William Kurkian | ea86948 | 2019-04-09 15:16:11 -0400 | [diff] [blame] | 1 | // Copyright (c) 2016 Uber Technologies, Inc. |
| 2 | // |
| 3 | // Permission is hereby granted, free of charge, to any person obtaining a copy |
| 4 | // of this software and associated documentation files (the "Software"), to deal |
| 5 | // in the Software without restriction, including without limitation the rights |
| 6 | // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 7 | // copies of the Software, and to permit persons to whom the Software is |
| 8 | // furnished to do so, subject to the following conditions: |
| 9 | // |
| 10 | // The above copyright notice and this permission notice shall be included in |
| 11 | // all copies or substantial portions of the Software. |
| 12 | // |
| 13 | // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 14 | // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 15 | // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE |
| 16 | // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 17 | // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 18 | // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| 19 | // THE SOFTWARE. |
| 20 | |
| 21 | package zapcore |
| 22 | |
| 23 | import ( |
| 24 | "io" |
| 25 | "sync" |
| 26 | |
| 27 | "go.uber.org/multierr" |
| 28 | ) |
| 29 | |
| 30 | // A WriteSyncer is an io.Writer that can also flush any buffered data. Note |
| 31 | // that *os.File (and thus, os.Stderr and os.Stdout) implement WriteSyncer. |
| 32 | type WriteSyncer interface { |
| 33 | io.Writer |
| 34 | Sync() error |
| 35 | } |
| 36 | |
| 37 | // AddSync converts an io.Writer to a WriteSyncer. It attempts to be |
| 38 | // intelligent: if the concrete type of the io.Writer implements WriteSyncer, |
| 39 | // we'll use the existing Sync method. If it doesn't, we'll add a no-op Sync. |
| 40 | func AddSync(w io.Writer) WriteSyncer { |
| 41 | switch w := w.(type) { |
| 42 | case WriteSyncer: |
| 43 | return w |
| 44 | default: |
| 45 | return writerWrapper{w} |
| 46 | } |
| 47 | } |
| 48 | |
| 49 | type lockedWriteSyncer struct { |
| 50 | sync.Mutex |
| 51 | ws WriteSyncer |
| 52 | } |
| 53 | |
| 54 | // Lock wraps a WriteSyncer in a mutex to make it safe for concurrent use. In |
| 55 | // particular, *os.Files must be locked before use. |
| 56 | func Lock(ws WriteSyncer) WriteSyncer { |
| 57 | if _, ok := ws.(*lockedWriteSyncer); ok { |
| 58 | // no need to layer on another lock |
| 59 | return ws |
| 60 | } |
| 61 | return &lockedWriteSyncer{ws: ws} |
| 62 | } |
| 63 | |
| 64 | func (s *lockedWriteSyncer) Write(bs []byte) (int, error) { |
| 65 | s.Lock() |
| 66 | n, err := s.ws.Write(bs) |
| 67 | s.Unlock() |
| 68 | return n, err |
| 69 | } |
| 70 | |
| 71 | func (s *lockedWriteSyncer) Sync() error { |
| 72 | s.Lock() |
| 73 | err := s.ws.Sync() |
| 74 | s.Unlock() |
| 75 | return err |
| 76 | } |
| 77 | |
| 78 | type writerWrapper struct { |
| 79 | io.Writer |
| 80 | } |
| 81 | |
| 82 | func (w writerWrapper) Sync() error { |
| 83 | return nil |
| 84 | } |
| 85 | |
| 86 | type multiWriteSyncer []WriteSyncer |
| 87 | |
| 88 | // NewMultiWriteSyncer creates a WriteSyncer that duplicates its writes |
| 89 | // and sync calls, much like io.MultiWriter. |
| 90 | func NewMultiWriteSyncer(ws ...WriteSyncer) WriteSyncer { |
| 91 | if len(ws) == 1 { |
| 92 | return ws[0] |
| 93 | } |
khenaidoo | 106c61a | 2021-08-11 18:05:46 -0400 | [diff] [blame] | 94 | return multiWriteSyncer(ws) |
William Kurkian | ea86948 | 2019-04-09 15:16:11 -0400 | [diff] [blame] | 95 | } |
| 96 | |
| 97 | // See https://golang.org/src/io/multi.go |
| 98 | // When not all underlying syncers write the same number of bytes, |
| 99 | // the smallest number is returned even though Write() is called on |
| 100 | // all of them. |
| 101 | func (ws multiWriteSyncer) Write(p []byte) (int, error) { |
| 102 | var writeErr error |
| 103 | nWritten := 0 |
| 104 | for _, w := range ws { |
| 105 | n, err := w.Write(p) |
| 106 | writeErr = multierr.Append(writeErr, err) |
| 107 | if nWritten == 0 && n != 0 { |
| 108 | nWritten = n |
| 109 | } else if n < nWritten { |
| 110 | nWritten = n |
| 111 | } |
| 112 | } |
| 113 | return nWritten, writeErr |
| 114 | } |
| 115 | |
| 116 | func (ws multiWriteSyncer) Sync() error { |
| 117 | var err error |
| 118 | for _, w := range ws { |
| 119 | err = multierr.Append(err, w.Sync()) |
| 120 | } |
| 121 | return err |
| 122 | } |