1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
// Copyright 2007 The Closure Library Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS-IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @fileoverview Definition of the goog.async.Throttle class.
*
* @see ../demos/timers.html
*/
goog.provide('goog.Throttle');
goog.provide('goog.async.Throttle');
goog.require('goog.Disposable');
goog.require('goog.Timer');
/**
* Throttle will perform an action that is passed in no more than once
* per interval (specified in milliseconds). If it gets multiple signals
* to perform the action while it is waiting, it will only perform the action
* once at the end of the interval.
* @param {Function} listener Function to callback when the action is triggered.
* @param {number} interval Interval over which to throttle. The handler can
* only be called once per interval.
* @param {Object=} opt_handler Object in whose scope to call the listener.
* @constructor
* @extends {goog.Disposable}
*/
goog.async.Throttle = function(listener, interval, opt_handler) {
goog.Disposable.call(this);
/**
* Function to callback
* @type {Function}
* @private
*/
this.listener_ = listener;
/**
* Interval for the throttle time
* @type {number}
* @private
*/
this.interval_ = interval;
/**
* "this" context for the listener
* @type {Object|undefined}
* @private
*/
this.handler_ = opt_handler;
/**
* Cached callback function invoked after the throttle timeout completes
* @type {Function}
* @private
*/
this.callback_ = goog.bind(this.onTimer_, this);
};
goog.inherits(goog.async.Throttle, goog.Disposable);
/**
* A deprecated alias.
* @deprecated Use goog.async.Throttle instead.
* @constructor
*/
goog.Throttle = goog.async.Throttle;
/**
* Indicates that the action is pending and needs to be fired.
* @type {boolean}
* @private
*/
goog.async.Throttle.prototype.shouldFire_ = false;
/**
* Indicates the count of nested pauses currently in effect on the throttle.
* When this count is not zero, fired actions will be postponed until the
* throttle is resumed enough times to drop the pause count to zero.
* @type {number}
* @private
*/
goog.async.Throttle.prototype.pauseCount_ = 0;
/**
* Timer for scheduling the next callback
* @type {?number}
* @private
*/
goog.async.Throttle.prototype.timer_ = null;
/**
* Notifies the throttle that the action has happened. It will throttle the call
* so that the callback is not called too often according to the interval
* parameter passed to the constructor.
*/
goog.async.Throttle.prototype.fire = function() {
if (!this.timer_ && !this.pauseCount_) {
this.doAction_();
} else {
this.shouldFire_ = true;
}
};
/**
* Cancels any pending action callback. The throttle can be restarted by
* calling {@link #fire}.
*/
goog.async.Throttle.prototype.stop = function() {
if (this.timer_) {
goog.Timer.clear(this.timer_);
this.timer_ = null;
this.shouldFire_ = false;
}
};
/**
* Pauses the throttle. All pending and future action callbacks will be
* delayed until the throttle is resumed. Pauses can be nested.
*/
goog.async.Throttle.prototype.pause = function() {
this.pauseCount_++;
};
/**
* Resumes the throttle. If doing so drops the pausing count to zero, pending
* action callbacks will be executed as soon as possible, but still no sooner
* than an interval's delay after the previous call. Future action callbacks
* will be executed as normal.
*/
goog.async.Throttle.prototype.resume = function() {
this.pauseCount_--;
if (!this.pauseCount_ && this.shouldFire_ && !this.timer_) {
this.shouldFire_ = false;
this.doAction_();
}
};
/** @override */
goog.async.Throttle.prototype.disposeInternal = function() {
goog.async.Throttle.superClass_.disposeInternal.call(this);
this.stop();
};
/**
* Handler for the timer to fire the throttle
* @private
*/
goog.async.Throttle.prototype.onTimer_ = function() {
this.timer_ = null;
if (this.shouldFire_ && !this.pauseCount_) {
this.shouldFire_ = false;
this.doAction_();
}
};
/**
* Calls the callback
* @private
*/
goog.async.Throttle.prototype.doAction_ = function() {
this.timer_ = goog.Timer.callOnce(this.callback_, this.interval_);
this.listener_.call(this.handler_);
};
|
