The first issue involved copied users which would lead to user updates
causing faster evictions of the cache than was expected.
The second issue involved users that weren't bound to an internal
lifetime eviction policy. These users would not get evicted.
For example, a user without mutual guilds or being part of the internal
cache in general (messages, DMs) would never end up being evicted for
some strange reason. To handle this case, store_user would get a
counterpart named create_user which would create a user without
potentially storing them in the cache. That way only users with a
bound lifetime within the library would be stored.
This changes the lookup from unnecessary O(n) to two amortised O(1)
lookups. This event pretty much always has a guild_id so the original
code was always a performance bottleneck.
Profiling showed that WeakValueDictionary caused rather significant
and noticeable slowdowns during startup. Since the only thing it was
used for was to automatically remove the key from the mapping when
the reference count reaches zero, the same could theoretically be
accomplished by using the __del__ special method. There is a chance
that this could lead to a memory leak since the __del__ method is not
always called, but the only instances of this happening are during
interpreter shutdown to my knowledge and at that point the mapping
is the least of my concern.
This patch also does the following:
* Sets some parameters to be positional only
* Changes Guild.edit to use the MISSING sentinel
* Changes the various create_channel methods to be type safe
* Changes many parameters from Optional[T] to use MISSING
* Changes Guild.create_role to use MISSING sentinel
This refactor is mostly partial but lays a decent foundation
This allows for DMChannels to work without falling back to the
Object error case since there is enough information to build a pseudo
DMChannel object.
This is a breaking change since it changes the type of
DMChannel.recipient to Optional[User] for when this faux object is
created.
