youtubebeat/vendor/github.com/elastic/beats/libbeat/publisher/pipeline/util.go

55 lines
1.3 KiB
Go

// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
package pipeline
import "sync"
type sema struct {
// simulate cancellable counting semaphore using counter + mutex + cond
mutex sync.Mutex
cond sync.Cond
count, max int
}
func newSema(max int) *sema {
s := &sema{max: max}
s.cond.L = &s.mutex
return s
}
func (s *sema) inc() {
s.mutex.Lock()
for s.count == s.max {
s.cond.Wait()
}
s.mutex.Unlock()
}
func (s *sema) release(n int) {
s.mutex.Lock()
old := s.count
s.count -= n
if old == s.max {
if n == 1 {
s.cond.Signal()
} else {
s.cond.Broadcast()
}
}
s.mutex.Unlock()
}