Implement cancellation support/protection for module callbacks (#12568)

There's no guarantee that module callbacks will handle cancellation
appropriately. Protect module callbacks with read semantics from
cancellation and avoid swallowing `CancelledError`s that arise.

Other module callbacks, such as the `on_*` callbacks, are presumed to
live on code paths that involve writes and aren't cancellation-friendly.
These module callbacks have been left alone.

Signed-off-by: Sean Quah <seanq@element.io>

1 files changed, 1 insertions, 0 deletions

diff --git a/changelog.d/12568.misc b/changelog.d/12568.misc
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index 0000000000..f64dc67c4f
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+Protect module callbacks with read semantics against cancellation.