124 lines
2.5 KiB
JavaScript
Executable File
124 lines
2.5 KiB
JavaScript
Executable File
/**
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* @license
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* Copyright The Closure Library Authors.
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* SPDX-License-Identifier: Apache-2.0
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*/
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goog.module('goog.async.WorkQueue');
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goog.module.declareLegacyNamespace();
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const FreeList = goog.require('goog.async.FreeList');
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const {assert} = goog.require('goog.asserts');
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// TODO(johnlenz): generalize the WorkQueue if this is used by more
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// than goog.async.run.
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/**
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* A low GC workqueue. The key elements of this design:
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* - avoids the need for goog.bind or equivalent by carrying scope
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* - avoids the need for array reallocation by using a linked list
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* - minimizes work entry objects allocation by recycling objects
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* @final
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* @struct
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*/
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class WorkQueue {
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constructor() {
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this.workHead_ = null;
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this.workTail_ = null;
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}
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/**
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* @param {function()} fn
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* @param {Object|null|undefined} scope
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*/
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add(fn, scope) {
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const item = this.getUnusedItem_();
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item.set(fn, scope);
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if (this.workTail_) {
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this.workTail_.next = item;
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this.workTail_ = item;
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} else {
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assert(!this.workHead_);
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this.workHead_ = item;
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this.workTail_ = item;
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}
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}
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/**
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* @return {?WorkItem}
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*/
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remove() {
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let item = null;
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if (this.workHead_) {
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item = this.workHead_;
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this.workHead_ = this.workHead_.next;
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if (!this.workHead_) {
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this.workTail_ = null;
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}
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item.next = null;
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}
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return item;
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}
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/**
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* @param {!WorkItem} item
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*/
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returnUnused(item) {
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WorkQueue.freelist_.put(item);
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}
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/**
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* @return {!WorkItem}
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* @private
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*/
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getUnusedItem_() {
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return WorkQueue.freelist_.get();
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}
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}
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/** @define {number} The maximum number of entries to keep for recycling. */
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WorkQueue.DEFAULT_MAX_UNUSED =
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goog.define('goog.async.WorkQueue.DEFAULT_MAX_UNUSED', 100);
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/** @const @private {!FreeList<!WorkItem>} */
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WorkQueue.freelist_ = new FreeList(
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() => new WorkItem(), item => item.reset(), WorkQueue.DEFAULT_MAX_UNUSED);
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/**
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* @final
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* @struct
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*/
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class WorkItem {
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constructor() {
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/** @type {?function()} */
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this.fn = null;
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/** @type {?Object|null|undefined} */
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this.scope = null;
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/** @type {?WorkItem} */
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this.next = null;
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}
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/**
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* @param {function()} fn
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* @param {Object|null|undefined} scope
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*/
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set(fn, scope) {
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'use strict';
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this.fn = fn;
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this.scope = scope;
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this.next = null;
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}
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/** Reset the work item so they don't prevent GC before reuse */
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reset() {
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this.fn = null;
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this.scope = null;
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this.next = null;
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}
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}
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exports = WorkQueue;
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