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fix: event-handler leakage (#788)
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Fixes an issue where event handlers could be leaked if the same handler
reference was added multiple times.

---------

Signed-off-by: Todd Baert <[email protected]>
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@toddbaert
toddbaert authored Jan 26, 2024
1 parent c6a357a commit 69c7f05
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Showing 2 changed files with 102 additions and 18 deletions.
29 changes: 20 additions & 9 deletions packages/shared/src/events/generic-event-emitter.ts
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
import { Logger, ManageLogger, SafeLogger } from '../logger';
import { EventContext, EventDetails, EventHandler } from './eventing';
import { AnyProviderEvent } from './events';
import { AllProviderEvents, AnyProviderEvent } from './events';

/**
* The GenericEventEmitter should only be used within the SDK. It supports additional properties that can be included
Expand All @@ -11,8 +11,13 @@ export abstract class GenericEventEmitter<E extends AnyProviderEvent, Additional
{
protected abstract readonly eventEmitter: PlatformEventEmitter;

// eslint-disable-next-line @typescript-eslint/no-explicit-any
private readonly _handlers = new WeakMap<EventHandler, EventHandler>();
private readonly _handlers: { [key in AnyProviderEvent]: WeakMap<EventHandler, EventHandler[]>} = {
[AllProviderEvents.ConfigurationChanged]: new WeakMap<EventHandler, EventHandler[]>(),
[AllProviderEvents.ContextChanged]: new WeakMap<EventHandler, EventHandler[]>(),
[AllProviderEvents.Ready]: new WeakMap<EventHandler, EventHandler[]>(),
[AllProviderEvents.Error]: new WeakMap<EventHandler, EventHandler[]>(),
[AllProviderEvents.Stale]: new WeakMap<EventHandler, EventHandler[]>(),
};
private _eventLogger?: Logger;

constructor(private readonly globalLogger?: () => Logger) {}
Expand All @@ -29,19 +34,25 @@ export abstract class GenericEventEmitter<E extends AnyProviderEvent, Additional
await handler(details);
};
// The async handler has to be written to the map, because we need to get the wrapper function when deleting a listener
this._handlers.set(handler, asyncHandler);
const existingAsyncHandlers = this._handlers[eventType].get(handler);

// we allow duplicate event handlers, similar to node,
// see: https://nodejs.org/api/events.html#emitteroneventname-listener
// and https://nodejs.org/api/events.html#emitterremovelistenereventname-listener
this._handlers[eventType].set(handler, [...(existingAsyncHandlers || []), asyncHandler]);
this.eventEmitter.on(eventType, asyncHandler);
}

removeHandler(eventType: AnyProviderEvent, handler: EventHandler): void {
// Get the wrapper function for this handler, to delete it from the event emitter
const asyncHandler = this._handlers.get(handler) as EventHandler | undefined;
const existingAsyncHandlers = this._handlers[eventType].get(handler);

if (!asyncHandler) {
return;
if (existingAsyncHandlers) {
const removedAsyncHandler = existingAsyncHandlers.pop();
if (removedAsyncHandler) {
this.eventEmitter.removeListener(eventType, removedAsyncHandler);
}
}

this.eventEmitter.removeListener(eventType, asyncHandler);
}

removeAllHandlers(eventType?: AnyProviderEvent): void {
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91 changes: 82 additions & 9 deletions packages/shared/test/events.spec.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,19 +13,27 @@ class TestEventEmitter extends GenericEventEmitter<AnyProviderEvent> {
}
}

// a little function to make sure we're at least waiting for the event loop
// to clear before we start making assertions
const wait = (millis = 0) => {
return new Promise(resolve => {setTimeout(resolve, millis);});
};

describe('GenericEventEmitter', () => {
describe('addHandler should', function () {
it('attach handler for event type', function () {
it('attach handler for event type', async function () {
const emitter = new TestEventEmitter();

const handler1 = jest.fn();
emitter.addHandler(AllProviderEvents.Ready, handler1);
emitter.emit(AllProviderEvents.Ready);

await wait();

expect(handler1).toHaveBeenCalledTimes(1);
});

it('attach several handlers for event type', function () {
it('attach several handlers for event type', async function () {
const emitter = new TestEventEmitter();

const handler1 = jest.fn();
Expand All @@ -38,6 +46,8 @@ describe('GenericEventEmitter', () => {

emitter.emit(AllProviderEvents.Ready);

await wait();

expect(handler1).toHaveBeenCalledTimes(1);
expect(handler2).toHaveBeenCalledTimes(1);
expect(handler3).not.toHaveBeenCalled();
Expand All @@ -62,28 +72,32 @@ describe('GenericEventEmitter', () => {
emitter.emit(AllProviderEvents.Ready);
});

