cubefs

1
/*
2
 *
3
 * Copyright 2018 gRPC authors.
4
 *
5
 * Licensed under the Apache License, Version 2.0 (the "License");
6
 * you may not use this file except in compliance with the License.
7
 * You may obtain a copy of the License at
8
 *
9
 *     http://www.apache.org/licenses/LICENSE-2.0
10
 *
11
 * Unless required by applicable law or agreed to in writing, software
12
 * distributed under the License is distributed on an "AS IS" BASIS,
13
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14
 * See the License for the specific language governing permissions and
15
 * limitations under the License.
16
 *
17
 */
18

19
// Package grpcsync implements additional synchronization primitives built upon
20
// the sync package.
21
package grpcsync
22

23
import (
24
	"sync"
25
	"sync/atomic"
26
)
27

28
// Event represents a one-time event that may occur in the future.
29
type Event struct {
30
	fired int32
31
	c     chan struct{}
32
	o     sync.Once
33
}
34

35
// Fire causes e to complete.  It is safe to call multiple times, and
36
// concurrently.  It returns true iff this call to Fire caused the signaling
37
// channel returned by Done to close.
38
func (e *Event) Fire() bool {
39
	ret := false
40
	e.o.Do(func() {
41
		atomic.StoreInt32(&e.fired, 1)
42
		close(e.c)
43
		ret = true
44
	})
45
	return ret
46
}
47

48
// Done returns a channel that will be closed when Fire is called.
49
func (e *Event) Done() <-chan struct{} {
50
	return e.c
51
}
52

53
// HasFired returns true if Fire has been called.
54
func (e *Event) HasFired() bool {
55
	return atomic.LoadInt32(&e.fired) == 1
56
}
57

58
// NewEvent returns a new, ready-to-use Event.
59
func NewEvent() *Event {
60
	return &Event{c: make(chan struct{})}
61
}
62