81 lines
1.6 KiB
Go
81 lines
1.6 KiB
Go
package xopen
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import (
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"compress/gzip"
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"io"
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"os/exec"
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)
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// from: https://gist.github.com/rasky/d42a52c16683f1a2f4dccdef80e2712d
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// fastGzReader is an API-compatible drop-in replacement
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// for gzip.Reader, that achieves a higher decoding speed
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// by spawning an external gzip instance and pipeing data
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// through it.
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// Go's native gzip implementation is about 2x slower at
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// decompressing data compared to zlib (mostly due to Go compiler
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// inefficiencies). So for tasks where the gzip decoding
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// speed is important, this is a quick workaround that doesn't
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// require cgo.
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// gzip is part of the gzip package and comes preinstalled on
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// most Linux distributions and on OSX.
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type fastGzReader struct {
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io.ReadCloser
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}
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func hasProg(prog ...string) bool {
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var cmd *exec.Cmd
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if len(prog) > 1 {
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cmd = exec.Command(prog[0], prog[1:]...)
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} else {
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cmd = exec.Command(prog[0])
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}
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err := cmd.Start()
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has := err == nil
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cmd.Wait()
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return has
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}
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var hasZlib = hasProg("gzip", "-d")
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var hasPigz = hasProg("pigz", "-d")
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func newFastGzReader(r io.Reader) (io.ReadCloser, error) {
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if hasZlib || hasPigz {
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var gz fastGzReader
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if err := gz.Reset(r); err != nil {
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return nil, err
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}
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return gz, nil
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}
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return gzip.NewReader(r)
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}
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func (gz *fastGzReader) Reset(r io.Reader) error {
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if gz.ReadCloser != nil {
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gz.Close()
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}
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var cmd *exec.Cmd
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if hasPigz {
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cmd = exec.Command("pigz", "-d")
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} else {
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cmd = exec.Command("gzip", "-d")
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}
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cmd.Stdin = r
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rpipe, err := cmd.StdoutPipe()
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if err != nil {
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return err
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}
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err = cmd.Start()
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if err != nil {
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rpipe.Close()
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return err
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}
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gz.ReadCloser = rpipe
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return nil
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}
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