dubbo.apache.org/dubbo-go/v3@v3.1.1/xds/utils/grpcsync/event.go (about)

     1  /*
     2   * Licensed to the Apache Software Foundation (ASF) under one or more
     3   * contributor license agreements.  See the NOTICE file distributed with
     4   * this work for additional information regarding copyright ownership.
     5   * The ASF licenses this file to You under the Apache License, Version 2.0
     6   * (the "License"); you may not use this file except in compliance with
     7   * the License.  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   *
    20   * Copyright 2018 gRPC authors.
    21   *
    22   */
    23  
    24  // Package grpcsync implements additional synchronization primitives built upon
    25  // the sync package.
    26  package grpcsync
    27  
    28  import (
    29  	"sync"
    30  	"sync/atomic"
    31  )
    32  
    33  // Event represents a one-time event that may occur in the future.
    34  type Event struct {
    35  	fired int32
    36  	c     chan struct{}
    37  	o     sync.Once
    38  }
    39  
    40  // Fire causes e to complete.  It is safe to call multiple times, and
    41  // concurrently.  It returns true iff this call to Fire caused the signaling
    42  // channel returned by Done to close.
    43  func (e *Event) Fire() bool {
    44  	ret := false
    45  	e.o.Do(func() {
    46  		atomic.StoreInt32(&e.fired, 1)
    47  		close(e.c)
    48  		ret = true
    49  	})
    50  	return ret
    51  }
    52  
    53  // Done returns a channel that will be closed when Fire is called.
    54  func (e *Event) Done() <-chan struct{} {
    55  	return e.c
    56  }
    57  
    58  // HasFired returns true if Fire has been called.
    59  func (e *Event) HasFired() bool {
    60  	return atomic.LoadInt32(&e.fired) == 1
    61  }
    62  
    63  // NewEvent returns a new, ready-to-use Event.
    64  func NewEvent() *Event {
    65  	return &Event{c: make(chan struct{})}
    66  }