/
max_counter.go
55 lines (47 loc) · 1.34 KB
/
max_counter.go
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/*
* Copyright 2021 CloudWeGo 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 utils
import "sync/atomic"
// MaxCounter is an integer counter with upper limit.
type MaxCounter struct {
now int64
max int
}
// NewMaxCounter returns a new MaxCounter.
func NewMaxCounter(max int) *MaxCounter {
return &MaxCounter{
max: max,
}
}
// Inc increases the counter by one and returns if the operation succeeds.
func (cl *MaxCounter) Inc() bool {
if atomic.AddInt64(&cl.now, 1) > int64(cl.max) {
atomic.AddInt64(&cl.now, -1)
return false
}
return true
}
// Dec decreases the counter by one.
func (cl *MaxCounter) Dec() {
atomic.AddInt64(&cl.now, -1)
}
// DecN decreases the counter by n.
func (cl *MaxCounter) DecN(n int64) {
atomic.AddInt64(&cl.now, -n)
}
func (cl *MaxCounter) Now() int64 {
return atomic.LoadInt64(&cl.now)
}