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/atomic"
25 )
26 27 // Event represents a one-time event that may occur in the future.
28 type Event struct {
29 fired atomic.Bool
30 c chan struct{}
31 }
32 33 // Fire causes e to complete. It is safe to call multiple times, and
34 // concurrently. It returns true iff this call to Fire caused the signaling
35 // channel returned by Done to close. If Fire returns false, it is possible
36 // the Done channel has not been closed yet.
37 func (e *Event) Fire() bool {
38 if e.fired.CompareAndSwap(false, true) {
39 close(e.c)
40 return true
41 }
42 return false
43 }
44 45 // Done returns a channel that will be closed when Fire is called.
46 func (e *Event) Done() <-chan struct{} {
47 return e.c
48 }
49 50 // HasFired returns true if Fire has been called.
51 func (e *Event) HasFired() bool {
52 return e.fired.Load()
53 }
54 55 // NewEvent returns a new, ready-to-use Event.
56 func NewEvent() *Event {
57 return &Event{c: make(chan struct{})}
58 }
59