Isomorphic read/write lock that works in single processes, node clusters and web workers.
- Reads occur concurrently
- Writes occur one at a time
- No reads occur while a write operation is in progress
- Locks can be created with different names
- Reads/writes can time out
$ npm install --save morticeconst mortice = require('mortice')
const delay = require('delay')
// the lock name & options objects are both optional
const mutex = mortice('my-lock', {
// how long before write locks time out (default: 24 hours)
timeout: 30000,
// control how many read operations are executed concurrently (default: Infinity)
concurrency: 5,
// by default the the lock will be held on the main thread, set this to true if the
// a lock should reside on each worker (default: false)
singleProcess: false
})
Promise.all([
(async () => {
const release = await mutex.readLock()
try {
console.info('read 1')
} finally {
release()
}
})(),
(async () => {
const release = await mutex.readLock()
try {
console.info('read 2')
} finally {
release()
}
})(),
(async () => {
const release = await mutex.writeLock()
try {
await delay(1000)
console.info('write 1')
} finally {
release()
}
})(),
(async () => {
const release = await mutex.readLock()
try {
console.info('read 3')
} finally {
release()
}
})()
])read 1
read 2
<small pause>
write 1
read 3
Because there's no global way to evesdrop on messages sent by Web Workers, please pass all created Web Workers to the observable-webworkers module:
// main.js
const mortice = require('mortice')
const observe = require('observable-webworkers')
// create our lock on the main thread, it will be held here
const mutex = mortice()
const worker = new Worker('worker.js')
observe(worker)// worker.js
const mortice = require('mortice')
const delay = require('delay')
const mutex = mortice()
let release = await mutex.readLock()
// read something
release()
release = await mutex.writeLock()
// write something
release()Alternatively you can use the bundled mortice.Worker to create web workers and save yourself an extra dependency.
const mortice = require('mortice')
const Worker = mortice.Worker
// create our lock on the main thread, it will be held here
const mutex = mortice()
const worker = new Worker('worker.js')