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Update dependencies

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This commit is contained in:
eleksir
2024-07-24 22:57:56 +03:00
parent ac243bf4fd
commit 00257b8e6c
729 changed files with 47714 additions and 29066 deletions
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686
vendor/github.com/cockroachdb/pebble/compaction_iter.go generated vendored
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@@ -15,9 +15,9 @@ import (
"github.com/cockroachdb/errors"
"github.com/cockroachdb/pebble/internal/base"
"github.com/cockroachdb/pebble/internal/bytealloc"
"github.com/cockroachdb/pebble/internal/invariants"
"github.com/cockroachdb/pebble/internal/keyspan"
"github.com/cockroachdb/pebble/internal/rangekey"
"github.com/cockroachdb/redact"
)
// compactionIter provides a forward-only iterator that encapsulates the logic
@@ -207,14 +207,6 @@ type compactionIter struct {
// its elision. This field only applies to point keys, and not to range
// deletions or range keys.
//
// snapshotPinned is also used to set the forceObsolete value in the call to
// Writer.AddWithForceObsolete. Note that in that call, it is sufficient to
// mark all keys obsoleted by RANGEDELs as forceObsolete=true and that the
// implementation of Writer.AddWithForceObsolete will itself discover other
// causes of obsolescence. We mention this since in the presence of MERGE,
// obsolescence due to multiple keys at the same user key is not fully
// represented by snapshotPinned=true:
//
// For MERGE, it is possible that doing the merge is interrupted even when
// the next point key is in the same stripe. This can happen if the loop in
// mergeNext gets interrupted by sameStripeNonSkippable.
@@ -222,6 +214,21 @@ type compactionIter struct {
// SET/MERGE/DEL with the same seqnum, so the RANGEDEL does not necessarily
// delete the subsequent SET/MERGE/DEL keys.
snapshotPinned bool
// forceObsoleteDueToRangeDel is set to true in a subset of the cases that
// snapshotPinned is true. This value is true when the point is obsolete due
// to a RANGEDEL but could not be deleted due to a snapshot.
//
// NB: it may seem that the additional cases that snapshotPinned captures
// are harmless in that they can also be used to mark a point as obsolete
// (it is merely a duplication of some logic that happens in
// Writer.AddWithForceObsolete), but that is not quite accurate as of this
// writing -- snapshotPinned originated in stats collection and for a
// sequence MERGE, SET, where the MERGE cannot merge with the (older) SET
// due to a snapshot, the snapshotPinned value for the SET is true.
//
// TODO(sumeer,jackson): improve the logic of snapshotPinned and reconsider
// whether we need forceObsoleteDueToRangeDel.
forceObsoleteDueToRangeDel bool
// The index of the snapshot for the current key within the snapshots slice.
curSnapshotIdx int
curSnapshotSeqNum uint64
@@ -249,10 +256,12 @@ type compactionIter struct {
// The fragmented range keys.
rangeKeys []keyspan.Span
// Byte allocator for the tombstone keys.
alloc bytealloc.A
allowZeroSeqNum bool
elideTombstone func(key []byte) bool
elideRangeTombstone func(start, end []byte) bool
alloc bytealloc.A
allowZeroSeqNum bool
elideTombstone func(key []byte) bool
elideRangeTombstone func(start, end []byte) bool
ineffectualSingleDeleteCallback func(userKey []byte)
singleDeleteInvariantViolationCallback func(userKey []byte)
// The on-disk format major version. This informs the types of keys that
// may be written to disk during a compaction.
formatVersion FormatMajorVersion
@@ -274,20 +283,24 @@ func newCompactionIter(
allowZeroSeqNum bool,
elideTombstone func(key []byte) bool,
elideRangeTombstone func(start, end []byte) bool,
ineffectualSingleDeleteCallback func(userKey []byte),
singleDeleteInvariantViolationCallback func(userKey []byte),
formatVersion FormatMajorVersion,
) *compactionIter {
i := &compactionIter{
equal: equal,
merge: merge,
iter: iter,
snapshots: snapshots,
frontiers: frontiers{cmp: cmp},
rangeDelFrag: rangeDelFrag,
rangeKeyFrag: rangeKeyFrag,
allowZeroSeqNum: allowZeroSeqNum,
elideTombstone: elideTombstone,
elideRangeTombstone: elideRangeTombstone,
formatVersion: formatVersion,
equal: equal,
merge: merge,
iter: iter,
snapshots: snapshots,
frontiers: frontiers{cmp: cmp},
rangeDelFrag: rangeDelFrag,
rangeKeyFrag: rangeKeyFrag,
allowZeroSeqNum: allowZeroSeqNum,
elideTombstone: elideTombstone,
elideRangeTombstone: elideRangeTombstone,
ineffectualSingleDeleteCallback: ineffectualSingleDeleteCallback,
singleDeleteInvariantViolationCallback: singleDeleteInvariantViolationCallback,
formatVersion: formatVersion,
}
i.rangeDelFrag.Cmp = cmp
i.rangeDelFrag.Format = formatKey
@@ -326,7 +339,7 @@ func (i *compactionIter) Next() (*InternalKey, []byte) {
return nil, nil
}
// Prior to this call to `Next()` we are in one of three situations with
// Prior to this call to `Next()` we are in one of four situations with
// respect to `iterKey` and related state:
//
// - `!skip && pos == iterPosNext`: `iterKey` is already at the next key.
