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closer.go
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closer.go
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// Licensed to Apache Software Foundation (ASF) under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Apache Software Foundation (ASF) licenses this file to you 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 run
import (
"context"
"sync"
)
var dummyCloserChan <-chan struct{}
// Closer can close a goroutine then wait for it to stop.
type Closer struct {
ctx context.Context
cancel context.CancelFunc
waiting sync.WaitGroup
lock sync.RWMutex
closed bool
}
// NewCloser instances a new Closer.
func NewCloser(initial int) *Closer {
c := &Closer{}
c.ctx, c.cancel = context.WithCancel(context.Background())
c.waiting.Add(initial)
return c
}
// AddRunning adds a running task.
func (c *Closer) AddRunning() bool {
if c == nil {
return false
}
c.lock.RLock()
defer c.lock.RUnlock()
if c.closed {
return false
}
c.waiting.Add(1)
return true
}
// Ctx returns the context of the Closer.
func (c *Closer) Ctx() context.Context {
if c == nil {
return context.Background()
}
return c.ctx
}
// CloseNotify receives a signal from Close.
func (c *Closer) CloseNotify() <-chan struct{} {
if c == nil {
return dummyCloserChan
}
return c.ctx.Done()
}
// Done notifies that one task is done.
func (c *Closer) Done() {
if c == nil {
return
}
c.waiting.Done()
}
// CloseThenWait closes all tasks then waits till they are done.
func (c *Closer) CloseThenWait() {
if c == nil {
return
}
c.cancel()
c.lock.Lock()
c.closed = true
c.lock.Unlock()
c.waiting.Wait()
}
// Closed returns whether the Closer is closed.
func (c *Closer) Closed() bool {
if c == nil {
return true
}
c.lock.RLock()
defer c.lock.RUnlock()
return c.closed
}