zio/zio.stm/TReentrantLock

TReentrantLock

final class TReentrantLock

A TReentrantLock is a reentrant read/write lock. Multiple readers may all concurrently acquire read locks. Only one writer is allowed to acquire a write lock at any given time. Read locks may be upgraded into write locks. A fiber that has a write lock may acquire other write locks or read locks.

The two primary methods of this structure are readLock, which acquires a read lock in a managed context, and writeLock, which acquires a write lock in a managed context.

Although located in the STM package, there is no need for locks within STM transactions. However, this lock can be quite useful in effectful code, to provide consistent read/write access to mutable state; and being in STM allows this structure to be composed into more complicated concurrent structures that are consumed from effectful code.

Companion:
object
class Object
trait Matchable
class Any

Value members

Concrete methods

def fiberReadLocks: USTM[Int]

Retrieves the number of acquired read locks for this fiber.

Retrieves the number of acquired read locks for this fiber.

def fiberWriteLocks: USTM[Int]

Retrieves the number of acquired write locks for this fiber.

Retrieves the number of acquired write locks for this fiber.

def locked: USTM[Boolean]

Determines if any fiber has a read or write lock.

Determines if any fiber has a read or write lock.

def readLocked: USTM[Boolean]

Determines if any fiber has a read lock.

Determines if any fiber has a read lock.

def readLocks: USTM[Int]

Retrieves the total number of acquired read locks.

Retrieves the total number of acquired read locks.

def writeLocked: USTM[Boolean]

Determines if a write lock is held by some fiber.

Determines if a write lock is held by some fiber.

def writeLocks: USTM[Int]

Computes the number of write locks held by fibers.

Computes the number of write locks held by fibers.

Concrete fields

lazy val acquireRead: USTM[Int]

Acquires a read lock. The transaction will suspend until no other fiber is holding a write lock. Succeeds with the number of read locks held by this fiber.

Acquires a read lock. The transaction will suspend until no other fiber is holding a write lock. Succeeds with the number of read locks held by this fiber.

lazy val acquireWrite: USTM[Int]

Acquires a write lock. The transaction will suspend until no other fibers are holding read or write locks. Succeeds with the number of write locks held by this fiber.

Acquires a write lock. The transaction will suspend until no other fibers are holding read or write locks. Succeeds with the number of write locks held by this fiber.

lazy val lock: UManaged[Int]

Just a convenience method for applications that only need reentrant locks, without needing a distinction between readers / writers.

Just a convenience method for applications that only need reentrant locks, without needing a distinction between readers / writers.

See writeLock.

lazy val readLock: UManaged[Int]

Obtains a read lock in a managed context.

Obtains a read lock in a managed context.

lazy val releaseRead: USTM[Int]

Releases a read lock held by this fiber. Succeeds with the outstanding number of read locks held by this fiber.

Releases a read lock held by this fiber. Succeeds with the outstanding number of read locks held by this fiber.

lazy val releaseWrite: USTM[Int]

Releases a write lock held by this fiber. Succeeds with the outstanding number of write locks held by this fiber.

Releases a write lock held by this fiber. Succeeds with the outstanding number of write locks held by this fiber.

lazy val writeLock: UManaged[Int]

Obtains a write lock in a managed context.

Obtains a write lock in a managed context.