tree ff13307f6694055b586908edbea64bb750c06f6f
parent 03668bef2e7fe7de8c7912ee9527e1db1573c4ac
author Barret Rhoden <brho@cs.berkeley.edu> 1583264201 -0500
committer Barret Rhoden <brho@cs.berkeley.edu> 1585780074 -0400

parlib: add a helper for "notify debugging"

Notification events carry payloads, unlike signals which are just a
bit per interrupt.  During debugging, I'll often hook up a handler to
the debug event EV_FREE_APPLE_PIE (9), and poke it from the shell with:

	$ notify PID 9 arg1 arg2

This commit adds a helper for hooking an event handler to event 9.  Note
you need a ev_mbox type that can handle a payload (e.g. a UCQ, but not a
bitmap) if you want to receive the actual arguments.

You can, of course, hook in to any event you'd like.  '9' is typically
free.  You can also do similar things with signals, but once you want to
do more than one thing with a command (like print different debug info,
or set different flags), you'll want the full capabilities of a
notification event.

Signed-off-by: Barret Rhoden <brho@cs.berkeley.edu>