mirror of
https://github.com/rclone/rclone.git
synced 2024-12-28 09:59:27 +01:00
71 lines
2.0 KiB
Go
71 lines
2.0 KiB
Go
// Copyright 2017 Google Inc. All Rights Reserved.
|
|
//
|
|
// 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 distribution
|
|
|
|
import (
|
|
"log"
|
|
"math"
|
|
"sort"
|
|
"sync/atomic"
|
|
)
|
|
|
|
// D is a distribution. Methods of D can be called concurrently by multiple
|
|
// goroutines.
|
|
type D struct {
|
|
buckets []uint64
|
|
}
|
|
|
|
// New creates a new distribution capable of holding values from 0 to n-1.
|
|
func New(n int) *D {
|
|
return &D{
|
|
buckets: make([]uint64, n),
|
|
}
|
|
}
|
|
|
|
// Record records value v to the distribution.
|
|
// To help with distributions with long tails, if v is larger than the maximum value,
|
|
// Record records the maximum value instead.
|
|
// If v is negative, Record panics.
|
|
func (d *D) Record(v int) {
|
|
if v < 0 {
|
|
log.Panicf("Record: value out of range: %d", v)
|
|
} else if v >= len(d.buckets) {
|
|
v = len(d.buckets) - 1
|
|
}
|
|
atomic.AddUint64(&d.buckets[v], 1)
|
|
}
|
|
|
|
// Percentile computes the p-th percentile of the distribution where
|
|
// p is between 0 and 1.
|
|
func (d *D) Percentile(p float64) int {
|
|
// NOTE: This implementation uses the nearest-rank method.
|
|
// https://en.wikipedia.org/wiki/Percentile#The_nearest-rank_method
|
|
|
|
if p < 0 || p > 1 {
|
|
log.Panicf("Percentile: percentile out of range: %f", p)
|
|
}
|
|
|
|
bucketSums := make([]uint64, len(d.buckets))
|
|
var sum uint64
|
|
for i := range bucketSums {
|
|
sum += atomic.LoadUint64(&d.buckets[i])
|
|
bucketSums[i] = sum
|
|
}
|
|
|
|
total := bucketSums[len(bucketSums)-1]
|
|
target := uint64(math.Ceil(float64(total) * p))
|
|
return sort.Search(len(bucketSums), func(i int) bool { return bucketSums[i] >= target })
|
|
}
|