This patch should ideally be split into multiple smaller ones, but life
is life.
This main purpose of this patch is to fix and to test
`SlidingSyncListRequestGenerator`. This quest has led me to rename
mutiple fields in `SlidingSyncList` and `SlidingSyncListBuilder`, like:
* `rooms_count` becomes `maximum_number_of_rooms`, it's not something
the _client_ counts, but it's a maximum number given by the server,
* `batch_size` becomes `full_sync_batch_size`, so that now, it
emphasizes that it's about full-sync only,
* `limit` becomes `full_sync_maximum_number_of_rooms_to_fetch`, so that
now, it also emphasizes that it's about ful-sync only _and_ what the
limit is about!
This quest has continued with the renaming of the `SlidingSyncMode`
variants. After a discussion with the ElementX team, we've agreed on the
following renamings:
* `Cold` becomes `NotLoaded`,
* `Preload` becomes `Preloaded`,
* `CatchingUp` becomes `PartiallyLoaded`,
* `Live` becomes `FullyLoaded`.
Finally, _le plat de résistance_.
In `SlidingSyncListRequestGenerator`, the `make_request_for_ranges`
has been renamed to `build_request` and no longer takes a `&mut self`
but a simpler `&self`! It didn't make sense to me that something
that make/build a request was modifying `Self`. Because the type of
`SlidingSyncListRequestGenerator::ranges` has changed, all ranges now
have a consistent type (within this module at least). Consequently, this
method no longer need to do a type conversion.
Still on the same type, the `update_state` method is much more
documented, and errors on range bounds (offset by 1) are now all fixed.
The creation of new ranges happens in a new dedicated pure function,
`create_range`. It returns an `Option` because it's possible to not be
able to compute a range (previously, invalid ranges were considered
valid). It's used in the `Iterator` implementation. This `Iterator`
implementation contains a liiiittle bit more code, but at least now
we understand what it does, and it's clear what `range_start` and
`desired_size` we calculate. By the way, the `prefetch_request` method
has been removed: it's not a prefetch, it's a regular request; it was
calculating the range. But now there is `create_range`, and since it's
pure, we can unit test it!
_Pour le dessert_, this patch adds multiple tests. It is now
possible because of the previous refactoring. First off, we test the
`create_range` in many configurations. It's pretty clear to understand,
and since it's core to `SlidingSyncListRequestGenerator`, I'm pretty
happy with how it ends. Second, we test paging-, growing- and selective-
mode with a new macro: `assert_request_and_response`, which allows to
“send” requests, and to “receive” responses. The design of `SlidingSync`
allows to mimic requests and responses, that's great. We don't really
care about the responses here, but we care about the requests' `ranges`,
and the `SlidingSyncList.state` after a response is received. It also
helps to see how ranges behaves when the state is `PartiallyLoaded`
or `FullyLoaded`.
This patch updates `SlidingSync.pos` and `.delta_token`. Each field has their
own lock. It's annoying because they must updated at the same time to not be
out-of-sync.
So a new field `SlidingSync.position` of type `SlidingSyncPositionMarkers` is
created. It holds `pos` and `delta_token. This new field is behind a single
`RwLock`.
Move all `SlidingSync`'s fields into a new `SlidingSyncInner` type, and then
update `SlidingSync` to contain a single `inner: Arc<SlidingSyncInner>` field.
First off, it's much simpler to understand what's behind an `Arc` for
“clonability” of `SlidingSync`, and what's not. We don't need to worry about
adding a new field that is not behind an `Arc` for a specific reason or
anything. The pattern is clear now.
Second, this is required for next commits.
Simplify handling of sliding sync extensions
This patch simplifies the logic for handling sliding sync extensions.
These extensions are sticky, meaning that once enabled in one request,
they do not need to be repeatedly enabled for subsequent requests.
However, the previous logic tried to accommodate the case where the
extensions were initially disabled to reduce the size and processing
time of the initial response. This resulted in complex and error-prone
code.
With this patch, we have removed support for disabling to-device events
and streamlined the handling of sync extensions.
Co-authored-by: Jonas Platte <jplatte@matrix.org>
This patch cleans up the `SlidingSync::stream` method. It renames variables,
improves log messages etc.
This patch also creates a new `MAXIMUM_SLIDING_SYNC_SESSION_EXPIRATION`
constant. This value was previously hardcoded and lost in the code, now it's
easier to spot it for further updates.
This patch finally renames the `failure_count` field to `reset_counter`,
because it doesn't count the number of failure, but the number of
`ErrorKind::UnknownPos` exactly, i.e. the number of times we reset the
`SlidingSync` state.
Ivan Enderlin
Jonas Platte
Kegan Dougal
Damir Jelić