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compress.go
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compress.go
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package fasthttp
import (
"fmt"
"io"
"os"
"sync"
"github.com/klauspost/compress/flate"
"github.com/klauspost/compress/gzip"
"github.com/klauspost/compress/zlib"
)
// Supported compression levels.
const (
CompressNoCompression = flate.NoCompression
CompressBestSpeed = flate.BestSpeed
CompressBestCompression = flate.BestCompression
CompressDefaultCompression = flate.DefaultCompression
)
func acquireGzipReader(r io.Reader) (*gzip.Reader, error) {
v := gzipReaderPool.Get()
if v == nil {
return gzip.NewReader(r)
}
zr := v.(*gzip.Reader)
if err := zr.Reset(r); err != nil {
return nil, err
}
return zr, nil
}
func releaseGzipReader(zr *gzip.Reader) {
zr.Close()
gzipReaderPool.Put(zr)
}
var gzipReaderPool sync.Pool
func acquireFlateReader(r io.Reader) (io.ReadCloser, error) {
v := flateReaderPool.Get()
if v == nil {
zr, err := zlib.NewReader(r)
if err != nil {
return nil, err
}
return zr, nil
}
zr := v.(io.ReadCloser)
if err := resetFlateReader(zr, r); err != nil {
return nil, err
}
return zr, nil
}
func releaseFlateReader(zr io.ReadCloser) {
zr.Close()
flateReaderPool.Put(zr)
}
func resetFlateReader(zr io.ReadCloser, r io.Reader) error {
zrr, ok := zr.(zlib.Resetter)
if !ok {
panic("BUG: zlib.Reader doesn't implement zlib.Resetter???")
}
return zrr.Reset(r, nil)
}
var flateReaderPool sync.Pool
func acquireGzipWriter(w io.Writer, level int) *gzipWriter {
p := gzipWriterPoolMap[level]
if p == nil {
panic(fmt.Sprintf("BUG: unexpected compression level passed: %d. See compress/gzip for supported levels", level))
}
v := p.Get()
if v == nil {
zw, err := gzip.NewWriterLevel(w, level)
if err != nil {
panic(fmt.Sprintf("BUG: unexpected error from gzip.NewWriterLevel(%d): %s", level, err))
}
return &gzipWriter{
Writer: zw,
p: p,
}
}
zw := v.(*gzipWriter)
zw.Reset(w)
return zw
}
func releaseGzipWriter(zw *gzipWriter) {
zw.Close()
zw.p.Put(zw)
}
type gzipWriter struct {
*gzip.Writer
p *sync.Pool
}
var gzipWriterPoolMap = func() map[int]*sync.Pool {
// Initialize pools for all the compression levels defined
// in https://golang.org/pkg/compress/gzip/#pkg-constants .
m := make(map[int]*sync.Pool, 11)
m[-1] = &sync.Pool{}
for i := 0; i < 10; i++ {
m[i] = &sync.Pool{}
}
return m
}()
// AppendGzipBytesLevel appends gzipped src to dst using the given
// compression level and returns the resulting dst.
//
// Supported compression levels are:
//
// * CompressNoCompression
// * CompressBestSpeed
// * CompressBestCompression
// * CompressDefaultCompression
func AppendGzipBytesLevel(dst, src []byte, level int) []byte {
w := &byteSliceWriter{dst}
WriteGzipLevel(w, src, level)
return w.b
}
// WriteGzipLevel writes gzipped p to w using the given compression level
// and returns the number of compressed bytes written to w.
