A redis binary semaphore with some consistency
npm install ioredfour> Originally forked from redfour. Main difference being that redfour uses node_redis + node-redis-scripty while ioredfour uses ioredis.
or
``sh`
npm install ioredfour --save
`js
const Lock = require('ioredfour');
(async () => {
const testLock = new Lock({
// Can also be an Object of options to pass to new Redis()
// https://www.npmjs.com/package/ioredis#connect-to-redis, or an existing
// instance of (if you want to reuse one connection, though this
// module must create a second).
redis: 'redis://localhost:6379',
namespace: 'mylock',
// Don't consider the lock owned until writes have been replicated at least this many times
minReplications: 1,
// Wait at most this many miliseconds for replication
replicationTimeout: 500
});
const id = Math.random();
// First, acquire the lock.
const firstlock = await testLock.acquireLock(id, 60 1000 / Lock expires after 60sec if not released */).catch(e => {
console.log('error acquiring first lock', e);
});
if (!firstlock.success) {
console.log('lock exists', firstlock);
} else {
console.log('lock acquired initially');
}
// Another server might be waiting for the lock like this.
testLock
.waitAcquireLock(id, 60 1000 / Lock expires after 60sec /, 10 1000 / Wait for lock for up to 10sec /)
.then(secondlock => {
if (secondlock.success) {
console.log('second lock acquired after wait!', secondlock);
} else {
console.log('second lock not acquired after wait!', secondlock);
}
})
.catch(e => {
console.log('error wait acquiring', e);
});
// When the original lock is released, waitAcquireLock is fired on the other server.`
setTimeout(async () => {
try {
await testLock.releaseLock(firstlock);
console.log('released lock');
} catch (e) {
console.log('error releasing', e);
}
}, 10 * 1000);
})();
We welcome pull requests! Please lint your code.
- 1.1.0 add Lock.extend, promisified interface, check for replication
- 1.0.2-ioredis Forked from redfour and switch node_redis with ioredis
- 1.0.2 Don't use instanceof to determine if the redis constructor option is ofredis.RedisClient`.
type
- 1.0.1 Fix issue where you could only pass in a Redis connection URI.
- 1.0.0 Initial release.
Shortened (and easier to pronouce) version of "Redis Semaphore"