Make locks generic

frontend/sync-client/src/file-operations/document-locks.ts

@@ -1,65 +0,0 @@
-import type { Logger } from "../tracing/logger";
-import type { RelativePath } from "../persistence/database";
-
-// Manages locks on documents to prevent concurrent modifications
-// allowing the client's FileOperations implementation to be simpler.
-// Locks are granted in a first-in-first-out order.
-export class DocumentLocks {
-	private readonly locked = new Set<RelativePath>();
-	private readonly waiters = new Map<RelativePath, (() => void)[]>();
-
-	public constructor(private readonly logger: Logger) {}
-
-	public tryLockDocument(relativePath: RelativePath): boolean {
-		if (this.locked.has(relativePath)) {
-			return false;
-		}
-
-		this.locked.add(relativePath);
-
-		return true;
-	}
-
-	public async waitForDocumentLock(
-		relativePath: RelativePath
-	): Promise<void> {
-		if (this.tryLockDocument(relativePath)) {
-			return Promise.resolve();
-		}
-
-		this.logger.debug(`Waiting for lock on ${relativePath}`);
-
-		return new Promise((resolve) => {
-			let waiting = this.waiters.get(relativePath);
-			if (!waiting) {
-				waiting = [];
-				this.waiters.set(relativePath, waiting);
-			}
-
-			waiting.push(resolve);
-		});
-	}
-
-	public unlockDocument(relativePath: RelativePath): void {
-		if (!this.locked.has(relativePath)) {
-			throw new Error(
-				`Document ${relativePath} is not locked, cannot unlock`
-			);
-		}
-
-		// Remove the first element to ensure FIFO unblocking order
-		const nextWaiting = this.waiters.get(relativePath)?.shift();
-
-		if (nextWaiting) {
-			this.logger.debug(`Granted lock on ${relativePath}`);
-			nextWaiting();
-		} else {
-			this.locked.delete(relativePath);
-		}
-	}
-
-	public reset(): void {
-		this.locked.clear();
-		this.waiters.clear();
-	}
-}

frontend/sync-client/src/utils/locks.test.ts

@@ -1,92 +1,88 @@
 import { Logger } from "../tracing/logger";
 import type { RelativePath } from "../persistence/database";
-import { DocumentLocks } from "./document-locks";
+import { Locks } from "./locks";
 
 describe("Document lock", () => {
 	const testPath: RelativePath = "test/document/path";
 	const logger = new Logger();
-	let locks = new DocumentLocks(logger);
+
+	// eslint-disable-next-line @typescript-eslint/init-declarations
+	let locks: Locks<RelativePath>;
 
 	beforeEach(() => {
-		locks = new DocumentLocks(logger);
+		locks = new Locks<RelativePath>(logger);
 	});
 
 	test("should lock a document successfully", () => {
-		const result = locks.tryLockDocument(testPath);
+		const result = locks.tryLock(testPath);
 		expect(result).toBe(true);
 	});
 
 	test("should not lock a document that is already locked", () => {
-		locks.tryLockDocument(testPath);
+		locks.tryLock(testPath);
-		const result = locks.tryLockDocument(testPath);
+		const result = locks.tryLock(testPath);
 		expect(result).toBe(false);
 	});
 
 	test("should unlock a locked document", () => {
-		locks.tryLockDocument(testPath);
+		locks.tryLock(testPath);
-		locks.unlockDocument(testPath);
+		locks.unlock(testPath);
-		const result = locks.tryLockDocument(testPath);
+		const result = locks.tryLock(testPath);
 		expect(result).toBe(true);
-		locks.unlockDocument(testPath);
+		locks.unlock(testPath);
 	});
 
 	test("should throw an error when unlocking a document that is not locked", () => {
 		expect(() => {
-			locks.unlockDocument(testPath);
+			locks.unlock(testPath);
 		}).toThrow(`Document ${testPath} is not locked, cannot unlock`);
 	});
 
 	test("should wait for a document lock and resolve when unlocked", async () => {
-		locks.tryLockDocument(testPath);
+		locks.tryLock(testPath);
 
 		let resolved = false;
-		const waitPromise = locks.waitForDocumentLock(testPath).then(() => {
+		const waitPromise = locks.waitForLock(testPath).then(() => {
 			resolved = true;
 		});
 
