The system clock may be adjusted and even go back, so caching system time in code sections where
it's not supposed to change may even protect from races/bugs.
Previously it was required that a directory path is provided to the import API.
Now it is possible to point directly to the .asc file containing a secret key.
This allows UI to present a file selection dialog to the user
and let select the file directly.
Selecting a directory is still supported for backwards compatibility.
If the user makes a backup from a UI that supports the experimental verified 1:1 chats (e.g. nightly Android) and imports it into a UI that doesn't, then this config should be cleared.
We already talked about this a long time ago after @Simon-Laux noticed this problem, but I think we didn't actually solve it back then?
Best to review with whitespace changes disabled.
Message.set_text() and Message.get_text() are modified accordingly
to accept String and return String.
Messages which previously contained None text
are now represented as messages with empty text.
Use Message.set_text("".to_string())
instead of Message.set_text(None).
Moved custom ToSql trait including Send + Sync from lib.rs to sql.rs.
Replaced most params! and paramsv! macro usage with tuples.
Replaced paramsv! and params_iterv! with params_slice!,
because there is no need to construct a vector.
This further reduces the cognitive overload of having many ways to do
something. The same is very easily done using composition. Followup
from 82ace72527.
This replaces the mechanism by which the IoPauseGuard makes sure the
IO scheduler is resumed: it really is a drop guard now by sending a
single message on drop.
This makes it not have to hold on to anything like the context so
makes it a lot easier to use.
The trade-off is that a long-running task is spawned when the guard is
created, this task needs to receive the message from the drop guard in
order for the scheduler to resume.
This makes the BackupProvider automatically invoke pause-io while it
is needed.
It needed to make the guard independent from the Context lifetime to
make this work. Which is a bit sad.
To handle backups the UIs have to make sure they do stop the IO
scheduler and also don't accidentally restart it while working on it.
Since they have to call start_io from a bunch of locations this can be
a bit difficult to manage.
This introduces a mechanism for the core to pause IO for some time,
which is used by the imex function. It interacts well with other
calls to dc_start_io() and dc_stop_io() making sure that when resumed
the scheduler will be running or not as the latest calls to them.
This was a little more invasive then hoped due to the scheduler. The
additional abstraction of the scheduler on the context seems a nice
improvement though.
We do not make all transactions
[IMMEDIATE](https://www.sqlite.org/lang_transaction.html#deferred_immediate_and_exclusive_transactions)
for more parallelism -- at least read transactions can be made DEFERRED to run in parallel
w/o any drawbacks. But if we make write transactions DEFERRED also w/o any external locking,
then they are upgraded from read to write ones on the first write statement. This has some
drawbacks:
- If there are other write transactions, we block the thread and the db connection until
upgraded. Also if some reader comes then, it has to get next, less used connection with a
worse per-connection page cache.
- If a transaction is blocked for more than busy_timeout, it fails with SQLITE_BUSY.
- Configuring busy_timeout is not the best way to manage transaction timeouts, we would
prefer it to be integrated with Rust/tokio asyncs. Moreover, SQLite implements waiting
using sleeps.
- If upon a successful upgrade to a write transaction the db has been modified by another
one, the transaction has to be rolled back and retried. It is an extra work in terms of
CPU/battery.
- Maybe minor, but we lose some fairness in servicing write transactions, i.e. we service
them in the order of the first write statement, not in the order they come.
The only pro of making write transactions DEFERRED w/o the external locking is some
parallelism between them. Also we have an option to make write transactions IMMEDIATE, also
w/o the external locking. But then the most of cons above are still valid. Instead, if we
perform all write transactions under an async mutex, the only cons is losing some
parallelism for write transactions.
.call() interface is safer because it ensures
that blocking operations on SQL connection
are called within tokio::task::block_in_place().
Previously some code called blocking operations
in async context, e.g. add_parts() in receive_imf module.
The underlying implementation of .call()
can later be replaced with an implementation
that does not require block_in_place(),
e.g. a worker pool,
without changing the code using the .call() interface.
We no longer need that in the transfer case, that would give very
weird results. This also means there is nothing imex-specific about
this anymore so move it to blobs.rs
This adds functionality to send and receive a backup over the network
using a QR code.
The sender or provider prepares the backup, sets up a server that
waits for clients. It provides a ticket in the form of a QR code
which contains connection and authentication information.
The receiver uses the QR code to connect to the provider and fetches
backup, restoring it locally.
