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path: root/vendor/github.com/klauspost/compress/zstd/enc_fast.go
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Diffstat (limited to 'vendor/github.com/klauspost/compress/zstd/enc_fast.go')
-rw-r--r--vendor/github.com/klauspost/compress/zstd/enc_fast.go371
1 files changed, 364 insertions, 7 deletions
diff --git a/vendor/github.com/klauspost/compress/zstd/enc_fast.go b/vendor/github.com/klauspost/compress/zstd/enc_fast.go
index 0045016d9..ba4a17e10 100644
--- a/vendor/github.com/klauspost/compress/zstd/enc_fast.go
+++ b/vendor/github.com/klauspost/compress/zstd/enc_fast.go
@@ -11,9 +11,11 @@ import (
)
const (
- tableBits = 15 // Bits used in the table
- tableSize = 1 << tableBits // Size of the table
- tableMask = tableSize - 1 // Mask for table indices. Redundant, but can eliminate bounds checks.
+ tableBits = 15 // Bits used in the table
+ tableSize = 1 << tableBits // Size of the table
+ tableShardCnt = 1 << (tableBits - dictShardBits) // Number of shards in the table
+ tableShardSize = tableSize / tableShardCnt // Size of an individual shard
+ tableMask = tableSize - 1 // Mask for table indices. Redundant, but can eliminate bounds checks.
maxMatchLength = 131074
)
@@ -24,8 +26,14 @@ type tableEntry struct {
type fastEncoder struct {
fastBase
- table [tableSize]tableEntry
- dictTable []tableEntry
+ table [tableSize]tableEntry
+}
+
+type fastEncoderDict struct {
+ fastEncoder
+ dictTable []tableEntry
+ tableShardDirty [tableShardCnt]bool
+ allDirty bool
}
// Encode mimmics functionality in zstd_fast.c
@@ -617,9 +625,323 @@ encodeLoop:
}
}
+// Encode will encode the content, with a dictionary if initialized for it.
+func (e *fastEncoderDict) Encode(blk *blockEnc, src []byte) {
+ const (
+ inputMargin = 8
+ minNonLiteralBlockSize = 1 + 1 + inputMargin
+ )
+ if e.allDirty || len(src) > 32<<10 {
+ e.fastEncoder.Encode(blk, src)
+ e.allDirty = true
+ return
+ }
+ // Protect against e.cur wraparound.
+ for e.cur >= bufferReset {
+ if len(e.hist) == 0 {
+ for i := range e.table[:] {
+ e.table[i] = tableEntry{}
+ }
+ e.cur = e.maxMatchOff
+ break
+ }
+ // Shift down everything in the table that isn't already too far away.
+ minOff := e.cur + int32(len(e.hist)) - e.maxMatchOff
+ for i := range e.table[:] {
+ v := e.table[i].offset
+ if v < minOff {
+ v = 0
+ } else {
+ v = v - e.cur + e.maxMatchOff
+ }
+ e.table[i].offset = v
+ }
+ e.cur = e.maxMatchOff
+ break
+ }
+
+ s := e.addBlock(src)
+ blk.size = len(src)
+ if len(src) < minNonLiteralBlockSize {
+ blk.extraLits = len(src)
+ blk.literals = blk.literals[:len(src)]
+ copy(blk.literals, src)
+ return
+ }
+
+ // Override src
+ src = e.hist
+ sLimit := int32(len(src)) - inputMargin
+ // stepSize is the number of bytes to skip on every main loop iteration.
+ // It should be >= 2.
+ const stepSize = 2
+
+ // TEMPLATE
+ const hashLog = tableBits
+ // seems global, but would be nice to tweak.
+ const kSearchStrength = 7
+
+ // nextEmit is where in src the next emitLiteral should start from.
+ nextEmit := s
+ cv := load6432(src, s)
+
+ // Relative offsets
+ offset1 := int32(blk.recentOffsets[0])
+ offset2 := int32(blk.recentOffsets[1])
+
+ addLiterals := func(s *seq, until int32) {
+ if until == nextEmit {
+ return
+ }
+ blk.literals = append(blk.literals, src[nextEmit:until]...)
+ s.litLen = uint32(until - nextEmit)
+ }
+ if debug {
+ println("recent offsets:", blk.recentOffsets)
+ }
+
+encodeLoop:
+ for {
+ // t will contain the match offset when we find one.
+ // When existing the search loop, we have already checked 4 bytes.
+ var t int32
+
+ // We will not use repeat offsets across blocks.
