VOL-2408 - Refactor / Use voltha-lib-go Logging
Change-Id: I6e7d9eaba49c104cd50bb5692a2ff9733014fac4
diff --git a/vendor/go.uber.org/zap/zapcore/sampler.go b/vendor/go.uber.org/zap/zapcore/sampler.go
new file mode 100644
index 0000000..e316418
--- /dev/null
+++ b/vendor/go.uber.org/zap/zapcore/sampler.go
@@ -0,0 +1,134 @@
+// Copyright (c) 2016 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package zapcore
+
+import (
+ "time"
+
+ "go.uber.org/atomic"
+)
+
+const (
+ _numLevels = _maxLevel - _minLevel + 1
+ _countersPerLevel = 4096
+)
+
+type counter struct {
+ resetAt atomic.Int64
+ counter atomic.Uint64
+}
+
+type counters [_numLevels][_countersPerLevel]counter
+
+func newCounters() *counters {
+ return &counters{}
+}
+
+func (cs *counters) get(lvl Level, key string) *counter {
+ i := lvl - _minLevel
+ j := fnv32a(key) % _countersPerLevel
+ return &cs[i][j]
+}
+
+// fnv32a, adapted from "hash/fnv", but without a []byte(string) alloc
+func fnv32a(s string) uint32 {
+ const (
+ offset32 = 2166136261
+ prime32 = 16777619
+ )
+ hash := uint32(offset32)
+ for i := 0; i < len(s); i++ {
+ hash ^= uint32(s[i])
+ hash *= prime32
+ }
+ return hash
+}
+
+func (c *counter) IncCheckReset(t time.Time, tick time.Duration) uint64 {
+ tn := t.UnixNano()
+ resetAfter := c.resetAt.Load()
+ if resetAfter > tn {
+ return c.counter.Inc()
+ }
+
+ c.counter.Store(1)
+
+ newResetAfter := tn + tick.Nanoseconds()
+ if !c.resetAt.CAS(resetAfter, newResetAfter) {
+ // We raced with another goroutine trying to reset, and it also reset
+ // the counter to 1, so we need to reincrement the counter.
+ return c.counter.Inc()
+ }
+
+ return 1
+}
+
+type sampler struct {
+ Core
+
+ counts *counters
+ tick time.Duration
+ first, thereafter uint64
+}
+
+// NewSampler creates a Core that samples incoming entries, which caps the CPU
+// and I/O load of logging while attempting to preserve a representative subset
+// of your logs.
+//
+// Zap samples by logging the first N entries with a given level and message
+// each tick. If more Entries with the same level and message are seen during
+// the same interval, every Mth message is logged and the rest are dropped.
+//
+// Keep in mind that zap's sampling implementation is optimized for speed over
+// absolute precision; under load, each tick may be slightly over- or
+// under-sampled.
+func NewSampler(core Core, tick time.Duration, first, thereafter int) Core {
+ return &sampler{
+ Core: core,
+ tick: tick,
+ counts: newCounters(),
+ first: uint64(first),
+ thereafter: uint64(thereafter),
+ }
+}
+
+func (s *sampler) With(fields []Field) Core {
+ return &sampler{
+ Core: s.Core.With(fields),
+ tick: s.tick,
+ counts: s.counts,
+ first: s.first,
+ thereafter: s.thereafter,
+ }
+}
+
+func (s *sampler) Check(ent Entry, ce *CheckedEntry) *CheckedEntry {
+ if !s.Enabled(ent.Level) {
+ return ce
+ }
+
+ counter := s.counts.get(ent.Level, ent.Message)
+ n := counter.IncCheckReset(ent.Time, s.tick)
+ if n > s.first && (n-s.first)%s.thereafter != 0 {
+ return ce
+ }
+ return s.Core.Check(ent, ce)
+}