diff --git a/synapse/util/logcontext.py b/synapse/util/logcontext.py
index e701092cd8..9134e67908 100644
--- a/synapse/util/logcontext.py
+++ b/synapse/util/logcontext.py
@@ -48,7 +48,7 @@ class LoggingContext(object):
__slots__ = [
"parent_context", "name", "usage_start", "usage_end", "main_thread",
- "__dict__", "tag",
+ "__dict__", "tag", "alive",
]
thread_local = threading.local()
@@ -88,6 +88,7 @@ class LoggingContext(object):
self.usage_start = None
self.main_thread = threading.current_thread()
self.tag = ""
+ self.alive = True
def __str__(self):
return "%s@%x" % (self.name, id(self))
@@ -106,6 +107,7 @@ class LoggingContext(object):
The context that was previously active
"""
current = cls.current_context()
+
if current is not context:
current.stop()
cls.thread_local.current_context = context
@@ -117,6 +119,7 @@ class LoggingContext(object):
if self.parent_context is not None:
raise Exception("Attempt to enter logging context multiple times")
self.parent_context = self.set_current_context(self)
+ self.alive = True
return self
def __exit__(self, type, value, traceback):
@@ -136,6 +139,7 @@ class LoggingContext(object):
self
)
self.parent_context = None
+ self.alive = False
def __getattr__(self, name):
"""Delegate member lookup to parent context"""
@@ -213,7 +217,7 @@ class PreserveLoggingContext(object):
exited. Used to restore the context after a function using
@defer.inlineCallbacks is resumed by a callback from the reactor."""
- __slots__ = ["current_context", "new_context"]
+ __slots__ = ["current_context", "new_context", "has_parent"]
def __init__(self, new_context=LoggingContext.sentinel):
self.new_context = new_context
@@ -224,11 +228,26 @@ class PreserveLoggingContext(object):
self.new_context
)
+ if self.current_context:
+ self.has_parent = self.current_context.parent_context is not None
+ if not self.current_context.alive:
+ logger.warn(
+ "Entering dead context: %s",
+ self.current_context,
+ )
+
def __exit__(self, type, value, traceback):
"""Restores the current logging context"""
- LoggingContext.set_current_context(self.current_context)
+ context = LoggingContext.set_current_context(self.current_context)
+
+ if context != self.new_context:
+ logger.warn(
+ "Unexpected logging context: %s is not %s",
+ context, self.new_context,
+ )
+
if self.current_context is not LoggingContext.sentinel:
- if self.current_context.parent_context is None:
+ if not self.current_context.alive:
logger.warn(
"Restoring dead context: %s",
self.current_context,
@@ -289,3 +308,74 @@ def preserve_context_over_deferred(deferred):
d = _PreservingContextDeferred(current_context)
deferred.chainDeferred(d)
return d
+
+
+def preserve_fn(f):
+ """Ensures that function is called with correct context and that context is
+ restored after return. Useful for wrapping functions that return a deferred
+ which you don't yield on.
+ """
+ current = LoggingContext.current_context()
+
+ def g(*args, **kwargs):
+ with PreserveLoggingContext(current):
+ return f(*args, **kwargs)
+
+ return g
+
+
+# modules to ignore in `logcontext_tracer`
+_to_ignore = [
+ "synapse.util.logcontext",
+ "synapse.http.server",
+ "synapse.storage._base",
+ "synapse.util.async",
+]
+
+
+def logcontext_tracer(frame, event, arg):
+ """A tracer that logs whenever a logcontext "unexpectedly" changes within
+ a function. Probably inaccurate.
+
+ Use by calling `sys.settrace(logcontext_tracer)` in the main thread.
+ """
+ if event == 'call':
+ name = frame.f_globals["__name__"]
+ if name.startswith("synapse"):
+ if name == "synapse.util.logcontext":
+ if frame.f_code.co_name in ["__enter__", "__exit__"]:
+ tracer = frame.f_back.f_trace
+ if tracer:
+ tracer.just_changed = True
+
+ tracer = frame.f_trace
+ if tracer:
+ return tracer
+
+ if not any(name.startswith(ig) for ig in _to_ignore):
+ return LineTracer()
+
+
+class LineTracer(object):
+ __slots__ = ["context", "just_changed"]
+
+ def __init__(self):
+ self.context = LoggingContext.current_context()
+ self.just_changed = False
+
+ def __call__(self, frame, event, arg):
+ if event in 'line':
+ if self.just_changed:
+ self.context = LoggingContext.current_context()
+ self.just_changed = False
+ else:
+ c = LoggingContext.current_context()
+ if c != self.context:
+ logger.info(
+ "Context changed! %s -> %s, %s, %s",
+ self.context, c,
+ frame.f_code.co_filename, frame.f_lineno
+ )
+ self.context = c
+
+ return self
|
