TxReentrantLock
Coordinates shared access inside transactions with read and write locks.
A TxReentrantLock lets many fibers hold read locks at the same time, or one fiber hold a write lock for exclusive access. Lock ownership is tracked by fiber, so a fiber that already holds the lock can acquire it again and later release each acquisition. Attempts that cannot proceed retry transactionally until the lock becomes available. This module includes manual, scoped, and wrapper-style operations for read and write locking.
Constructors
Getters
Checks whether the lock is held by any fiber (read or write).
Signature
declare function locked(self: TxReentrantLock): Effect<boolean>;readLocked
Checks whether any fiber holds a read lock.
Signature
declare function readLocked(self: TxReentrantLock): Effect<boolean>;Returns the total number of read locks held across all fibers.
Signature
declare function readLocks(self: TxReentrantLock): Effect<number>;writeLocked
Checks whether any fiber holds a write lock.
Signature
declare function writeLocked(self: TxReentrantLock): Effect<boolean>;writeLocks
Returns the number of write locks held (0 or the reentrant count).
Signature
declare function writeLocks(self: TxReentrantLock): Effect<number>;Guards
isTxReentrantLock
Checks whether the given value is a TxReentrantLock.
Signature
declare function isTxReentrantLock(u: unknown): u is TxReentrantLock;Models
TxReentrantLock interface
A TxReentrantLock provides a transactional read/write lock with reentrant semantics. Multiple readers can hold the lock concurrently, or a single writer can hold exclusive access. A fiber holding the write lock may acquire additional read/write locks (reentrancy).
Signature
interface TxReentrantLock extends Inspectable, Pipeable {
readonly "~effect/transactions/TxReentrantLock": "~effect/transactions/TxReentrantLock";
}Mutations
acquireRead
Acquires a read lock. Blocks if another fiber holds the write lock. If the current fiber already holds the write lock, the read lock is granted (reentrancy). Returns the current number of read locks held by this fiber.
Signature
declare function acquireRead(self: TxReentrantLock): Effect<number>;acquireWrite
Acquires the write lock for the current fiber.
When to use
Use to enter an exclusive section manually when withWriteLock is not the right shape.
Details
Blocks if any other fiber holds a read or write lock. If the current fiber already holds the write lock, the count is incremented. If the current fiber holds a read lock, the write lock is granted as an upgrade.
Returns the current number of write locks held by this fiber.
Signature
declare function acquireWrite(self: TxReentrantLock): Effect<number>;Acquires a read lock for the duration of the scope. The lock is automatically released when the scope closes.
Signature
declare function readLock(self: TxReentrantLock): Effect<number, never, Scope>;Runs an effect while holding a write lock.
When to use
Use when you need to run an effect with exclusive write access through a TxReentrantLock and prefer the concise lock helper.
Signature
declare const withLock: {
<A, E, R>(effect: Effect<A, E, R>): (self: TxReentrantLock) => Effect<A, E, R>;
<A, E, R>(self: TxReentrantLock, effect: Effect<A, E, R>): Effect<A, E, R>;
};withReadLock
Runs the provided effect while holding a read lock. The lock is automatically released after the effect completes, fails, or is interrupted.
Signature
declare const withReadLock: {
<A, E, R>(effect: Effect<A, E, R>): (self: TxReentrantLock) => Effect<A, E, R>;
<A, E, R>(self: TxReentrantLock, effect: Effect<A, E, R>): Effect<A, E, R>;
};withWriteLock
Runs the provided effect while holding a write lock. The lock is automatically released after the effect completes, fails, or is interrupted.
Signature
declare const withWriteLock: {
<A, E, R>(effect: Effect<A, E, R>): (self: TxReentrantLock) => Effect<A, E, R>;
<A, E, R>(self: TxReentrantLock, effect: Effect<A, E, R>): Effect<A, E, R>;
};Acquires a write lock for the duration of the scope. The lock is automatically released when the scope closes.
Signature
declare function writeLock(self: TxReentrantLock): Effect<number, never, Scope>;Other
Signature
declare function releaseRead(self: TxReentrantLock): Effect<number>;Signature
declare function releaseWrite(self: TxReentrantLock): Effect<number>;
Creates a new TxReentrantLock.