gitee.com/ks-custle/core-gm@v0.0.0-20230922171213-b83bdd97b62c/grpc/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"
    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  }