Class RwLock

An asynchronous read-write lock (RwLock) for coordinating access to shared resources.

Allows multiple concurrent readers or exclusive access for a single writer.

All lock/unlock operations are asynchronous and must be awaited.

WARNING: Deadlock is possible if:

A task attempts to acquire a lock it already holds (no reentrancy).
Locks are acquired in inconsistent order across tasks.
A task forgets to unlock after acquiring.

Best practices:

Always use try/finally to ensure unlock.
Avoid holding locks across await points that may block indefinitely.
Never call lock methods from within unlock callbacks.

Example usage: await rwLock.readLock(); try { // read shared resource } finally { rwLock.readUnlock(); }

Index

Constructors

Methods

readLock readToWriteLock readUnlock tryReadLock tryWriteLock writeLock writeToReadLock writeUnlock

Constructors

constructor

new RwLock(): RwLock
Returns RwLock

Methods

readLock

readLock(signal?: AbortSignal | null): Promise<void>
Acquire a read lock. Multiple readers may hold the lock concurrently unless a writer is waiting or active.
Parameters
- Optionalsignal: AbortSignal | null
  Optional AbortSignal to cancel the wait.
Returns Promise<void>
Throws
Error if the lock cannot be acquired due to cancellation.
- Defined in packages/misc-util/src/async/synchro/rw-lock.ts:43

readToWriteLock

readToWriteLock(signal?: AbortSignal | null): Promise<void>
Upgrade a held read lock to a write lock. The caller must already hold a read lock.
Parameters
- Optionalsignal: AbortSignal | null
  Optional AbortSignal to cancel the wait.
Returns Promise<void>
Throws
Error if the upgrade cannot be completed due to cancellation.
- Defined in packages/misc-util/src/async/synchro/rw-lock.ts:121

readUnlock

readUnlock(): Promise<void>
Release a previously acquired read lock.

WARNING: Failing to call readUnlock() after readLock() will cause deadlock.

Returns Promise<void>
- Defined in packages/misc-util/src/async/synchro/rw-lock.ts:177

tryReadLock

tryReadLock(): boolean
Attempt to acquire a read lock without waiting. Returns true if successful.

Returns boolean
True if the read lock was acquired, false otherwise.
- Defined in packages/misc-util/src/async/synchro/rw-lock.ts:80

tryWriteLock

tryWriteLock(): boolean
Attempt to acquire a write lock without waiting. Returns true if successful.

Returns boolean
True if the write lock was acquired, false otherwise.
- Defined in packages/misc-util/src/async/synchro/rw-lock.ts:100

writeLock

writeLock(signal?: AbortSignal | null): Promise<void>
Acquire a write lock. Only one writer may hold the lock, and no readers may be active.
Parameters
- Optionalsignal: AbortSignal | null
  Optional AbortSignal to cancel the wait.
Returns Promise<void>
Throws
Error if the lock cannot be acquired due to cancellation.
- Defined in packages/misc-util/src/async/synchro/rw-lock.ts:61

writeToReadLock

writeToReadLock(): Promise<void>
Downgrade a held write lock to a read lock. The caller must already hold the write lock.

Returns Promise<void>
- Defined in packages/misc-util/src/async/synchro/rw-lock.ts:157

writeUnlock

writeUnlock(): Promise<void>
Release a previously acquired write lock.

WARNING: Failing to call writeUnlock() after writeLock() will cause deadlock.

Returns Promise<void>
- Defined in packages/misc-util/src/async/synchro/rw-lock.ts:198