Blame · featureFlags.ts

b69ab31	1	/**
b69ab31	2	* Copyright (c) Meta Platforms, Inc. and affiliates.
b69ab31	3	*
b69ab31	4	* This source code is licensed under the MIT license found in the
b69ab31	5	* LICENSE file in the root directory of this source tree.
b69ab31	6	*/
b69ab31	7
b69ab31	8	import {atom, useAtomValue} from 'jotai';
b69ab31	9	import {loadable} from 'jotai/utils';
b69ab31	10	import {randomId} from 'shared/utils';
b69ab31	11	import serverAPI from './ClientToServerAPI';
b69ab31	12	import {Internal} from './Internal';
b69ab31	13	import {atomFamilyWeak, readAtom} from './jotaiUtils';
b69ab31	14
b69ab31	15	const bulkFetchedFlagsAtom = atom<Promise<Record<string, boolean>>>(() => {
b69ab31	16	if (Internal.featureFlags == null) {
b69ab31	17	return Promise.resolve({});
b69ab31	18	}
b69ab31	19	const knownFlags: Array<string> = Object.values(Internal.featureFlags ?? {});
b69ab31	20	return bulkFetchFeatureFlags(knownFlags);
b69ab31	21	});
b69ab31	22
b69ab31	23	/**
b69ab31	24	* Boolean values to enable features via remote config.
b69ab31	25	* TODO: we could cache values in localstorage to avoid async lookup time if you've previously fetched it
b69ab31	26	*/
b69ab31	27	export const featureFlagAsync = atomFamilyWeak((name?: string) => {
b69ab31	28	if (name == null) {
b69ab31	29	// OSS doesn't have access to feature flags, so they are always "false" by setting the name to null
b69ab31	30	return atom(Promise.resolve(false));
b69ab31	31	}
b69ab31	32
b69ab31	33	const knownFlags: Array<string> = Object.values(Internal.featureFlags ?? {});
b69ab31	34	if (knownFlags.includes(name)) {
b69ab31	35	return atom(get => get(bulkFetchedFlagsAtom).then(flags => flags[name]));
b69ab31	36	}
b69ab31	37
b69ab31	38	return atom(fetchFeatureFlag(name));
b69ab31	39	});
b69ab31	40
b69ab31	41	export const qeFlagAsync = atomFamilyWeak((name?: string) => {
b69ab31	42	if (name == null) {
b69ab31	43	// OSS doesn't have access to feature flags, so they are always "false" by setting the name to null
b69ab31	44	return atom(Promise.resolve(false));
b69ab31	45	}
b69ab31	46	return atom(fetchQeFlag(name));
b69ab31	47	});
b69ab31	48
b69ab31	49	export const featureFlagLoadable = atomFamilyWeak((name?: string) => {
b69ab31	50	return loadable(featureFlagAsync(name));
b69ab31	51	});
b69ab31	52
b69ab31	53	/** Access featureFlag state without suspending or throwing */
b69ab31	54	export function useFeatureFlagSync(name: string \| undefined) {
b69ab31	55	const flag = useAtomValue(featureFlagLoadable(name));
b69ab31	56	return flag.state === 'hasData' ? flag.data : false;
b69ab31	57	}
b69ab31	58
b69ab31	59	/** Access featureFlag, suspending if not yet loaded */
b69ab31	60	export function useFeatureFlagAsync(name: string \| undefined) {
b69ab31	61	const flag = useAtomValue(featureFlagAsync(name));
b69ab31	62	return flag;
b69ab31	63	}
b69ab31	64
b69ab31	65	export function getFeatureFlag(name: string \| undefined, default_?: boolean): Promise<boolean> {
b69ab31	66	if (name == null) {
b69ab31	67	return Promise.resolve(default_ ?? false);
b69ab31	68	}
b69ab31	69	return readAtom(featureFlagAsync(name));
b69ab31	70	}
b69ab31	71
b69ab31	72	export function getQeFlag(name: string \| undefined, default_?: boolean): Promise<boolean> {
b69ab31	73	if (name == null) {
b69ab31	74	return Promise.resolve(default_ ?? false);
b69ab31	75	}
b69ab31	76	return readAtom(qeFlagAsync(name));
b69ab31	77	}
b69ab31	78
b69ab31	79	async function fetchFeatureFlag(name: string \| undefined, default_?: boolean): Promise<boolean> {
b69ab31	80	if (name == null) {
b69ab31	81	return default_ ?? false;
b69ab31	82	}
b69ab31	83	serverAPI.postMessage({
b69ab31	84	type: 'fetchFeatureFlag',
b69ab31	85	name,
b69ab31	86	});
b69ab31	87	const response = await serverAPI.nextMessageMatching(
b69ab31	88	'fetchedFeatureFlag',
b69ab31	89	message => message.name === name,
b69ab31	90	);
b69ab31	91	return response.passes;
b69ab31	92	}
b69ab31	93
b69ab31	94	async function fetchQeFlag(name: string \| undefined, default_?: boolean): Promise<boolean> {
b69ab31	95	if (name == null) {
b69ab31	96	return default_ ?? false;
b69ab31	97	}
b69ab31	98	serverAPI.postMessage({
b69ab31	99	type: 'fetchQeFlag',
b69ab31	100	name,
b69ab31	101	});
b69ab31	102	const response = await serverAPI.nextMessageMatching(
b69ab31	103	'fetchedQeFlag',
b69ab31	104	message => message.name === name,
b69ab31	105	);
b69ab31	106	return response.passes;
b69ab31	107	}
b69ab31	108
b69ab31	109	let featureFlagOverrides: Record<string, boolean> \| undefined = undefined;
b69ab31	110	export const __TEST__ = {
b69ab31	111	overrideFeatureFlag: (name: string, value: boolean) => {
b69ab31	112	featureFlagOverrides ??= {};
b69ab31	113	featureFlagOverrides[name] = value;
b69ab31	114	},
b69ab31	115	clearFeatureFlagOverrides: () => {
b69ab31	116	featureFlagOverrides = undefined;
b69ab31	117	},
b69ab31	118	};
b69ab31	119
b69ab31	120	export async function bulkFetchFeatureFlags(
b69ab31	121	names: Array<string>,
b69ab31	122	): Promise<Record<string, boolean>> {
b69ab31	123	if (featureFlagOverrides) {
b69ab31	124	return Object.fromEntries(names.map(name => [name, featureFlagOverrides?.[name] ?? false]));
b69ab31	125	}
b69ab31	126	const id = randomId();
b69ab31	127	serverAPI.postMessage({
b69ab31	128	type: 'bulkFetchFeatureFlags',
b69ab31	129	names,
b69ab31	130	id,
b69ab31	131	});
b69ab31	132	const response = await serverAPI.nextMessageMatching(
b69ab31	133	'bulkFetchedFeatureFlags',
b69ab31	134	message => message.id === id,
b69ab31	135	);
b69ab31	136	return response.result;
b69ab31	137	}