1 files changed, 134 insertions, 0 deletions
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 000000000..e31641863
--- /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)
+}