mirror of https://github.com/docker/cli.git
62 lines
1.5 KiB
Go
62 lines
1.5 KiB
Go
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/*
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*
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* Copyright 2018 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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// Package grpcsync implements additional synchronization primitives built upon
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// the sync package.
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package grpcsync
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import (
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"sync"
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"sync/atomic"
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)
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// Event represents a one-time event that may occur in the future.
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type Event struct {
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fired int32
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c chan struct{}
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o sync.Once
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}
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// Fire causes e to complete. It is safe to call multiple times, and
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// concurrently. It returns true iff this call to Fire caused the signaling
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// channel returned by Done to close.
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func (e *Event) Fire() bool {
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ret := false
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e.o.Do(func() {
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atomic.StoreInt32(&e.fired, 1)
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close(e.c)
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ret = true
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})
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return ret
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}
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// Done returns a channel that will be closed when Fire is called.
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func (e *Event) Done() <-chan struct{} {
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return e.c
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}
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// HasFired returns true if Fire has been called.
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func (e *Event) HasFired() bool {
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return atomic.LoadInt32(&e.fired) == 1
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}
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// NewEvent returns a new, ready-to-use Event.
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func NewEvent() *Event {
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return &Event{c: make(chan struct{})}
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}
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