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Upgrade versions of vendored libs

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This commit is contained in:
eleksir
2022-11-04 16:20:16 +03:00
parent d9de157ad8
commit 76a660ebed
931 changed files with 215108 additions and 23070 deletions
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223
vendor/github.com/cockroachdb/pebble/level_iter.go generated vendored
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@@ -7,20 +7,30 @@ package pebble
import (
"fmt"
"runtime/debug"
"unsafe"
"github.com/cockroachdb/pebble/internal/base"
"github.com/cockroachdb/pebble/internal/invariants"
"github.com/cockroachdb/pebble/internal/keyspan"
"github.com/cockroachdb/pebble/internal/manifest"
"github.com/cockroachdb/pebble/sstable"
)
// tableNewIters creates a new point and range-del iterator for the given file
// number. If bytesIterated is specified, it is incremented as the given file is
// iterated through.
type tableNewIters func(
file *manifest.FileMetadata, opts *IterOptions, bytesIterated *uint64,
file *manifest.FileMetadata,
opts *IterOptions,
internalOpts internalIterOpts,
) (internalIterator, keyspan.FragmentIterator, error)
type internalIterOpts struct {
bytesIterated *uint64
stats *base.InternalIteratorStats
boundLimitedFilter sstable.BoundLimitedBlockPropertyFilter
}
// levelIter provides a merged view of the sstables in a level.
//
// levelIter is used during compaction and as part of the Iterator
@@ -81,7 +91,7 @@ type levelIter struct {
// - err != nil
// - some other constraint, like the bounds in opts, caused the file at index to not
// be relevant to the iteration.
iter internalIteratorWithStats
iter internalIterator
iterFile *fileMetadata
// filteredIter is an optional interface that may be implemented by internal
// iterators that perform filtering of keys. When a new file's iterator is
@@ -107,8 +117,6 @@ type levelIter struct {
rangeDelIterCopy keyspan.FragmentIterator
files manifest.LevelIterator
err error
// stats accumulates the stats of iters that have been closed.
stats InternalIteratorStats
// Pointer into this level's entry in `mergingIterLevel::levelIterBoundaryContext`.
// We populate it with the corresponding bounds for the currently opened file. It is used for
@@ -158,8 +166,9 @@ type levelIter struct {
// - `*Boundary` is not exposed to the next higher-level iterator, i.e., `mergingIter`.
boundaryContext *levelIterBoundaryContext
// bytesIterated keeps track of the number of bytes iterated during compaction.
bytesIterated *uint64
// internalOpts holds the internal iterator options to pass to the table
// cache when constructing new table iterators.
internalOpts internalIterOpts
// Disable invariant checks even if they are otherwise enabled. Used by tests
// which construct "impossible" situations (e.g. seeking to a key before the
@@ -205,7 +214,7 @@ func newLevelIter(
bytesIterated *uint64,
) *levelIter {
l := &levelIter{}
l.init(opts, cmp, split, newIters, files, level, bytesIterated)
l.init(opts, cmp, split, newIters, files, level, internalIterOpts{bytesIterated: bytesIterated})
return l
}
@@ -216,7 +225,7 @@ func (l *levelIter) init(
newIters tableNewIters,
files manifest.LevelIterator,
level manifest.Level,
bytesIterated *uint64,
internalOpts internalIterOpts,
) {
l.err = nil
l.level = level
@@ -232,7 +241,7 @@ func (l *levelIter) init(
l.iterFile = nil
l.newIters = newIters
l.files = files
l.bytesIterated = bytesIterated
l.internalOpts = internalOpts
}
func (l *levelIter) initRangeDel(rangeDelIter *keyspan.FragmentIterator) {
@@ -260,9 +269,16 @@ func (l *levelIter) maybeTriggerCombinedIteration(file *fileMetadata, dir int) {
// configured to observe range keys. Either way, there's nothing to do.
// If false, trigger the switch to combined iteration, using the the
// file's bounds to seek the range-key iterator appropriately.