it('trigger handler for event type', function () {
it('trigger handler for event type', async function () {
const emitter = new TestEventEmitter();

const handler1 = jest.fn();
emitter.addHandler(AllProviderEvents.Ready, handler1);
emitter.emit(AllProviderEvents.Ready);

await wait();

expect(handler1).toHaveBeenCalledTimes(1);
});

it('trigger handler for event type with event data', function () {
it('trigger handler for event type with event data', async function () {
const event: ReadyEvent = { message: 'message' };
const emitter = new TestEventEmitter();

const handler1 = jest.fn();
emitter.addHandler(AllProviderEvents.Ready, handler1);
emitter.emit(AllProviderEvents.Ready, event);

await wait();

expect(handler1).toHaveBeenNthCalledWith(1, event);
});

it('trigger several handlers for event type', function () {
it('trigger several handlers for event type', async function () {
const emitter = new TestEventEmitter();

const handler1 = jest.fn();
Expand All @@ -96,14 +110,16 @@ describe('GenericEventEmitter', () => {

emitter.emit(AllProviderEvents.Ready);

await wait();

expect(handler1).toHaveBeenCalledTimes(1);
expect(handler2).toHaveBeenCalledTimes(1);
expect(handler3).not.toHaveBeenCalled();
});
});

describe('removeHandler should', () => {
it('remove single handler', function () {
it('remove single handler', async function () {
const emitter = new TestEventEmitter();

const handler1 = jest.fn();
Expand All @@ -113,12 +129,14 @@ describe('GenericEventEmitter', () => {
emitter.removeHandler(AllProviderEvents.Ready, handler1);
emitter.emit(AllProviderEvents.Ready);

await wait();

expect(handler1).toHaveBeenCalledTimes(1);
});
});

describe('removeAllHandlers should', () => {
it('remove all handlers for event type', function () {
it('remove all handlers for event type', async function () {
const emitter = new TestEventEmitter();

const handler1 = jest.fn();
Expand All @@ -130,11 +148,62 @@ describe('GenericEventEmitter', () => {
emitter.emit(AllProviderEvents.Ready);
emitter.emit(AllProviderEvents.Error);

await wait();

expect(handler1).toHaveBeenCalledTimes(0);
expect(handler2).toHaveBeenCalledTimes(1);
});

it('remove all handlers only for event type', function () {
it('remove same handler when assigned to multiple events', async function () {
const emitter = new TestEventEmitter();

const handler = jest.fn();
emitter.addHandler(AllProviderEvents.Stale, handler);
emitter.addHandler(AllProviderEvents.ContextChanged, handler);

emitter.removeHandler(AllProviderEvents.Stale, handler);
emitter.removeHandler(AllProviderEvents.ContextChanged, handler);

emitter.emit(AllProviderEvents.Stale);
emitter.emit(AllProviderEvents.ContextChanged);

await wait();

expect(handler).toHaveBeenCalledTimes(0);
});

it('allow addition/removal of duplicate handlers', async function () {
const emitter = new TestEventEmitter();

const handler = jest.fn();
emitter.addHandler(AllProviderEvents.Stale, handler);
emitter.addHandler(AllProviderEvents.Stale, handler);

emitter.removeHandler(AllProviderEvents.Stale, handler);
emitter.removeHandler(AllProviderEvents.Stale, handler);

emitter.emit(AllProviderEvents.Stale);

await wait();

expect(handler).toHaveBeenCalledTimes(0);
});

it('allow duplicate event handlers and call them', async function () {
const emitter = new TestEventEmitter();

const handler = jest.fn();
emitter.addHandler(AllProviderEvents.Stale, handler);
emitter.addHandler(AllProviderEvents.Stale, handler);

emitter.emit(AllProviderEvents.Stale);

await wait();

expect(handler).toHaveBeenCalledTimes(2);
});

it('remove all handlers only for event type', async function () {
const emitter = new TestEventEmitter();

const handler1 = jest.fn();
Expand All @@ -146,11 +215,13 @@ describe('GenericEventEmitter', () => {
emitter.removeAllHandlers(AllProviderEvents.Ready);
emitter.emit(AllProviderEvents.Ready);

await wait();

expect(handler1).toHaveBeenCalledTimes(1);
expect(handler2).toHaveBeenCalledTimes(0);
});

it('remove all handlers if no event type is given', function () {
it('remove all handlers if no event type is given', async function () {
const emitter = new TestEventEmitter();

const handler1 = jest.fn();
Expand All @@ -164,6 +235,8 @@ describe('GenericEventEmitter', () => {
emitter.emit(AllProviderEvents.Ready);
emitter.emit(AllProviderEvents.Error);

await wait();

expect(handler1).toHaveBeenCalledTimes(1);
expect(handler2).toHaveBeenCalledTimes(1);
});
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