diff options
Diffstat (limited to 'synapse/util')
| -rw-r--r-- | synapse/util/patch_inline_callbacks.py | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/synapse/util/patch_inline_callbacks.py b/synapse/util/patch_inline_callbacks.py new file mode 100644 index 0000000000..4fb49b0b2b --- /dev/null +++ b/synapse/util/patch_inline_callbacks.py @@ -0,0 +1,179 @@ +# -*- coding: utf-8 -*- +# Copyright 2018 New Vector Ltd +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +from __future__ import print_function + +import functools +import sys + +from twisted.internet import defer +from twisted.internet.defer import Deferred +from twisted.python.failure import Failure + + +def do_patch(): + """ + Patch defer.inlineCallbacks so that it checks the state of the logcontext on exit + """ + + from synapse.logging.context import LoggingContext + + orig_inline_callbacks = defer.inlineCallbacks + if hasattr(orig_inline_callbacks, "patched_by_synapse"): + return + + def new_inline_callbacks(f): + @functools.wraps(f) + def wrapped(*args, **kwargs): + start_context = LoggingContext.current_context() + changes = [] + orig = orig_inline_callbacks(_check_yield_points(f, changes, start_context)) + + try: + res = orig(*args, **kwargs) + except Exception: + if LoggingContext.current_context() != start_context: + for err in changes: + print(err, file=sys.stderr) + + err = "%s changed context from %s to %s on exception" % ( + f, + start_context, + LoggingContext.current_context(), + ) + print(err, file=sys.stderr) + raise Exception(err) + raise + + if not isinstance(res, Deferred) or res.called: + if LoggingContext.current_context() != start_context: + for err in changes: + print(err, file=sys.stderr) + + err = "Completed %s changed context from %s to %s" % ( + f, + start_context, + LoggingContext.current_context(), + ) + # print the error to stderr because otherwise all we + # see in travis-ci is the 500 error + print(err, file=sys.stderr) + raise Exception(err) + return res + + if LoggingContext.current_context() != LoggingContext.sentinel: + err = ( + "%s returned incomplete deferred in non-sentinel context " + "%s (start was %s)" + ) % (f, LoggingContext.current_context(), start_context) + print(err, file=sys.stderr) + raise Exception(err) + + def check_ctx(r): + if LoggingContext.current_context() != start_context: + for err in changes: + print(err, file=sys.stderr) + err = "%s completion of %s changed context from %s to %s" % ( + "Failure" if isinstance(r, Failure) else "Success", + f, + start_context, + LoggingContext.current_context(), + ) + print(err, file=sys.stderr) + raise Exception(err) + return r + + res.addBoth(check_ctx) + return res + + return wrapped + + defer.inlineCallbacks = new_inline_callbacks + new_inline_callbacks.patched_by_synapse = True + + +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. + """ + + from synapse.logging.context import LoggingContext + + @functools.wraps(f) + def check_yield_points_inner(*args, **kwargs): + expected_context = start_context + + gen = f(*args, **kwargs) + + last_yield_line_no = 1 + result = None + while True: + try: + isFailure = isinstance(result, Failure) + if isFailure: + d = result.throwExceptionIntoGenerator(gen) + else: + d = gen.send(result) + except (StopIteration, defer._DefGen_Return) as e: + if LoggingContext.current_context() != expected_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. + err = ( + "Function %r returned and changed context from %s to %s," + " in %s between %d and end of func" + % ( + f.__qualname__, + start_context, + LoggingContext.current_context(), + f.__code__.co_filename, + last_yield_line_no, + ) + ) + changes.append(err) + # raise Exception(err) + return getattr(e, "value", None) + + try: + result = yield d + except Exception as e: + result = Failure(e) + + frame = gen.gi_frame + + 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. + err = ( + "%s changed context from %s to %s, happened between lines %d and %d in %s" + % ( + frame.f_code.co_name, + start_context, + LoggingContext.current_context(), + last_yield_line_no, + frame.f_lineno, + frame.f_code.co_filename, + ) + ) + changes.append(err) + # raise Exception(err) + + expected_context = LoggingContext.current_context() + + last_yield_line_no = frame.f_lineno + + return check_yield_points_inner |