test that callers are adhering to promise P1. In the sstable
// iterators, when invariants are enabled, create a testingFetcher struct that
// contains the sstable name and the []byte backing for the last fetched
// value. The sstable iterator, instead of returning an in-place value, will
// return a copy of the key in ValueOrHandle, and a ValueFetcher implemented
// by testingFetcher.valueFetcher. Each time this method is called, it will
// mangle the last fetched value []byte slice, allocate a new one, open the
// sstable, seek to the key, and copy the value into this new byte slice and
// return.

13
vendor/github.com/cockroachdb/pebble/internal/base/metrics.go generated vendored
View File

@@ -29,6 +29,13 @@ func (tm *ThroughputMetric) Merge(x ThroughputMetric) {
tm.IdleDuration += x.IdleDuration
}
// Subtract subtracts the information from another ThroughputMetric
func (tm *ThroughputMetric) Subtract(x ThroughputMetric) {
tm.Bytes -= x.Bytes
tm.WorkDuration -= x.WorkDuration
tm.IdleDuration -= x.IdleDuration
}
// PeakRate returns the approximate peak rate if there was no idling.
func (tm *ThroughputMetric) PeakRate() int64 {
if tm.Bytes == 0 {
@@ -67,6 +74,12 @@ func (gsm *GaugeSampleMetric) Merge(x GaugeSampleMetric) {
gsm.count += x.count
}
// Subtract subtracts the information from another gauge metric.
func (gsm *GaugeSampleMetric) Subtract(x GaugeSampleMetric) {
gsm.sampleSum -= x.sampleSum
gsm.count -= x.count
}
// Mean returns the mean value.
func (gsm *GaugeSampleMetric) Mean() float64 {
if gsm.count == 0 {