This is cleaner and avoids lockups in obscure cases where a Queue
is instantiated while the import lock is already held by another thread.
OKed by Tim Peters.
I don't agree it had a bug (see the report), so this is *not* a candidate
for backporting, but the docs were confusing and the Queue implementation
was old enough to vote.
Rewrote put/put_nowait/get/get_nowait from scratch, to use a pair of
Conditions (not_full and not_empty), sharing a common mutex. The code
is 1/4 the size now, and 6.25x easier to understand. For blocking
with timeout, we also get to reuse (indirectly) the tedious timeout
code from threading.Condition. The Full and Empty exceptions raised
by non-blocking calls are now easy (instead of nearly impossible) to
explain truthfully: Full is raised if and only if the Queue truly
is full when the non-blocking put call checks the queue size, and
similarly for Empty versus non-blocking get.
What I don't know is whether the new implementation is slower (or
faster) than the old one. I don't really care. Anyone who cares
a lot is encouraged to check that.
added test script and expected output file as well
this closes patch 103297.
__all__ attributes will be added to other modules without first submitting
a patch, just adding the necessary line to the test script to verify
more-or-less correct implementation.
