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| /**
* Copyright 2017 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import { assert, fail } from './assert';
import * as log from './log';
import { AnyJs } from './misc';
import { Deferred, CancelablePromise } from './promise';
import { Code, FirestoreError } from './error';
// tslint:disable-next-line:no-any Accept any return type from setTimeout().
type TimerHandle = any;
/**
* Wellknown "timer" IDs used when scheduling delayed operations on the
* AsyncQueue. These IDs can then be used from tests to check for the presence
* of operations or to run them early.
*/
export enum TimerId {
ListenStreamIdle,
ListenStreamConnection,
WriteStreamIdle,
WriteStreamConnection
}
/**
* Represents an operation scheduled to be run in the future on an AsyncQueue.
*
* It is created via DelayedOperation.createAndSchedule().
*
* Supports cancellation (via cancel()) and early execution (via skipDelay()).
*/
class DelayedOperation<T> implements CancelablePromise<T> {
// handle for use with clearTimeout(), or null if the operation has been
// executed or canceled already.
private timerHandle: TimerHandle | null;
private readonly deferred = new Deferred<T>();
private constructor(
private readonly asyncQueue: AsyncQueue,
readonly timerId: TimerId,
readonly targetTimeMs: number,
private readonly op: () => Promise<T>,
private readonly removalCallback: (op: DelayedOperation<T>) => void
) {}
/**
* Creates and returns a DelayedOperation that has been scheduled to be
* executed on the provided asyncQueue after the provided delayMs.
*
* @param asyncQueue The queue to schedule the operation on.
* @param id A Timer ID identifying the type of operation this is.
* @param delayMs The delay (ms) before the operation should be scheduled.
* @param op The operation to run.
* @param removalCallback A callback to be called synchronously once the
* operation is executed or canceled, notifying the AsyncQueue to remove it
* from its delayedOperations list.
* PORTING NOTE: This exists to prevent making removeDelayedOperation() and
* the DelayedOperation class public.
*/
static createAndSchedule<T>(
asyncQueue: AsyncQueue,
timerId: TimerId,
delayMs: number,
op: () => Promise<T>,
removalCallback: (op: DelayedOperation<T>) => void
): DelayedOperation<T> {
const targetTime = Date.now() + delayMs;
const delayedOp = new DelayedOperation(
asyncQueue,
timerId,
targetTime,
op,
removalCallback
);
delayedOp.start(delayMs);
return delayedOp;
}
/**
* Starts the timer. This is called immediately after construction by
* createAndSchedule().
*/
private start(delayMs: number): void {
this.timerHandle = setTimeout(() => this.handleDelayElapsed(), delayMs);
}
/**
* Queues the operation to run immediately (if it hasn't already been run or
* canceled).
*/
skipDelay(): void {
return this.handleDelayElapsed();
}
/**
* Cancels the operation if it hasn't already been executed or canceled. The
* promise will be rejected.
*
* As long as the operation has not yet been run, calling cancel() provides a
* guarantee that the operation will not be run.
*/
cancel(reason?: string): void {
if (this.timerHandle !== null) {
this.clearTimeout();
this.deferred.reject(
new FirestoreError(
Code.CANCELLED,
'Operation cancelled' + (reason ? ': ' + reason : '')
)
);
}
}
// Promise implementation.
readonly [Symbol.toStringTag]: 'Promise';
then = this.deferred.promise.then.bind(this.deferred.promise);
catch = this.deferred.promise.catch.bind(this.deferred.promise);
private handleDelayElapsed(): void {
this.asyncQueue.enqueue(() => {
Eif (this.timerHandle !== null) {
this.clearTimeout();
return this.op().then(result => {
return this.deferred.resolve(result);
});
} else {
return Promise.resolve();
}
});
}
private clearTimeout() {
Eif (this.timerHandle !== null) {
this.removalCallback(this);
clearTimeout(this.timerHandle);
this.timerHandle = null;
}
}
}
export class AsyncQueue {
// The last promise in the queue.
private tail: Promise<AnyJs | void> = Promise.resolve();
// Operations scheduled to be queued in the future. Operations are
// automatically removed after they are run or canceled.
private delayedOperations: Array<DelayedOperation<AnyJs>> = [];
// visible for testing
failure: Error;
// Flag set while there's an outstanding AsyncQueue operation, used for
// assertion sanity-checks.
private operationInProgress = false;
/**
* Adds a new operation to the queue. Returns a promise that will be resolved
* when the promise returned by the new operation is (with its value).
