mirror of https://github.com/perkeep/perkeep.git
95 lines
2.0 KiB
Go
95 lines
2.0 KiB
Go
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/*
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Copyright 2012 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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// Worker pools of functions processing channel input.
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// TODO(brafitz): move this to a common library, making it operate on interface{} instead?
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package main
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import (
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"container/list"
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)
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type nodeWorker struct {
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c chan *node
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donec chan bool
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workc chan *node
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fn func(n *node, ok bool)
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buf *list.List
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}
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// NewNodeWorker starts nWorkers goroutines running fn on incoming
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// nodes sent on the returned channel. fn may block; writes to the
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// channel will buffer.
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func NewNodeWorker(nWorkers int, fn func(n *node, ok bool)) chan<- *node {
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w := &nodeWorker{
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c: make(chan *node, buffered),
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workc: make(chan *node, buffered),
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donec: make(chan bool), // when workers finish
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fn: fn,
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buf: list.New(),
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}
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go w.pump()
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for i := 0; i < nWorkers; i++ {
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go w.work()
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}
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go func() {
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for i := 0; i < nWorkers; i++ {
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<-w.donec
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}
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fn(nil, false) // final sentinel
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}()
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return w.c
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}
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func (w *nodeWorker) pump() {
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inc := w.c
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for inc != nil || w.buf.Len() > 0 {
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outc := w.workc
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var frontNode *node
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if e := w.buf.Front(); e != nil {
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frontNode = e.Value.(*node)
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} else {
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outc = nil
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}
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select {
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case outc <- frontNode:
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w.buf.Remove(w.buf.Front())
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case n, ok := <-inc:
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if !ok {
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inc = nil
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continue
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}
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w.buf.PushBack(n)
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}
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}
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close(w.workc)
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}
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func (w *nodeWorker) work() {
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for {
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select {
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case n, ok := <-w.workc:
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if !ok {
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w.donec <- true
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return
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}
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w.fn(n, true)
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}
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}
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}
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