//
// We only need to trigger combined iteration if the file contains
// RangeKeySets: if there are only Unsets and Dels, the user will observe no
// range keys regardless. If this file has table stats available, they'll
// tell us whether the file has any RangeKeySets. Otherwise, we must
// fallback to assuming it does if HasRangeKeys=true.
if file != nil && file.HasRangeKeys && l.combinedIterState != nil && !l.combinedIterState.initialized &&
(l.upper == nil || l.cmp(file.SmallestRangeKey.UserKey, l.upper) < 0) &&
(l.lower == nil || l.cmp(file.LargestRangeKey.UserKey, l.lower) > 0) {
(l.lower == nil || l.cmp(file.LargestRangeKey.UserKey, l.lower) > 0) &&
(!file.StatsValid() || file.Stats.NumRangeKeySets > 0) {
// The file contains range keys, and we're not using combined iteration yet.
// Trigger a switch to combined iteration. It's possible that a switch has
// already been triggered if multiple levels encounter files containing
@@ -294,22 +310,64 @@ func (l *levelIter) maybeTriggerCombinedIteration(file *fileMetadata, dir int) {
}
}
func (l *levelIter) findFileGE(key []byte, isRelativeSeek bool) *fileMetadata {
// Find the earliest file whose largest key is >= ikey.
func (l *levelIter) findFileGE(key []byte, flags base.SeekGEFlags) *fileMetadata {
// Find the earliest file whose largest key is >= key.
// Ordinarily we seek the LevelIterator using SeekGE.
if invariants.Enabled && flags.TrySeekUsingNext() && disableSeekOpt(key, uintptr(unsafe.Pointer(l))) {
flags = flags.DisableTrySeekUsingNext()
}
// Ordinarily we seek the LevelIterator using SeekGE. In some instances, we
// Next instead. In other instances, we try Next-ing first, falling back to
// seek:
// a) flags.TrySeekUsingNext(): The top-level Iterator knows we're seeking
// to a key later than the current iterator position. We don't know how
// much later the seek key is, so it's possible there are many sstables
// between the current position and the seek key. However in most real-
// world use cases, the seek key is likely to be nearby. Rather than
// performing a log(N) seek through the file metadata, we next a few
// times from from our existing location. If we don't find a file whose
// largest is >= key within a few nexts, we fall back to seeking.
//
// When lazy combined iteration is enabled, there's a complication. The
// level iterator is responsible for watching for files containing range
// keys and triggering the switch to combined iteration when such a file is
// observed. If a range deletion was observed in a higher level causing the
// merging iterator to seek the level to the range deletion's end key, we
// need to check whether all of the files between the old position and the
// new position contain any range keys.
// Note that in this case, the file returned by findFileGE may be
// different than the file returned by a raw binary search (eg, when
// TrySeekUsingNext=false). This is possible because the most recent
// positioning operation may have already determined that previous
// files' keys that are ≥ key are all deleted. This information is
// encoded within the iterator's current iterator position and is
// unavailable to a fresh binary search.
//
// In this scenario, we don't seek the LevelIterator and instead we Next it,
// one file at a time, checking each for range keys.
nextInsteadOfSeek := isRelativeSeek && l.combinedIterState != nil && !l.combinedIterState.initialized
// b) flags.RelativeSeek(): The merging iterator decided to re-seek this
// level according to a range tombstone. When lazy combined iteration
// is enabled, the level iterator is responsible for watching for
// files containing range keys and triggering the switch to combined
// iteration when such a file is observed. If a range deletion was
// observed in a higher level causing the merging iterator to seek the
// level to the range deletion's end key, we need to check whether all
// of the files between the old position and the new position contain
// any range keys.
//
// In this scenario, we don't seek the LevelIterator and instead we
// Next it, one file at a time, checking each for range keys. The
// merging iterator sets this flag to inform us that we're moving
// forward relative to the existing position and that we must examine
// each intermediate sstable's metadata for lazy-combined iteration.
// In this case, we only Next and never Seek. We set nextsUntilSeek=-1
// to signal this intention.