//
// Supported compression levels are:
//
// * CompressNoCompression
// * CompressBestSpeed
// * CompressBestCompression
// * CompressDefaultCompression
func WriteGzipLevel(w io.Writer, p []byte, level int) (int, error) {
zw := acquireGzipWriter(w, level)
n, err := zw.Write(p)
releaseGzipWriter(zw)
return n, err
}
// WriteGzip writes gzipped p to w and returns the number of compressed
// bytes written to w.
func WriteGzip(w io.Writer, p []byte) (int, error) {
return WriteGzipLevel(w, p, CompressDefaultCompression)
}
// AppendGzipBytes appends gzipped src to dst and returns the resulting dst.
func AppendGzipBytes(dst, src []byte) []byte {
return AppendGzipBytesLevel(dst, src, CompressDefaultCompression)
}
// WriteGunzip writes ungzipped p to w and returns the number of uncompressed
// bytes written to w.
func WriteGunzip(w io.Writer, p []byte) (int, error) {
r := &byteSliceReader{p}
zr, err := acquireGzipReader(r)
if err != nil {
return 0, err
}
n, err := copyZeroAlloc(w, zr)
releaseGzipReader(zr)
nn := int(n)
if int64(nn) != n {
return 0, fmt.Errorf("too much data gunzipped: %d", n)
}
return nn, err
}
// WriteInflate writes inflated p to w and returns the number of uncompressed
// bytes written to w.
func WriteInflate(w io.Writer, p []byte) (int, error) {
r := &byteSliceReader{p}
zr, err := acquireFlateReader(r)
if err != nil {
return 0, err
}
n, err := copyZeroAlloc(w, zr)
releaseFlateReader(zr)
nn := int(n)
if int64(nn) != n {
return 0, fmt.Errorf("too much data inflated: %d", n)
}
return nn, err
}
// AppendGunzipBytes append gunzipped src to dst and returns the resulting dst.
func AppendGunzipBytes(dst, src []byte) ([]byte, error) {
w := &byteSliceWriter{dst}
_, err := WriteGunzip(w, src)
return w.b, err
}
type byteSliceWriter struct {
b []byte
}
func (w *byteSliceWriter) Write(p []byte) (int, error) {
w.b = append(w.b, p...)
return len(p), nil
}
type byteSliceReader struct {
b []byte
}
func (r *byteSliceReader) Read(p []byte) (int, error) {
if len(r.b) == 0 {
return 0, io.EOF
}
n := copy(p, r.b)
r.b = r.b[n:]
return n, nil
}
func acquireFlateWriter(w io.Writer, level int) *flateWriter {
p := flateWriterPoolMap[level]
if p == nil {
panic(fmt.Sprintf("BUG: unexpected compression level passed: %d. See compress/flate for supported levels", level))
}
v := p.Get()
if v == nil {
zw, err := zlib.NewWriterLevel(w, level)
if err != nil {
panic(fmt.Sprintf("BUG: unexpected error in zlib.NewWriterLevel(%d): %s", level, err))
}
return &flateWriter{
Writer: zw,
p: p,
}
}
zw := v.(*flateWriter)
zw.Reset(w)
return zw
}
func releaseFlateWriter(zw *flateWriter) {
zw.Close()
zw.p.Put(zw)
}
type flateWriter struct {
*zlib.Writer
p *sync.Pool
}
var flateWriterPoolMap = func() map[int]*sync.Pool {
// Initialize pools for all the compression levels defined
// in https://golang.org/pkg/compress/flate/#pkg-constants .
m := make(map[int]*sync.Pool, 11)
m[-1] = &sync.Pool{}
for i := 0; i < 10; i++ {
m[i] = &sync.Pool{}
}
return m
}()
func isFileCompressible(f *os.File, minCompressRatio float64) bool {
// Try compressing the first 4kb of of the file
// and see if it can be compressed by more than
// the given minCompressRatio.
b := AcquireByteBuffer()
zw := acquireGzipWriter(b, CompressDefaultCompression)
lr := &io.LimitedReader{
R: f,
N: 4096,
}
_, err := copyZeroAlloc(zw, lr)
releaseGzipWriter(zw)
f.Seek(0, 0)
if err != nil {
return false
}
n := 4096 - lr.N
zn := len(b.B)
ReleaseByteBuffer(b)
return float64(zn) < float64(n)*minCompressRatio
}