@orbit/core
Version:
Core library for Orbit - a flexible data access and synchronization layer.
78 lines • 7.53 kB
JavaScript
/**
* A `TaskProcessor` performs a `Task` by calling `perform()` on its target.
* This is triggered by calling `process()` on the processor.
*
* A processor maintains a promise that represents the eventual state (resolved
* or rejected) of the task. This promise is created upon construction, and
* will be returned by calling `settle()`.
*
* A task can be re-tried by first calling `reset()` on the processor. This
* will clear the processor's state and allow `process()` to be invoked again.
*/
export class TaskProcessor {
/**
* Creates an instance of TaskProcessor.
*/
constructor(target, task) {
this.target = target;
this.task = task;
this.reset();
}
/**
* Clears the processor state, allowing for a fresh call to `process()`.
*/
reset() {
this._started = false;
this._settled = false;
this._settlement = new Promise((resolve, reject) => {
this._success = (r) => {
this._settled = true;
resolve(r);
};
this._fail = (e) => {
this._settled = true;
reject(e);
};
});
}
/**
* Has `process` been invoked?
*/
get started() {
return this._started;
}
/**
* Has promise settled, either via `process` or `reject`?
*/
get settled() {
return this._settled;
}
/**
* The eventual result of processing.
*/
settle() {
return this._settlement;
}
/**
* Invokes `perform` on the target.
*/
process() {
if (!this._started) {
this._started = true;
this.target.perform(this.task).then(this._success, this._fail);
}
return this.settle();
}
/**
* Reject the current promise with a specific error.
*/
reject(e) {
if (this._settled) {
throw new Error('TaskProcessor#reject can not be invoked when processing has already settled.');
}
else if (this._fail) {
this._fail(e);
}
}
}
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AqIFJlamVjdCB0aGUgY3VycmVudCBwcm9taXNlIHdpdGggYSBzcGVjaWZpYyBlcnJvci5cbiAgICovXG4gIHJlamVjdChlOiBFcnJvcik6IHZvaWQge1xuICAgIGlmICh0aGlzLl9zZXR0bGVkKSB7XG4gICAgICB0aHJvdyBuZXcgRXJyb3IoXG4gICAgICAgICdUYXNrUHJvY2Vzc29yI3JlamVjdCBjYW4gbm90IGJlIGludm9rZWQgd2hlbiBwcm9jZXNzaW5nIGhhcyBhbHJlYWR5IHNldHRsZWQuJ1xuICAgICAgKTtcbiAgICB9IGVsc2UgaWYgKHRoaXMuX2ZhaWwpIHtcbiAgICAgIHRoaXMuX2ZhaWwoZSk7XG4gICAgfVxuICB9XG59XG4iXX0=