@@ -335,12 +348,34 @@ func (i *compactionIter) Next() (*InternalKey, []byte) {
// snapshot stripe.
// - `skip && pos == iterPosCurForward`: We are at the key that has been returned.
// To move forward we skip skippable entries in the stripe.
// - `skip && pos == iterPosNext && i.iterStripeChange == sameStripeNonSkippable`:
// This case may occur when skipping within a snapshot stripe and we
// encounter either:
// a) an invalid key kind; The previous call will have returned
// whatever key it was processing and deferred handling of the
// invalid key to this invocation of Next(). We're responsible for
// ignoring skip=true and falling into the invalid key kind case
// down below.
// b) an interleaved range delete; This is a wart of the current code
// structure. While skipping within a snapshot stripe, a range
// delete interleaved at its start key and sequence number
// interrupts the sequence of point keys. After we return the range
// delete to the caller, we need to pick up skipping at where we
// left off, so we preserve skip=true.
// TODO(jackson): This last case is confusing and can be removed if we
// interleave range deletions at the maximal sequence number using the
// keyspan interleaving iterator. This is the treatment given to range
// keys today.
if i.pos == iterPosCurForward {
if i.skip {
i.skipInStripe()
} else {
i.nextInStripe()
}
} else if i.skip {
if i.iterStripeChange != sameStripeNonSkippable {
panic(errors.AssertionFailedf("compaction iterator has skip=true, but iterator is at iterPosNext"))
}
}
i.pos = iterPosCurForward
@@ -394,6 +429,10 @@ func (i *compactionIter) Next() (*InternalKey, []byte) {
return &i.key, i.value
}
// TODO(sumeer): we could avoid calling Covers if i.iterStripeChange ==
// sameStripeSameKey since that check has already been done in
// nextInStripeHelper. However, we also need to handle the case of
// CoversInvisibly below.
if cover := i.rangeDelFrag.Covers(*i.iterKey, i.curSnapshotSeqNum); cover == keyspan.CoversVisibly {
// A pending range deletion deletes this key. Skip it.
i.saveKey()
@@ -410,6 +449,9 @@ func (i *compactionIter) Next() (*InternalKey, []byte) {
// key is in the same snapshot stripe. Hence, snapshotPinned is by
// definition false in those cases.
i.snapshotPinned = true
i.forceObsoleteDueToRangeDel = true
} else {
i.forceObsoleteDueToRangeDel = false
}
switch i.iterKey.Kind() {
@@ -419,7 +461,17 @@ func (i *compactionIter) Next() (*InternalKey, []byte) {
// If we're at the last snapshot stripe and the tombstone
// can be elided skip skippable keys in the same stripe.
i.saveKey()
i.skipInStripe()
if i.key.Kind() == InternalKeyKindSingleDelete {
i.skipDueToSingleDeleteElision()
} else {
i.skipInStripe()
if !i.skip && i.iterStripeChange != newStripeNewKey {
panic(errors.AssertionFailedf("pebble: skipInStripe in last stripe disabled skip without advancing to new key"))
}
}
if i.iterStripeChange == newStripeSameKey {
panic(errors.AssertionFailedf("pebble: skipInStripe in last stripe found a new stripe within the same key"))
}
continue
} else {
// We're not at the last snapshot stripe, so the tombstone
@@ -446,8 +498,14 @@ func (i *compactionIter) Next() (*InternalKey, []byte) {
case InternalKeyKindSingleDelete:
if i.singleDeleteNext() {
return &i.key, i.value
} else if i.err != nil {
return nil, nil
}
continue
default:
panic(errors.AssertionFailedf(
"unexpected kind %s", redact.SafeString(i.iterKey.Kind().String())))
}
case InternalKeyKindSet, InternalKeyKindSetWithDelete:
@@ -457,6 +515,9 @@ func (i *compactionIter) Next() (*InternalKey, []byte) {
// preserving the original value, and potentially mutating the key
// kind.
i.setNext()
if i.err != nil {
return nil, nil
}
return &i.key, i.value
case InternalKeyKindMerge:
@@ -473,7 +534,15 @@ func (i *compactionIter) Next() (*InternalKey, []byte) {
if i.err == nil {
// includesBase is true whenever we've transformed the MERGE record
// into a SET.
includesBase := i.key.Kind() == InternalKeyKindSet
var includesBase bool
switch i.key.Kind() {
case InternalKeyKindSet, InternalKeyKindSetWithDelete:
includesBase = true
case InternalKeyKindMerge:
default:
panic(errors.AssertionFailedf(
"unexpected kind %s", redact.SafeString(i.key.Kind().String())))
}
i.value, needDelete, i.valueCloser, i.err = finishValueMerger(valueMerger, includesBase)
}
if i.err == nil {
@@ -502,6 +571,8 @@ func (i *compactionIter) Next() (*InternalKey, []byte) {
}
if i.err != nil {
i.valid = false
// TODO(sumeer): why is MarkCorruptionError only being called for
// MERGE?
i.err = base.MarkCorruptionError(i.err)
}
return nil, nil
@@ -541,10 +612,16 @@ func snapshotIndex(seq uint64, snapshots []uint64) (int, uint64) {
return index, snapshots[index]
}
// skipInStripe skips over skippable keys in the same stripe and user key.
