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 // Core is a minimal, fast logger interface. It's designed for library authors 24 // to wrap in a more user-friendly API. 25 type Core interface { 26 LevelEnabler 27 28 // With adds structured context to the Core. 29 With([]Field) Core 30 // Check determines whether the supplied Entry should be logged (using the 31 // embedded LevelEnabler and possibly some extra logic). If the entry 32 // should be logged, the Core adds itself to the CheckedEntry and returns 33 // the result. 34 // 35 // Callers must use Check before calling Write. 36 Check(Entry, *CheckedEntry) *CheckedEntry 37 // Write serializes the Entry and any Fields supplied at the log site and 38 // writes them to their destination. 39 // 40 // If called, Write should always log the Entry and Fields; it should not 41 // replicate the logic of Check. 42 Write(Entry, []Field) error 43 // Sync flushes buffered logs (if any). 44 Sync() error 45 } 46 47 type nopCore struct{} 48 49 // NewNopCore returns a no-op Core. 50 func NewNopCore() Core { return nopCore{} } 51 func (nopCore) Enabled(Level) bool { return false } 52 func (n nopCore) With([]Field) Core { return n } 53 func (nopCore) Check(_ Entry, ce *CheckedEntry) *CheckedEntry { return ce } 54 func (nopCore) Write(Entry, []Field) error { return nil } 55 func (nopCore) Sync() error { return nil } 56 57 // NewCore creates a Core that writes logs to a WriteSyncer. 58 func NewCore(enc Encoder, ws WriteSyncer, enab LevelEnabler) Core { 59 return &ioCore{ 60 LevelEnabler: enab, 61 enc: enc, 62 out: ws, 63 } 64 } 65 66 type ioCore struct { 67 LevelEnabler 68 enc Encoder 69 out WriteSyncer 70 } 71 72 var ( 73 _ Core = (*ioCore)(nil) 74 _ leveledEnabler = (*ioCore)(nil) 75 ) 76 77 func (c *ioCore) Level() Level { 78 return LevelOf(c.LevelEnabler) 79 } 80 81 func (c *ioCore) With(fields []Field) Core { 82 clone := c.clone() 83 addFields(clone.enc, fields) 84 return clone 85 } 86 87 func (c *ioCore) Check(ent Entry, ce *CheckedEntry) *CheckedEntry { 88 if c.Enabled(ent.Level) { 89 return ce.AddCore(ent, c) 90 } 91 return ce 92 } 93 94 func (c *ioCore) Write(ent Entry, fields []Field) error { 95 buf, err := c.enc.EncodeEntry(ent, fields) 96 if err != nil { 97 return err 98 } 99 _, err = c.out.Write(buf.Bytes()) 100 buf.Free() 101 if err != nil { 102 return err 103 } 104 if ent.Level > ErrorLevel { 105 // Since we may be crashing the program, sync the output. 106 // Ignore Sync errors, pending a clean solution to issue #370. 107 _ = c.Sync() 108 } 109 return nil 110 } 111 112 func (c *ioCore) Sync() error { 113 return c.out.Sync() 114 } 115 116 func (c *ioCore) clone() *ioCore { 117 return &ioCore{ 118 LevelEnabler: c.LevelEnabler, 119 enc: c.enc.Clone(), 120 out: c.out, 121 } 122 } 123