jochen
be92762969
The live tests reached one shared bus and assert, read and remove the mesh's own objects by their fixed names, so packages run in parallel deleted what each other read and the suite passed only one package at a time; a red suite read as noise. internal/testbus starts a server per test, linked in at the nats-server release go.mod pins, and a test holds that pin to the catalogue's bus image and to the facts snapshot's bus when there is one, so the tests never run a bus the mesh does not. The waiter test read a timing (the most connections held at one look) and now reads the state it means (the fewest held across the wait). make check runs the packages in parallel under the race detector, with a timeout.
419 lines
12 KiB
Go
419 lines
12 KiB
Go
// Copyright 2011 The Snappy-Go Authors. All rights reserved.
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// Copyright (c) 2019 Klaus Post. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package s2
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import (
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"encoding/binary"
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"math"
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"math/bits"
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"sync"
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"github.com/klauspost/compress/internal/race"
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)
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// Encode returns the encoded form of src. The returned slice may be a sub-
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// slice of dst if dst was large enough to hold the entire encoded block.
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// Otherwise, a newly allocated slice will be returned.
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//
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// The dst and src must not overlap. It is valid to pass a nil dst.
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//
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// The blocks will require the same amount of memory to decode as encoding,
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// and does not make for concurrent decoding.
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// Also note that blocks do not contain CRC information, so corruption may be undetected.
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//
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// If you need to encode larger amounts of data, consider using
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// the streaming interface which gives all of these features.
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func Encode(dst, src []byte) []byte {
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if n := MaxEncodedLen(len(src)); n < 0 {
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panic(ErrTooLarge)
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} else if cap(dst) < n {
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dst = make([]byte, n)
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} else {
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dst = dst[:n]
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}
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// The block starts with the varint-encoded length of the decompressed bytes.
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d := binary.PutUvarint(dst, uint64(len(src)))
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if len(src) == 0 {
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return dst[:d]
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}
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if len(src) < minNonLiteralBlockSize {
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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n := encodeBlock(dst[d:], src)
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if n > 0 {
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d += n
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return dst[:d]
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}
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// Not compressible
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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var estblockPool [2]sync.Pool
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// EstimateBlockSize will perform a very fast compression
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// without outputting the result and return the compressed output size.
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// The function returns -1 if no improvement could be achieved.
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// Using actual compression will most often produce better compression than the estimate.
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func EstimateBlockSize(src []byte) (d int) {
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if len(src) <= inputMargin || int64(len(src)) > 0xffffffff {
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return -1
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}
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if len(src) <= 1024 {
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const sz, pool = 2048, 0
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tmp, ok := estblockPool[pool].Get().(*[sz]byte)
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if !ok {
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tmp = &[sz]byte{}
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}
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race.WriteSlice(tmp[:])
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defer estblockPool[pool].Put(tmp)
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d = calcBlockSizeSmall(src, tmp)
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} else {
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const sz, pool = 32768, 1
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tmp, ok := estblockPool[pool].Get().(*[sz]byte)
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if !ok {
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tmp = &[sz]byte{}
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}
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race.WriteSlice(tmp[:])
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defer estblockPool[pool].Put(tmp)
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d = calcBlockSize(src, tmp)
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}
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if d == 0 {
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return -1
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}
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// Size of the varint encoded block size.
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d += (bits.Len64(uint64(len(src))) + 7) / 7
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if d >= len(src) {
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return -1
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}
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return d
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}
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// EncodeBetter returns the encoded form of src. The returned slice may be a sub-
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// slice of dst if dst was large enough to hold the entire encoded block.
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// Otherwise, a newly allocated slice will be returned.
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//
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// EncodeBetter compresses better than Encode but typically with a
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// 10-40% speed decrease on both compression and decompression.
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//
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// The dst and src must not overlap. It is valid to pass a nil dst.
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//
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// The blocks will require the same amount of memory to decode as encoding,
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// and does not make for concurrent decoding.
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// Also note that blocks do not contain CRC information, so corruption may be undetected.
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//
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// If you need to encode larger amounts of data, consider using
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// the streaming interface which gives all of these features.
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func EncodeBetter(dst, src []byte) []byte {
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if n := MaxEncodedLen(len(src)); n < 0 {
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panic(ErrTooLarge)
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} else if cap(dst) < n {
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dst = make([]byte, n)
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} else {
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dst = dst[:n]
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}
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// The block starts with the varint-encoded length of the decompressed bytes.