// skipInStripe skips over skippable keys in the same stripe and user key. It
// may set i.err, in which case i.iterKey will be nil.
func (i *compactionIter) skipInStripe() {
i.skip = true
// TODO(sumeer): we can avoid the overhead of calling i.rangeDelFrag.Covers,
// in this case of nextInStripe, since we are skipping all of them anyway.
for i.nextInStripe() == sameStripeSkippable {
if i.err != nil {
panic(i.err)
}
}
// Reset skip if we landed outside the original stripe. Otherwise, we landed
// in the same stripe on a non-skippable key. In that case we should preserve
@@ -582,11 +659,17 @@ const (
// nextInStripe advances the iterator and returns one of the above const ints
// indicating how its state changed.
//
// All sameStripeSkippable keys that are covered by a RANGEDEL will be skipped
// and not returned.
//
// Calls to nextInStripe must be preceded by a call to saveKey to retain a
// temporary reference to the original key, so that forward iteration can
// proceed with a reference to the original key. Care should be taken to avoid
// overwriting or mutating the saved key or value before they have been returned
// to the caller of the exported function (i.e. the caller of Next, First, etc.)
//
// nextInStripe may set i.err, in which case the return value will be
// newStripeNewKey, and i.iterKey will be nil.
func (i *compactionIter) nextInStripe() stripeChangeType {
i.iterStripeChange = i.nextInStripeHelper()
return i.iterStripeChange
@@ -595,58 +678,72 @@ func (i *compactionIter) nextInStripe() stripeChangeType {
// nextInStripeHelper is an internal helper for nextInStripe; callers should use
// nextInStripe and not call nextInStripeHelper.
func (i *compactionIter) nextInStripeHelper() stripeChangeType {
if !i.iterNext() {
return newStripeNewKey
}
key := i.iterKey
origSnapshotIdx := i.curSnapshotIdx
for {
if !i.iterNext() {
return newStripeNewKey
}
key := i.iterKey
// NB: The below conditional is an optimization to avoid a user key
// comparison in many cases. Internal keys with the same user key are
// ordered in (strictly) descending order by trailer. If the new key has a
// greater or equal trailer, or the previous key had a zero sequence number,
// the new key must have a new user key.
//
// A couple things make these cases common:
// - Sequence-number zeroing ensures ~all of the keys in L6 have a zero
// sequence number.
// - Ingested sstables' keys all adopt the same sequence number.
if i.keyTrailer <= base.InternalKeyZeroSeqnumMaxTrailer || key.Trailer >= i.keyTrailer {
if invariants.Enabled && i.equal(i.key.UserKey, key.UserKey) {
if !i.equal(i.key.UserKey, key.UserKey) {
i.curSnapshotIdx, i.curSnapshotSeqNum = snapshotIndex(key.SeqNum(), i.snapshots)
return newStripeNewKey
}
// If i.key and key have the same user key, then
// 1. i.key must not have had a zero sequence number (or it would've be the last
// key with its user key).
// 2. i.key must have a strictly larger sequence number
// There's an exception in that either key may be a range delete. Range
// deletes may share a sequence number with a point key if the keys were
// ingested together. Range keys may also share the sequence number if they
// were ingested, but range keys are interleaved into the compaction
// iterator's input iterator at the maximal sequence number so their
// original sequence number will not be observed here.
if prevSeqNum := base.SeqNumFromTrailer(i.keyTrailer); (prevSeqNum == 0 || prevSeqNum <= key.SeqNum()) &&
i.key.Kind() != InternalKeyKindRangeDelete && key.Kind() != InternalKeyKindRangeDelete {
prevKey := i.key
prevKey.Trailer = i.keyTrailer
panic(fmt.Sprintf("pebble: invariant violation: %s and %s out of order", key, prevKey))
panic(errors.AssertionFailedf("pebble: invariant violation: %s and %s out of order", prevKey, key))
}
i.curSnapshotIdx, i.curSnapshotSeqNum = snapshotIndex(key.SeqNum(), i.snapshots)
return newStripeNewKey
} else if !i.equal(i.key.UserKey, key.UserKey) {
i.curSnapshotIdx, i.curSnapshotSeqNum = snapshotIndex(key.SeqNum(), i.snapshots)
return newStripeNewKey
}
origSnapshotIdx := i.curSnapshotIdx
i.curSnapshotIdx, i.curSnapshotSeqNum = snapshotIndex(key.SeqNum(), i.snapshots)
switch key.Kind() {
case InternalKeyKindRangeDelete:
// Range tombstones need to be exposed by the compactionIter to the upper level
// `compaction` object, so return them regardless of whether they are in the same
// snapshot stripe.
