Previously every `tokio_postgres` error became a bare `RuntimeError`. Synapse's
transaction driver, though, branches on the *type* of a database error and on
its `pgcode`: `new_transaction` retries `OperationalError`, retries deadlocks it
recognises via `is_deadlock` (which reads `pgcode`) on a `DatabaseError`, and
`simple_upsert` retries `IntegrityError`. With everything collapsed to
`RuntimeError` none of that fired.
Add just the distinctions Synapse acts on, rather than psycopg2's full PEP-249
hierarchy: `Error` -> `DatabaseError` -> {`OperationalError`, `IntegrityError`},
exposed on the `postgres` submodule, each instance tagged with `pgcode` (the
SQLSTATE string, or `None`). A small classifier maps the SQLSTATE class:
constraint violations (`23`) to `IntegrityError`, connection/resource classes
(`08`/`53`/`57`/`58`) to `OperationalError`, everything else (incl. `40*`
deadlocks, which retry via `pgcode`) to `DatabaseError`. Codeless errors are
split with `is_closed()`: a lost connection is operational, any other (a bad
parameter, a failed connect) is a plain `DatabaseError` so it isn't retried.
Errors surfacing while a result stream is drained (the usual case for an
`INSERT` constraint violation) now route through the same mapping, so they carry
the right class and `pgcode` too.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Add the end-to-end test suite for the Rust DBAPI2 backend, driving the real
tokio-postgres client against a live Postgres server. It is skipped unless
the suite is configured for Postgres (SYNAPSE_POSTGRES), the same switch the
rest of the suite uses.
These cover the behaviours that need a real server rather than the
in-memory fakes the Rust unit tests use: connect (good and bad DSN),
run_interaction (return value, arg/kwarg forwarding, commit on success,
rollback on a Python exception, and recovery after both a Python-raised and
a server-rejected statement, including a constraint violation), cursor
reuse across queries, the fetch_one/fetch_all/fetch_next_batch/rowcount
surface (including batching across a 1000-row result set and the
exhausted-vs-no-active-query error distinction), and value round-trips for
every supported type (NULL, bytea with NUL/high bytes, float4 lossiness,
and an out-of-range int bound to a real int4 column).
A separately-guarded case exercises the libpq default-host fixup by
connecting with a DSN that omits the host.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
