google.golang.org/grpc@v1.74.2/internal/grpcsync/event.go (about)

     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  }