if i.curSnapshotIdx == origSnapshotIdx {
return sameStripeNonSkippable
switch key.Kind() {
case InternalKeyKindRangeDelete:
// Range tombstones need to be exposed by the compactionIter to the upper level
// `compaction` object, so return them regardless of whether they are in the same
// snapshot stripe.
if i.curSnapshotIdx == origSnapshotIdx {
return sameStripeNonSkippable
}
return newStripeSameKey
case InternalKeyKindRangeKeySet, InternalKeyKindRangeKeyUnset, InternalKeyKindRangeKeyDelete:
// Range keys are interleaved at the max sequence number for a given user
// key, so we should not see any more range keys in this stripe.
panic("unreachable")
case InternalKeyKindInvalid:
if i.curSnapshotIdx == origSnapshotIdx {
return sameStripeNonSkippable
}
return newStripeSameKey
case InternalKeyKindDelete, InternalKeyKindSet, InternalKeyKindMerge, InternalKeyKindSingleDelete,
InternalKeyKindSetWithDelete, InternalKeyKindDeleteSized:
// Fall through
default:
i.iterKey = nil
i.err = base.CorruptionErrorf("invalid internal key kind: %d", errors.Safe(i.iterKey.Kind()))
i.valid = false
return newStripeNewKey
}
return newStripeSameKey
case InternalKeyKindRangeKeySet, InternalKeyKindRangeKeyUnset, InternalKeyKindRangeKeyDelete:
// Range keys are interleaved at the max sequence number for a given user
// key, so we should not see any more range keys in this stripe.
panic("unreachable")
case InternalKeyKindInvalid:
if i.curSnapshotIdx == origSnapshotIdx {
return sameStripeNonSkippable
// Same snapshot.
if i.rangeDelFrag.Covers(*i.iterKey, i.curSnapshotSeqNum) == keyspan.CoversVisibly {
continue
}
return sameStripeSkippable
}
return newStripeSameKey
}
if i.curSnapshotIdx == origSnapshotIdx {
return sameStripeSkippable
}
return newStripeSameKey
}
func (i *compactionIter) setNext() {
@@ -672,6 +769,10 @@ func (i *compactionIter) setNext() {
// Else, we continue to loop through entries in the stripe looking for a
// DEL. Note that we may stop *before* encountering a DEL, if one exists.
//
// NB: nextInStripe will skip sameStripeSkippable keys that are visibly
// covered by a RANGEDEL. This can include DELs -- this is fine since such
// DELs don't need to be combined with SET to make SETWITHDEL.
for {
switch i.nextInStripe() {
case newStripeNewKey, newStripeSameKey:
@@ -722,12 +823,16 @@ func (i *compactionIter) setNext() {
// We're still in the same stripe. If this is a
// DEL/SINGLEDEL/DELSIZED, we stop looking and emit a SETWITHDEL.
// Subsequent keys are eligible for skipping.
if i.iterKey.Kind() == InternalKeyKindDelete ||
i.iterKey.Kind() == InternalKeyKindSingleDelete ||
i.iterKey.Kind() == InternalKeyKindDeleteSized {
switch i.iterKey.Kind() {
case InternalKeyKindDelete, InternalKeyKindSingleDelete, InternalKeyKindDeleteSized:
i.key.SetKind(InternalKeyKindSetWithDelete)
i.skip = true
return
case InternalKeyKindSet, InternalKeyKindMerge, InternalKeyKindSetWithDelete:
// Do nothing
default:
i.err = base.CorruptionErrorf("invalid internal key kind: %d", errors.Safe(i.iterKey.Kind()))
i.valid = false
}
default:
panic("pebble: unexpected stripeChangeType: " + strconv.Itoa(int(i.iterStripeChange)))
@@ -747,13 +852,24 @@ func (i *compactionIter) mergeNext(valueMerger ValueMerger) stripeChangeType {
i.pos = iterPosNext
return i.iterStripeChange
}
if i.err != nil {
panic(i.err)
}
// NB: MERGE#10+RANGEDEL#9 stays a MERGE, since nextInStripe skips
// sameStripeSkippable keys that are visibly covered by a RANGEDEL. There
// may be MERGE#7 that is invisibly covered and will be preserved, but
// there is no risk that MERGE#10 and MERGE#7 will get merged in the
// future as the RANGEDEL still exists and will be used in user-facing
// reads that see MERGE#10, and will also eventually cause MERGE#7 to be
// deleted in a compaction.
key := i.iterKey
switch key.Kind() {
case InternalKeyKindDelete, InternalKeyKindSingleDelete, InternalKeyKindDeleteSized:
// We've hit a deletion tombstone. Return everything up to this point and
// then skip entries until the next snapshot stripe. We change the kind
// of the result key to a Set so that it shadows keys in lower
// levels. That is, MERGE+DEL -> SET.
// levels. That is, MERGE+DEL -> SETWITHDEL.
