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

     1  // Copyright (c) 2016-2022 Uber Technologies, Inc.
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     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
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     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 zaputil
    22  
    23  import (
    24  	"sync/atomic"
    25  	"time"
    26  
    27  	"github.com/zeebo/xxh3"
    28  	"go.uber.org/zap/zapcore"
    29  )
    30  
    31  // this is lifted almost entirely from zap but with one significant change -
    32  // the state is injected into the sampler core to allow rebuilding the logger
    33  // without resetting the counts.
    34  
    35  const (
    36  	minLevel = zapcore.DebugLevel
    37  	maxLevel = zapcore.FatalLevel
    38  
    39  	numLevels        = maxLevel - minLevel + 1
    40  	countersPerLevel = 4096
    41  )
    42  
    43  type counter struct {
    44  	resetAt atomic.Int64
    45  	counter atomic.Uint64
    46  }
    47  
    48  type counters [numLevels][countersPerLevel]counter
    49  
    50  func newCounters() *counters {
    51  	return &counters{}
    52  }
    53  
    54  func (cs *counters) get(lvl zapcore.Level, key string) *counter {
    55  	i := lvl - minLevel
    56  	j := xxh3.HashString(key) % countersPerLevel
    57  	return &cs[i][j]
    58  }
    59  
    60  func (c *counter) IncCheckReset(t time.Time, tick time.Duration) uint64 {
    61  	tn := t.UnixNano()
    62  	resetAfter := c.resetAt.Load()
    63  	if resetAfter > tn {
    64  		return c.counter.Add(1)
    65  	}
    66  
    67  	c.counter.Store(1)
    68  
    69  	newResetAfter := tn + tick.Nanoseconds()
    70  	if !c.resetAt.CompareAndSwap(resetAfter, newResetAfter) {
    71  		// We raced with another goroutine trying to reset, and it also reset
    72  		// the counter to 1, so we need to reincrement the counter.
    73  		return c.counter.Add(1)
    74  	}
    75  
    76  	return 1
    77  }
    78  
    79  type Sampler struct {
    80  	counts            *counters
    81  	tick              time.Duration
    82  	first, thereafter uint64
    83  }
    84  
    85  func NewSampler(tick time.Duration, first, thereafter int) *Sampler {
    86  	return &Sampler{
    87  		tick:       tick,
    88  		counts:     newCounters(),
    89  		first:      uint64(first),
    90  		thereafter: uint64(thereafter),
    91  	}
    92  }
    93  
    94  func NewSamplerCore(core zapcore.Core, s *Sampler) zapcore.Core {
    95  	return &sampler{
    96  		Core: core,
    97  		s:    s,
    98  	}
    99  }
   100  
   101  type sampler struct {
   102  	zapcore.Core
   103  	s *Sampler
   104  }
   105  
   106  func (s *sampler) Level() zapcore.Level {
   107  	return zapcore.LevelOf(s.Core)
   108  }
   109  
   110  func (s *sampler) With(fields []zapcore.Field) zapcore.Core {
   111  	return &sampler{
   112  		Core: s.Core.With(fields),
   113  		s:    s.s,
   114  	}
   115  }
   116  
   117  func (s *sampler) Check(ent zapcore.Entry, ce *zapcore.CheckedEntry) *zapcore.CheckedEntry {
   118  	if !s.Enabled(ent.Level) {
   119  		return ce
   120  	}
   121  
   122  	if ent.Level >= minLevel && ent.Level <= maxLevel {
   123  		counter := s.s.counts.get(ent.Level, ent.Message)
   124  		n := counter.IncCheckReset(ent.Time, s.s.tick)
   125  		if n > s.s.first && (s.s.thereafter == 0 || (n-s.s.first)%s.s.thereafter != 0) {
   126  			return ce
   127  		}
   128  	}
   129  	return s.Core.Check(ent, ce)
   130  }