mirror of
https://github.com/cubefs/cubefs.git
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123 lines
2.6 KiB
Go
123 lines
2.6 KiB
Go
// Copyright 2023 The CubeFS Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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// implied. See the License for the specific language governing
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// permissions and limitations under the License.
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// Package ratelimit RateLimit Algorithm Based on Token Bucket
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package flowctrl
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import (
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"io"
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"sync"
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"time"
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)
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const (
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tokenWindow = 50 * time.Millisecond
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minWindowCap = 64
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)
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type Controller struct {
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capacity int
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threshold int
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cond *sync.Cond
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done chan struct{}
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ratePerSecond int
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closeOnce *sync.Once
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}
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func NewController(ratePerSecond int) *Controller {
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capacity := ratePerSecond * int(tokenWindow) / int(time.Second)
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if capacity < minWindowCap {
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capacity = minWindowCap
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}
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self := &Controller{
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ratePerSecond: ratePerSecond,
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threshold: capacity,
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capacity: capacity,
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cond: sync.NewCond(new(sync.Mutex)),
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done: make(chan struct{}, 1),
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closeOnce: &sync.Once{},
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}
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// produce token asynchronously
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go self.run(capacity)
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return self
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}
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func (self *Controller) acquire(size int) int {
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self.cond.L.Lock()
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for self.capacity == 0 {
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self.cond.Wait()
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}
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if size > self.capacity {
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size = self.capacity
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}
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self.capacity -= size
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self.cond.L.Unlock()
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return size
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}
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func (self *Controller) fill(size int) {
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if size <= 0 {
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return
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}
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self.cond.L.Lock()
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self.capacity += size
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if self.capacity > self.threshold {
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self.capacity = self.threshold
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}
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self.cond.L.Unlock()
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self.cond.Broadcast()
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}
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func (self *Controller) run(capacity int) {
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t := time.NewTicker(tokenWindow)
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for {
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select {
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case <-t.C:
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self.cond.L.Lock()
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self.capacity = capacity
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self.cond.L.Unlock()
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self.cond.Broadcast()
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case <-self.done:
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t.Stop()
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return
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}
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}
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}
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// Close release token-producing goroutine
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func (self *Controller) Close() error {
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self.closeOnce.Do(func() {
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self.done <- struct{}{}
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})
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return nil
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}
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func (self *Controller) Reader(underlying io.Reader) io.Reader {
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return &rateReader{
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underlying: underlying,
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c: self,
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}
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}
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func (self *Controller) Writer(underlying io.Writer) io.Writer {
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return &rateWriter{
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underlying: underlying,
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c: self,
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}
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}
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func (self *Controller) GetRateLimit() int {
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return self.ratePerSecond
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}
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