AsyncAction.js
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"use strict";
var __extends = (this && this.__extends) || function (d, b) {
for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
function __() { this.constructor = d; }
d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};
var root_1 = require('../util/root');
var Action_1 = require('./Action');
/**
* We need this JSDoc comment for affecting ESDoc.
* @ignore
* @extends {Ignored}
*/
var AsyncAction = (function (_super) {
__extends(AsyncAction, _super);
function AsyncAction(scheduler, work) {
_super.call(this, scheduler, work);
this.scheduler = scheduler;
this.work = work;
this.pending = false;
}
AsyncAction.prototype.schedule = function (state, delay) {
if (delay === void 0) { delay = 0; }
if (this.closed) {
return this;
}
// Always replace the current state with the new state.
this.state = state;
// Set the pending flag indicating that this action has been scheduled, or
// has recursively rescheduled itself.
this.pending = true;
var id = this.id;
var scheduler = this.scheduler;
//
// Important implementation note:
//
// Actions only execute once by default, unless rescheduled from within the
// scheduled callback. This allows us to implement single and repeat
// actions via the same code path, without adding API surface area, as well
// as mimic traditional recursion but across asynchronous boundaries.
//
// However, JS runtimes and timers distinguish between intervals achieved by
// serial `setTimeout` calls vs. a single `setInterval` call. An interval of
// serial `setTimeout` calls can be individually delayed, which delays
// scheduling the next `setTimeout`, and so on. `setInterval` attempts to
// guarantee the interval callback will be invoked more precisely to the
// interval period, regardless of load.
//
// Therefore, we use `setInterval` to schedule single and repeat actions.
// If the action reschedules itself with the same delay, the interval is not
// canceled. If the action doesn't reschedule, or reschedules with a
// different delay, the interval will be canceled after scheduled callback
// execution.
//
if (id != null) {
this.id = this.recycleAsyncId(scheduler, id, delay);
}
this.delay = delay;
// If this action has already an async Id, don't request a new one.
this.id = this.id || this.requestAsyncId(scheduler, this.id, delay);
return this;
};
AsyncAction.prototype.requestAsyncId = function (scheduler, id, delay) {
if (delay === void 0) { delay = 0; }
return root_1.root.setInterval(scheduler.flush.bind(scheduler, this), delay);
};
AsyncAction.prototype.recycleAsyncId = function (scheduler, id, delay) {
if (delay === void 0) { delay = 0; }
// If this action is rescheduled with the same delay time, don't clear the interval id.
if (delay !== null && this.delay === delay) {
return id;
}
// Otherwise, if the action's delay time is different from the current delay,
// clear the interval id
return root_1.root.clearInterval(id) && undefined || undefined;
};
/**
* Immediately executes this action and the `work` it contains.
* @return {any}
*/
AsyncAction.prototype.execute = function (state, delay) {
if (this.closed) {
return new Error('executing a cancelled action');
}
this.pending = false;
var error = this._execute(state, delay);
if (error) {
return error;
}
else if (this.pending === false && this.id != null) {
// Dequeue if the action didn't reschedule itself. Don't call
// unsubscribe(), because the action could reschedule later.
// For example:
// ```
// scheduler.schedule(function doWork(counter) {
// /* ... I'm a busy worker bee ... */
// var originalAction = this;
// /* wait 100ms before rescheduling the action */
// setTimeout(function () {
// originalAction.schedule(counter + 1);
// }, 100);
// }, 1000);
// ```
this.id = this.recycleAsyncId(this.scheduler, this.id, null);
}
};
AsyncAction.prototype._execute = function (state, delay) {
var errored = false;
var errorValue = undefined;
try {
this.work(state);
}
catch (e) {
errored = true;
errorValue = !!e && e || new Error(e);
}
if (errored) {
this.unsubscribe();
return errorValue;
}
};
AsyncAction.prototype._unsubscribe = function () {
var id = this.id;
var scheduler = this.scheduler;
var actions = scheduler.actions;
var index = actions.indexOf(this);
this.work = null;
this.delay = null;
this.state = null;
this.pending = false;
this.scheduler = null;
if (index !== -1) {
actions.splice(index, 1);
}
if (id != null) {
this.id = this.recycleAsyncId(scheduler, id, null);
}
};
return AsyncAction;
}(Action_1.Action));
exports.AsyncAction = AsyncAction;
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