mirror of
https://github.com/rocky-linux/peridot.git
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193 lines
5.6 KiB
Go
193 lines
5.6 KiB
Go
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//go:build go1.21
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// +build go1.21
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/*
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Copyright 2023 The logr Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package logr
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import (
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"context"
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"log/slog"
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)
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type slogHandler struct {
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// May be nil, in which case all logs get discarded.
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sink LogSink
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// Non-nil if sink is non-nil and implements SlogSink.
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slogSink SlogSink
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// groupPrefix collects values from WithGroup calls. It gets added as
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// prefix to value keys when handling a log record.
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groupPrefix string
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// levelBias can be set when constructing the handler to influence the
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// slog.Level of log records. A positive levelBias reduces the
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// slog.Level value. slog has no API to influence this value after the
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// handler got created, so it can only be set indirectly through
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// Logger.V.
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levelBias slog.Level
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}
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var _ slog.Handler = &slogHandler{}
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// groupSeparator is used to concatenate WithGroup names and attribute keys.
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const groupSeparator = "."
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// GetLevel is used for black box unit testing.
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func (l *slogHandler) GetLevel() slog.Level {
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return l.levelBias
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}
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func (l *slogHandler) Enabled(_ context.Context, level slog.Level) bool {
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return l.sink != nil && (level >= slog.LevelError || l.sink.Enabled(l.levelFromSlog(level)))
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}
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func (l *slogHandler) Handle(ctx context.Context, record slog.Record) error {
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if l.slogSink != nil {
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// Only adjust verbosity level of log entries < slog.LevelError.
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if record.Level < slog.LevelError {
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record.Level -= l.levelBias
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}
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return l.slogSink.Handle(ctx, record)
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}
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// No need to check for nil sink here because Handle will only be called
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// when Enabled returned true.
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kvList := make([]any, 0, 2*record.NumAttrs())
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record.Attrs(func(attr slog.Attr) bool {
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kvList = attrToKVs(attr, l.groupPrefix, kvList)
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return true
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})
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if record.Level >= slog.LevelError {
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l.sinkWithCallDepth().Error(nil, record.Message, kvList...)
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} else {
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level := l.levelFromSlog(record.Level)
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l.sinkWithCallDepth().Info(level, record.Message, kvList...)
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}
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return nil
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}
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// sinkWithCallDepth adjusts the stack unwinding so that when Error or Info
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// are called by Handle, code in slog gets skipped.
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//
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// This offset currently (Go 1.21.0) works for calls through
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// slog.New(ToSlogHandler(...)). There's no guarantee that the call
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// chain won't change. Wrapping the handler will also break unwinding. It's
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// still better than not adjusting at all....
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//
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// This cannot be done when constructing the handler because FromSlogHandler needs
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// access to the original sink without this adjustment. A second copy would
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// work, but then WithAttrs would have to be called for both of them.
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func (l *slogHandler) sinkWithCallDepth() LogSink {
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if sink, ok := l.sink.(CallDepthLogSink); ok {
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return sink.WithCallDepth(2)
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}
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return l.sink
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}
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func (l *slogHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
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if l.sink == nil || len(attrs) == 0 {
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return l
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}
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clone := *l
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if l.slogSink != nil {
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clone.slogSink = l.slogSink.WithAttrs(attrs)
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clone.sink = clone.slogSink
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} else {
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kvList := make([]any, 0, 2*len(attrs))
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for _, attr := range attrs {
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kvList = attrToKVs(attr, l.groupPrefix, kvList)
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}
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clone.sink = l.sink.WithValues(kvList...)
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}
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return &clone
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}
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func (l *slogHandler) WithGroup(name string) slog.Handler {
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if l.sink == nil {
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return l
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}
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if name == "" {
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// slog says to inline empty groups
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return l
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}
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clone := *l
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if l.slogSink != nil {
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clone.slogSink = l.slogSink.WithGroup(name)
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clone.sink = clone.slogSink
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} else {
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clone.groupPrefix = addPrefix(clone.groupPrefix, name)
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}
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return &clone
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}
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// attrToKVs appends a slog.Attr to a logr-style kvList. It handle slog Groups
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// and other details of slog.
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func attrToKVs(attr slog.Attr, groupPrefix string, kvList []any) []any {
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attrVal := attr.Value.Resolve()
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if attrVal.Kind() == slog.KindGroup {
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groupVal := attrVal.Group()
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grpKVs := make([]any, 0, 2*len(groupVal))
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prefix := groupPrefix
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if attr.Key != "" {
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prefix = addPrefix(groupPrefix, attr.Key)
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}
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for _, attr := range groupVal {
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grpKVs = attrToKVs(attr, prefix, grpKVs)
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}
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kvList = append(kvList, grpKVs...)
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} else if attr.Key != "" {
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kvList = append(kvList, addPrefix(groupPrefix, attr.Key), attrVal.Any())
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}
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return kvList
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}
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func addPrefix(prefix, name string) string {
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if prefix == "" {
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return name
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}
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if name == "" {
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return prefix
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}
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return prefix + groupSeparator + name
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}
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// levelFromSlog adjusts the level by the logger's verbosity and negates it.
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// It ensures that the result is >= 0. This is necessary because the result is
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// passed to a LogSink and that API did not historically document whether
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// levels could be negative or what that meant.
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//
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// Some example usage:
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//
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// logrV0 := getMyLogger()
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// logrV2 := logrV0.V(2)
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// slogV2 := slog.New(logr.ToSlogHandler(logrV2))
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// slogV2.Debug("msg") // =~ logrV2.V(4) =~ logrV0.V(6)
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// slogV2.Info("msg") // =~ logrV2.V(0) =~ logrV0.V(2)
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// slogv2.Warn("msg") // =~ logrV2.V(-4) =~ logrV0.V(0)
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func (l *slogHandler) levelFromSlog(level slog.Level) int {
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result := -level
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result += l.levelBias // in case the original Logger had a V level
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if result < 0 {
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result = 0 // because LogSink doesn't expect negative V levels
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}
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return int(result)
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}
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