def test_two_arg_exception(self):
# This test would fail on python 3 if raise_exc_info were simply
# a three-argument raise statement, because TwoArgException
# doesn't have a "copy constructor"
class TwoArgException(Exception):
def __init__(self, a, b):
super(TwoArgException, self).__init__()
self.a, self.b = a, b
try:
raise TwoArgException(1, 2)
except TwoArgException:
exc_info = sys.exc_info()
try:
raise_exc_info(exc_info)
self.fail("didn't get expected exception")
except TwoArgException as e:
self.assertIs(e, exc_info[1])
def wrapper(*args, **kwargs):
future = TracebackFuture()
callback, args, kwargs = replacer.replace(
lambda value=_NO_RESULT: future.set_result(value),
args, kwargs)
def handle_error(typ, value, tb):
future.set_exc_info((typ, value, tb))
return True
exc_info = None
with ExceptionStackContext(handle_error):
try:
result = f(*args, **kwargs)
if result is not None:
raise ReturnValueIgnoredError(
"@return_future should not be used with functions "
"that return values")
except:
exc_info = sys.exc_info()
raise
if exc_info is not None:
# If the initial synchronous part of f() raised an exception,
# go ahead and raise it to the caller directly without waiting
# for them to inspect the Future.
raise_exc_info(exc_info)
# If the caller passed in a callback, schedule it to be called
# when the future resolves. It is important that this happens
# just before we return the future, or else we risk confusing
# stack contexts with multiple exceptions (one here with the
# immediate exception, and again when the future resolves and
# the callback triggers its exception by calling future.result()).
if callback is not None:
def run_callback(future):
result = future.result()
if result is _NO_RESULT:
callback()
else:
callback(future.result())
future.add_done_callback(wrap(run_callback))
return future
def result(self, timeout=None):
if self.__exc_info is not None:
raise_exc_info(self.__exc_info)
else:
return super(TracebackFuture, self).result(timeout=timeout)
def wrapped(*args, **kwargs):
ret = None
try:
# Capture old state
current_state = _state.contexts
# Remove deactivated items
cap_contexts[0] = contexts = _remove_deactivated(cap_contexts[0])
# Force new state
_state.contexts = contexts
# Current exception
exc = (None, None, None)
top = None
# Apply stack contexts
last_ctx = 0
stack = contexts[0]
# Apply state
for n in stack:
try:
n.enter()
last_ctx += 1
except:
# Exception happened. Record exception info and store top-most handler
exc = sys.exc_info()
top = n.old_contexts[1]
# Execute callback if no exception happened while restoring state
if top is None:
try:
ret = fn(*args, **kwargs)
except:
exc = sys.exc_info()
top = contexts[1]
# If there was exception, try to handle it by going through the exception chain
if top is not None:
exc = _handle_exception(top, exc)
else:
# Otherwise take shorter path and run stack contexts in reverse order
while last_ctx > 0:
last_ctx -= 1
c = stack[last_ctx]
try:
c.exit(*exc)
except:
exc = sys.exc_info()
top = c.old_contexts[1]
break
else:
top = None
# If if exception happened while unrolling, take longer exception handler path
if top is not None:
exc = _handle_exception(top, exc)
# If exception was not handled, raise it
if exc != (None, None, None):
raise_exc_info(exc)
finally:
_state.contexts = current_state
return ret
def __rethrow(self):
if self.__failure is not None:
failure = self.__failure
self.__failure = None
raise_exc_info(failure)
