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
|
import indexOf from 'lodash/_baseIndexOf';
import isArray from 'lodash/isArray';
import noop from 'lodash/noop';
import rest from './rest';
import onlyOnce from './onlyOnce';
import setImmediate from './setImmediate';
import DLL from './DoublyLinkedList';
export default function queue(worker, concurrency, payload) {
if (concurrency == null) {
concurrency = 1;
}
else if(concurrency === 0) {
throw new Error('Concurrency must not be zero');
}
function _insert(data, insertAtFront, callback) {
if (callback != null && typeof callback !== 'function') {
throw new Error('task callback must be a function');
}
q.started = true;
if (!isArray(data)) {
data = [data];
}
if (data.length === 0 && q.idle()) {
// call drain immediately if there are no tasks
return setImmediate(function() {
q.drain();
});
}
for (var i = 0, l = data.length; i < l; i++) {
var item = {
data: data[i],
callback: callback || noop
};
if (insertAtFront) {
q._tasks.unshift(item);
} else {
q._tasks.push(item);
}
}
setImmediate(q.process);
}
function _next(tasks) {
return rest(function(args){
workers -= 1;
for (var i = 0, l = tasks.length; i < l; i++) {
var task = tasks[i];
var index = indexOf(workersList, task, 0);
if (index >= 0) {
workersList.splice(index)
}
task.callback.apply(task, args);
if (args[0] != null) {
q.error(args[0], task.data);
}
}
if (workers <= (q.concurrency - q.buffer) ) {
q.unsaturated();
}
if (q.idle()) {
q.drain();
}
q.process();
});
}
var workers = 0;
var workersList = [];
var q = {
_tasks: new DLL(),
concurrency: concurrency,
payload: payload,
saturated: noop,
unsaturated:noop,
buffer: concurrency / 4,
empty: noop,
drain: noop,
error: noop,
started: false,
paused: false,
push: function (data, callback) {
_insert(data, false, callback);
},
kill: function () {
q.drain = noop;
q._tasks.empty();
},
unshift: function (data, callback) {
_insert(data, true, callback);
},
process: function () {
while(!q.paused && workers < q.concurrency && q._tasks.length){
var tasks = [], data = [];
var l = q._tasks.length;
if (q.payload) l = Math.min(l, q.payload);
for (var i = 0; i < l; i++) {
var node = q._tasks.shift();
tasks.push(node);
data.push(node.data);
}
if (q._tasks.length === 0) {
q.empty();
}
workers += 1;
workersList.push(tasks[0]);
if (workers === q.concurrency) {
q.saturated();
}
var cb = onlyOnce(_next(tasks));
worker(data, cb);
}
},
length: function () {
return q._tasks.length;
},
running: function () {
return workers;
},
workersList: function () {
return workersList;
},
idle: function() {
return q._tasks.length + workers === 0;
},
pause: function () {
q.paused = true;
},
resume: function () {
if (q.paused === false) { return; }
q.paused = false;
var resumeCount = Math.min(q.concurrency, q._tasks.length);
// Need to call q.process once per concurrent
// worker to preserve full concurrency after pause
for (var w = 1; w <= resumeCount; w++) {
setImmediate(q.process);
}
}
};
return q;
}
|
