diff options
Diffstat (limited to 'vendor/github.com/klauspost/compress/s2/encode_best.go')
| -rw-r--r-- | vendor/github.com/klauspost/compress/s2/encode_best.go | 35 |
1 files changed, 28 insertions, 7 deletions
diff --git a/vendor/github.com/klauspost/compress/s2/encode_best.go b/vendor/github.com/klauspost/compress/s2/encode_best.go index 4bc80bc6a..1b7ea394f 100644 --- a/vendor/github.com/klauspost/compress/s2/encode_best.go +++ b/vendor/github.com/klauspost/compress/s2/encode_best.go @@ -15,8 +15,9 @@ import ( // been written. // // It also assumes that: +// // len(dst) >= MaxEncodedLen(len(src)) && -// minNonLiteralBlockSize <= len(src) && len(src) <= maxBlockSize +// minNonLiteralBlockSize <= len(src) && len(src) <= maxBlockSize func encodeBlockBest(dst, src []byte) (d int) { // Initialize the hash tables. const ( @@ -176,14 +177,21 @@ func encodeBlockBest(dst, src []byte) (d int) { best = bestOf(best, matchAt(getPrev(nextLong), s, uint32(cv), false)) } // Search for a match at best match end, see if that is better. - if sAt := best.s + best.length; sAt < sLimit { - sBack := best.s - backL := best.length + // Allow some bytes at the beginning to mismatch. + // Sweet spot is around 1-2 bytes, but depends on input. + // The skipped bytes are tested in Extend backwards, + // and still picked up as part of the match if they do. + const skipBeginning = 2 + const skipEnd = 1 + if sAt := best.s + best.length - skipEnd; sAt < sLimit { + + sBack := best.s + skipBeginning - skipEnd + backL := best.length - skipBeginning // Load initial values cv = load64(src, sBack) - // Search for mismatch + + // Grab candidates... next := lTable[hash8(load64(src, sAt), lTableBits)] - //next := sTable[hash4(load64(src, sAt), sTableBits)] if checkAt := getCur(next) - backL; checkAt > 0 { best = bestOf(best, matchAt(checkAt, sBack, uint32(cv), false)) @@ -191,6 +199,16 @@ func encodeBlockBest(dst, src []byte) (d int) { if checkAt := getPrev(next) - backL; checkAt > 0 { best = bestOf(best, matchAt(checkAt, sBack, uint32(cv), false)) } + // Disabled: Extremely small gain + if false { + next = sTable[hash4(load64(src, sAt), sTableBits)] + if checkAt := getCur(next) - backL; checkAt > 0 { + best = bestOf(best, matchAt(checkAt, sBack, uint32(cv), false)) + } + if checkAt := getPrev(next) - backL; checkAt > 0 { + best = bestOf(best, matchAt(checkAt, sBack, uint32(cv), false)) + } + } } } } @@ -288,8 +306,9 @@ emitRemainder: // been written. // // It also assumes that: +// // len(dst) >= MaxEncodedLen(len(src)) && -// minNonLiteralBlockSize <= len(src) && len(src) <= maxBlockSize +// minNonLiteralBlockSize <= len(src) && len(src) <= maxBlockSize func encodeBlockBestSnappy(dst, src []byte) (d int) { // Initialize the hash tables. const ( @@ -546,6 +565,7 @@ emitRemainder: // emitCopySize returns the size to encode the offset+length // // It assumes that: +// // 1 <= offset && offset <= math.MaxUint32 // 4 <= length && length <= 1 << 24 func emitCopySize(offset, length int) int { @@ -584,6 +604,7 @@ func emitCopySize(offset, length int) int { // emitCopyNoRepeatSize returns the size to encode the offset+length // // It assumes that: +// // 1 <= offset && offset <= math.MaxUint32 // 4 <= length && length <= 1 << 24 func emitCopyNoRepeatSize(offset, length int) int { |