//
// NB: At most one of flags.RelativeSeek() and flags.TrySeekUsingNext() may
// be set, because the merging iterator re-seeks relative seeks with
// explicitly only the RelativeSeek flag set.
var nextsUntilSeek int
var nextInsteadOfSeek bool
if flags.TrySeekUsingNext() {
nextInsteadOfSeek = true
nextsUntilSeek = 4 // arbitrary
}
if flags.RelativeSeek() && l.combinedIterState != nil && !l.combinedIterState.initialized {
nextInsteadOfSeek = true
nextsUntilSeek = -1
}
var m *fileMetadata
if nextInsteadOfSeek {
@@ -349,11 +407,22 @@ func (l *levelIter) findFileGE(key []byte, isRelativeSeek bool) *fileMetadata {
// If the file does not contain point keys ≥ `key`, next to continue
// looking for a file that does.
if (m.HasRangeKeys || nextInsteadOfSeek) && l.cmp(m.LargestPointKey.UserKey, key) < 0 {
// If nextInsteadOfSeek is set and nextsUntilSeek is non-negative,
// the iterator has been nexting hoping to discover the relevant
// file without seeking. It's exhausted the allotted nextsUntilSeek
// and should seek to the sought key.
if nextInsteadOfSeek && nextsUntilSeek == 0 {
nextInsteadOfSeek = false
m = l.files.SeekGE(l.cmp, key)
continue
} else if nextsUntilSeek > 0 {
nextsUntilSeek--
}
m = l.files.Next()
continue
}
// This file has point key bound ≥ `key`. But the largest point key
// This file has a point key bound ≥ `key`. But the largest point key
// bound may still be a range deletion sentinel, which is exclusive. In
// this case, the file doesn't actually contain any point keys equal to
// `key`. We next to keep searching for a file that actually contains
@@ -374,7 +443,7 @@ func (l *levelIter) findFileGE(key []byte, isRelativeSeek bool) *fileMetadata {
return m
}
func (l *levelIter) findFileLT(key []byte, isRelativeSeek bool) *fileMetadata {
func (l *levelIter) findFileLT(key []byte, flags base.SeekLTFlags) *fileMetadata {
// Find the last file whose smallest key is < ikey.
// Ordinarily we seek the LevelIterator using SeekLT.
@@ -389,7 +458,7 @@ func (l *levelIter) findFileLT(key []byte, isRelativeSeek bool) *fileMetadata {
//
// In this scenario, we don't seek the LevelIterator and instead we Prev it,
// one file at a time, checking each for range keys.
prevInsteadOfSeek := isRelativeSeek && l.combinedIterState != nil && !l.combinedIterState.initialized
prevInsteadOfSeek := flags.RelativeSeek() && l.combinedIterState != nil && !l.combinedIterState.initialized
var m *fileMetadata
if prevInsteadOfSeek {
@@ -563,8 +632,8 @@ func (l *levelIter) loadFile(file *fileMetadata, dir int) loadFileReturnIndicato
var rangeDelIter keyspan.FragmentIterator
var iter internalIterator
iter, rangeDelIter, l.err = l.newIters(l.files.Current(), &l.tableOpts, l.bytesIterated)
l.iter = base.WrapIterWithStats(iter)
iter, rangeDelIter, l.err = l.newIters(l.files.Current(), &l.tableOpts, l.internalOpts)
l.iter = iter
if l.err != nil {
return noFileLoaded
}
@@ -594,7 +663,7 @@ func (l *levelIter) loadFile(file *fileMetadata, dir int) loadFileReturnIndicato
// In race builds we verify that the keys returned by levelIter lie within
// [lower,upper).
func (l *levelIter) verify(key *InternalKey, val []byte) (*InternalKey, []byte) {
func (l *levelIter) verify(key *InternalKey, val base.LazyValue) (*InternalKey, base.LazyValue) {
// Note that invariants.Enabled is a compile time constant, which means the
// block of code will be compiled out of normal builds making this method
// eligible for inlining. Do not change this to use a variable.
@@ -612,7 +681,7 @@ func (l *levelIter) verify(key *InternalKey, val []byte) (*InternalKey, []byte)
return key, val
}
func (l *levelIter) SeekGE(key []byte, flags base.SeekGEFlags) (*InternalKey, []byte) {
func (l *levelIter) SeekGE(key []byte, flags base.SeekGEFlags) (*InternalKey, base.LazyValue) {
l.err = nil // clear cached iteration error
if l.boundaryContext != nil {
l.boundaryContext.isSyntheticIterBoundsKey = false
@@ -621,9 +690,9 @@ func (l *levelIter) SeekGE(key []byte, flags base.SeekGEFlags) (*InternalKey, []
// NB: the top-level Iterator has already adjusted key based on
// IterOptions.LowerBound.