*/
enqueue<T>(op: () => Promise<T>): Promise<T> {
this.verifyNotFailed();
const newTail = this.tail.then(() => {
this.operationInProgress = true;
return op()
.catch(error => {
this.failure = error;
this.operationInProgress = false;
const message = error.stack || error.message || '';
log.error('INTERNAL UNHANDLED ERROR: ', message);
// Escape the promise chain and throw the error globally so that
// e.g. any global crash reporting library detects and reports it.
// (but not for simulated errors in our tests since this breaks mocha)
Iif (message.indexOf('Firestore Test Simulated Error') < 0) {
setTimeout(() => {
throw error;
}, 0);
}
// Re-throw the error so that this.tail becomes a rejected Promise and
// all further attempts to chain (via .then) will just short-circuit
// and return the rejected Promise.
throw error;
})
.then(result => {
this.operationInProgress = false;
return result;
});
});
this.tail = newTail;
return newTail;
}
/**
* Schedules an operation to be queued on the AsyncQueue once the specified
* `delayMs` has elapsed. The returned CancelablePromise can be used to cancel
* the operation prior to its running.
*/
enqueueAfterDelay<T>(
timerId: TimerId,
delayMs: number,
op: () => Promise<T>
): CancelablePromise<T> {
this.verifyNotFailed();
// While not necessarily harmful, we currently don't expect to have multiple
// ops with the same timer id in the queue, so defensively reject them.
assert(
!this.containsDelayedOperation(timerId),
`Attempted to schedule multiple operations with timer id ${
TimerId[timerId]
}.`
);
const delayedOp = DelayedOperation.createAndSchedule(
this,
timerId,
delayMs,
op,
op => this.removeDelayedOperation(op)
);
this.delayedOperations.push(delayedOp);
return delayedOp;
}
private verifyNotFailed(): void {
if (this.failure) {
fail(
'AsyncQueue is already failed: ' +
(this.failure.stack || this.failure.message)
);
}
}
/**
* Verifies there's an operation currently in-progress on the AsyncQueue.
* Unfortunately we can't verify that the running code is in the promise chain
* of that operation, so this isn't a foolproof check, but it should be enough
* to catch some bugs.
*/
verifyOperationInProgress(): void {
assert(
this.operationInProgress,
'verifyOpInProgress() called when no op in progress on this queue.'
);
}
/**
* Waits until all currently queued tasks are finished executing. Delayed
* operations are not run.
*/
drain(): Promise<void> {
return this.enqueue(() => Promise.resolve());
}
/**
* For Tests: Determine if a delayed operation with a particular TimerId
* exists.
*/
containsDelayedOperation(timerId: TimerId): boolean {
return this.delayedOperations.findIndex(op => op.timerId === timerId) >= 0;
}
/**
* For Tests: Runs some or all delayed operations early.
*
* @param lastTimerId If specified, only delayed operations up to and
* including this TimerId will be drained. Throws if no such operation
* exists.
* @returns a Promise that resolves once all operations have been run.
*/
runDelayedOperationsEarly(lastTimerId?: TimerId): Promise<void> {
// Note that draining may generate more delayed ops, so we do that first.
return this.drain().then(() => {
assert(
lastTimerId === undefined || this.containsDelayedOperation(lastTimerId),
`Attempted to drain to missing operation ${lastTimerId}`
);
// Run ops in the same order they'd run if they ran naturally.
this.delayedOperations.sort((a, b) => a.targetTimeMs - b.targetTimeMs);
for (const op of this.delayedOperations) {
op.skipDelay();
if (lastTimerId !== undefined && op.timerId === lastTimerId) {
break;
}
}
return this.drain();
});
}
/** Called once a DelayedOperation is run or canceled. */
private removeDelayedOperation<T>(op: DelayedOperation<T>) {
// NOTE: indexOf / slice are O(n), but delayedOperations is expected to be small.
const index = this.delayedOperations.indexOf(op);
assert(index >= 0, 'Delayed operation not found.');
this.delayedOperations.splice(index, 1);
}
}
|