基本代码

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
function FQKTask(params) { this.params = params; }
FQKTask.prototype = {func: undefined};

function FQKTaskQueue() {
    this._pendingTasks = [];
    this._runningTasks = [];
}
FQKTaskQueue.prototype = {
    _maxOperationCount: 1,
    _pendingTasks: undefined,
    _runningTasks: undefined,
    isFunction: function (functionToCheck) {
        var getType = {};
        return functionToCheck && getType.toString.call(functionToCheck) === '[object Function]';
    },
    setMaxOperationCount: function (count) {
        if(count > 0)
        {
            this._maxOperationCount = Number(count);
        }
    },
    addTask: function (task) {
        if(!(task instanceof FQKTask))
        {
            return ;
        }

        if(!this.isFunction(task.func))
        {
            throw new Error('You must define task\'s func');
        }

        if(this._runningTasks.length < this._maxOperationCount)
        {
            this._runningTasks.push(task);
            task.func(task);
        }
        else
        {
            this._pendingTasks.push(task);
        }
    },
    removeTask: function (task) {
        if(!(task instanceof FQKTask))
        {
            return ;
        }

        var index = this._runningTasks.indexOf(task);
        if (index >= 0) {
            this._runningTasks.splice(index, 1);
        }

        if(this._pendingTasks.length > 0)
        {
            var pendingTask = this._pendingTasks[0];
            this._pendingTasks.splice(0, 1);
            this.addTask(pendingTask);
        }
    }
};

说明及测试代码

  1. 必须实现 task.func 函数
  2. task.func 回调函数的参数为 task 本身，写作 _this
  3. task.func 函数体为需要执行的任务，一般为带回调函数的异步任务
  4. 在异步任务回调中，需要调用 taskQueue.removeTask(_this)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
var taskQueue = new FQKTaskQueue();
taskQueue.setMaxOperationCount(5);

for(var i = 0; i < 10; ++i)
{
    var task = new FQKTask();
    task.func = function (_this) {
        setTimeout(function () {
            console.log(_this.index);
            taskQueue.removeTask(_this);
        }, 2000);
    };
    task.index = i;
    taskQueue.addTask(task);
}