mirror of https://github.com/prometheus/prometheus
65 lines
2.1 KiB
Go
65 lines
2.1 KiB
Go
package diskv
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import (
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"compress/flate"
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"compress/gzip"
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"compress/zlib"
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"io"
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)
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// Compression is an interface that Diskv uses to implement compression of
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// data. Writer takes a destination io.Writer and returns a WriteCloser that
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// compresses all data written through it. Reader takes a source io.Reader and
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// returns a ReadCloser that decompresses all data read through it. You may
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// define these methods on your own type, or use one of the NewCompression
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// helpers.
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type Compression interface {
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Writer(dst io.Writer) (io.WriteCloser, error)
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Reader(src io.Reader) (io.ReadCloser, error)
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}
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// NewGzipCompression returns a Gzip-based Compression.
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func NewGzipCompression() Compression {
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return NewGzipCompressionLevel(flate.DefaultCompression)
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}
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// NewGzipCompressionLevel returns a Gzip-based Compression with the given level.
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func NewGzipCompressionLevel(level int) Compression {
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return &genericCompression{
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wf: func(w io.Writer) (io.WriteCloser, error) { return gzip.NewWriterLevel(w, level) },
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rf: func(r io.Reader) (io.ReadCloser, error) { return gzip.NewReader(r) },
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}
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}
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// NewZlibCompression returns a Zlib-based Compression.
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func NewZlibCompression() Compression {
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return NewZlibCompressionLevel(flate.DefaultCompression)
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}
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// NewZlibCompressionLevel returns a Zlib-based Compression with the given level.
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func NewZlibCompressionLevel(level int) Compression {
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return NewZlibCompressionLevelDict(level, nil)
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}
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// NewZlibCompressionLevelDict returns a Zlib-based Compression with the given
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// level, based on the given dictionary.
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func NewZlibCompressionLevelDict(level int, dict []byte) Compression {
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return &genericCompression{
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func(w io.Writer) (io.WriteCloser, error) { return zlib.NewWriterLevelDict(w, level, dict) },
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func(r io.Reader) (io.ReadCloser, error) { return zlib.NewReaderDict(r, dict) },
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}
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}
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type genericCompression struct {
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wf func(w io.Writer) (io.WriteCloser, error)
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rf func(r io.Reader) (io.ReadCloser, error)
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}
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func (g *genericCompression) Writer(dst io.Writer) (io.WriteCloser, error) {
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return g.wf(dst)
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}
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func (g *genericCompression) Reader(src io.Reader) (io.ReadCloser, error) {
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return g.rf(src)
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}
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