Class Semaphore

Semaphore instance.

Permits pre-configured maximum simultaneous acquires.

It is expected that each acquire is followed by corresponding release.

Hierarchy

Semaphore

Index

Constructors

Accessors

maxPermits permits

Methods

acquire close isClosed release

Constructors

constructor

new Semaphore(init?): Semaphore
Constructs a semaphore.
Parameters
- init: number | SemaphoreInit = 1
  
  Either the maximum simultaneous acquires permitted, or semaphore initialization parameters. 1 by default.
Returns Semaphore
- Defined in proc7ts/async/src/semaphore.ts:25

Accessors

maxPermits

get maxPermits(): number
The maximum simultaneous acquires permitted.

Returns number
- Defined in proc7ts/async/src/semaphore.ts:40

permits

get permits(): number
Simultaneous acquires permitted at the moment.

Decreased with each acquire, and increased with each release. When dropped to zero, the next call to acquire would block.

Returns number
- Defined in proc7ts/async/src/semaphore.ts:50

Methods

acquire

acquire(acquirer?): Promise<void>
Acquires lock.

Decreases the number of available permits when available, or blocks until one available.
Parameters
- Optional acquirer: AbortSignal
Returns Promise<void>
A promise resolved either immediately if permit available, or once permit becomes available after release call. This promise may be rejected with LockFailedError when semaphore closed, or when the lock acquire aborted.

Params
acquirer - Semaphore acquire abort signal. The returned promise would be rejected once the acquire aborted.
- Defined in proc7ts/async/src/semaphore.ts:74

close

close(reason?): void
Closes semaphore and aborts all pending lock acquires with the given reason.

Locks can not be acquired once semaphore closed. All acquire method calls would result to an error after that.
Parameters
- reason: LockFailedError = ...
  
  Optional acquire abort reason. Defaults to LockFailedError with appropriate message.
Returns void
- Defined in proc7ts/async/src/semaphore.ts:162

isClosed

isClosed(): boolean
Informs whether this semaphore is closed.

Returns boolean
true after the close method has been called, or false otherwise.
- Defined in proc7ts/async/src/semaphore.ts:59

release

release(): void
Releases previously acquired lock.

Increases the number of available permits. If there are pending acquires awaiting for the lock, the very first one receives it, while the rest continue to wait.

Returns void
- Defined in proc7ts/async/src/semaphore.ts:125

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