loadFileIndicator := l.loadFile(l.findFileGE(key, flags.RelativeSeek()), +1)
loadFileIndicator := l.loadFile(l.findFileGE(key, flags), +1)
if loadFileIndicator == noFileLoaded {
return nil, nil
return nil, base.LazyValue{}
}
if loadFileIndicator == newFileLoaded {
// File changed, so l.iter has changed, and that iterator is not
@@ -638,7 +707,7 @@ func (l *levelIter) SeekGE(key []byte, flags base.SeekGEFlags) (*InternalKey, []
func (l *levelIter) SeekPrefixGE(
prefix, key []byte, flags base.SeekGEFlags,
) (*base.InternalKey, []byte) {
) (*base.InternalKey, base.LazyValue) {
l.err = nil // clear cached iteration error
if l.boundaryContext != nil {
l.boundaryContext.isSyntheticIterBoundsKey = false
@@ -647,9 +716,9 @@ func (l *levelIter) SeekPrefixGE(
// NB: the top-level Iterator has already adjusted key based on
// IterOptions.LowerBound.
loadFileIndicator := l.loadFile(l.findFileGE(key, flags.RelativeSeek()), +1)
loadFileIndicator := l.loadFile(l.findFileGE(key, flags), +1)
if loadFileIndicator == noFileLoaded {
return nil, nil
return nil, base.LazyValue{}
}
if loadFileIndicator == newFileLoaded {
// File changed, so l.iter has changed, and that iterator is not
@@ -673,7 +742,7 @@ func (l *levelIter) SeekPrefixGE(
l.boundaryContext.isSyntheticIterBoundsKey = true
l.boundaryContext.isIgnorableBoundaryKey = false
}
return l.verify(l.largestBoundary, nil)
return l.verify(l.largestBoundary, base.LazyValue{})
}
// Return the file's largest bound, ensuring this file stays open until
// the mergingIter advances beyond the file's bounds. We set
@@ -684,7 +753,7 @@ func (l *levelIter) SeekPrefixGE(
l.boundaryContext.isSyntheticIterBoundsKey = false
l.boundaryContext.isIgnorableBoundaryKey = true
}
return l.verify(l.largestBoundary, nil)
return l.verify(l.largestBoundary, base.LazyValue{})
}
// It is possible that we are here because bloom filter matching failed. In
// that case it is likely that all keys matching the prefix are wholly
@@ -695,12 +764,12 @@ func (l *levelIter) SeekPrefixGE(
// called with flags.TrySeekUsingNext(), since for sparse key spaces it is
// likely that the next key will also be contained in the current file.
if n := l.split(l.iterFile.LargestPointKey.UserKey); l.cmp(prefix, l.iterFile.LargestPointKey.UserKey[:n]) < 0 {
return nil, nil
return nil, base.LazyValue{}
}
return l.verify(l.skipEmptyFileForward())
}
func (l *levelIter) SeekLT(key []byte, flags base.SeekLTFlags) (*InternalKey, []byte) {
func (l *levelIter) SeekLT(key []byte, flags base.SeekLTFlags) (*InternalKey, base.LazyValue) {
l.err = nil // clear cached iteration error
if l.boundaryContext != nil {
l.boundaryContext.isSyntheticIterBoundsKey = false
@@ -709,8 +778,8 @@ func (l *levelIter) SeekLT(key []byte, flags base.SeekLTFlags) (*InternalKey, []
// NB: the top-level Iterator has already adjusted key based on
// IterOptions.UpperBound.
if l.loadFile(l.findFileLT(key, flags.RelativeSeek()), -1) == noFileLoaded {
return nil, nil
if l.loadFile(l.findFileLT(key, flags), -1) == noFileLoaded {
return nil, base.LazyValue{}
}
if key, val := l.iter.SeekLT(key, flags); key != nil {
return l.verify(key, val)
@@ -718,7 +787,7 @@ func (l *levelIter) SeekLT(key []byte, flags base.SeekLTFlags) (*InternalKey, []
return l.verify(l.skipEmptyFileBackward())
}
func (l *levelIter) First() (*InternalKey, []byte) {
func (l *levelIter) First() (*InternalKey, base.LazyValue) {
l.err = nil // clear cached iteration error
if l.boundaryContext != nil {
l.boundaryContext.isSyntheticIterBoundsKey = false
@@ -728,7 +797,7 @@ func (l *levelIter) First() (*InternalKey, []byte) {
// NB: the top-level Iterator will call SeekGE if IterOptions.LowerBound is
// set.
