perf(api): memoise the effective bluesky oauth config (#2156)

fluxer_api/src/api/instance/InstanceConfigRepository.test.ts

@@ -81,6 +81,40 @@ describe('InstanceConfigRepository', () => {
 		});
 	});
 
+	it('reuses the memoized effective bluesky config until the integrations blob changes', async () => {
+		const executor = new CountingInMemoryCassandraQueryExecutor();
+		setCassandraQueryExecutorForTesting(executor);
+		const kvProvider = new MockKVProvider();
+		const repository = createRepository(kvProvider);
+
+		const first = await repository.getEffectiveBlueskyConfig();
+		expect(await repository.getEffectiveBlueskyConfig()).toBe(first);
+
+		await repository.setInstanceIntegrationsConfig({bluesky: {client_name: 'Memoized Instance'}});
+
+		const updated = await repository.getEffectiveBlueskyConfig();
+		expect(updated).not.toBe(first);
+		expect(updated.client_name).toBe('Memoized Instance');
+		expect(await repository.getEffectiveBlueskyConfig()).toBe(updated);
+	});
+
+	it('recomputes the effective bluesky config after another repository publishes an integrations update', async () => {
+		const executor = new CountingInMemoryCassandraQueryExecutor();
+		setCassandraQueryExecutorForTesting(executor);
+		const kvProvider = new MockKVProvider();
+		const reader = createRepository(kvProvider);
+		const writer = createRepository(kvProvider);
+
+		const before = await reader.getEffectiveBlueskyConfig();
+		expect(await reader.getEffectiveBlueskyConfig()).toBe(before);
+
+		await writer.setInstanceIntegrationsConfig({bluesky: {client_name: 'Refreshed Instance'}});
+
+		await vi.waitFor(async () => {
+			expect((await reader.getEffectiveBlueskyConfig()).client_name).toBe('Refreshed Instance');
+		});
+	});
+
 	it('uses the registration URL id as the admin-visible registration code', async () => {
 		const executor = new CountingInMemoryCassandraQueryExecutor();
 		setCassandraQueryExecutorForTesting(executor);

fluxer_api/src/api/instance/InstanceConfigRepository.ts

@@ -800,6 +800,8 @@ export class InstanceConfigRepository {
 	private subscriberInitialized = false;
 	private subscriberInitializationPromise: Promise<boolean> | null = null;
 	private messageHandler: ((channel: string, message: string) => void) | null = null;
+	private effectiveBlueskyConfig: BlueskyOAuthConfig | null = null;
+	private effectiveBlueskyConfigSource: string | null = null;
 
 	constructor(kvClient: IKVProvider | null = null) {
 		this.kvClient = kvClient;
@@ -1303,14 +1305,19 @@ export class InstanceConfigRepository {
 	}
 
 	async getEffectiveBlueskyConfig(): Promise<BlueskyOAuthConfig> {
-		const integrations = await this.getInstanceIntegrationsConfig();
+		const raw = await this.getConfig(INSTANCE_INTEGRATIONS_CONFIG_KEY);
+		const memoized = this.effectiveBlueskyConfig;
+		if (memoized && this.effectiveBlueskyConfigSource === raw) {
+			return memoized;
+		}
+		const integrations = normalizeInstanceIntegrationsConfig(raw ? parseJsonRecord(raw) : null);
 		const runtimeKeys = integrations.bluesky.keys.flatMap((key): Array<BlueskyOAuthKeyConfig> => {
 			if (!key.private_key) return [];
 			return [{kid: key.kid, private_key: key.private_key}];
 		});
 		const keys = runtimeKeys.length > 0 ? runtimeKeys : Config.auth.bluesky.keys;
 		const enabled = (integrations.bluesky.enabled ?? Config.auth.bluesky.enabled) && keys.length > 0;
-		return {
+		const effective: BlueskyOAuthConfig = {
 			...Config.auth.bluesky,
 			enabled,
 			client_name: integrations.bluesky.client_name ?? Config.auth.bluesky.client_name,
@@ -1320,6 +1327,9 @@ export class InstanceConfigRepository {
 			policy_uri: integrations.bluesky.policy_uri ?? Config.auth.bluesky.policy_uri,
 			keys,
 		};
+		this.effectiveBlueskyConfigSource = raw;
+		this.effectiveBlueskyConfig = effective;
+		return effective;
 	}
 
 	async getInstanceIntegrationsAdminConfig(): Promise<InstanceIntegrationsAdminConfig> {

fluxer_api/src/api/middleware/ServiceRegistry.ts

@@ -181,6 +181,8 @@ let _blueskyOAuthService: IBlueskyOAuthService | undefined;
 let _blueskyOAuthInitializationPromise: Promise<IBlueskyOAuthService> | null = null;
 let _blueskyOAuthConfigSignature: string | null = null;
 let _blueskyOAuthInitializationSignature: string | null = null;
+let _blueskyOAuthSignatureSource: BlueskyOAuthConfig | null = null;
+let _blueskyOAuthSignatureValue: string | null = null;
 let _disabledBlueskyOAuthService: DisabledBlueskyOAuthService | undefined;
 
 export function setInjectedBlueskyOAuthService(service: IBlueskyOAuthService | undefined): void {
@@ -195,7 +197,13 @@ function getDisabledBlueskyOAuthService(): DisabledBlueskyOAuthService {
 }
 
 function getBlueskyOAuthConfigSignature(config: BlueskyOAuthConfig): string {
-	return JSON.stringify(config);
+	if (_blueskyOAuthSignatureSource === config && _blueskyOAuthSignatureValue !== null) {
+		return _blueskyOAuthSignatureValue;
+	}
+	const signature = JSON.stringify(config);
+	_blueskyOAuthSignatureSource = config;
+	_blueskyOAuthSignatureValue = signature;
+	return signature;
 }
 
 export async function resolveBlueskyOAuthService(
@@ -315,6 +323,8 @@ export function resetServiceRegistryForTesting(): void {
 	_blueskyOAuthInitializationPromise = null;
 	_blueskyOAuthConfigSignature = null;
 	_blueskyOAuthInitializationSignature = null;
+	_blueskyOAuthSignatureSource = null;
+	_blueskyOAuthSignatureValue = null;
 	_disabledBlueskyOAuthService = undefined;
 	voiceTopology = null;
 	voiceAvailabilityService = null;