forked from klauspost/compress
-
Notifications
You must be signed in to change notification settings - Fork 0
/
gzkp.go
85 lines (72 loc) · 2 KB
/
gzkp.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
// package gzkp provides gzip compression through github.com/klauspost/compress/gzip.
package gzkp
import (
"io"
"sync"
"github.com/klauspost/compress/gzhttp/writer"
"github.com/klauspost/compress/gzip"
)
// gzipWriterPools stores a sync.Pool for each compression level for reuse of
// gzip.Writers. Use poolIndex to covert a compression level to an index into
// gzipWriterPools.
var gzipWriterPools [gzip.BestCompression - gzip.StatelessCompression + 1]*sync.Pool
func init() {
for i := gzip.StatelessCompression; i <= gzip.BestCompression; i++ {
addLevelPool(i)
}
}
// poolIndex maps a compression level to its index into gzipWriterPools. It
// assumes that level is a valid gzip compression level.
func poolIndex(level int) int {
if level > gzip.BestCompression {
level = gzip.BestCompression
}
if level < gzip.StatelessCompression {
level = gzip.BestSpeed
}
return level - gzip.StatelessCompression
}
func addLevelPool(level int) {
gzipWriterPools[poolIndex(level)] = &sync.Pool{
New: func() interface{} {
// NewWriterLevel only returns error on a bad level, we are guaranteeing
// that this will be a valid level so it is okay to ignore the returned
// error.
w, _ := gzip.NewWriterLevel(nil, level)
return w
},
}
}
type pooledWriter struct {
*gzip.Writer
index int
}
func (pw *pooledWriter) Close() error {
err := pw.Writer.Close()
gzipWriterPools[pw.index].Put(pw.Writer)
pw.Writer = nil
return err
}
func NewWriter(w io.Writer, level int) writer.GzipWriter {
index := poolIndex(level)
gzw := gzipWriterPools[index].Get().(*gzip.Writer)
gzw.Reset(w)
return &pooledWriter{
Writer: gzw,
index: index,
}
}
// SetHeader will override the gzip header on pw.
func (pw *pooledWriter) SetHeader(h writer.Header) {
pw.Name = h.Name
pw.Extra = h.Extra
pw.Comment = h.Comment
pw.ModTime = h.ModTime
pw.OS = h.OS
}
func Levels() (min, max int) {
return gzip.StatelessCompression, gzip.BestCompression
}
func ImplementationInfo() string {
return "klauspost/compress/gzip"
}