feat: Add ParallelHandler.

This commit is contained in:
Ruben Verborgh 2021-01-26 23:02:04 +01:00 committed by Joachim Van Herwegen
parent eb1440851a
commit 817cf3ac0d
3 changed files with 124 additions and 0 deletions

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@ -189,6 +189,7 @@ export * from './util/errors/UnsupportedMediaTypeHttpError';
// Util/Handlers
export * from './util/handlers/AsyncHandler';
export * from './util/handlers/ParallelHandler';
export * from './util/handlers/SequenceHandler';
export * from './util/handlers/UnsupportedAsyncHandler';
export * from './util/handlers/WaterfallHandler';

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@ -0,0 +1,23 @@
import { AsyncHandler } from './AsyncHandler';
/**
* A composite handler that executes handlers in parallel.
*/
export class ParallelHandler<TIn = void, TOut = void> extends AsyncHandler<TIn, TOut[]> {
private readonly handlers: AsyncHandler<TIn, TOut>[];
public constructor(handlers: AsyncHandler<TIn, TOut>[]) {
super();
this.handlers = [ ...handlers ];
}
public async canHandle(input: TIn): Promise<void> {
// eslint-disable-next-line @typescript-eslint/promise-function-async
await Promise.all(this.handlers.map((handler): Promise<void> => handler.canHandle(input)));
}
public async handle(input: TIn): Promise<TOut[]> {
// eslint-disable-next-line @typescript-eslint/promise-function-async
return Promise.all(this.handlers.map((handler): Promise<TOut> => handler.handle(input)));
}
}

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@ -0,0 +1,100 @@
import type { AsyncHandler } from '../../../../src/util/handlers/AsyncHandler';
import { ParallelHandler } from '../../../../src/util/handlers/ParallelHandler';
describe('A ParallelHandler', (): void => {
const handlers: jest.Mocked<AsyncHandler<string, string>>[] = [
{
canHandle: jest.fn(),
handle: jest.fn().mockResolvedValue('0'),
},
{
canHandle: jest.fn(),
handle: jest.fn().mockResolvedValue('1'),
},
{
canHandle: jest.fn(),
handle: jest.fn().mockResolvedValue('2'),
},
] as any;
const composite: ParallelHandler<string, string> = new ParallelHandler<string, string>(handlers);
afterEach(jest.clearAllMocks);
describe('canHandle', (): void => {
it('succeeds if all handlers succeed.', async(): Promise<void> => {
await expect(composite.canHandle('abc')).resolves.toBeUndefined();
expect(handlers[0].canHandle).toHaveBeenCalledTimes(1);
expect(handlers[1].canHandle).toHaveBeenCalledTimes(1);
expect(handlers[2].canHandle).toHaveBeenCalledTimes(1);
expect(handlers[0].canHandle).toHaveBeenCalledWith('abc');
expect(handlers[1].canHandle).toHaveBeenCalledWith('abc');
expect(handlers[2].canHandle).toHaveBeenCalledWith('abc');
});
it('fails if one handler fails.', async(): Promise<void> => {
const error = new Error('failure');
handlers[1].canHandle.mockRejectedValueOnce(error);
await expect(composite.canHandle('abc')).rejects.toThrow(error);
});
});
describe('handle', (): void => {
it('succeeds if all handlers succeed.', async(): Promise<void> => {
await expect(composite.handle('abc')).resolves.toEqual([ '0', '1', '2' ]);
expect(handlers[0].handle).toHaveBeenCalledTimes(1);
expect(handlers[1].handle).toHaveBeenCalledTimes(1);
expect(handlers[2].handle).toHaveBeenCalledTimes(1);
expect(handlers[0].handle).toHaveBeenCalledWith('abc');
expect(handlers[1].handle).toHaveBeenCalledWith('abc');
expect(handlers[2].handle).toHaveBeenCalledWith('abc');
});
it('fails if one handler fails.', async(): Promise<void> => {
const error = new Error('failure');
handlers[1].handle.mockRejectedValueOnce(error);
await expect(composite.handle('abc')).rejects.toThrow(error);
});
});
describe('handleSafe', (): void => {
it('succeeds if all handlers succeed.', async(): Promise<void> => {
await expect(composite.handleSafe('abc')).resolves.toEqual([ '0', '1', '2' ]);
expect(handlers[0].canHandle).toHaveBeenCalledTimes(1);
expect(handlers[1].canHandle).toHaveBeenCalledTimes(1);
expect(handlers[2].canHandle).toHaveBeenCalledTimes(1);
expect(handlers[0].canHandle).toHaveBeenCalledWith('abc');
expect(handlers[1].canHandle).toHaveBeenCalledWith('abc');
expect(handlers[2].canHandle).toHaveBeenCalledWith('abc');
expect(handlers[0].handle).toHaveBeenCalledTimes(1);
expect(handlers[1].handle).toHaveBeenCalledTimes(1);
expect(handlers[2].handle).toHaveBeenCalledTimes(1);
expect(handlers[0].handle).toHaveBeenCalledWith('abc');
expect(handlers[1].handle).toHaveBeenCalledWith('abc');
expect(handlers[2].handle).toHaveBeenCalledWith('abc');
});
it('fails if one canHandle fails.', async(): Promise<void> => {
const error = new Error('failure');
handlers[1].canHandle.mockRejectedValueOnce(error);
await expect(composite.handleSafe('abc')).rejects.toThrow(error);
expect(handlers[0].handle).toHaveBeenCalledTimes(0);
expect(handlers[1].handle).toHaveBeenCalledTimes(0);
expect(handlers[2].handle).toHaveBeenCalledTimes(0);
});
it('fails if one handle fails.', async(): Promise<void> => {
const error = new Error('failure');
handlers[1].handle.mockRejectedValueOnce(error);
await expect(composite.handleSafe('abc')).rejects.toThrow(error);
});
});
});