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d := binary.PutUvarint(dst, uint64(len(src)))
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if len(src) == 0 {
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return dst[:d]
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}
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if len(src) < minNonLiteralBlockSize {
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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n := encodeBlockBetter(dst[d:], src)
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if n > 0 {
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d += n
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return dst[:d]
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}
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// Not compressible
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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// EncodeBest returns the encoded form of src. The returned slice may be a sub-
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// slice of dst if dst was large enough to hold the entire encoded block.
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// Otherwise, a newly allocated slice will be returned.
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//
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// EncodeBest compresses as good as reasonably possible but with a
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// big speed decrease.
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//
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// The dst and src must not overlap. It is valid to pass a nil dst.
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//
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// The blocks will require the same amount of memory to decode as encoding,
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// and does not make for concurrent decoding.
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// Also note that blocks do not contain CRC information, so corruption may be undetected.
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//
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// If you need to encode larger amounts of data, consider using
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// the streaming interface which gives all of these features.
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func EncodeBest(dst, src []byte) []byte {
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if n := MaxEncodedLen(len(src)); n < 0 {
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panic(ErrTooLarge)
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} else if cap(dst) < n {
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dst = make([]byte, n)
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} else {
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dst = dst[:n]
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}
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// The block starts with the varint-encoded length of the decompressed bytes.
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d := binary.PutUvarint(dst, uint64(len(src)))
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if len(src) == 0 {
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return dst[:d]
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}
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if len(src) < minNonLiteralBlockSize {
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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n := encodeBlockBest(dst[d:], src, nil)
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if n > 0 {
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d += n
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return dst[:d]
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}
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// Not compressible
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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// EncodeSnappy returns the encoded form of src. The returned slice may be a sub-
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// slice of dst if dst was large enough to hold the entire encoded block.
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// Otherwise, a newly allocated slice will be returned.
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//
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// The output is Snappy compatible and will likely decompress faster.
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//
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// The dst and src must not overlap. It is valid to pass a nil dst.
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//
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// The blocks will require the same amount of memory to decode as encoding,
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// and does not make for concurrent decoding.
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// Also note that blocks do not contain CRC information, so corruption may be undetected.
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//
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// If you need to encode larger amounts of data, consider using
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// the streaming interface which gives all of these features.
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func EncodeSnappy(dst, src []byte) []byte {
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if n := MaxEncodedLen(len(src)); n < 0 {
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panic(ErrTooLarge)
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} else if cap(dst) < n {
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dst = make([]byte, n)
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} else {
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dst = dst[:n]
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}
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// The block starts with the varint-encoded length of the decompressed bytes.
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d := binary.PutUvarint(dst, uint64(len(src)))
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if len(src) == 0 {
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return dst[:d]
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}
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if len(src) < minNonLiteralBlockSize {
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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n := encodeBlockSnappy(dst[d:], src)
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if n > 0 {
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d += n
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return dst[:d]
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}
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// Not compressible
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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// EncodeSnappyBetter returns the encoded form of src. The returned slice may be a sub-
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// slice of dst if dst was large enough to hold the entire encoded block.
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// Otherwise, a newly allocated slice will be returned.
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//
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// The output is Snappy compatible and will likely decompress faster.
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//
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// The dst and src must not overlap. It is valid to pass a nil dst.
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//
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// The blocks will require the same amount of memory to decode as encoding,
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// and does not make for concurrent decoding.
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// Also note that blocks do not contain CRC information, so corruption may be undetected.
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//
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// If you need to encode larger amounts of data, consider using
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// the streaming interface which gives all of these features.
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func EncodeSnappyBetter(dst, src []byte) []byte {
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if n := MaxEncodedLen(len(src)); n < 0 {
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panic(ErrTooLarge)
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} else if cap(dst) < n {
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dst = make([]byte, n)
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} else {
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dst = dst[:n]
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}
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// The block starts with the varint-encoded length of the decompressed bytes.
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d := binary.PutUvarint(dst, uint64(len(src)))
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if len(src) == 0 {
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return dst[:d]
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}
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if len(src) < minNonLiteralBlockSize {
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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n := encodeBlockBetterSnappy(dst[d:], src)
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if n > 0 {
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d += n
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return dst[:d]
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}
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// Not compressible
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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// EncodeSnappyBest returns the encoded form of src. The returned slice may be a sub-
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// slice of dst if dst was large enough to hold the entire encoded block.
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// Otherwise, a newly allocated slice will be returned.
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//
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// The output is Snappy compatible and will likely decompress faster.
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//
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// The dst and src must not overlap. It is valid to pass a nil dst.
