Source: event.go in package google.golang.org/grpc/internal/grpcsync

* * Copyright 2018 gRPC 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 grpcsync implements additional synchronization primitives built upon the sync package.

package grpcsync

import (
	"sync"
	"sync/atomic"
)

Event represents a one-time event that may occur in the future.

type Event struct {
	fired int32
	c     chan struct{}
	o     sync.Once
}

Fire causes e to complete. It is safe to call multiple times, and concurrently. It returns true iff this call to Fire caused the signaling channel returned by Done to close.

func (e *Event) Fire() bool {
	ret := false
	e.o.Do(func() {
		atomic.StoreInt32(&e.fired, 1)
		close(e.c)
		ret = true
	})
	return ret
}

Done returns a channel that will be closed when Fire is called.

func (e *Event) Done() <-chan struct{} {
	return e.c
}

HasFired returns true if Fire has been called.

func (e *Event) HasFired() bool {
	return atomic.LoadInt32(&e.fired) == 1
}

NewEvent returns a new, ready-to-use Event.

func NewEvent() *Event {
	return &Event{c: make(chan struct{})}