56 lines
1.3 KiB
Go
56 lines
1.3 KiB
Go
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// Licensed to Elasticsearch B.V. under one or more contributor
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// license agreements. See the NOTICE file distributed with
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// this work for additional information regarding copyright
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// ownership. Elasticsearch B.V. licenses this file to you under
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// the Apache License, Version 2.0 (the "License"); you may
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// 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,
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// software distributed under the License is distributed on an
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// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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// KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations
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// under the License.
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package pipeline
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import "sync"
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type sema struct {
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// simulate cancellable counting semaphore using counter + mutex + cond
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mutex sync.Mutex
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cond sync.Cond
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count, max int
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}
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func newSema(max int) *sema {
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s := &sema{max: max}
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s.cond.L = &s.mutex
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return s
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}
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func (s *sema) inc() {
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s.mutex.Lock()
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for s.count == s.max {
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s.cond.Wait()
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}
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s.mutex.Unlock()
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}
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func (s *sema) release(n int) {
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s.mutex.Lock()
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old := s.count
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s.count -= n
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if old == s.max {
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if n == 1 {
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s.cond.Signal()
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} else {
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s.cond.Broadcast()
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}
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}
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s.mutex.Unlock()
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}
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