forked from cerc-io/plugeth
f78ffc0545
* les: move execqueue into utilities package execqueue is a util for executing queued functions in a serial order which is used by both les server and les client. Move it to common package. * les: move randselect to utilities package weighted_random_selector is a helpful tool for randomly select items maintained in a set but based on the item weight. It's used anywhere is LES package, mainly by les client but will be used in les server with very high chance. So move it into a common package as the second step for les separation. * les: rename to utils
106 lines
2.7 KiB
Go
106 lines
2.7 KiB
Go
// 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 utils
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import "sync"
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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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mu sync.Mutex
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cond *sync.Cond
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funcs []func()
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closeWait chan struct{}
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}
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// NewExecQueue creates a new execution Queue.
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func NewExecQueue(capacity int) *ExecQueue {
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q := &ExecQueue{funcs: make([]func(), 0, capacity)}
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q.cond = sync.NewCond(&q.mu)
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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 := q.waitNext(false); f != nil; f = q.waitNext(true) {
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f()
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}
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close(q.closeWait)
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}
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func (q *ExecQueue) waitNext(drop bool) (f func()) {
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q.mu.Lock()
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if drop && len(q.funcs) > 0 {
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// Remove the function that just executed. We do this here instead of when
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// dequeuing so len(q.funcs) includes the function that is running.
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q.funcs = append(q.funcs[:0], q.funcs[1:]...)
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}
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for !q.isClosed() {
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if len(q.funcs) > 0 {
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f = q.funcs[0]
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break
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}
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q.cond.Wait()
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}
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q.mu.Unlock()
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return f
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}
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func (q *ExecQueue) isClosed() bool {
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return q.closeWait != nil
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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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q.mu.Lock()
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ok := !q.isClosed() && len(q.funcs) < cap(q.funcs)
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q.mu.Unlock()
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return ok
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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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q.mu.Lock()
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ok := !q.isClosed() && len(q.funcs) < cap(q.funcs)
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if ok {
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q.funcs = append(q.funcs, f)
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q.cond.Signal()
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}
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q.mu.Unlock()
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return ok
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}
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// Clear drops all queued functions.
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func (q *ExecQueue) Clear() {
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q.mu.Lock()
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q.funcs = q.funcs[:0]
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q.mu.Unlock()
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}
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// Quit stops the exec Queue.
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//
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// Quit waits for the current execution to finish before returning.
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func (q *ExecQueue) Quit() {
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q.mu.Lock()
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if !q.isClosed() {
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q.closeWait = make(chan struct{})
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q.cond.Signal()
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}
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q.mu.Unlock()
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<-q.closeWait
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}
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