mirror of
https://github.com/Luzifer/nginx-sso.git
synced 2024-12-20 21:01:17 +00:00
130 lines
3.3 KiB
Go
130 lines
3.3 KiB
Go
// Copyright 2017, OpenCensus Authors
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package trace
|
|
|
|
import (
|
|
"time"
|
|
)
|
|
|
|
// samplePeriod is the minimum time between accepting spans in a single bucket.
|
|
const samplePeriod = time.Second
|
|
|
|
// defaultLatencies contains the default latency bucket bounds.
|
|
// TODO: consider defaults, make configurable
|
|
var defaultLatencies = [...]time.Duration{
|
|
10 * time.Microsecond,
|
|
100 * time.Microsecond,
|
|
time.Millisecond,
|
|
10 * time.Millisecond,
|
|
100 * time.Millisecond,
|
|
time.Second,
|
|
10 * time.Second,
|
|
time.Minute,
|
|
}
|
|
|
|
// bucket is a container for a set of spans for a particular error code or latency range.
|
|
type bucket struct {
|
|
nextTime time.Time // next time we can accept a span
|
|
buffer []*SpanData // circular buffer of spans
|
|
nextIndex int // location next SpanData should be placed in buffer
|
|
overflow bool // whether the circular buffer has wrapped around
|
|
}
|
|
|
|
func makeBucket(bufferSize int) bucket {
|
|
return bucket{
|
|
buffer: make([]*SpanData, bufferSize),
|
|
}
|
|
}
|
|
|
|
// add adds a span to the bucket, if nextTime has been reached.
|
|
func (b *bucket) add(s *SpanData) {
|
|
if s.EndTime.Before(b.nextTime) {
|
|
return
|
|
}
|
|
if len(b.buffer) == 0 {
|
|
return
|
|
}
|
|
b.nextTime = s.EndTime.Add(samplePeriod)
|
|
b.buffer[b.nextIndex] = s
|
|
b.nextIndex++
|
|
if b.nextIndex == len(b.buffer) {
|
|
b.nextIndex = 0
|
|
b.overflow = true
|
|
}
|
|
}
|
|
|
|
// size returns the number of spans in the bucket.
|
|
func (b *bucket) size() int {
|
|
if b.overflow {
|
|
return len(b.buffer)
|
|
}
|
|
return b.nextIndex
|
|
}
|
|
|
|
// span returns the ith span in the bucket.
|
|
func (b *bucket) span(i int) *SpanData {
|
|
if !b.overflow {
|
|
return b.buffer[i]
|
|
}
|
|
if i < len(b.buffer)-b.nextIndex {
|
|
return b.buffer[b.nextIndex+i]
|
|
}
|
|
return b.buffer[b.nextIndex+i-len(b.buffer)]
|
|
}
|
|
|
|
// resize changes the size of the bucket to n, keeping up to n existing spans.
|
|
func (b *bucket) resize(n int) {
|
|
cur := b.size()
|
|
newBuffer := make([]*SpanData, n)
|
|
if cur < n {
|
|
for i := 0; i < cur; i++ {
|
|
newBuffer[i] = b.span(i)
|
|
}
|
|
b.buffer = newBuffer
|
|
b.nextIndex = cur
|
|
b.overflow = false
|
|
return
|
|
}
|
|
for i := 0; i < n; i++ {
|
|
newBuffer[i] = b.span(i + cur - n)
|
|
}
|
|
b.buffer = newBuffer
|
|
b.nextIndex = 0
|
|
b.overflow = true
|
|
}
|
|
|
|
// latencyBucket returns the appropriate bucket number for a given latency.
|
|
func latencyBucket(latency time.Duration) int {
|
|
i := 0
|
|
for i < len(defaultLatencies) && latency >= defaultLatencies[i] {
|
|
i++
|
|
}
|
|
return i
|
|
}
|
|
|
|
// latencyBucketBounds returns the lower and upper bounds for a latency bucket
|
|
// number.
|
|
//
|
|
// The lower bound is inclusive, the upper bound is exclusive (except for the
|
|
// last bucket.)
|
|
func latencyBucketBounds(index int) (lower time.Duration, upper time.Duration) {
|
|
if index == 0 {
|
|
return 0, defaultLatencies[index]
|
|
}
|
|
if index == len(defaultLatencies) {
|
|
return defaultLatencies[index-1], 1<<63 - 1
|
|
}
|
|
return defaultLatencies[index-1], defaultLatencies[index]
|
|
}
|