compass-bot/utils/task.mjs
2023-10-30 22:18:05 +08:00

89 lines
1.8 KiB
JavaScript

export class TaskInteruptedError extends Error {
constructor() { super('Task has been interupted.'); }
};
export class Task {
constructor() {
this.status = Task.STATUS.pending;
this.error = null;
this.result = null;
this.result_listeners = [];
}
_ready(result) {
this.result = result;
this.status = Task.STATUS.ready;
this.#notifySuccess();
}
_fail(error) {
if (this.status == Task.STATUS.interupted) { return; }
this.error = error;
this.status = Task.STATUS.failed;
this.#notifyFailure();
}
_start() {
if (this.status != Task.STATUS.pending) {
throw new Error('Task has already left pending stage');
}
this.status = Task.STATUS.running;
}
interupt() {
if (this.status == Task.STATUS.pending) { this._confirmInterupt(); }
else { this.status = Task.STATUS.interupting; }
}
_shouldInterupt() {
return this.status == Task.STATUS.interupting;
}
_confirmInterupt() {
this.status = Task.STATUS.interupted;
this.error = new TaskInteruptedError();
this.#notifyFailure();
}
_interuptableHere() {
if (this._shouldInterupt()) {
this._confirmInterupt();
throw this.error;
}
}
get() {
if (this.status == Task.STATUS.ready) { return Promise.resolve(this.result); }
if (this.status == Task.STATUS.failed || this.status == Task.STATUS.interupted) {
return Promise.reject(this.error);
}
return new Promise((resolve, reject) => {
this.result_listeners.push([resolve, reject]);
});
}
#notifyFailure() {
for (let [_resolve, reject] of this.result_listeners) {
reject(this.error);
}
this.result_listeners = [];
}
#notifySuccess() {
for (let [resolve, _reject] of this.result_listeners) {
resolve(this.result);
}
this.result_listeners = [];
}
};
Task.STATUS = {
pending: 0,
running: 1,
interupting: 2,
ready: 3,
interupted: 4,
failed: 5,
};