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