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author | Sean Quah <8349537+squahtx@users.noreply.github.com> | 2021-09-14 13:01:30 +0100 |
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committer | GitHub <noreply@github.com> | 2021-09-14 13:01:30 +0100 |
commit | 14b8c0476f93ea2ed3134e75733e45aa0ab6f5a5 (patch) | |
tree | b2192f768d007e54316d9e705d342ae229dac3ad /setup.py | |
parent | Merge tag 'v1.43.0rc1' into develop (diff) | |
download | synapse-14b8c0476f93ea2ed3134e75733e45aa0ab6f5a5.tar.xz |
Prevent logging context going missing on federation request timeout (#10810)
In `MatrixFederationHttpClient._send_request()`, we make a HTTP request using an `Agent`, wrap that request in a timeout and await the resulting `Deferred`. On its own, the `Agent` performing the HTTP request correctly stashes and restores the logging context while waiting. The addition of the timeout introduces a path where the logging context is not restored when execution resumes. To address this, we wrap the timeout `Deferred` in a `make_deferred_yieldable()` to stash the logging context and restore it on completion of the `await`. However this is not sufficient, since by the time we construct the timeout `Deferred`, the `Agent` has already stashed and cleared the logging context when using `make_deferred_yieldable()` to produce its `Deferred` for the request. Hence, we wrap the `Agent` request in a `run_in_background()` to "fork" and preserve the logging context so that we can stash and restore it when `await`ing the timeout `Deferred`. This approach is similar to the one used with `defer.gatherResults`. Note that the code is still not fully correct. When a timeout occurs, the request remains running in the background (existing behavior which is nothing to do with the new call to `run_in_background`) and may re-start the logging context after it has finished.
Diffstat (limited to 'setup.py')
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