-		locks.unlockDocument(testPath);
+		locks.unlock(testPath);
 		await waitPromise;
 
 		expect(resolved).toBe(true);
 	});
 
 	test("should resolve multiple waiters in FIFO order", async () => {
-		locks.tryLockDocument(testPath);
+		locks.tryLock(testPath);
 
 		let firstResolved = false;
 		let secondResolved = false;
 		let thirdResolved = false;
 
-		const firstWaitPromise = locks
+		const firstWaitPromise = locks.waitForLock(testPath).then(() => {
-			.waitForDocumentLock(testPath)
+			firstResolved = true;
-			.then(() => {
+		});
-				firstResolved = true;
-			});
 
-		const secondWaitPromise = locks
+		const secondWaitPromise = locks.waitForLock(testPath).then(() => {
-			.waitForDocumentLock(testPath)
+			secondResolved = true;
-			.then(() => {
+		});
-				secondResolved = true;
-			});
 
-		const thirdWaitPromise = locks
+		const thirdWaitPromise = locks.waitForLock(testPath).then(() => {
-			.waitForDocumentLock(testPath)
+			thirdResolved = true;
-			.then(() => {
+		});
-				thirdResolved = true;
-			});
 
-		locks.unlockDocument(testPath);
+		locks.unlock(testPath);
 		await firstWaitPromise;
 		expect(firstResolved).toBe(true);
 		expect(secondResolved).toBe(false);
 		expect(thirdResolved).toBe(false);
 
-		locks.unlockDocument(testPath);
+		locks.unlock(testPath);
 		await secondWaitPromise;
 		expect(secondResolved).toBe(true);
 		expect(thirdResolved).toBe(false);
 
-		locks.unlockDocument(testPath);
+		locks.unlock(testPath);
 		await thirdWaitPromise;
 		expect(thirdResolved).toBe(true);
 	});

frontend/sync-client/src/utils/locks.ts

@@ -0,0 +1,60 @@
+import type { Logger } from "../tracing/logger";
+
+// Manages locks on T to prevent concurrent modifications
+// allowing the client's FileOperations implementation to be simpler.
+// Locks are granted in a first-in-first-out order.
+export class Locks<T> {
+	private readonly locked = new Set<T>();
+	private readonly waiters = new Map<T, (() => void)[]>();
+
+	public constructor(private readonly logger: Logger) {}
+
+	public tryLock(key: T): boolean {
+		if (this.locked.has(key)) {
+			return false;
+		}
+
+		this.locked.add(key);
+
+		return true;
+	}
+
+	public async waitForLock(key: T): Promise<void> {
+		if (this.tryLock(key)) {
+			return Promise.resolve();
+		}
+
+		this.logger.debug(`Waiting for lock on ${key}`);
+
+		return new Promise((resolve) => {
+			let waiting = this.waiters.get(key);
+			if (!waiting) {
+				waiting = [];
+				this.waiters.set(key, waiting);
+			}
+
+			waiting.push(resolve);
+		});
+	}
+
+	public unlock(key: T): void {
+		if (!this.locked.has(key)) {
+			throw new Error(`Document ${key} is not locked, cannot unlock`);
+		}
+
+		// Remove the first element to ensure FIFO unblocking order
+		const nextWaiting = this.waiters.get(key)?.shift();
+
+		if (nextWaiting) {
+			this.logger.debug(`Granted lock on ${key}`);
+			nextWaiting();
+		} else {
+			this.locked.delete(key);
+		}
+	}
+
+	public reset(): void {
+		this.locked.clear();
+		this.waiters.clear();
+	}
+}