* Working on a better database abstraction
After [this question in the chat](https://matrix.to/#/!oJFtttFHGfnTGrIjvD:matrix.cashu.space/$oJFtttFHGfnTGrIjvD:matrix.cashu.space/$I5ZtjJtBM0ctltThDYpoCwClZFlM6PHzf8q2Rjqmso8)
regarding a database transaction within the same function, I realized a few
design flaws in our SQL database abstraction, particularly regarding
transactions.
1. Our upper abstraction got it right, where a transaction is bound with `&mut
self`, so Rust knows how to handle its lifetime with' async/await'.
2. The raw database does not; instead, it returns &self, and beginning a
transaction takes &self as well, which is problematic for Rust, but that's not
all. It is fundamentally wrong. A transaction should take &mut self when
beginning a transaction, as that connection is bound to a transaction and
should not be returned to the pool. Currently, that responsibility lies with
the implementor. If a mistake is made, a transaction could be executed in two
or more connections.
3. The way a database is bound to our store layer is through a single struct,
which may or may not internally utilize our connection pool. This is also
another design flow, in this PR, a connection pool is owned, and to use a
connection, it should be requested, and that connection is reference with
mutable when beginning a transaction
* Improve the abstraction with fewer generics
As suggested by @thesimplekid
* Add BEGIN IMMEDIATE for SQLite
The primary purpose of this new crate is to have a common and shared codebase
for all SQL storage systems. It would force us to write standard SQL using best
practices for all databases.
This crate has been extracted from #878
* Migrate from `sqlx` to rusqlite
1. Add rusqlite with rusqlite with a working thread
2. Add wallet without a thread (synchronous)
3. Add custom migration
Co-authored-by: thesimplekid <tsk@thesimplekid.com>
Add a strict set of updates to prevent incorrect state changes and correct
usage. Supporting the transaction at the trait level prevented some cases, but
having a strict set of state change flows is better.
This bug was found while developing the signatory. The keys are read from
memory, triggering race conditions at the database, and some `Pending` states
are selected (instead of just selecting `Unspent`).
This PR also introduces a set of generic database tests to be executed for all
database implementations, this test suite will make sure writing and
maintaining new database drivers
The bug comes with the SQLx-sqlite pool bug, where several connections are
created by default, but the `new` function takes care of that, fixing that bug
by making a single instance of the database.
If constructed directly, the pool would create several connections to the
database, which in most instances is fine, but with SQLite :memory: each
connection is entirely independent.
Also follow documentation to make sure that failed `acquire` will not end up
dropping connections by setting test_before_acquire to false
However, if your workload is sensitive to dropped connections such as using an in-memory
SQLite database with a pool size of 1, you can pretty easily ensure that a cancelled
`acquire()` call will never drop connections by tweaking your [`PoolOptions`]:
* Set [`test_before_acquire(false)`][PoolOptions::test_before_acquire]
* Never set [`before_acquire`][PoolOptions::before_acquire] or
[`after_connect`][PoolOptions::after_connect].
* Drop the in-memory database
Fixes#607
This PR drops the implementation of in-memory database traits.
They are useful for testing purposes since the tests should test our codebase
and assume the database works as expected (although a follow-up PR should write
a sanity test suite for all database trait implementors).
As complexity is worth with database requirements to simplify complexity and
add more robustness, for instance, with the following plans to add support for
transactions or buffered writes, it would become more complex and
time-consuming to support a correct database trait. This PR drops the
implementation and replaces it with a SQLite memory instance
* Remove OnceCell<Mint>
Without this change, a single Mint is shared for all tests, and the first tests
to run and shutdown makes the other databases (not-reachable, as dropping the
tokio engine would also drop the database instance).
There is no real reason, other than perhaps performance. The mint should
perhaps run in their own tokio engine and share channels as API interfaces, or
a new instance should be created in each tests
* Fixed bug with foreign keys
[1] https://gist.github.com/crodas/bad00997c63bd5ac58db3c5bd90747ed
* Show more debug on failure
* Remove old code
* Remove old references to WalletMemoryDatabase
Instead, use `INSERT` and `ON CONFLICT`. The reason is that in case of
conflicts, the `REPLACE` will trigger a DELETE and then perform an INSERT, as
outlined in the documentation[1], and that may cause a cascade of deletion due
to our FOREIGN KEYs.
Here is the official documentation:
```
When a UNIQUE or PRIMARY KEY constraint violation occurs, the REPLACE algorithm
deletes pre-existing rows that are causing the constraint violation prior to
inserting or updating the current row and the command continues executing
normally. If a NOT NULL constraint violation occurs, the REPLACE conflict
resolution replaces the NULL value with the default value for that column, or
if the column has no default value, then the ABORT algorithm is used. If
a CHECK constraint or foreign key constraint violation occurs, the REPLACE
conflict resolution algorithm works like ABORT. When the REPLACE conflict
resolution strategy deletes rows in order to satisfy a constraint, delete
triggers fire if and only if recursive triggers are enabled. The update
hook is not invoked for rows that are deleted by the REPLACE conflict
resolution strategy. Nor does REPLACE increment the change counter. The
exceptional behaviors defined in this paragraph might change in a future
release.
```
[1] https://www.sqlite.org/lang_conflict.html
fix(mint/sqlite): add pending proof state
fix(mint): adding proof to pending before checking current
fix(mint): remove double call to verify melt quote
