forked from tikv/client-go
/
rate_limit.go
52 lines (46 loc) · 1.23 KB
/
rate_limit.go
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// Copyright 2021 PingCAP, Inc.
//
// 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,
// See the License for the specific language governing permissions and
// limitations under the License.
package util
// RateLimit wraps a fix sized channel to control concurrency.
type RateLimit struct {
capacity int
token chan struct{}
}
// NewRateLimit creates a limit controller with capacity n.
func NewRateLimit(n int) *RateLimit {
return &RateLimit{
capacity: n,
token: make(chan struct{}, n),
}
}
// GetToken acquires a token.
func (r *RateLimit) GetToken(done <-chan struct{}) (exit bool) {
select {
case <-done:
return true
case r.token <- struct{}{}:
return false
}
}
// PutToken puts a token back.
func (r *RateLimit) PutToken() {
select {
case <-r.token:
default:
panic("put a redundant token")
}
}
// GetCapacity returns the token capacity.
func (r *RateLimit) GetCapacity() int {
return r.capacity
}