1//go:build go1.21
2// +build go1.21
3
4/*
5Copyright 2023 The logr Authors.
6
7Licensed under the Apache License, Version 2.0 (the "License");
8you may not use this file except in compliance with the License.
9You may obtain a copy of the License at
10
11 http://www.apache.org/licenses/LICENSE-2.0
12
13Unless required by applicable law or agreed to in writing, software
14distributed under the License is distributed on an "AS IS" BASIS,
15WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16See the License for the specific language governing permissions and
17limitations under the License.
18*/
19
20package funcr
21
22import (
23 "context"
24 "log/slog"
25
26 "github.com/go-logr/logr"
27)
28
29var _ logr.SlogSink = &fnlogger{}
30
31const extraSlogSinkDepth = 3 // 2 for slog, 1 for SlogSink
32
33func (l fnlogger) Handle(_ context.Context, record slog.Record) error {
34 kvList := make([]any, 0, 2*record.NumAttrs())
35 record.Attrs(func(attr slog.Attr) bool {
36 kvList = attrToKVs(attr, kvList)
37 return true
38 })
39
40 if record.Level >= slog.LevelError {
41 l.WithCallDepth(extraSlogSinkDepth).Error(nil, record.Message, kvList...)
42 } else {
43 level := l.levelFromSlog(record.Level)
44 l.WithCallDepth(extraSlogSinkDepth).Info(level, record.Message, kvList...)
45 }
46 return nil
47}
48
49func (l fnlogger) WithAttrs(attrs []slog.Attr) logr.SlogSink {
50 kvList := make([]any, 0, 2*len(attrs))
51 for _, attr := range attrs {
52 kvList = attrToKVs(attr, kvList)
53 }
54 l.AddValues(kvList)
55 return &l
56}
57
58func (l fnlogger) WithGroup(name string) logr.SlogSink {
59 l.startGroup(name)
60 return &l
61}
62
63// attrToKVs appends a slog.Attr to a logr-style kvList. It handle slog Groups
64// and other details of slog.
65func attrToKVs(attr slog.Attr, kvList []any) []any {
66 attrVal := attr.Value.Resolve()
67 if attrVal.Kind() == slog.KindGroup {
68 groupVal := attrVal.Group()
69 grpKVs := make([]any, 0, 2*len(groupVal))
70 for _, attr := range groupVal {
71 grpKVs = attrToKVs(attr, grpKVs)
72 }
73 if attr.Key == "" {
74 // slog says we have to inline these
75 kvList = append(kvList, grpKVs...)
76 } else {
77 kvList = append(kvList, attr.Key, PseudoStruct(grpKVs))
78 }
79 } else if attr.Key != "" {
80 kvList = append(kvList, attr.Key, attrVal.Any())
81 }
82
83 return kvList
84}
85
86// levelFromSlog adjusts the level by the logger's verbosity and negates it.
87// It ensures that the result is >= 0. This is necessary because the result is
88// passed to a LogSink and that API did not historically document whether
89// levels could be negative or what that meant.
90//
91// Some example usage:
92//
93// logrV0 := getMyLogger()
94// logrV2 := logrV0.V(2)
95// slogV2 := slog.New(logr.ToSlogHandler(logrV2))
96// slogV2.Debug("msg") // =~ logrV2.V(4) =~ logrV0.V(6)
97// slogV2.Info("msg") // =~ logrV2.V(0) =~ logrV0.V(2)
98// slogv2.Warn("msg") // =~ logrV2.V(-4) =~ logrV0.V(0)
99func (l fnlogger) levelFromSlog(level slog.Level) int {
100 result := -level
101 if result < 0 {
102 result = 0 // because LogSink doesn't expect negative V levels
103 }
104 return int(result)
105}