RFC: support advanced notification and require cache swap, vs full process reload

[cdaringe]

Problem

I could iterate faster if I could avoid a full process restart, but am limited to a full proc restart ATM.

I want

1. notification of change, and
2. swapping/re-processing of content into the require cache on change

vs a process restart.

Motivating context

I have a mock server.

Every handler to the mock server invokes a import('./path/to/mock'). When someone changes a mock, I want instant reloads. I have so many mocks in my applications, that a full server restart takes nearly 7 seconds to launch fully from a cold start. This is a ton of data (arguably too much :) ), but the arch i'm stuck w/ at the time.

If I could just invalidate the require cache on change, i'd be happy!

Discussion

Currently, the hook + wrap simply notifies the parent. If I could configure node-dev to invalidate/clear the module and simply notify via IPC, I could go super fast!

I think that consideration for such a feature is arguably in scope. node-dev's core value is fast, consumed module-aware development iteration. This feature is in line with that goal.