event.go (1586B)
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 }