```py
@trace
@tag_args
async def get_oldest_event_ids_with_depth_in_room(...)
...
```
Before this PR, you would see a warning in the logs and the span was not exported:
```
2022-08-03 19:11:59,383 - synapse.logging.opentracing - 835 - ERROR - GET-0 - @trace may not have wrapped EventFederationWorkerStore.get_oldest_event_ids_with_depth_in_room correctly! The function is not async but returned a coroutine.
```
`start_active_span` was inconsistent as to whether it would activate the span
immediately, or wait for `scope.__enter__` to happen (it depended on whether
the current logcontext already had an associated scope). The inconsistency was
rather confusing if you were hoping to set up a couple of separate spans before
activating either.
Looking at the other implementations of opentracing `ScopeManager`s, the
intention is that it *should* be activated immediately, as the name
implies. Indeed, the idea is that you don't have to use the scope as a
contextmanager at all - you can just call `.close` on the result. Hence, our
cleanup has to happen in `.close` rather than `.__exit__`.
So, the main change here is to ensure that `start_active_span` does activate
the span, and that `scope.close()` does close the scope.
We also add some tests, which requires a `tracer` param so that we don't have
to rely on the global variable in unit tests.
As far as I can tell our logging contexts are meant to log the request ID, or sometimes the request ID followed by a suffix (this is generally stored in the name field of LoggingContext). There's also code to log the name@memory location, but I'm not sure this is ever used.
This simplifies the code paths to require every logging context to have a name and use that in logging. For sub-contexts (created via nested_logging_contexts, defer_to_threadpool, Measure) we use the current context's str (which becomes their name or the string "sentinel") and then potentially modify that (e.g. add a suffix).
Part of #9744
Removes all redundant `# -*- coding: utf-8 -*-` lines from files, as python 3 automatically reads source code as utf-8 now.
`Signed-off-by: Jonathan de Jong <jonathan@automatia.nl>`
This modifies the configuration of structured logging to be usable from
the standard Python logging configuration.
This also separates the formatting of logs from the transport allowing
JSON logs to files or standard logs to sockets.
