def wrapper(*args, **kwargs):
future = TracebackFuture()
if replace_callback and 'callback' in kwargs:
callback = kwargs.pop('callback')
IOLoop.current().add_future(
future, lambda future: callback(future.result()))
try:
result = func(*args, **kwargs)
except (Return, StopIteration) as e:
result = _value_from_stopiteration(e)
except Exception:
future.set_exc_info(sys.exc_info())
return future
else:
if isinstance(result, GeneratorType):
# Inline the first iteration of Runner.run. This lets us
# avoid the cost of creating a Runner when the coroutine
# never actually yields, which in turn allows us to
# use "optional" coroutines in critical path code without
# performance penalty for the synchronous case.
try:
orig_stack_contexts = stack_context._state.contexts
yielded = next(result)
if stack_context._state.contexts is not orig_stack_contexts:
yielded = TracebackFuture()
yielded.set_exception(
stack_context.StackContextInconsistentError(
'stack_context inconsistency (probably caused '
'by yield within a "with StackContext" block)')
)
except (StopIteration, Return) as e:
future.set_result(_value_from_stopiteration(e))
except Exception:
future.set_exc_info(sys.exc_info())
else:
_futures_to_runners[future] = Runner(
result, future, yielded)
try:
return future
finally:
# Subtle memory optimization: if next() raised an exception,
# the future's exc_info contains a traceback which
# includes this stack frame. This creates a cycle,
# which will be collected at the next full GC but has
# been shown to greatly increase memory usage of
# benchmarks (relative to the refcount-based scheme
# used in the absence of cycles). We can avoid the
# cycle by clearing the local variable after we return it.
future = None
future.set_result(result)
return future
class Runner(object):
"""Internal implementation of `tornado.gen.engine`.
Maintains information about pending callbacks and their results.
The results of the generator are stored in ``result_future`` (a
`.TracebackFuture`)
"""
def __init__(self, gen, result_future, first_yielded):
self.gen = gen
self.result_future = result_future
self.future = _null_future
self.yield_point = None
self.pending_callbacks = None
self.results = None
self.running = False
self.finished = False
self.had_exception = False
self.io_loop = IOLoop.current()
# For efficiency, we do not create a stack context until we
# reach a YieldPoint (stack contexts are required for the historical
# semantics of YieldPoints, but not for Futures). When we have
# done so, this field will be set and must be called at the end
# of the coroutine.
self.stack_context_deactivate = None
if self.handle_yield(first_yielded):
self.run()
def register_callback(self, key):
"""Adds ``key`` to the list of callbacks."""
if self.pending_callbacks is None:
# Lazily initialize the old-style YieldPoint data structures.
self.pending_callbacks = set()
self.results = {}
if key in self.pending_callbacks:
raise KeyReuseError("key %r is already pending" % (key, ))
self.pending_callbacks.add(key)
def is_ready(self, key):
"""Returns true if a result is available for ``key``."""
if self.pending_callbacks is None or key not in self.pending_callbacks:
raise UnknownKeyError("key %r is not pending" % (key, ))
return key in self.results
def set_result(self, key, result):
"""Sets the result for ``key`` and attempts to resume the generator."""
self.results[key] = result
if self.yield_point is not None and self.yield_point.is_ready():
try:
self.future.set_result(self.yield_point.get_result())
except:
self.future.set_exc_info(sys.exc_info())
self.yield_point = None
self.run()
def pop_result(self, key):
"""Returns the result for ``key`` and unregisters it."""
self.pending_callbacks.remove(key)
return self.results.pop(key)
def run(self):
"""Starts or resumes the generator, running until it reaches a
yield point that is not ready.
"""
if self.running or self.finished:
return
try:
self.running = True
while True:
future = self.future
if not future.done():
return
self.future = None
try:
orig_stack_contexts = stack_context._state.contexts
exc_info = None
try:
value = future.result()
except Exception:
self.had_exception = True
exc_info = sys.exc_info()
if exc_info is not None:
yielded = self.gen.throw(*exc_info)
exc_info = None
else:
yielded = self.gen.send(value)
if stack_context._state.contexts is not orig_stack_contexts:
self.gen.throw(
stack_context.StackContextInconsistentError(
'stack_context inconsistency (probably caused '
'by yield within a "with StackContext" block)')
)
except (StopIteration, Return) as e:
self.finished = True
self.future = _null_future
if self.pending_callbacks and not self.had_exception:
# If we ran cleanly without waiting on all callbacks
# raise an error (really more of a warning). If we
# had an exception then some callbacks may have been
# orphaned, so skip the check in that case.
raise LeakedCallbackError(
"finished without waiting for callbacks %r" %
self.pending_callbacks)
self.result_future.set_result(_value_from_stopiteration(e))
self.result_future = None
self._deactivate_stack_context()
return
except Exception:
self.finished = True
self.future = _null_future
self.result_future.set_exc_info(sys.exc_info())
self.result_future = None
self._deactivate_stack_context()
return
if not self.handle_yield(yielded):
return
finally:
self.running = False
def handle_yield(self, yielded):
# Lists containing YieldPoints require stack contexts;
# other lists are handled in convert_yielded.
if _contains_yieldpoint(yielded):
yielded = multi(yielded)
if isinstance(yielded, YieldPoint):
# YieldPoints are too closely coupled to the Runner to go
# through the generic convert_yielded mechanism.
self.future = TracebackFuture()
def start_yield_point():
try:
yielded.start(self)
if yielded.is_ready():
self.future.set_result(yielded.get_result())
else:
self.yield_point = yielded
except Exception:
self.future = TracebackFuture()
self.future.set_exc_info(sys.exc_info())
if self.stack_context_deactivate is None:
# Start a stack context if this is the first
# YieldPoint we've seen.
with stack_context.ExceptionStackContext(
self.handle_exception) as deactivate:
self.stack_context_deactivate = deactivate
def cb():
start_yield_point()
self.run()
self.io_loop.add_callback(cb)
return False
else:
start_yield_point()
else:
try:
self.future = convert_yielded(yielded)
except BadYieldError:
self.future = TracebackFuture()
self.future.set_exc_info(sys.exc_info())
if not self.future.done() or self.future is moment:
self.io_loop.add_future(self.future, lambda f: self.run())
return False
return True
def result_callback(self, key):
return stack_context.wrap(
_argument_adapter(functools.partial(self.set_result, key)))
def handle_exception(self, typ, value, tb):
if not self.running and not self.finished:
self.future = TracebackFuture()
self.future.set_exc_info((typ, value, tb))
self.run()
return True
else:
return False
def _deactivate_stack_context(self):
if self.stack_context_deactivate is not None:
self.stack_context_deactivate()
self.stack_context_deactivate = None