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// Copyright ©2011-2012 The bíogo Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package concurrent
import (
"fmt"
"runtime"
"sync"
)
// Interface is a type that performs an operation on itself, returning any error.
type Operator interface {
Operation() (interface{}, error)
}
// The Processor type manages a number of concurrent Processes.
type Processor struct {
in chan Operator
out chan Result
stop chan struct{}
work chan struct{}
threads int
wg *sync.WaitGroup
}
// Return a new Processor to operate the function f over the number of threads specified taking
// input from queue and placing the result in buffer. Threads is limited by GOMAXPROCS, if threads is greater
// GOMAXPROCS or less than 1 then threads is set to GOMAXPROCS.
func NewProcessor(queue chan Operator, buffer int, threads int) (p *Processor) {
if available := runtime.GOMAXPROCS(0); threads > available || threads < 1 {
threads = available
}
p = &Processor{
in: queue,
out: make(chan Result, buffer),
stop: make(chan struct{}),
work: make(chan struct{}, threads),
threads: threads,
wg: &sync.WaitGroup{},
}
for i := 0; i < threads; i++ {
p.work <- struct{}{}
}
for i := 0; i < threads; i++ {
p.wg.Add(1)
go func() {
<-p.work
defer func() {
if err := recover(); err != nil {
p.out <- Result{nil, fmt.Errorf("concurrent: processor panic: %v", err)}
}
p.work <- struct{}{}
if len(p.work) == p.threads {
close(p.out)
}
p.wg.Done()
}()
for input := range p.in {
v, e := input.Operation()
if p.out != nil {
p.out <- Result{v, e}
}
select {
case <-p.stop:
return
default:
}
}
}()
}
return
}
// Submit values for processing.
func (p *Processor) Process(value ...Operator) {
for _, v := range value {
p.in <- v
}
}
// Get the next available result.
func (p *Processor) Result() (interface{}, error) {
r := <-p.out
return r.Value, r.Err
}
// Close the queue.
func (p *Processor) Close() {
close(p.in)
}
// Return the number of working goroutines.
func (p *Processor) Working() int {
return p.threads - len(p.work)
}
// Terminate the goroutines.
func (p *Processor) Stop() {
close(p.stop)
}
// Wait for all running processes to finish.
func (p *Processor) Wait() {
p.wg.Wait()
}
type Result struct {
Value interface{}
Err error
}
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