atcheck/lsscanner/new_ubuntu/node_modules_win/pend/index.js

56 lines
1.1 KiB
JavaScript
Raw Normal View History

2019-12-16 18:42:21 +01:00
module.exports = Pend;
function Pend() {
this.pending = 0;
this.max = Infinity;
this.listeners = [];
this.waiting = [];
this.error = null;
}
Pend.prototype.go = function(fn) {
if (this.pending < this.max) {
pendGo(this, fn);
} else {
this.waiting.push(fn);
}
};
Pend.prototype.wait = function(cb) {
if (this.pending === 0) {
cb(this.error);
} else {
this.listeners.push(cb);
}
};
Pend.prototype.hold = function() {
return pendHold(this);
};
function pendHold(self) {
self.pending += 1;
var called = false;
return onCb;
function onCb(err) {
if (called) throw new Error("callback called twice");
called = true;
self.error = self.error || err;
self.pending -= 1;
if (self.waiting.length > 0 && self.pending < self.max) {
pendGo(self, self.waiting.shift());
} else if (self.pending === 0) {
var listeners = self.listeners;
self.listeners = [];
listeners.forEach(cbListener);
}
}
function cbListener(listener) {
listener(self.error);
}
}
function pendGo(self, fn) {
fn(pendHold(self));
}