+ // By not using them for the first 3 matches
+ canRepeat := len(blk.sequences) > 2
+
+ for {
+ if debugAsserts && canRepeat && offset1 == 0 {
+ panic("offset0 was 0")
+ }
+
+ nextHash := hash6(cv, hashLog)
+ nextHash2 := hash6(cv>>8, hashLog)
+ candidate := e.table[nextHash]
+ candidate2 := e.table[nextHash2]
+ repIndex := s - offset1 + 2
+
+ e.table[nextHash] = tableEntry{offset: s + e.cur, val: uint32(cv)}
+ e.markShardDirty(nextHash)
+ e.table[nextHash2] = tableEntry{offset: s + e.cur + 1, val: uint32(cv >> 8)}
+ e.markShardDirty(nextHash2)
+
+ if canRepeat && repIndex >= 0 && load3232(src, repIndex) == uint32(cv>>16) {
+ // Consider history as well.
+ var seq seq
+ var length int32
+ // length = 4 + e.matchlen(s+6, repIndex+4, src)
+ {
+ a := src[s+6:]
+ b := src[repIndex+4:]
+ endI := len(a) & (math.MaxInt32 - 7)
+ length = int32(endI) + 4
+ for i := 0; i < endI; i += 8 {
+ if diff := load64(a, i) ^ load64(b, i); diff != 0 {
+ length = int32(i+bits.TrailingZeros64(diff)>>3) + 4
+ break
+ }
+ }
+ }
+
+ seq.matchLen = uint32(length - zstdMinMatch)
+
+ // We might be able to match backwards.
+ // Extend as long as we can.
+ start := s + 2
+ // We end the search early, so we don't risk 0 literals
+ // and have to do special offset treatment.
+ startLimit := nextEmit + 1
+
+ sMin := s - e.maxMatchOff
+ if sMin < 0 {
+ sMin = 0
+ }
+ for repIndex > sMin && start > startLimit && src[repIndex-1] == src[start-1] && seq.matchLen < maxMatchLength-zstdMinMatch {
+ repIndex--
+ start--
+ seq.matchLen++
+ }
+ addLiterals(&seq, start)
+
+ // rep 0
+ seq.offset = 1
+ if debugSequences {
+ println("repeat sequence", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+ s += length + 2
+ nextEmit = s
+ if s >= sLimit {
+ if debug {
+ println("repeat ended", s, length)
+
+ }
+ break encodeLoop
+ }
+ cv = load6432(src, s)
+ continue
+ }
+ coffset0 := s - (candidate.offset - e.cur)
+ coffset1 := s - (candidate2.offset - e.cur) + 1
+ if coffset0 < e.maxMatchOff && uint32(cv) == candidate.val {
+ // found a regular match
+ t = candidate.offset - e.cur
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ break
+ }
+
+ if coffset1 < e.maxMatchOff && uint32(cv>>8) == candidate2.val {
+ // found a regular match
+ t = candidate2.offset - e.cur
+ s++
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+ if debugAsserts && s-t > e.maxMatchOff {
+ panic("s - t >e.maxMatchOff")
+ }
+ if debugAsserts && t < 0 {
+ panic("t<0")
+ }
+ break
+ }
+ s += stepSize + ((s - nextEmit) >> (kSearchStrength - 1))
+ if s >= sLimit {
+ break encodeLoop
+ }
+ cv = load6432(src, s)
+ }
+ // A 4-byte match has been found. We'll later see if more than 4 bytes.
+ offset2 = offset1
+ offset1 = s - t
+
+ if debugAsserts && s <= t {
+ panic(fmt.Sprintf("s (%d) <= t (%d)", s, t))
+ }
+
+ if debugAsserts && canRepeat && int(offset1) > len(src) {
+ panic("invalid offset")
+ }
+
+ // Extend the 4-byte match as long as possible.
+ //l := e.matchlen(s+4, t+4, src) + 4
+ var l int32
+ {
+ a := src[s+4:]
+ b := src[t+4:]
+ endI := len(a) & (math.MaxInt32 - 7)
+ l = int32(endI) + 4
+ for i := 0; i < endI; i += 8 {
+ if diff := load64(a, i) ^ load64(b, i); diff != 0 {
+ l = int32(i+bits.TrailingZeros64(diff)>>3) + 4
+ break
+ }
+ }
+ }
+
+ // Extend backwards
+ tMin := s - e.maxMatchOff
+ if tMin < 0 {
+ tMin = 0
+ }
+ for t > tMin && s > nextEmit && src[t-1] == src[s-1] && l < maxMatchLength {
+ s--
+ t--
+ l++
+ }
+
+ // Write our sequence.
