A counting semaphore for node based on Java's Sempahore.
npm install ts-async-semaphoreA counting semaphore based on Java's Concurrent Semaphore.
Install the module via npm:
npm install ts-async-semaphore
``typescript
// fairness false
import { Semaphore } from 'ts-async-semaphore';
const semaphore = new Semaphore(0);
semaphore.acquire(2).then(() => {
console.log('Hello');
});
semaphore.acquire().then(() => {
console.log('World');
semaphore.release(2);
});
setTimeout(function () {
semaphore.release();
}, 2000);
`
`typescript
// fairness true
import { Semaphore } from 'ts-async-semaphore';
const semaphore = new Semaphore(0, true);
semaphore.acquire(2).then(() => {
console.log('Hello');
});
semaphore.acquire().then(() => {
console.log('World');
});
semaphore.release(1);
setTimeout(function () {
semaphore.release(2);
}, 2000);
`
`typescript
import { Semaphore } from 'ts-async-semaphore';
const semaphore = new Semaphore(0, true);
semaphore.tryAcquire(1, 50).then((val) => {
console.log(Acquire ${val ? 'success' : 'fail'});`
});
#### Constructor: Semaphore([permits], [fairness])
permits: Integer Initial available permits of semaphore. Default: 0.
fairness: Boolean Fairness of semaphore. If set to true, a FIFO rules applied, else, look on each acquirers permit value.
---
#### #availablePermits()
Returns the current number of permits available in this semaphore.
Returns: number
---
#### #acquire([permits])
Acquires the given number of permits from this semaphore.
permits: number The number of permits to acquire. Default: 0.
#### #getQueuedAcquirers()
Returns an estimate of the number of acquirers waiting to acquire.
Returns: Function[]
---
#### #getQueueLength()
Returns an estimate of the number of acquirers waiting to acquire.
Returns: number
---
#### #release([permits])
Releases the given number of permits, returning them to the semaphore.
permits: number The number of permits to release. Default: 0.
---
#### #drainPermits()
Acquires and returns all permits that are immediately available.
Returns: number
---
#### #reducePermits(permits)
Shrinks the number of available permits by the indicated reduction.
permits: number The number of permits to remove.
---
#### #tryAcquire([permits], [timeoutMs])
Acquires the given number of permits from this semaphore.
permits: number The number of permits to acquire. Default: 0.timeoutMs: number The timeout after which the acquire will fail
Returns: Boolean Promise true if success, false` false if fail