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package zerolog
import (
"io"
"sync"
)
// LevelWriter defines as interface a writer may implement in order
// to receive level information with payload.
type LevelWriter interface {
io.Writer
WriteLevel(level Level, p []byte) (n int, err error)
}
type levelWriterAdapter struct {
io.Writer
}
func (lw levelWriterAdapter) WriteLevel(l Level, p []byte) (n int, err error) {
return lw.Write(p)
}
type syncWriter struct {
mu sync.Mutex
lw LevelWriter
}
// SyncWriter wraps w so that each call to Write is synchronized with a mutex.
// This syncer can be the call to writer's Write method is not thread safe.
// Note that os.File Write operation is using write() syscall which is supposed
// to be thread-safe on POSIX systems. So there is no need to use this with
// os.File on such systems as zerolog guaranties to issue a single Write call
// per log event.
func SyncWriter(w io.Writer) io.Writer {
if lw, ok := w.(LevelWriter); ok {
return &syncWriter{lw: lw}
}
return &syncWriter{lw: levelWriterAdapter{w}}
}
// Write implements the io.Writer interface.
func (s *syncWriter) Write(p []byte) (n int, err error) {
s.mu.Lock()
defer s.mu.Unlock()
return s.lw.Write(p)
}
// WriteLevel implements the LevelWriter interface.
func (s *syncWriter) WriteLevel(l Level, p []byte) (n int, err error) {
s.mu.Lock()
defer s.mu.Unlock()
return s.lw.WriteLevel(l, p)
}
type multiLevelWriter struct {
writers []LevelWriter
}
func (t multiLevelWriter) Write(p []byte) (n int, err error) {
for _, w := range t.writers {
n, err = w.Write(p)
if err != nil {
return
}
if n != len(p) {
err = io.ErrShortWrite
return
}
}
return len(p), nil
}
func (t multiLevelWriter) WriteLevel(l Level, p []byte) (n int, err error) {
for _, w := range t.writers {
n, err = w.WriteLevel(l, p)
if err != nil {
return
}
if n != len(p) {
err = io.ErrShortWrite
return
}
}
return len(p), nil
}
// MultiLevelWriter creates a writer that duplicates its writes to all the
// provided writers, similar to the Unix tee(1) command. If some writers
// implement LevelWriter, their WriteLevel method will be used instead of Write.
func MultiLevelWriter(writers ...io.Writer) LevelWriter {
lwriters := make([]LevelWriter, 0, len(writers))
for _, w := range writers {
if lw, ok := w.(LevelWriter); ok {
lwriters = append(lwriters, lw)
} else {
lwriters = append(lwriters, levelWriterAdapter{w})
}
}
return multiLevelWriter{lwriters}
}