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

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();
});

Async/Await

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

Timeout

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

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

new RWLock()

• Returns: instance of RWLock.

readLock([timeout])

• timeout?: number. Default: Infinity.
• Returns: Promise<void>.

writeLock([timeout])

• timeout?: number. Default: Infinity.
• Returns: Promise<void>.

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