@apiratorjs/locking/dist/src/read-write-lock.d.ts

A lightweight library providing both local and distributed locking primitives (mutexes, semaphores, and read-write locks) for managing concurrency in Node.js.

import { AcquireParams, ExclusiveCallback, IReadWriteLock, IReleaser, ReadLockToken, RWLockConstructorProps, WriteLockToken } from "./types";
/**
 * ReadWriteLock (short for Read-Write Lock) is a synchronization mechanism that allows multiple threads to read from a resource simultaneously,
 * but prohibits writing if someone is reading, and vice versa: if writing is in progress, no one can read or write.
 *
 * The main principles of ReadWriteLock operation:
 *    • Multiple threads can read simultaneously if there is no writing.
 *    • Only one thread can write, and during writing, no reads are allowed.
 *    • This improves performance with a large number of read operations and infrequent writes.
 *
 * This implementation handles locks in the order they are requested:
 *    • Readers can acquire locks concurrently as long as no writer is active
 *    • Writers must wait for all active readers to release their locks before acquiring the write lock
 *    • New readers can acquire locks even if writers are waiting, as long as no writer is currently active
 *
 * Explanation in simple terms:
 * 1. There are multiple threads reading data — that's fine, they can do it simultaneously.
 * 2. At some point, a thread wants to write — it calls acquireWrite():
 *    • It cannot write while others are reading, so it queues and waits.
 * 3. Meanwhile, new read requests can still be granted while writers are waiting.
 */
export declare class ReadWriteLock implements IReadWriteLock {
    private _readSemaphore;
    private _writeSemaphore;
    constructor(props?: RWLockConstructorProps);
    maxReaders(): Promise<number>;
    activeReaders(): Promise<number>;
    acquireRead(params?: AcquireParams): Promise<IReleaser<ReadLockToken>>;
    acquireWrite(params?: AcquireParams): Promise<IReleaser<WriteLockToken>>;
    cancelAll(errMessage?: string): Promise<void>;
    withReadLock<T>(fn: ExclusiveCallback<T>): Promise<T>;
    withReadLock<T>(params: AcquireParams, fn: ExclusiveCallback<T>): Promise<T>;
    withWriteLock<T>(fn: ExclusiveCallback<T>): Promise<T>;
    withWriteLock<T>(params: AcquireParams, fn: ExclusiveCallback<T>): Promise<T>;
    isWriteLocked(): Promise<boolean>;
    isReadLocked(): Promise<boolean>;
}
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