//
// We do the same for SingleDelete since SingleDelete is only
// permitted (with deterministic behavior) for keys that have been
// set once since the last SingleDelete/Delete, so everything
@@ -766,21 +882,11 @@ func (i *compactionIter) mergeNext(valueMerger ValueMerger) stripeChangeType {
// single Set, and then merge in any following Sets, but that is
// complicated wrt code and unnecessary given the narrow permitted
// use of SingleDelete.
i.key.SetKind(InternalKeyKindSet)
i.key.SetKind(InternalKeyKindSetWithDelete)
i.skip = true
return sameStripeSkippable
case InternalKeyKindSet, InternalKeyKindSetWithDelete:
if i.rangeDelFrag.Covers(*key, i.curSnapshotSeqNum) == keyspan.CoversVisibly {
// We change the kind of the result key to a Set so that it shadows
// keys in lower levels. That is, MERGE+RANGEDEL -> SET. This isn't
// strictly necessary, but provides consistency with the behavior of
// MERGE+DEL.
i.key.SetKind(InternalKeyKindSet)
i.skip = true
return sameStripeSkippable
}
// We've hit a Set or SetWithDel value. Merge with the existing
// value and return. We change the kind of the resulting key to a
// Set so that it shadows keys in lower levels. That is:
@@ -795,16 +901,6 @@ func (i *compactionIter) mergeNext(valueMerger ValueMerger) stripeChangeType {
return sameStripeSkippable
case InternalKeyKindMerge:
if i.rangeDelFrag.Covers(*key, i.curSnapshotSeqNum) == keyspan.CoversVisibly {
// We change the kind of the result key to a Set so that it shadows
// keys in lower levels. That is, MERGE+RANGEDEL -> SET. This isn't
// strictly necessary, but provides consistency with the behavior of
// MERGE+DEL.
i.key.SetKind(InternalKeyKindSet)
i.skip = true
return sameStripeSkippable
}
// We've hit another Merge value. Merge with the existing value and
// continue looping.
i.err = valueMerger.MergeOlder(i.iterValue)
@@ -821,6 +917,16 @@ func (i *compactionIter) mergeNext(valueMerger ValueMerger) stripeChangeType {
}
}
// singleDeleteNext processes a SingleDelete point tombstone. A SingleDelete, or
// SINGLEDEL, is unique in that it deletes exactly 1 internal key. It's a
// performance optimization when the client knows a user key has not been
// overwritten, allowing the elision of the tombstone earlier, avoiding write
// amplification.
//
// singleDeleteNext returns a boolean indicating whether or not the caller
// should yield the SingleDelete key to the consumer of the compactionIter. If
// singleDeleteNext returns false, the caller may consume/elide the
// SingleDelete.
func (i *compactionIter) singleDeleteNext() bool {
// Save the current key.
i.saveKey()
@@ -829,26 +935,85 @@ func (i *compactionIter) singleDeleteNext() bool {
// Loop until finds a key to be passed to the next level.
for {
// If we find a key that can't be skipped, return true so that the
// caller yields the SingleDelete to the caller.
if i.nextInStripe() != sameStripeSkippable {
// This defers additional error checking regarding single delete
// invariants to the compaction where the keys with the same user key as
// the single delete are in the same stripe.
i.pos = iterPosNext
return true
return i.err == nil
}
if i.err != nil {
panic(i.err)
}
// INVARIANT: sameStripeSkippable.
key := i.iterKey
switch key.Kind() {
case InternalKeyKindDelete, InternalKeyKindMerge, InternalKeyKindSetWithDelete, InternalKeyKindDeleteSized:
// We've hit a Delete, DeleteSized, Merge, SetWithDelete, transform
kind := key.Kind()
switch kind {
case InternalKeyKindDelete, InternalKeyKindSetWithDelete, InternalKeyKindDeleteSized:
if (kind == InternalKeyKindDelete || kind == InternalKeyKindDeleteSized) &&
i.ineffectualSingleDeleteCallback != nil {
i.ineffectualSingleDeleteCallback(i.key.UserKey)
}
// We've hit a Delete, DeleteSized, SetWithDelete, transform
// the SingleDelete into a full Delete.
i.key.SetKind(InternalKeyKindDelete)
i.skip = true
return true
case InternalKeyKindSet:
i.nextInStripe()
case InternalKeyKindSet, InternalKeyKindMerge:
// This SingleDelete deletes the Set/Merge, and we can now elide the
// SingleDel as well. We advance past the Set and return false to
// indicate to the main compaction loop that we should NOT yield the
// current SingleDel key to the compaction loop.
