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 "go.uber.org/multierr"
24 25 type hooked struct {
26 Core
27 funcs []func(Entry) error
28 }
29 30 var (
31 _ Core = (*hooked)(nil)
32 _ leveledEnabler = (*hooked)(nil)
33 )
34 35 // RegisterHooks wraps a Core and runs a collection of user-defined callback
36 // hooks each time a message is logged. Execution of the callbacks is blocking.
37 //
38 // This offers users an easy way to register simple callbacks (e.g., metrics
39 // collection) without implementing the full Core interface.
40 func RegisterHooks(core Core, hooks ...func(Entry) error) Core {
41 funcs := append([]func(Entry) error{}, hooks...)
42 return &hooked{
43 Core: core,
44 funcs: funcs,
45 }
46 }
47 48 func (h *hooked) Level() Level {
49 return LevelOf(h.Core)
50 }
51 52 func (h *hooked) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
53 // Let the wrapped Core decide whether to log this message or not. This
54 // also gives the downstream a chance to register itself directly with the
55 // CheckedEntry.
56 if downstream := h.Core.Check(ent, ce); downstream != nil {
57 return downstream.AddCore(ent, h)
58 }
59 return ce
60 }
61 62 func (h *hooked) With(fields []Field) Core {
63 return &hooked{
64 Core: h.Core.With(fields),
65 funcs: h.funcs,
66 }
67 }
68 69 func (h *hooked) Write(ent Entry, _ []Field) error {
70 // Since our downstream had a chance to register itself directly with the
71 // CheckedMessage, we don't need to call it here.
72 var err error
73 for i := range h.funcs {
74 err = multierr.Append(err, h.funcs[i](ent))
75 }
76 return err
77 }
78