Integrate AsyncLocalStorage with EventEmitter
Is your feature request related to a problem? Please describe.
I'm going to port this library to AsyncLocalStorage
. As a part of this migration I need to make ALS play nicely with events emitted by request and response objects. Current version of the library uses ns.bindEmitter()
method available in cls-hooked
(it's also present in continuation-local-storage
).
Describe the solution you'd like
It's enough to add .bindEmitter(emitter, store)
method into ALS:
const store = { foo: 'bar' };
als.bindEmitter(req, store);
req.on('close', () => {
console.log(als.getStore()); // prints "{ foo: 'bar' }"
});
Describe alternatives you've considered
Of course, this integration can be implemented as a user-land module. But I believe that this will be a common case among ALS users, so it's probably worth to consider integrating ALS with EventEmitter
in the core.
As more of such changes can bloat ALS API, I'd like to hear opinions from @nodejs/async_hooks
before starting to work on the implementation.
Update. The consensus is to add something like AsyncResource#bind()
method that would allow to do the following:
als.run({ foo: 'bar' }, () => {
AsyncResource res = new AsyncResource('foobar');
req.on('close', res.bind(() => {
console.log(als.getStore()); // prints "{ foo: 'bar' }"
}));
});