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Eric Eastwood
c63d77a79d
This is a stepping stone before we can go full Rust everywhere. We're providing a generic interface as we want database access to work in Synapse and `synapse-rust-apps`. In `synapse-rust-apps`, we will use a `tokio-postgres` based database connection pool so it's full Rust. We want to avoid the situation where we have two database connection pools (one for Python, one for Rust) as we've run into connection exhaustion problems on Matrix.org before. As an example of using it and sanity check for all this work (including tests), I've also ported over the `/versions` handler to the Rust side with database access. The `/versions` endpoint is the simplest endpoint I could find that still had some database access. Hopefully the refactor on `/versions` isn't that controversial as it's not really the point of this PR. We can always remove it from this PR but it's just here as a sanity check that all of this works. ### Why `runInteraction(...)`? Using the same `runInteraction` pattern that we already have in Synapse means we can port over existing Synapse code/endpoints without much thought. But this pattern also makes sense because we want[^1] transactions to have repeatable-read isolation (easy to think about, less foot-guns). Having everything thappen in a function callback means we can do retries for serialization/deadlock errors. [^1]: To note: Ideally, we'd want the least isolation possible but the problem is that there is no tooling to yell at you when your queries/logic is wrong so repeatable-read isolation is a great balance. > When an application receives this error message, it should abort the current transaction and retry the whole transaction from the beginning. The second time through, the transaction will see the previously-committed change as part of its initial view of the database, so there is no logical conflict in using the new version of the row as the starting point for the new transaction's update. > > Note that only updating transactions might need to be retried; read-only transactions will never have serialization conflicts. > > *-- https://www.postgresql.org/docs/current/transaction-iso.html#XACT-REPEATABLE-READ* As a note, this strategy is less of an impedance mismatch (aligns more closely) with Synapse so the glue code for the `python_db_pool` should also be simpler. ### How does this interact with logcontext (`LoggingContext`)? See [docs on log contexts](https://github.com/element-hq/synapse/blob/4e9f7757f17ba81b8747b7f8f9646d17df145aa3/docs/log_contexts.md) for more background. We already support normal logging from Rust -> Python with `pyo3-log` and `log` but as soon as we pass a thread boundary, everything is logged against the `sentinel` log context. Normally, we want logs and CPU/DB usage correlated with the request that spawned the work. You can see how I took a stab at fixing this in https://github.com/element-hq/synapse/pull/19846 by capturing the logcontext in a Tokio task local and re-activating as necessary. For example, in that PR, I reactivated the logcontext in `run_python_awaitable(...)` which we use to call `runInteraction(...)` from the Rust side which means all of the database usage is correlated with the request as expected. It also means any `log:info!(...)` done in `run_interaction(...)` is correlated correctly. But there needs to be a better story for when you want to log everywhere else. I haven't explored tracking CPU usage on the Rust side. I've left all of this out of this PR as I think it will be better to tackle this as a dedicated follow-up. For example, I'm thinking about instead creating a new `LoggingContext` with the `parent_context` set to the calling context and try to avoid needing to call `set_current_context(...)` on the Python side where possible (like tracking CPU). ### Testing strategy Added some tests that exercise some `async` Rust handlers for the `/versions` endpoint: ``` SYNAPSE_TEST_LOG_LEVEL=INFO poetry run trial tests.rest.client.test_versions.VersionsTestCase ``` Real-world: 1. `poetry run synapse_homeserver --config-path homeserver.yaml` 1. `GET http://localhost:8008/_matrix/client/versions`
.. image:: https://github.com/element-hq/synapse/raw/develop/docs/element_logo_white_bg.svg :height: 60px **Element Synapse - Matrix homeserver implementation** |support| |development| |documentation| |license| |pypi| |python| Synapse is an open source `Matrix <https://matrix.org>`__ homeserver implementation, written and maintained by `Element <https://element.io>`_. `Matrix <https://github.com/matrix-org>`__ is the open standard for secure and interoperable real-time communications. You can directly run and manage the source code in this repository, available under an AGPL license (or alternatively under a commercial license from Element). There is no support provided by Element unless you have a subscription from Element. 