Asynchronous read/write lock implementation for Node.js.
- there may be zero or more readers at a time,
- there may be only one writer at a time,
- there may be no writer if there are one or more readers already.
It's on npmjs:
$ npm install rwlock
Requiring the package, creating an instance:
var ReadWriteLock = ;var lock = ;
Acquiring a read lock:
Acquiring a write lock:
Locks can be released later:
Upgrading to a write lock
ReadWriteLock does not explicitly support upgrading but you can take advantage of the asynchronous-ness:
Downgrading to a read lock
Similar to upgrading:
Every ReadWriteLock instance allows you to work on a virtually unlimited number of completely independent read/write locks.
Locks are identified by names called "keys". Every exposed method has an optional "key" first argument indicating the lock to work on; if you don't specify a key, the default lock is used.
The previous example logs:
writing 1... writing 2... done 2. done 1.
The ReadWriteLock class does not return errors to your callbacks, but many APIs in Node do. The
async module uses that as a convention: callbacks usually receive two arguments, a possibly
null error object and the actual result in case there is no error.
async compatibility, ReadWriteLock sends
null errors if you specify the
async flag like in the following example:
You can use
async together like in this example:
var releaseLock = null;async;
Building from source and testing
You don't need this, but in case you want:
$ sudo npm install -g grunt-cli$ cd$ git clone https://github.com/71104/rwlock.git$ cd rwlock$ npm install$ grunt all
The following folders will be generated:
- lib, containing the minified ReadWriteLock class to
- doc, containing the API reference documentation in HTML format.
MIT. Copyright 2013 Alberto La Rocca