+ var seq seq
+ seq.litLen = uint32(s - nextEmit)
+ seq.matchLen = uint32(l - zstdMinMatch)
+ if seq.litLen > 0 {
+ blk.literals = append(blk.literals, src[nextEmit:s]...)
+ }
+ // Don't use repeat offsets
+ seq.offset = uint32(s-t) + 3
+ s += l
+ if debugSequences {
+ println("sequence", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+ nextEmit = s
+ if s >= sLimit {
+ break encodeLoop
+ }
+ cv = load6432(src, s)
+
+ // Check offset 2
+ if o2 := s - offset2; canRepeat && load3232(src, o2) == uint32(cv) {
+ // We have at least 4 byte match.
+ // No need to check backwards. We come straight from a match
+ //l := 4 + e.matchlen(s+4, o2+4, src)
+ var l int32
+ {
+ a := src[s+4:]
+ b := src[o2+4:]
+ endI := len(a) & (math.MaxInt32 - 7)
+ l = int32(endI) + 4
+ for i := 0; i < endI; i += 8 {
+ if diff := load64(a, i) ^ load64(b, i); diff != 0 {
+ l = int32(i+bits.TrailingZeros64(diff)>>3) + 4
+ break
+ }
+ }
+ }
+
+ // Store this, since we have it.
+ nextHash := hash6(cv, hashLog)
+ e.table[nextHash] = tableEntry{offset: s + e.cur, val: uint32(cv)}
+ e.markShardDirty(nextHash)
+ seq.matchLen = uint32(l) - zstdMinMatch
+ seq.litLen = 0
+ // Since litlen is always 0, this is offset 1.
+ seq.offset = 1
+ s += l
+ nextEmit = s
+ if debugSequences {
+ println("sequence", seq, "next s:", s)
+ }
+ blk.sequences = append(blk.sequences, seq)
+
+ // Swap offset 1 and 2.
+ offset1, offset2 = offset2, offset1
+ if s >= sLimit {
+ break encodeLoop
+ }
+ // Prepare next loop.
+ cv = load6432(src, s)
+ }
+ }
+
+ if int(nextEmit) < len(src) {
+ blk.literals = append(blk.literals, src[nextEmit:]...)
+ blk.extraLits = len(src) - int(nextEmit)
+ }
+ blk.recentOffsets[0] = uint32(offset1)
+ blk.recentOffsets[1] = uint32(offset2)
+ if debug {
+ println("returning, recent offsets:", blk.recentOffsets, "extra literals:", blk.extraLits)
+ }
+}
+
// ResetDict will reset and set a dictionary if not nil
func (e *fastEncoder) Reset(d *dict, singleBlock bool) {
e.resetBase(d, singleBlock)
+ if d != nil {
+ panic("fastEncoder: Reset with dict")
+ }
+}
+
+// ResetDict will reset and set a dictionary if not nil
+func (e *fastEncoderDict) Reset(d *dict, singleBlock bool) {
+ e.resetBase(d, singleBlock)
if d == nil {
return
}
@@ -653,9 +975,44 @@ func (e *fastEncoder) Reset(d *dict, singleBlock bool) {
}
}
e.lastDictID = d.id
+ e.allDirty = true
}
e.cur = e.maxMatchOff
- // Reset table to initial state
- copy(e.table[:], e.dictTable)
+ dirtyShardCnt := 0
+ if !e.allDirty {
+ for i := range e.tableShardDirty {
+ if e.tableShardDirty[i] {
+ dirtyShardCnt++
+ }
+ }
+ }
+
+ const shardCnt = tableShardCnt
+ const shardSize = tableShardSize
+ if e.allDirty || dirtyShardCnt > shardCnt*4/6 {
+ copy(e.table[:], e.dictTable)
+ for i := range e.tableShardDirty {
+ e.tableShardDirty[i] = false
+ }
+ e.allDirty = false
+ return
+ }
+ for i := range e.tableShardDirty {
+ if !e.tableShardDirty[i] {
+ continue
+ }
+
+ copy(e.table[i*shardSize:(i+1)*shardSize], e.dictTable[i*shardSize:(i+1)*shardSize])
+ e.tableShardDirty[i] = false
+ }
+ e.allDirty = false
+}
+
+func (e *fastEncoderDict) markAllShardsDirty() {
+ e.allDirty = true
+}
+
+func (e *fastEncoderDict) markShardDirty(entryNum uint32) {
+ e.tableShardDirty[entryNum/tableShardSize] = true
}
generated by cgit v1.2.3-54-g00ecf (git 2.39.0) at 2024-10-19 02:27:18 +0000