🚀 Getting started ================== This component is developed and maintained by `Element <https://element.io>`_. It gets shipped as part of the **Element Server Suite (ESS)** which provides the official means of deployment. ESS is a Matrix distribution from Element with focus on quality and ease of use. It ships a full Matrix stack tailored to the respective use case. There are three editions of ESS: - `ESS Community <https://github.com/element-hq/ess-helm>`_ - the free Matrix distribution from Element tailored to small-/mid-scale, non-commercial community use cases - `ESS Pro <https://element.io/server-suite>`_ - the commercial Matrix distribution from Element for professional use - `ESS TI-M <https://element.io/server-suite/ti-messenger>`_ - a special version of ESS Pro focused on the requirements of TI-Messenger Pro and ePA as specified by the German National Digital Health Agency Gematik 🛠️ Standalone installation and configuration ============================================ The Synapse documentation describes `options for installing Synapse standalone <https://element-hq.github.io/synapse/latest/setup/installation.html>`_. See below for more useful documentation links. - `Synapse configuration options <https://element-hq.github.io/synapse/latest/usage/configuration/config_documentation.html>`_ - `Synapse configuration for federation <https://element-hq.github.io/synapse/latest/federate.html>`_ - `Using a reverse proxy with Synapse <https://element-hq.github.io/synapse/latest/reverse_proxy.html>`_ - `Upgrading Synapse <https://element-hq.github.io/synapse/develop/upgrade.html>`_ 🎯 Troubleshooting and support ============================== 🚀 Professional support ----------------------- Enterprise quality support for Synapse including SLAs is available as part of an `Element Server Suite (ESS) <https://element.io/pricing>`_ subscription. If you are an existing ESS subscriber then you can raise a `support request <https://ems.element.io/support>`_ and access the `Element product documentation <https://docs.element.io>`_. 🤝 Community support -------------------- The `Admin FAQ <https://element-hq.github.io/synapse/latest/usage/administration/admin_faq.html>`_ includes tips on dealing with some common problems. For more details, see `Synapse's wider documentation <https://element-hq.github.io/synapse/latest/>`_. For additional support installing or managing Synapse, please ask in the community support room |room|_ (from a matrix.org account if necessary). We do not use GitHub issues for support requests, only for bug reports and feature requests. .. |room| replace:: ``#synapse:matrix.org`` .. _room: https://matrix.to/#/#synapse:matrix.org .. |docs| replace:: ``docs`` .. _docs: docs 🛠️ Development ============== We welcome contributions to Synapse from the community! The best place to get started is our `guide for contributors <https://element-hq.github.io/synapse/latest/development/contributing_guide.html>`_. This is part of our broader `documentation <https://element-hq.github.io/synapse/latest>`_, which includes information for Synapse developers as well as Synapse administrators. Developers might be particularly interested in: * `Synapse's database schema <https://element-hq.github.io/synapse/latest/development/database_schema.html>`_, * `notes on Synapse's implementation details <https://element-hq.github.io/synapse/latest/development/internal_documentation/index.html>`_, and * `how we use git <https://element-hq.github.io/synapse/latest/development/git.html>`_. Alongside all that, join our developer community on Matrix: `#synapse-dev:matrix.org <https://matrix.to/#/#synapse-dev:matrix.org>`_, featuring real humans! Copyright and Licensing ======================= | Copyright 2014–2017 OpenMarket Ltd | Copyright 2017 Vector Creations Ltd | Copyright 2017–2025 New Vector Ltd | Copyright 2025 Element Creations Ltd This software is dual-licensed by Element Creations Ltd (Element). It can be used either: (1) for free under the terms of the GNU Affero General Public License (as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version); OR (2) under the terms of a paid-for Element Commercial License agreement between you and Element (the terms of which may vary depending on what you and Element have agreed to). Unless required by applicable law or agreed to in writing, software distributed under the Licenses is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the Licenses for the specific language governing permissions and limitations under the Licenses. Please contact `licensing@element.io <mailto:licensing@element.io>`_ to purchase an Element commercial license for this software. .. |support| image:: https://img.shields.io/badge/matrix-community%20support-success :alt: (get community support in #synapse:matrix.org) :target: https://matrix.to/#/#synapse:matrix.org .. |development| image:: https://img.shields.io/matrix/synapse-dev:matrix.org?label=development&logo=matrix :alt: (discuss development on #synapse-dev:matrix.org) :target: https://matrix.to/#/#synapse-dev:matrix.org .. |documentation| image:: https://img.shields.io/badge/documentation-%E2%9C%93-success :alt: (Rendered documentation on GitHub Pages) :target: https://element-hq.github.io/synapse/latest/ .. |license| image:: https://img.shields.io/github/license/element-hq/synapse :alt: (check license in LICENSE file) :target: LICENSE .. |pypi| image:: https://img.shields.io/pypi/v/matrix-synapse :alt: (latest version released on PyPi) :target: https://pypi.org/project/matrix-synapse .. |python| image:: https://img.shields.io/pypi/pyversions/matrix-synapse :alt: (supported python versions) :target: https://pypi.org/project/matrix-synapse