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// Copyright (c) 2018, Sylabs Inc. All rights reserved.
// This software is licensed under a 3-clause BSD license. Please consult the
// LICENSE.md file distributed with the sources of this project regarding your
// rights to use or distribute this software.
package copy
import (
"io"
"sync"
)
// MultiWriter creates a writer that duplicates its writes to all the provided writers,
// writers can be added / removed dynamically.
type MultiWriter struct {
mutex sync.Mutex
writers []io.Writer
}
// Write implements the standard Write interface to duplicate data to all writers.
func (mw *MultiWriter) Write(p []byte) (n int, err error) {
mw.mutex.Lock()
defer mw.mutex.Unlock()
l := len(p)
for _, w := range mw.writers {
n, err = w.Write(p)
if err != nil {
return
}
if n != l {
err = io.ErrShortWrite
return
}
}
return l, nil
}
// Add adds a writer.
func (mw *MultiWriter) Add(writer io.Writer) {
if writer == nil {
return
}
mw.mutex.Lock()
mw.writers = append(mw.writers, writer)
mw.mutex.Unlock()
}
// Del removes a writer.
func (mw *MultiWriter) Del(writer io.Writer) {
mw.mutex.Lock()
for i, w := range mw.writers {
if writer == w {
mw.writers = append(mw.writers[:i], mw.writers[i+1:]...)
break
}
}
mw.mutex.Unlock()
}
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