Add coments

This commit is contained in:
Erik Johnston 2019-10-10 11:53:57 +01:00
parent 9970f955ce
commit 791a8c559b

View file

@ -107,6 +107,19 @@ def do_patch():
def _check_yield_points(f, changes, start_context):
"""Wraps a generator that is about to be passed to defer.inlineCallbacks
checking that after every yield the log contexts are correct.
Its perfectly valid for log contexts to change within a function, e.g. due
to new Measure blocks, so such changes are added to the given `changes`
list instead of triggering an exception.
Args:
f: generator function to wrap
changes (list[str]): A list of strings detailing how the contexts
changed within a function.
start_context (LoggingContext): The initial context we're expecting
Returns:
function
"""
from synapse.logging.context import LoggingContext
@ -131,6 +144,10 @@ def _check_yield_points(f, changes, start_context):
# This happens when the context is lost sometime *after* the
# final yield and returning. E.g. we forgot to yield on a
# function that returns a deferred.
#
# We don't raise here as its perfectly valid for contexts to
# change in a function, as long as it sets the correct context
# on resolving (which is checked separately).
err = (
"Function %r returned and changed context from %s to %s,"
" in %s between %d and end of func"
@ -143,14 +160,14 @@ def _check_yield_points(f, changes, start_context):
)
)
changes.append(err)
# raise Exception(err)
return getattr(e, "value", None)
frame = gen.gi_frame
if isinstance(d, defer.Deferred) and not d.called:
# This happens if we yield on a deferred that doesn't follow
# the log context rules without wrappin in a `make_deferred_yieldable`
# the log context rules without wrappin in a `make_deferred_yieldable`.
# We raise here as this should never happen.
if LoggingContext.current_context() is not LoggingContext.sentinel:
err = (
"%s yielded with context %s rather than sentinel,"
@ -162,8 +179,7 @@ def _check_yield_points(f, changes, start_context):
frame.f_code.co_filename,
)
)
changes.append(err)
# raise Exception(err)
raise Exception(err)
try:
result = yield d
@ -171,10 +187,15 @@ def _check_yield_points(f, changes, start_context):
result = Failure(e)
if LoggingContext.current_context() != expected_context:
# This happens because the context is lost sometime *after* the
# previous yield and *after* the current yield. E.g. the
# deferred we waited on didn't follow the rules, or we forgot to
# yield on a function between the two yield points.
#
# We don't raise here as its perfectly valid for contexts to
# change in a function, as long as it sets the correct context
# on resolving (which is checked separately).
err = (
"%s changed context from %s to %s, happened between lines %d and %d in %s"
% (
@ -187,7 +208,6 @@ def _check_yield_points(f, changes, start_context):
)
)
changes.append(err)
# raise Exception(err)
expected_context = LoggingContext.current_context()