Merge pull request #2061 from balena-os/unnecessary-reduce

Remove some unnecessary usage of `.reduce`

src/compose/app.ts

@@ -444,10 +444,8 @@ export class App {
 					// FIXME: We should add to the changingServices array, as we could emit several
 					// kill steps for a service
 					steps = steps.concat(
-						dependencies.reduce(
+						dependencies.flatMap((svc) =>
-							(acc, svc) =>
+							this.generateKillStep(svc, changingServices),
-								acc.concat(this.generateKillStep(svc, changingServices)),
-							[] as CompositionStep[],
 						),
 					);
 				} else {

src/compose/application-manager.ts

@@ -1081,37 +1081,41 @@ export async function getState() {
 			.concat(stateFromServices);
 
 	// Get the list of commits for all appIds from the database
-	const commitsForApp = (
+	const commitsForApp: Dictionary<string | undefined> = {};
-		await Promise.all(
+	// Deduplicate appIds first
-			// Deduplicate appIds first
+	await Promise.all(
-			[...new Set(servicesToReport.map((svc) => svc.appId))].map(
+		[...new Set(servicesToReport.map((svc) => svc.appId))].map(
-				async (appId) => ({
+			async (appId) => {
-					[appId]: await commitStore.getCommitForApp(appId),
+				commitsForApp[appId] = await commitStore.getCommitForApp(appId);
-				}),
+			},
-			),
+		),
-		)
+	);
-	).reduce((commits, c) => ({ ...commits, ...c }), {});
 
 	// Assemble the state of apps
-	return servicesToReport.reduce(
+	const state: { [appUuid: string]: AppState } = {};
-		(apps, { appId, appUuid, commit, serviceName, createdAt, ...svc }) => ({
+	for (const {
-			...apps,
+		appId,
-			[appUuid]: {
+		appUuid,
-				...(apps[appUuid] ?? {}),
+		commit,
-				// Add the release_uuid if the commit has been stored in the database
+		serviceName,
-				...(commitsForApp[appId] && { release_uuid: commitsForApp[appId] }),
+		createdAt,
-				releases: {
+		...svc
-					...(apps[appUuid]?.releases ?? {}),
+	} of servicesToReport) {
-					[commit]: {
+		state[appUuid] = {
-						...(apps[appUuid]?.releases[commit] ?? {}),
+			...state[appUuid],
-						services: {
+			// Add the release_uuid if the commit has been stored in the database
-							...(apps[appUuid]?.releases[commit]?.services ?? {}),
+			...(commitsForApp[appId] && { release_uuid: commitsForApp[appId] }),
-							[serviceName]: svc,
+			releases: {
-						},
+				...state[appUuid]?.releases,
+				[commit]: {
+					...state[appUuid]?.releases[commit],
+					services: {
+						...state[appUuid]?.releases[commit]?.services,
+						[serviceName]: svc,
 					},
 				},
 			},
-		}),
+		};
-		{} as { [appUuid: string]: AppState },
+	}
-	);
+	return state;
 }

src/compose/images.ts

@@ -597,12 +597,15 @@ export async function inspectByName(imageName: string) {
 
 	// Run the queries in sequence, return the first one that matches or
 	// the error from the last query
-	return await [inspectByURI, inspectByReference, inspectByDigest].reduce(
+	let err;
-		(promise, query) => promise.catch(() => query(imageName)),
+	for (const query of [inspectByURI, inspectByReference, inspectByDigest]) {
-		Promise.reject(
+		try {
-			'Promise sequence in inspectByName is broken. This is a bug.',
+			return await query(imageName);
-		),
+		} catch ($err) {
-	);
+			err = $err;
+		}
+	}
+	throw err;
 }
 
 export async function cleanup() {
@@ -681,10 +684,7 @@ async function removeImageIfNotNeeded(image: Image): Promise<void> {
 				digests: true,
 				filters: { reference: [reference] },
 			})
-		).reduce(
+		).flatMap((imgInfo) => imgInfo.RepoTags || []);
-			(tagList, imgInfo) => tagList.concat(imgInfo.RepoTags || []),
-			[] as string[],
-		);
 
 		reportEvent('start', { ...image, status: 'Deleting' });
 		logger.logSystemEvent(LogTypes.deleteImage, { image });
@@ -700,10 +700,9 @@ async function removeImageIfNotNeeded(image: Image): Promise<void> {
 		// Remove all matching tags in sequence
 		// as removing in parallel causes some engine weirdness (see above)
 		// this stops on the first error
-		await tags.reduce(
+		for (const tag of tags) {
-			(promise, tag) => promise.then(() => docker.getImage(tag).remove()),
+			await docker.getImage(tag).remove();
-			Promise.resolve(),
+		}
-		);
 