if l.loadFile(l.files.First(), +1) == noFileLoaded {
return nil, nil
return nil, base.LazyValue{}
}
if key, val := l.iter.First(); key != nil {
return l.verify(key, val)
@@ -736,7 +805,7 @@ func (l *levelIter) First() (*InternalKey, []byte) {
return l.verify(l.skipEmptyFileForward())
}
func (l *levelIter) Last() (*InternalKey, []byte) {
func (l *levelIter) Last() (*InternalKey, base.LazyValue) {
l.err = nil // clear cached iteration error
if l.boundaryContext != nil {
l.boundaryContext.isSyntheticIterBoundsKey = false
@@ -746,7 +815,7 @@ func (l *levelIter) Last() (*InternalKey, []byte) {
// NB: the top-level Iterator will call SeekLT if IterOptions.UpperBound is
// set.
if l.loadFile(l.files.Last(), -1) == noFileLoaded {
return nil, nil
return nil, base.LazyValue{}
}
if key, val := l.iter.Last(); key != nil {
return l.verify(key, val)
@@ -754,9 +823,9 @@ func (l *levelIter) Last() (*InternalKey, []byte) {
return l.verify(l.skipEmptyFileBackward())
}
func (l *levelIter) Next() (*InternalKey, []byte) {
func (l *levelIter) Next() (*InternalKey, base.LazyValue) {
if l.err != nil || l.iter == nil {
return nil, nil
return nil, base.LazyValue{}
}
if l.boundaryContext != nil {
l.boundaryContext.isSyntheticIterBoundsKey = false
@@ -774,7 +843,7 @@ func (l *levelIter) Next() (*InternalKey, []byte) {
if l.rangeDelIterPtr != nil {
*l.rangeDelIterPtr = nil
}
return nil, nil
return nil, base.LazyValue{}
}
// We're stepping past the boundary key, so now we can load the next file.
if l.loadFile(l.files.Next(), +1) != noFileLoaded {
@@ -783,7 +852,7 @@ func (l *levelIter) Next() (*InternalKey, []byte) {
}
return l.verify(l.skipEmptyFileForward())
}
return nil, nil
return nil, base.LazyValue{}
default:
// Reset the smallest boundary since we're moving away from it.
@@ -795,9 +864,9 @@ func (l *levelIter) Next() (*InternalKey, []byte) {
return l.verify(l.skipEmptyFileForward())
}
func (l *levelIter) Prev() (*InternalKey, []byte) {
func (l *levelIter) Prev() (*InternalKey, base.LazyValue) {
if l.err != nil || l.iter == nil {
return nil, nil
return nil, base.LazyValue{}
}
if l.boundaryContext != nil {
l.boundaryContext.isSyntheticIterBoundsKey = false
@@ -815,7 +884,7 @@ func (l *levelIter) Prev() (*InternalKey, []byte) {
if l.rangeDelIterPtr != nil {
*l.rangeDelIterPtr = nil
}
return nil, nil
return nil, base.LazyValue{}
}
// We're stepping past the boundary key, so now we can load the prev file.
if l.loadFile(l.files.Prev(), -1) != noFileLoaded {
@@ -824,7 +893,7 @@ func (l *levelIter) Prev() (*InternalKey, []byte) {
}
return l.verify(l.skipEmptyFileBackward())
}
return nil, nil
return nil, base.LazyValue{}
default:
// Reset the largest boundary since we're moving away from it.
@@ -836,9 +905,9 @@ func (l *levelIter) Prev() (*InternalKey, []byte) {
return l.verify(l.skipEmptyFileBackward())
}
func (l *levelIter) skipEmptyFileForward() (*InternalKey, []byte) {
func (l *levelIter) skipEmptyFileForward() (*InternalKey, base.LazyValue) {
var key *InternalKey
var val []byte
var val base.LazyValue
// The first iteration of this loop starts with an already exhausted
// l.iter. The reason for the exhaustion is either that we iterated to the
// end of the sstable, or our iteration was terminated early due to the
@@ -875,18 +944,18 @@ func (l *levelIter) skipEmptyFileForward() (*InternalKey, []byte) {
if l.boundaryContext != nil {
l.boundaryContext.isSyntheticIterBoundsKey = true
}
return l.largestBoundary, nil
return l.largestBoundary, base.LazyValue{}
}
// Else there are no range deletions in this sstable. This
// helps with performance when many levels are populated with
// sstables and most don't have any actual keys within the
// bounds.
