Preserve an active domain on I/O in native bindings

[andreypopp]

Native binding didn't preserve an active domain on I/O because of native connection didn't handle it. I've provided a fix with two test cases.

[brianc]

This is perfectamundo. 👍

You probably know using the connection pool + domains is a whole other nightmare. I think the node core team plans on addressing that somewhat in the future, but I still might work on a patch within node-postgres until core addresses the issue.

[andreypopp]

You probably know using the connection pool + domains is a whole other nightmare

That's interesting, can you share what exact problems did you have there?

[brianc]

In the pure javascript version the Client object, each query, the connection (used by the client internally) and the stream are all event emitters. When you call pg.connect if there is no client in the pool (like on the first request) it will create the client/connection/stream & bind them to the current domain. Next request to the pool if the client has been returned it will come back out of the pool on the same domain as it was created, regardless of the requesting domain. The solution is rather simple...switch all the event emitters to the new domain when it's checked out and remove it from a domain when its returned. I just haven't done it yet. I use https://github.com/brianc/node-okay to handle a lot of callback stuff so it isn't a huge deal in my apps, but definitely needs to and will be fixed pretty soon.