//
// NB: singleDeleteNext was called with i.pos == iterPosCurForward, and
// after the call to nextInStripe, we are still at iterPosCurForward,
// since we are at the key after the Set/Merge that was single deleted.
change := i.nextInStripe()
switch change {
case sameStripeSkippable, newStripeSameKey:
// On the same user key.
nextKind := i.iterKey.Kind()
switch nextKind {
case InternalKeyKindSet, InternalKeyKindSetWithDelete, InternalKeyKindMerge:
if i.singleDeleteInvariantViolationCallback != nil {
// sameStripeSkippable keys returned by nextInStripe() are already
// known to not be covered by a RANGEDEL, so it is an invariant
// violation. The rare case is newStripeSameKey, where it is a
// violation if not covered by a RANGEDEL.
if change == sameStripeSkippable ||
i.rangeDelFrag.Covers(*i.iterKey, i.curSnapshotSeqNum) == keyspan.NoCover {
i.singleDeleteInvariantViolationCallback(i.key.UserKey)
}
}
case InternalKeyKindDelete, InternalKeyKindDeleteSized, InternalKeyKindSingleDelete,
InternalKeyKindRangeDelete:
default:
panic(errors.AssertionFailedf(
"unexpected internal key kind: %d", errors.Safe(i.iterKey.Kind())))
}
case sameStripeNonSkippable:
// No ability to check whether there is another Set/Merge below with
// the same user key.
//
// TODO(sumeer): once range deletions are interleaved at the maximal
// sequence number, this case will go away.
case newStripeNewKey:
default:
panic("unreachable")
}
i.valid = false
return false
case InternalKeyKindSingleDelete:
// Two single deletes met in a compaction. The first single delete is
// ineffectual.
if i.ineffectualSingleDeleteCallback != nil {
i.ineffectualSingleDeleteCallback(i.key.UserKey)
}
// Continue to apply the second single delete.
continue
default:
@@ -859,6 +1024,135 @@ func (i *compactionIter) singleDeleteNext() bool {
}
}
// skipDueToSingleDeleteElision is called when the SingleDelete is being
// elided because it is in the final snapshot stripe and there are no keys
// with the same user key in lower levels in the LSM (below the files in this
// compaction).
//
// TODO(sumeer): the only difference between singleDeleteNext and
// skipDueToSingleDeleteElision is the fact that the caller knows it will be
// eliding the single delete in the latter case. There are some similar things
// happening in both implementations. My first attempt at combining them into
// a single method was hard to comprehend. Try again.
func (i *compactionIter) skipDueToSingleDeleteElision() {
for {
stripeChange := i.nextInStripe()
if i.err != nil {
panic(i.err)
}
switch stripeChange {
case newStripeNewKey:
// The single delete is only now being elided, meaning it did not elide
// any keys earlier in its descent down the LSM. We stepped onto a new
// user key, meaning that even now at its moment of elision, it still
// hasn't elided any other keys. The single delete was ineffectual (a
// no-op).
if i.ineffectualSingleDeleteCallback != nil {
i.ineffectualSingleDeleteCallback(i.key.UserKey)
}
i.skip = false
return
case newStripeSameKey:
// This should be impossible. If we're eliding a single delete, we
// determined that the tombstone is in the final snapshot stripe, but we
// stepped into a new stripe of the same key.
panic(errors.AssertionFailedf("eliding single delete followed by same key in new stripe"))
case sameStripeNonSkippable:
// There's a key that we cannot skip. There are two possible cases:
// a. The key is invalid. This is an error.
// b. The key is a range deletion.
// The second case may also be an ineffectual single delete. However, it
// is possible that there is a SET that is at the same seqnum as the
// RANGEDEL, and so is not deleted by that RANGEDEL, and will be deleted
// by this single delete. So we cannot be certain that this is an
// ineffectual single delete.
//
// TODO(sumeer): the existing todo to interleave range deletions at the
// maximal sequence number will allow us to address this ambiguity.
//
// TODO(sumeer): by setting skip to true, the compactionIter is making a
// single delete stronger (like a del), which will hide bugs in the use of
// single delete.
i.skip = true
return
case sameStripeSkippable:
kind := i.iterKey.Kind()
switch kind {
case InternalKeyKindDelete, InternalKeyKindDeleteSized, InternalKeyKindSingleDelete:
if i.ineffectualSingleDeleteCallback != nil {
i.ineffectualSingleDeleteCallback(i.key.UserKey)
}
switch kind {
case InternalKeyKindDelete, InternalKeyKindDeleteSized:
i.skipInStripe()
return
case InternalKeyKindSingleDelete:
// Repeat the same with this SingleDelete. We don't want to simply
// call skipInStripe(), since it increases the strength of the
// SingleDel, which hides bugs in the use of single delete.
continue
default:
panic(errors.AssertionFailedf(
"unexpected internal key kind: %d", errors.Safe(i.iterKey.Kind())))
}
case InternalKeyKindSetWithDelete:
// The SingleDelete should behave like a Delete.
i.skipInStripe()
return
case InternalKeyKindSet, InternalKeyKindMerge:
// This SingleDelete deletes the Set/Merge, and we are eliding the
// SingleDel as well. Step to the next key (this is not deleted by the
// SingleDelete).
