mirror of
https://github.com/element-hq/synapse.git
synced 2026-09-16 12:42:43 +00:00
Matthew Hodgson
24724a810e
**Goal**: Switch live context tracking to `contextvars.ContextVar`. This is the foundational change everything else depends on — `contextvars` propagates automatically into `asyncio.Task` children, which is essential for native asyncio. **Files modified**: - `synapse/logging/context.py` (lines 736-766) — Replace `_thread_local = threading.local()` with `_current_context: ContextVar[LoggingContextOrSentinel]`. Update `current_context()` and `set_current_context()`. `LoggingContext.__enter__/__exit__` (lines 377-417) use `ContextVar.set()` token API. `PreserveLoggingContext` (line 677) works unchanged since it calls the same functions. - `synapse/util/patch_inline_callbacks.py` — Update logcontext checks if needed for contextvars semantics. **Key constraint**: This is backward-compatible with Twisted. Deferred callbacks run on the main thread; `ContextVar` works fine with single-threaded access. DB thread pool interactions need verification — `adbapi.ConnectionPool` uses Twisted's `ThreadPool`, and each thread gets its own contextvars copy by default, which matches current `threading.local` behavior. Key finding: The original plan to directly replace threading.local with ContextVar was not possible while Twisted Deferreds are in use. asyncio's event loop runs call_later/call_soon callbacks in context copies, so _set_context_cb's ContextVar write would be isolated and invisible to the awaiting code. This is fundamentally different from threading.local where writes are globally visible on the thread. What was implemented instead (revised Phase 1): synapse/logging/context.py: - _thread_local remains the primary storage for current_context() / set_current_context() — backward compatible with Twisted Deferred callback patterns - _current_context_var (ContextVar) is kept in sync — every set_current_context() call also writes to the ContextVar - _native_current_context() / _native_set_current_context() — operate on ContextVar only, for asyncio-native code paths (Tasks) where ContextVar propagation is correct - make_future_yieldable(), run_coroutine_in_background_native(), run_in_background_native() — all use _native_* functions since they run inside asyncio Tasks Migration path: The full switch from threading.local → ContextVar as sole storage happens in Phase 7 when all Deferred usage is removed. Until then, both storage mechanisms coexist. Verification: 4462 tests passed, 169 skipped, 0 new failures. mypy clean.
.. 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