72 lines
2.0 KiB
Go
72 lines
2.0 KiB
Go
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// Copyright 2017 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package les
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import (
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"sync/atomic"
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)
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// ExecQueue implements a queue that executes function calls in a single thread,
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// in the same order as they have been queued.
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type execQueue struct {
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chn chan func()
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cnt, stop, capacity int32
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}
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// NewExecQueue creates a new execution queue.
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func newExecQueue(capacity int32) *execQueue {
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q := &execQueue{
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chn: make(chan func(), capacity),
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capacity: capacity,
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}
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go q.loop()
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return q
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}
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func (q *execQueue) loop() {
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for f := range q.chn {
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atomic.AddInt32(&q.cnt, -1)
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if atomic.LoadInt32(&q.stop) != 0 {
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return
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}
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f()
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}
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}
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// CanQueue returns true if more function calls can be added to the execution queue.
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func (q *execQueue) canQueue() bool {
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return atomic.LoadInt32(&q.stop) == 0 && atomic.LoadInt32(&q.cnt) < q.capacity
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}
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// Queue adds a function call to the execution queue. Returns true if successful.
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func (q *execQueue) queue(f func()) bool {
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if atomic.LoadInt32(&q.stop) != 0 {
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return false
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}
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if atomic.AddInt32(&q.cnt, 1) > q.capacity {
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atomic.AddInt32(&q.cnt, -1)
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return false
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}
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q.chn <- f
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return true
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}
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// Stop stops the exec queue.
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func (q *execQueue) quit() {
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atomic.StoreInt32(&q.stop, 1)
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}
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