//
// NB: skipDueToSingleDeleteElision was called with i.pos ==
// iterPosCurForward, and after the call to nextInStripe, we are still
// at iterPosCurForward, since we are at the key after the Set/Merge
// that was single deleted.
change := i.nextInStripe()
if i.err != nil {
panic(i.err)
}
switch change {
case newStripeSameKey:
panic(errors.AssertionFailedf("eliding single delete followed by same key in new stripe"))
case newStripeNewKey:
case sameStripeSkippable:
// On the same key.
nextKind := i.iterKey.Kind()
switch nextKind {
case InternalKeyKindSet, InternalKeyKindSetWithDelete, InternalKeyKindMerge:
if i.singleDeleteInvariantViolationCallback != nil {
i.singleDeleteInvariantViolationCallback(i.key.UserKey)
}
case InternalKeyKindDelete, InternalKeyKindDeleteSized, InternalKeyKindSingleDelete,
InternalKeyKindRangeDelete:
default:
panic(errors.AssertionFailedf(
"unexpected internal key kind: %d", errors.Safe(i.iterKey.Kind())))
}
case sameStripeNonSkippable:
// No ability to check whether there is another Set/Merge below with
// the same user key.
//
// TODO(sumeer): once range deletions are interleaved at the maximal
// sequence number, this case will go away.
default:
panic("unreachable")
}
// Whether in same stripe or new stripe, this key is not consumed by
// the SingleDelete.
i.skip = false
return
default:
panic(errors.AssertionFailedf(
"unexpected internal key kind: %d", errors.Safe(i.iterKey.Kind())))
}
default:
panic("unreachable")
}
}
}
// deleteSizedNext processes a DELSIZED point tombstone. Unlike ordinary DELs,
// these tombstones carry a value that's a varint indicating the size of the
// entry (len(key)+len(value)) that the tombstone is expected to delete.
@@ -881,28 +1175,137 @@ func (i *compactionIter) deleteSizedNext() (*base.InternalKey, []byte) {
i.value = i.valueBuf
}
// Loop through all the keys within this stripe that are skippable,
// totalling the size of their keys and values.
// Loop through all the keys within this stripe that are skippable.
i.pos = iterPosNext
var elidedSize uint64
for i.nextInStripe() == sameStripeSkippable {
elidedSize += uint64(len(i.iterKey.UserKey)) + uint64(len(i.iterValue))
if i.iterKey.Kind() == InternalKeyKindDeleteSized {
// We encountered a DELSIZED that's deleted by the original
// DELSIZED. These tombstones could've been intended to delete two
// distinct values, eg:
if i.err != nil {
panic(i.err)
}
switch i.iterKey.Kind() {
case InternalKeyKindDelete, InternalKeyKindDeleteSized, InternalKeyKindSingleDelete:
// We encountered a tombstone (DEL, or DELSIZED) that's deleted by
// the original DELSIZED tombstone. This can happen in two cases:
//
// (1) These tombstones were intended to delete two distinct values,
// and this DELSIZED has already dropped the relevant key. For
// example:
//
// a.DELSIZED.9 a.SET.7 a.DELSIZED.5 a.SET.4
//
// If a.DELSIZED.9 has already deleted a.SET.7, its size has already
// been zeroed out. In this case, we want to adopt the value of the
// DELSIZED with the lower sequence number, in case the a.SET.4 key
// has not yet been elided.
// If a.DELSIZED.9 has already deleted a.SET.7, its size has
// already been zeroed out. In this case, we want to adopt the
// value of the DELSIZED with the lower sequence number, in
// case the a.SET.4 key has not yet been elided.
//
// (2) This DELSIZED was missized. The user thought they were
// deleting a key with this user key, but this user key had
// already been deleted.
//
// We can differentiate these two cases by examining the length of
// the DELSIZED's value. A DELSIZED's value holds the size of both
// the user key and value that it intends to delete. For any user
// key with a length > 0, a DELSIZED that has not deleted a key must
// have a value with a length > 0.
//
// We treat both cases the same functionally, adopting the identity
// of the lower-sequence numbered tombstone. However in the second
// case, we also increment the stat counting missized tombstones.
if len(i.value) > 0 {
// The original DELSIZED key was missized. The key that the user
// thought they were deleting does not exist.
i.stats.countMissizedDels++
}
i.valueBuf = append(i.valueBuf[:0], i.iterValue...)
i.value = i.valueBuf
// Reset the elided total.
elidedSize = 0
if i.iterKey.Kind() != InternalKeyKindDeleteSized {
// Convert the DELSIZED to a DEL—The DEL/SINGLEDEL we're eliding
// may not have deleted the key(s) it was intended to yet. The
// ordinary DEL compaction heuristics are better suited at that,
// plus we don't want to count it as a missized DEL. We early
// exit in this case, after skipping the remainder of the
// snapshot stripe.
i.key.SetKind(InternalKeyKindDelete)
// NB: We skipInStripe now, rather than returning leaving
// i.skip=true and returning early, because Next() requires
// that i.skip=true only if i.iterPos = iterPosCurForward.
