forked from MirrorHub/synapse
Implement reset_context_after_deferred
to correctly reset the context when we fire off a deferred we aren't going to wait for.
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@ -308,6 +308,31 @@ def preserve_context_over_deferred(deferred, context=None):
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return d
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def reset_context_after_deferred(deferred):
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"""If the deferred is incomplete, add a callback which will reset the
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context.
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This is useful when you want to fire off a deferred, but don't want to
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wait for it to complete. (The deferred will restore the current log context
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when it completes, so if you don't do anything, it will leak log context.)
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(If this feels asymmetric, consider it this way: we are effectively forking
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a new thread of execution. We are probably currently within a
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``with LoggingContext()`` block, which is supposed to have a single entry
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and exit point. But by spawning off another deferred, we are effectively
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adding a new exit point.)
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Args:
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deferred (defer.Deferred): deferred
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"""
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def reset_context(result):
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LoggingContext.set_current_context(LoggingContext.sentinel)
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return result
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if not deferred.called:
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deferred.addBoth(reset_context)
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def preserve_fn(f):
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"""Ensures that function is called with correct context and that context is
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restored after return. Useful for wrapping functions that return a deferred
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