* Refactor media sync handling
- The media USN is now returned in sync/meta, which avoids an extra
round-trip.
- Media syncing is now automatically started by the syncing code at
the end of a normal or full sync, which avoids it competing for bandwidth
and resources, and avoids duplicate invalid login messages when the auth
token is invalid.
- Added a new media_sync_progress() method to both check if media is
syncing, and get access to the latest progress.
- Updated the sync log screen to only show the latest line, like AnkiMobile.
- Show media sync errors in a pop-up, so they don't get missed. Use a non-modal
pop-up to avoid potential conflicts with other modals.
* Remove print statement
Previously it was Backend's responsibility to store the last progress,
and when calling routines in Collection, one had to construct and pass
in a Fn, which wasn't the most ergonomic. This PR adds the last progress
state to the collection, so that the routines no longer need a separate
progress arg, and makes some other tweaks to improve ergonomics.
ThrottlingProgressHandler has been tweaked so that it now stores the
current state, so that callers don't need to store it separately. When
a long-running routine starts, it calls col.new_progress_handler(),
which automatically initializes the data to defaults, and updates the
shared UI state, so we no longer need to manually update the state at
the start of an operation.
The backend shares the Arc<Mutex<>> with the collection, so it can get
at the current state, and so we can update the state when importing a
backup.
Other tweaks:
- The current Incrementor was awkward to use in the media check, which
uses a single incrementing value across multiple method calls, so I've
added a simpler alternative for such cases. The old incrementor method
has been kept, but implemented directly on ThrottlingProgressHandler.
- The full sync code was passing the progress handler in a complicated
way that may once have been required, but no longer is.
- On the Qt side, timers are now stopped before deletion, or they keep
running for a few seconds.
- I left the ChangeTracker using a closure, as it's used for both importing
and syncing.
This PR replaces the existing Python-driven sync server with a new one in Rust.
The new server supports both collection and media syncing, and is compatible
with both the new protocol mentioned below, and older clients. A setting has
been added to the preferences screen to point Anki to a local server, and a
similar setting is likely to come to AnkiMobile soon.
Documentation is available here: <https://docs.ankiweb.net/sync-server.html>
In addition to the new server and refactoring, this PR also makes changes to the
sync protocol. The existing sync protocol places payloads and metadata inside a
multipart POST body, which causes a few headaches:
- Legacy clients build the request in a non-deterministic order, meaning the
entire request needs to be scanned to extract the metadata.
- Reqwest's multipart API directly writes the multipart body, without exposing
the resulting stream to us, making it harder to track the progress of the
transfer. We've been relying on a patched version of reqwest for timeouts,
which is a pain to keep up to date.
To address these issues, the metadata is now sent in a HTTP header, with the
data payload sent directly in the body. Instead of the slower gzip, we now
use zstd. The old timeout handling code has been replaced with a new implementation
that wraps the request and response body streams to track progress, allowing us
to drop the git dependencies for reqwest, hyper-timeout and tokio-io-timeout.
The main other change to the protocol is that one-way syncs no longer need to
downgrade the collection to schema 11 prior to sending.
