From 8ddb2de55387d54bac53138f374f55c7608991ce Mon Sep 17 00:00:00 2001 From: Eric Eastwood Date: Tue, 13 Jun 2023 16:34:54 -0500 Subject: [PATCH] Document `looping_call()` functionality that will wait for the given function to finish before scheduling another (#15772) Thanks to @erikjohnston for clarifying, https://github.com/matrix-org/synapse/pull/15743#discussion_r1226544457 We don't have to worry about calls stacking up if the given function takes longer than the scheduled time. --- changelog.d/15772.doc | 1 + synapse/util/__init__.py | 5 +++++ 2 files changed, 6 insertions(+) create mode 100644 changelog.d/15772.doc diff --git a/changelog.d/15772.doc b/changelog.d/15772.doc new file mode 100644 index 000000000..4d6c933c7 --- /dev/null +++ b/changelog.d/15772.doc @@ -0,0 +1 @@ +Document `looping_call()` functionality that will wait for the given function to finish before scheduling another. diff --git a/synapse/util/__init__.py b/synapse/util/__init__.py index 7ea0c4c36..9f3b8741c 100644 --- a/synapse/util/__init__.py +++ b/synapse/util/__init__.py @@ -116,6 +116,11 @@ class Clock: Waits `msec` initially before calling `f` for the first time. + If the function given to `looping_call` returns an awaitable/deferred, the next + call isn't scheduled until after the returned awaitable has finished. We get + this functionality thanks to this function being a thin wrapper around + `twisted.internet.task.LoopingCall`. + Note that the function will be called with no logcontext, so if it is anything other than trivial, you probably want to wrap it in run_as_background_process.