109 lines
2.5 KiB
Go
109 lines
2.5 KiB
Go
// Copyright 2016 The Gogs Authors. All rights reserved.
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// Copyright 2019 The Gitea Authors. All rights reserved.
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// Use of this source code is governed by a MIT-style
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// license that can be found in the LICENSE file.
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package sync
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import (
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"github.com/unknwon/com"
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)
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// UniqueQueue is a queue which guarantees only one instance of same
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// identity is in the line. Instances with same identity will be
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// discarded if there is already one in the line.
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//
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// This queue is particularly useful for preventing duplicated task
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// of same purpose.
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type UniqueQueue struct {
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table *StatusTable
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queue chan string
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closed chan struct{}
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}
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// NewUniqueQueue initializes and returns a new UniqueQueue object.
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func NewUniqueQueue(queueLength int) *UniqueQueue {
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if queueLength <= 0 {
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queueLength = 100
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}
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return &UniqueQueue{
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table: NewStatusTable(),
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queue: make(chan string, queueLength),
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closed: make(chan struct{}),
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}
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}
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// Close closes this queue
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func (q *UniqueQueue) Close() {
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select {
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case <-q.closed:
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default:
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q.table.lock.Lock()
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select {
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case <-q.closed:
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default:
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close(q.closed)
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}
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q.table.lock.Unlock()
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}
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}
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// IsClosed returns a channel that is closed when this Queue is closed
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func (q *UniqueQueue) IsClosed() <-chan struct{} {
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return q.closed
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}
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// IDs returns the current ids in the pool
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func (q *UniqueQueue) IDs() []interface{} {
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q.table.lock.Lock()
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defer q.table.lock.Unlock()
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ids := make([]interface{}, 0, len(q.table.pool))
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for id := range q.table.pool {
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ids = append(ids, id)
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}
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return ids
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}
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// Queue returns channel of queue for retrieving instances.
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func (q *UniqueQueue) Queue() <-chan string {
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return q.queue
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}
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// Exist returns true if there is an instance with given identity
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// exists in the queue.
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func (q *UniqueQueue) Exist(id interface{}) bool {
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return q.table.IsRunning(com.ToStr(id))
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}
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// AddFunc adds new instance to the queue with a custom runnable function,
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// the queue is blocked until the function exits.
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func (q *UniqueQueue) AddFunc(id interface{}, fn func()) {
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idStr := com.ToStr(id)
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q.table.lock.Lock()
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if _, ok := q.table.pool[idStr]; ok {
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q.table.lock.Unlock()
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return
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}
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q.table.pool[idStr] = struct{}{}
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if fn != nil {
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fn()
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}
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q.table.lock.Unlock()
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select {
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case <-q.closed:
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return
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case q.queue <- idStr:
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return
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}
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}
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// Add adds new instance to the queue.
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func (q *UniqueQueue) Add(id interface{}) {
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q.AddFunc(id, nil)
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}
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// Remove removes instance from the queue.
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func (q *UniqueQueue) Remove(id interface{}) {
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q.table.Stop(com.ToStr(id))
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}
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