return nil, nil
return nil, base.LazyValue{}
}
// If the boundary is a range deletion tombstone, return that key.
if l.iterFile.LargestPointKey.Kind() == InternalKeyKindRangeDelete {
l.largestBoundary = &l.iterFile.LargestPointKey
return l.largestBoundary, nil
return l.largestBoundary, base.LazyValue{}
}
// If the last point iterator positioning op might've skipped keys,
// it's possible the file's range deletions are still relevant to
@@ -912,21 +981,21 @@ func (l *levelIter) skipEmptyFileForward() (*InternalKey, []byte) {
l.filteredIter.MaybeFilteredKeys() {
l.largestBoundary = &l.iterFile.Largest
l.boundaryContext.isIgnorableBoundaryKey = true
return l.largestBoundary, nil
return l.largestBoundary, base.LazyValue{}
}
}
// Current file was exhausted. Move to the next file.
if l.loadFile(l.files.Next(), +1) == noFileLoaded {
return nil, nil
return nil, base.LazyValue{}
}
}
return key, val
}
func (l *levelIter) skipEmptyFileBackward() (*InternalKey, []byte) {
func (l *levelIter) skipEmptyFileBackward() (*InternalKey, base.LazyValue) {
var key *InternalKey
var val []byte
var val base.LazyValue
// The first iteration of this loop starts with an already exhausted
// l.iter. The reason for the exhaustion is either that we iterated to the
// end of the sstable, or our iteration was terminated early due to the
@@ -962,18 +1031,18 @@ func (l *levelIter) skipEmptyFileBackward() (*InternalKey, []byte) {
if l.boundaryContext != nil {
l.boundaryContext.isSyntheticIterBoundsKey = true
}
return l.smallestBoundary, nil
return l.smallestBoundary, base.LazyValue{}
}
// Else there are no range deletions in this sstable. This
// helps with performance when many levels are populated with
// sstables and most don't have any actual keys within the
// bounds.
return nil, nil
return nil, base.LazyValue{}
}
// If the boundary is a range deletion tombstone, return that key.
if l.iterFile.SmallestPointKey.Kind() == InternalKeyKindRangeDelete {
l.smallestBoundary = &l.iterFile.SmallestPointKey
return l.smallestBoundary, nil
return l.smallestBoundary, base.LazyValue{}
}
// If the last point iterator positioning op skipped keys, it's
// possible the file's range deletions are still relevant to other
@@ -998,13 +1067,13 @@ func (l *levelIter) skipEmptyFileBackward() (*InternalKey, []byte) {
if *l.rangeDelIterPtr != nil && l.filteredIter != nil && l.filteredIter.MaybeFilteredKeys() {
l.smallestBoundary = &l.iterFile.Smallest
l.boundaryContext.isIgnorableBoundaryKey = true
return l.smallestBoundary, nil
return l.smallestBoundary, base.LazyValue{}
}
}
// Current file was exhausted. Move to the previous file.
if l.loadFile(l.files.Prev(), -1) == noFileLoaded {
return nil, nil
return nil, base.LazyValue{}
}
}
return key, val
@@ -1019,7 +1088,6 @@ func (l *levelIter) Error() error {
func (l *levelIter) Close() error {
if l.iter != nil {
l.stats.Merge(l.iter.Stats())
l.err = l.iter.Close()
l.iter = nil
}
@@ -1060,21 +1128,4 @@ func (l *levelIter) String() string {
return fmt.Sprintf("%s: fileNum=<nil>", l.level)
}
var _ internalIteratorWithStats = &levelIter{}
// Stats implements InternalIteratorWithStats.
func (l *levelIter) Stats() base.InternalIteratorStats {
stats := l.stats
if l.iter != nil {
stats.Merge(l.iter.Stats())
}
return stats
}
// ResetStats implements InternalIteratorWithStats.
func (l *levelIter) ResetStats() {
l.stats = base.InternalIteratorStats{}
if l.iter != nil {
l.iter.ResetStats()
}
}
var _ internalIterator = &levelIter{}