While I was going through uses of preserve_fn for other PRs, I converted places
which only use the wrapped function once to use run_in_background, to avoid
creating the function object.
We need to be careful (under python 2, at least) that when we reraise an
exception after doing some error handling, we actually reraise the original
exception rather than anything that might have been raised (and handled) during
the error handling.
This is in preparation for using contexts that may or may not have the
current_state_ids set. This will allow us to avoid unnecessarily pulling
out state for an event on the master process when using workers.
We also add a check to see if the state groups of the old extremities
are the same as the new ones.
There were a bunch of places where we fire off a process to happen in the
background, but don't have any exception handling on it - instead relying on
the unhandled error being logged when the relevent deferred gets
garbage-collected.
This is unsatisfactory for a number of reasons:
- logging on garbage collection is best-effort and may happen some time after
the error, if at all
- it can be hard to figure out where the error actually happened.
- it is logged as a scary CRITICAL error which (a) I always forget to grep for
and (b) it's not really CRITICAL if a background process we don't care about
fails.
So this is an attempt to add exception handling to everything we fire off into
the background.
It turns out that most of the time we were calling have_events, we were only
using half of the result. Replace have_events with have_seen_events and
get_rejection_reasons, so that we can see what's going on a bit more clearly.
In most cases, we limit the number of prev_events for a given event to 10
events. This fixes a particular code path which created events with huge
numbers of prev_events.
Doing this I learned e.message was pretty shortlived, added in 2.6,
they realized it was a bad idea and deprecated it in 2.7
Signed-off-by: Adrian Tschira <nota@notafile.com>
They raised KeyError before. I'm changing this because the code uses
hasattr() to check for the presence of a key. This worked accidentally
before, because hasattr() silences all exceptions in python 2. However,
in python3, this isn't the case anymore.
I had a look around to see if anything depended on this raising a
KeyError and I couldn't find anything. Of course, I could have simply
missed it.
Signed-off-by: Adrian Tschira <nota@notafile.com>
This reverts commit 9fbe70a7dc3afabfdac176ba1f4be32dd44602aa.
It turns out that sortedcontainers.SortedDict is not an exact match for
blist.sorteddict; in particular, `popitem()` removes things from the opposite
end of the dict.
This is trivial to fix, but I want to add some unit tests, and potentially some
more thought about it, before we do so.