//
// Ignore any error caused by skipInStripe since it does not affect
// the key/value being returned here, and the next call to Next() will
// expose it.
i.skipInStripe()
return &i.key, i.value
}
// Continue, in case we uncover another DELSIZED or a key this
// DELSIZED deletes.
case InternalKeyKindSet, InternalKeyKindMerge, InternalKeyKindSetWithDelete:
// If the DELSIZED is value-less, it already deleted the key that it
// was intended to delete. This is possible with a sequence like:
//
// DELSIZED.8 SET.7 SET.3
//
// The DELSIZED only describes the size of the SET.7, which in this
// case has already been elided. We don't count it as a missizing,
// instead converting the DELSIZED to a DEL. Skip the remainder of
// the snapshot stripe and return.
if len(i.value) == 0 {
i.key.SetKind(InternalKeyKindDelete)
// NB: We skipInStripe now, rather than returning leaving
// i.skip=true and returning early, because Next() requires
// that i.skip=true only if i.iterPos = iterPosCurForward.
//
// Ignore any error caused by skipInStripe since it does not affect
// the key/value being returned here, and the next call to Next() will
// expose it.
i.skipInStripe()
return &i.key, i.value
}
// The deleted key is not a DEL, DELSIZED, and the DELSIZED in i.key
// has a positive size.
expectedSize, n := binary.Uvarint(i.value)
if n != len(i.value) {
i.err = base.CorruptionErrorf("DELSIZED holds invalid value: %x", errors.Safe(i.value))
i.valid = false
return nil, nil
}
elidedSize := uint64(len(i.iterKey.UserKey)) + uint64(len(i.iterValue))
if elidedSize != expectedSize {
// The original DELSIZED key was missized. It's unclear what to
// do. The user-provided size was wrong, so it's unlikely to be
// accurate or meaningful. We could:
//
// 1. return the DELSIZED with the original user-provided size unmodified
// 2. return the DELZIZED with a zeroed size to reflect that a key was
// elided, even if it wasn't the anticipated size.
// 3. subtract the elided size from the estimate and re-encode.
// 4. convert the DELSIZED into a value-less DEL, so that
// ordinary DEL heuristics apply.
//
// We opt for (4) under the rationale that we can't rely on the
// user-provided size for accuracy, so ordinary DEL heuristics
// are safer.
i.stats.countMissizedDels++
i.key.SetKind(InternalKeyKindDelete)
i.value = i.valueBuf[:0]
// NB: We skipInStripe now, rather than returning leaving
// i.skip=true and returning early, because Next() requires
// that i.skip=true only if i.iterPos = iterPosCurForward.
//
// Ignore any error caused by skipInStripe since it does not affect
// the key/value being returned here, and the next call to Next() will
// expose it.
i.skipInStripe()
return &i.key, i.value
}
// NB: We remove the value regardless of whether the key was sized
// appropriately. The size encoded is 'consumed' the first time it
// meets a key that it deletes.
i.value = i.valueBuf[:0]
default:
i.err = base.CorruptionErrorf("invalid internal key kind: %d", errors.Safe(i.iterKey.Kind()))
i.valid = false
return nil, nil
}
}
// Reset skip if we landed outside the original stripe. Otherwise, we landed
@@ -912,53 +1315,8 @@ func (i *compactionIter) deleteSizedNext() (*base.InternalKey, []byte) {
if i.iterStripeChange == newStripeNewKey || i.iterStripeChange == newStripeSameKey {
i.skip = false
}
if elidedSize == 0 {
// If we didn't find any keys that we could elide due to this tombstone
// (or at least none since the last DELSIZED encountered), we can return
// the key and our existing saved value verbatim.
return &i.key, i.value
}
// Some key(s) were elided as a result of this tombstone. Decode the
// tombstone's value to see if it matches the amount of data actually
// elided.
var v uint64
if len(i.value) > 0 {
var n int
v, n = binary.Uvarint(i.value)
if n != len(i.value) {
i.err = base.CorruptionErrorf("DELSIZED holds invalid value: %x", errors.Safe(i.value))
i.valid = false
return nil, nil
}
}
// If the user's prediction of the value size was correct, then from now on
// it's predicted to delete nothing. Return an empty value.
//
// NB: It's important that we still always return the tombstone, because
// DELSIZED's values are a best effort optimization, not a correctness
// mechanic. There is no guarantee that this key was only set once before
// the DELSIZED was written.
// If the tombstone carried a larger size than what was actually elided,
// it's unclear what to do. The user-provided size was wrong, so it's
// unlikely to be accurate or meaningful. We could:
//
// 1. return the DELSIZED with the original user-provided size unmodified
// 2. return the DELZIZED with a zeroed size to reflect that a key was
// elided, even if it wasn't the anticipated size.
// 3. subtract the elided size from the estimate and re-encode.
// 4. convert the DELSIZED into a value-less DEL, so that ordinary DEL
// heuristics apply.
//
// We opt for (4) under the rationale that we can't rely on the
// user-provided size for accuracy, so ordinary DEL heuristics are safer.
i.value = i.valueBuf[:0]
if elidedSize != v {
i.stats.countMissizedDels++
i.key.SetKind(InternalKeyKindDelete)
if i.err != nil {
return nil, nil
}
return &i.key, i.value
}