 		// Check for any remaining digests.
 		const digests = (
@@ -711,16 +710,12 @@ async function removeImageIfNotNeeded(image: Image): Promise<void> {
 				digests: true,
 				filters: { reference: [reference] },
 			})
-		).reduce(
+		).flatMap((imgInfo) => imgInfo.RepoDigests || []);
-			(digestList, imgInfo) => digestList.concat(imgInfo.RepoDigests || []),
-			[] as string[],
-		);
 
 		// Remove all remaining digests
-		await digests.reduce(
+		for (const digest of digests) {
-			(promise, digest) => promise.then(() => docker.getImage(digest).remove()),
+			await docker.getImage(digest).remove();
-			Promise.resolve(),
+		}
-		);
 
 		// Mark the image as removed
 		removed = true;

src/config/backends/extra-uEnv.ts

@@ -223,27 +223,26 @@ export class ExtraUEnv extends ConfigBackend {
 
 	private static configToMap(configs: ConfigOptions): Map<string, string> {
 		// Reduce ConfigOptions into a Map that joins collections
-		return Object.entries(configs).reduce(
+		const configMap = new Map();
-			(configMap: Map<string, string>, [configKey, configValue]) => {
+		for (const [configKey, configValue] of Object.entries(configs)) {
-				const { key: ENTRY_KEY, collection: ENTRY_IS_COLLECTION } =
+			const { key: ENTRY_KEY, collection: ENTRY_IS_COLLECTION } =
-					ExtraUEnv.supportedConfigs[configKey];
+				ExtraUEnv.supportedConfigs[configKey];
-				// Check if we have to build the value for the entry
+			// Check if we have to build the value for the entry
-				if (ENTRY_IS_COLLECTION) {
+			if (ENTRY_IS_COLLECTION) {
-					return configMap.set(
+				configMap.set(
-						ENTRY_KEY,
+					ENTRY_KEY,
-						ExtraUEnv.appendToCollection(
+					ExtraUEnv.appendToCollection(
-							configMap.get(ENTRY_KEY),
+						configMap.get(ENTRY_KEY),
-							configKey,
+						configKey,
-							configValue,
+						configValue,
-						),
+					),
-					);
+				);
-				}
+			} else {
 				// Set the value of this config
-				return configMap.set(ENTRY_KEY, `${configValue}`);
+				configMap.set(ENTRY_KEY, `${configValue}`);
-			},
+			}
-			// Start with empty Map
+		}
-			new Map(),
+		return configMap;
-		);
 	}
 
 	private static appendToCollection(

src/config/backends/odmdata.ts

@@ -127,19 +127,15 @@ export class Odmdata extends ConfigBackend {
 			);
 		}
 		// Find the configuration given the optionsBuffer
-		const configIndex = this.CONFIG_BYTES.reduce(
+		const configIndex = this.CONFIG_BYTES.findIndex(
-			(currentIndex: number, _config: number, index: number) => {
+			(_config: number, index: number) => {
-				if (
+				return (
 					this.CONFIG_BUFFER.readUInt8(index) === optionsBuffer.readUInt8(0)
-				) {
+				);
-					return index;
-				}
-				return currentIndex;
 			},
-			null,
 		);
 		// Check if we found a configuration we support
-		if (configIndex === null) {
+		if (configIndex === -1) {
 			log.error(
 				`ODMDATA is set with an unsupported byte: 0x${optionsBuffer.readUInt8(
 					0,

src/device-state/preload.ts

@@ -117,7 +117,7 @@ export async function loadTargetFromFile(appsPath: string): Promise<boolean> {
 					return imageFromService(svc);
 				});
 			})
-			.reduce((res, images) => res.concat(images), []);
+			.flat();
 
 		for (const image of imgs) {
 			const name = imageManager.normalise(image.name);

src/lib/system-info.ts

@@ -11,9 +11,9 @@ import { exec } from './fs-utils';
 
 export async function getCpuUsage(): Promise<number> {
 	const cpuData = await systeminformation.currentLoad();
-	const totalLoad = cpuData.cpus.reduce((load, cpuLoad) => {
+	const totalLoad = _.sumBy(cpuData.cpus, ({ load }) => {
-		return load + cpuLoad.load;
+		return load;
-	}, 0);
+	});
 	return Math.round(totalLoad / cpuData.cpus.length);
 }