forked from mystiq/dex
53 lines
1.1 KiB
Go
53 lines
1.1 KiB
Go
package gexec
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import (
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"io"
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"sync"
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)
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/*
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PrefixedWriter wraps an io.Writer, emiting the passed in prefix at the beginning of each new line.
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This can be useful when running multiple gexec.Sessions concurrently - you can prefix the log output of each
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session by passing in a PrefixedWriter:
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gexec.Start(cmd, NewPrefixedWriter("[my-cmd] ", GinkgoWriter), NewPrefixedWriter("[my-cmd] ", GinkgoWriter))
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*/
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type PrefixedWriter struct {
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prefix []byte
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writer io.Writer
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lock *sync.Mutex
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atStartOfLine bool
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}
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func NewPrefixedWriter(prefix string, writer io.Writer) *PrefixedWriter {
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return &PrefixedWriter{
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prefix: []byte(prefix),
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writer: writer,
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lock: &sync.Mutex{},
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atStartOfLine: true,
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}
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}
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func (w *PrefixedWriter) Write(b []byte) (int, error) {
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w.lock.Lock()
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defer w.lock.Unlock()
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toWrite := []byte{}
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for _, c := range b {
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if w.atStartOfLine {
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toWrite = append(toWrite, w.prefix...)
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}
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toWrite = append(toWrite, c)
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w.atStartOfLine = c == '\n'
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}
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_, err := w.writer.Write(toWrite)
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if err != nil {
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return 0, err
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}
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return len(b), nil
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}
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