async-rwlock

Promise-based asynchronous readers-writers lock. Timeout is also supported.

Install

``
$ npm install --save async-rwlock
`
or
`
$ yarn add async-rwlock
`

Quick Usage

`js
const RWLock = require('async-rwlock').RWLock;

const lock = new RWLock();

lock.readLock()
.then(() => {
console.log('read lock acquired');
lock.unlock();
});

lock.writeLock()
.then(() => {
console.log('write lock acquired');
lock.unlock();
});
`

$3

`ts
import RWLock from 'async-rwlock';

async function testLock() {
const lock = new RWLock();

await lock.readLock();
console.log('read lock acquired');
lock.unlock();

await lock.writeLock();
console.log('write lock acquired');
lock.unlock();
}

(async () => { await testLock(); })();
`

Advanced Usage

$3


`js
const RWLock = require('async-rwlock').RWLock;

const lock = new RWLock();

lock.readLock()
.then(() => {
console.log('read lock acquired');
// lock.unlock() // oops!
});

lock.writeLock(1000) // 1 second
.then(() => {
console.log('write lock will never be acquired');
})
.catch((err) => {
console.error('promise will be rejected if timeout occured');
console.error(err);
});
`

#### Async/Await

`ts
import RWLock from 'async-rwlock';

async function testLock() {
const lock = new RWLock();

await lock.readLock();
console.log('read lock acquired');
// lock.unlock() // oops!

try {
await lock.writeLock(1000); // 1 second
console.log('write lock will never be acquired');
} catch (err) {
console.error('error will be thrown if timeout occured');
console.error(err);
}
}

(async () => { await testLock(); })();
`

API

$3


- Returns: instance of RWLock.

#### readLock([timeout])
- timeout?: number. Default: Infinity.
- Returns: Promise.

#### writeLock([timeout])
- timeout?: number. Default: Infinity.
- Returns: Promise.

Acquire a read/write lock.

timeout is how long it will wait to acquire the lock before promise is rejected in milliseconds. If timeout is not in range 0 <= timeout < Infinity, it will wait indefinitely.

#### unlock()
- Returns: void.

Release current lock. Must be called after operation using read/write lock is finished.

#### getState()
- Returns: State.

Get current state of lock. The states are either Idle, Reading, or Writing`.

License

MIT