github.com/livekit/protocol@v1.16.1-0.20240517185851-47e4c6bba773/logger/zaputil/deferrer.go (about)

     1  // Copyright 2023 LiveKit, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package zaputil
    16  
    17  import (
    18  	"sync"
    19  
    20  	"go.uber.org/zap"
    21  	"go.uber.org/zap/zapcore"
    22  )
    23  
    24  type deferredWrite struct {
    25  	core   zapcore.Core
    26  	ent    zapcore.Entry
    27  	fields []zapcore.Field
    28  }
    29  
    30  type Deferrer struct {
    31  	mu     sync.Mutex
    32  	ready  bool
    33  	fields []zapcore.Field
    34  	writes []*deferredWrite
    35  }
    36  
    37  func (b *Deferrer) buffer(core zapcore.Core, ent zapcore.Entry, fields []zapcore.Field) bool {
    38  	b.mu.Lock()
    39  	defer b.mu.Unlock()
    40  	if b.ready {
    41  		return false
    42  	}
    43  	b.writes = append(b.writes, &deferredWrite{core, ent, fields})
    44  	return true
    45  }
    46  
    47  func (b *Deferrer) flush() {
    48  	b.mu.Lock()
    49  	b.ready = true
    50  	writes := b.writes
    51  	b.writes = nil
    52  	b.mu.Unlock()
    53  
    54  	var fields []zapcore.Field
    55  	for _, w := range writes {
    56  		fields = append(fields[:0], b.fields...)
    57  		fields = append(fields, w.fields...)
    58  		w.core.Write(w.ent, fields)
    59  	}
    60  }
    61  
    62  func (b *Deferrer) write(core zapcore.Core, ent zapcore.Entry, fields []zapcore.Field) error {
    63  	if !b.buffer(core, ent, fields) {
    64  		return core.Write(ent, append(fields[0:len(fields):len(fields)], b.fields...))
    65  	}
    66  	return nil
    67  }
    68  
    69  type DeferredFieldResolver func(args ...any)
    70  
    71  func NewDeferrer() (*Deferrer, DeferredFieldResolver) {
    72  	buf := &Deferrer{}
    73  	var resolveOnce sync.Once
    74  	resolve := func(args ...any) {
    75  		resolveOnce.Do(func() {
    76  			fields := make([]zapcore.Field, 0, len(args))
    77  			for i := 0; i < len(args); i++ {
    78  				switch arg := args[i].(type) {
    79  				case zapcore.Field:
    80  					fields = append(fields, arg)
    81  				case string:
    82  					if i < len(args)-1 {
    83  						fields = append(fields, zap.Any(arg, args[i+1]))
    84  						i++
    85  					}
    86  				}
    87  			}
    88  
    89  			buf.fields = fields
    90  			buf.flush()
    91  		})
    92  	}
    93  	return buf, resolve
    94  }
    95  
    96  type deferredValueCore struct {
    97  	zapcore.Core
    98  	def *Deferrer
    99  }
   100  
   101  func NewDeferredValueCore(core zapcore.Core, def *Deferrer) zapcore.Core {
   102  	def.mu.Lock()
   103  	defer def.mu.Unlock()
   104  	return &deferredValueCore{core, def}
   105  }
   106  
   107  func (c *deferredValueCore) With(fields []zapcore.Field) zapcore.Core {
   108  	return &deferredValueCore{
   109  		Core: c.Core.With(fields),
   110  		def:  c.def,
   111  	}
   112  }
   113  
   114  func (c *deferredValueCore) Check(ent zapcore.Entry, ce *zapcore.CheckedEntry) *zapcore.CheckedEntry {
   115  	if c.Enabled(ent.Level) {
   116  		return ce.AddCore(ent, c)
   117  	}
   118  	return ce
   119  }
   120  
   121  func (c *deferredValueCore) Write(ent zapcore.Entry, fields []zapcore.Field) error {
   122  	return c.def.write(c.Core, ent, fields)
   123  }