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42 lines
1.0 KiB
Go
42 lines
1.0 KiB
Go
/*
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Copyright 2013 Google Inc.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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package syncutil
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// A Gate limits concurrency.
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type Gate struct {
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c chan struct{}
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}
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// NewGate returns a new gate that will only permit max operations at once.
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func NewGate(max int) *Gate {
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return &Gate{make(chan struct{}, max)}
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}
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// Start starts an operation, blocking until the gate has room.
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func (g *Gate) Start() {
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g.c <- struct{}{}
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}
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// Done finishes an operation.
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func (g *Gate) Done() {
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select {
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case <-g.c:
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default:
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panic("Done called more than Start")
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}
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}
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