github.com/pubgo/xprocess@v0.1.11/xprocess_event/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 xprocess_event implements additional synchronization primitives built upon
    20  // the sync package.
    21  
    22  package xprocess_event
    23  
    24  import (
    25  	"sync"
    26  	"sync/atomic"
    27  )
    28  
    29  // Event represents a one-time event that may occur in the future.
    30  type Event struct {
    31  	fired int32
    32  	c     chan struct{}
    33  	o     sync.Once
    34  }
    35  
    36  // Fire causes e to complete.  It is safe to call multiple times, and
    37  // concurrently.  It returns true iff this call to Fire caused the signaling
    38  // channel returned by Done to close.
    39  func (e *Event) Fire() bool {
    40  	ret := false
    41  	e.o.Do(func() {
    42  		atomic.StoreInt32(&e.fired, 1)
    43  		close(e.c)
    44  		ret = true
    45  	})
    46  	return ret
    47  }
    48  
    49  // Done returns a channel that will be closed when Fire is called.
    50  func (e *Event) Done() <-chan struct{} { return e.c }
    51  
    52  // HasFired returns true if Fire has been called.
    53  func (e *Event) HasFired() bool { return atomic.LoadInt32(&e.fired) == 1 }
    54  
    55  // NewEvent returns a new, ready-to-use Event.
    56  func New() *Event { return &Event{c: make(chan struct{})} }