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//
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// The blocks will require the same amount of memory to decode as encoding,
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// and does not make for concurrent decoding.
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// Also note that blocks do not contain CRC information, so corruption may be undetected.
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//
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// If you need to encode larger amounts of data, consider using
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// the streaming interface which gives all of these features.
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func EncodeSnappyBest(dst, src []byte) []byte {
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if n := MaxEncodedLen(len(src)); n < 0 {
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panic(ErrTooLarge)
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} else if cap(dst) < n {
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dst = make([]byte, n)
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} else {
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dst = dst[:n]
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}
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// The block starts with the varint-encoded length of the decompressed bytes.
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d := binary.PutUvarint(dst, uint64(len(src)))
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if len(src) == 0 {
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return dst[:d]
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}
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if len(src) < minNonLiteralBlockSize {
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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n := encodeBlockBestSnappy(dst[d:], src)
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if n > 0 {
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d += n
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return dst[:d]
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}
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// Not compressible
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d += emitLiteral(dst[d:], src)
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return dst[:d]
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}
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// ConcatBlocks will concatenate the supplied blocks and append them to the supplied destination.
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// If the destination is nil or too small, a new will be allocated.
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// The blocks are not validated, so garbage in = garbage out.
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// dst may not overlap block data.
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// Any data in dst is preserved as is, so it will not be considered a block.
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func ConcatBlocks(dst []byte, blocks ...[]byte) ([]byte, error) {
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totalSize := uint64(0)
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compSize := 0
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for _, b := range blocks {
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l, hdr, err := decodedLen(b)
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if err != nil {
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return nil, err
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}
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totalSize += uint64(l)
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compSize += len(b) - hdr
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}
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if totalSize == 0 {
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dst = append(dst, 0)
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return dst, nil
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}
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if totalSize > math.MaxUint32 {
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return nil, ErrTooLarge
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}
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var tmp [binary.MaxVarintLen32]byte
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hdrSize := binary.PutUvarint(tmp[:], totalSize)
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wantSize := hdrSize + compSize
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if cap(dst)-len(dst) < wantSize {
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dst = append(make([]byte, 0, wantSize+len(dst)), dst...)
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}
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dst = append(dst, tmp[:hdrSize]...)
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for _, b := range blocks {
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_, hdr, err := decodedLen(b)
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if err != nil {
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return nil, err
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}
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dst = append(dst, b[hdr:]...)
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}
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return dst, nil
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}
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// inputMargin is the minimum number of extra input bytes to keep, inside
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// encodeBlock's inner loop. On some architectures, this margin lets us
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// implement a fast path for emitLiteral, where the copy of short (<= 16 byte)
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// literals can be implemented as a single load to and store from a 16-byte
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// register. That literal's actual length can be as short as 1 byte, so this
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// can copy up to 15 bytes too much, but that's OK as subsequent iterations of
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// the encoding loop will fix up the copy overrun, and this inputMargin ensures
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// that we don't overrun the dst and src buffers.
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const inputMargin = 8
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// minNonLiteralBlockSize is the minimum size of the input to encodeBlock that
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// will be accepted by the encoder.
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const minNonLiteralBlockSize = 32
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const intReduction = 2 - (1 << (^uint(0) >> 63)) // 1 (32 bits) or 0 (64 bits)
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// MaxBlockSize is the maximum value where MaxEncodedLen will return a valid block size.
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// Blocks this big are highly discouraged, though.
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// Half the size on 32 bit systems.
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const MaxBlockSize = (1<<(32-intReduction) - 1) - binary.MaxVarintLen32 - 5
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// MaxEncodedLen returns the maximum length of a snappy block, given its
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// uncompressed length.
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//
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// It will return a negative value if srcLen is too large to encode.
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// 32 bit platforms will have lower thresholds for rejecting big content.
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func MaxEncodedLen(srcLen int) int {
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n := uint64(srcLen)
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if intReduction == 1 {
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// 32 bits
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if n > math.MaxInt32 {
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// Also includes negative.
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return -1
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}
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} else if n > 0xffffffff {
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// 64 bits
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// Also includes negative.
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return -1
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}
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// Size of the varint encoded block size.
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n = n + uint64((bits.Len64(n)+7)/7)
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// Add maximum size of encoding block as literals.
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n += uint64(literalExtraSize(int64(srcLen)))
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if intReduction == 1 {
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// 32 bits
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if n > math.MaxInt32 {
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return -1
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}
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} else if n > 0xffffffff {
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// 64 bits
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// Also includes negative.
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return -1
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}
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return int(n)
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}
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