124 lines
3.4 KiB
Go
124 lines
3.4 KiB
Go
// Copyright (c) 2016 Uber Technologies, Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in
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// all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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// THE SOFTWARE.
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package zapcore
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import (
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"io"
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"sync"
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"go.uber.org/multierr"
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)
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// A WriteSyncer is an io.Writer that can also flush any buffered data. Note
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// that *os.File (and thus, os.Stderr and os.Stdout) implement WriteSyncer.
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type WriteSyncer interface {
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io.Writer
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Sync() error
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}
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// AddSync converts an io.Writer to a WriteSyncer. It attempts to be
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// intelligent: if the concrete type of the io.Writer implements WriteSyncer,
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// we'll use the existing Sync method. If it doesn't, we'll add a no-op Sync.
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func AddSync(w io.Writer) WriteSyncer {
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switch w := w.(type) {
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case WriteSyncer:
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return w
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default:
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return writerWrapper{w}
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}
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}
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type lockedWriteSyncer struct {
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sync.Mutex
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ws WriteSyncer
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}
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// Lock wraps a WriteSyncer in a mutex to make it safe for concurrent use. In
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// particular, *os.Files must be locked before use.
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func Lock(ws WriteSyncer) WriteSyncer {
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if _, ok := ws.(*lockedWriteSyncer); ok {
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// no need to layer on another lock
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return ws
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}
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return &lockedWriteSyncer{ws: ws}
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}
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func (s *lockedWriteSyncer) Write(bs []byte) (int, error) {
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s.Lock()
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n, err := s.ws.Write(bs)
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s.Unlock()
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return n, err
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}
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func (s *lockedWriteSyncer) Sync() error {
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s.Lock()
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err := s.ws.Sync()
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s.Unlock()
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return err
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}
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type writerWrapper struct {
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io.Writer
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}
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func (w writerWrapper) Sync() error {
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return nil
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}
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type multiWriteSyncer []WriteSyncer
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// NewMultiWriteSyncer creates a WriteSyncer that duplicates its writes
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// and sync calls, much like io.MultiWriter.
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func NewMultiWriteSyncer(ws ...WriteSyncer) WriteSyncer {
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if len(ws) == 1 {
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return ws[0]
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}
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// Copy to protect against https://github.com/golang/go/issues/7809
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return multiWriteSyncer(append([]WriteSyncer(nil), ws...))
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}
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// See https://golang.org/src/io/multi.go
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// When not all underlying syncers write the same number of bytes,
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// the smallest number is returned even though Write() is called on
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// all of them.
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func (ws multiWriteSyncer) Write(p []byte) (int, error) {
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var writeErr error
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nWritten := 0
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for _, w := range ws {
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n, err := w.Write(p)
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writeErr = multierr.Append(writeErr, err)
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if nWritten == 0 && n != 0 {
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nWritten = n
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} else if n < nWritten {
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nWritten = n
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}
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}
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return nWritten, writeErr
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}
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func (ws multiWriteSyncer) Sync() error {
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var err error
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for _, w := range ws {
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err = multierr.Append(err, w.Sync())
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}
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return err
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}
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