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// Copyright 2015 Emmanuel Odeke. All Rights Reserved.
//
// Licensed 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 semalim
type ackType struct{}
var sentinel = ackType{}
type Job interface {
Id() interface{}
Do() (interface{}, error)
}
type Result interface {
Err() error
Id() interface{}
Value() interface{}
}
type resultSt struct {
err error
id interface{}
value interface{}
}
func (rs resultSt) Err() error { return rs.err }
func (rs resultSt) Id() interface{} { return rs.id }
func (rs resultSt) Value() interface{} { return rs.value }
func Run(jobs chan Job, workerCount uint64) chan Result {
results := make(chan Result)
doneChan := make(chan ackType)
slots := make(chan ackType, workerCount)
slotWait := func() { <-slots }
slotReady := func() { slots <- sentinel }
jobDone := func() { doneChan <- sentinel }
if workerCount < 1 {
workerCount = 8 // TODO: Define a proper default
}
// Make free room for the workerCount
for i := uint64(0); i < workerCount; i++ {
slotReady()
}
doneCounterChan := make(chan ackType)
go func() {
defer close(doneCounterChan)
for job := range jobs {
if job != nil {
doneCounterChan <- sentinel
go func(j Job) {
slotWait()
result, err := j.Do()
results <- resultSt{id: j.Id(), err: err, value: result}
slotReady()
jobDone()
}(job)
}
}
}()
go func() {
defer close(results)
doneCount := uint64(0)
for _ = range doneCounterChan {
doneCount += 1
}
// Then finally wait until:
for i := uint64(0); i < doneCount; i++ {
<-doneChan
}
}()
return results
}
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