def add_callback(self, callback, *args, **kwargs):
if thread.get_ident() != self._thread_ident:
# If we're not on the IOLoop's thread, we need to synchronize
# with other threads, or waking logic will induce a race.
with self._callback_lock:
if self._closing:
return
list_empty = not self._callbacks
self._callbacks.append(
functools.partial(stack_context.wrap(callback), *args,
**kwargs))
if list_empty:
# If we're not in the IOLoop's thread, and we added the
# first callback to an empty list, we may need to wake it
# up (it may wake up on its own, but an occasional extra
# wake is harmless). Waking up a polling IOLoop is
# relatively expensive, so we try to avoid it when we can.
self._waker.wake()
else:
if self._closing:
return
# If we're on the IOLoop's thread, we don't need the lock,
# since we don't need to wake anyone, just add the
# callback. Blindly insert into self._callbacks. This is
# safe even from signal handlers because the GIL makes
# list.append atomic. One subtlety is that if the signal
# is interrupting another thread holding the
# _callback_lock block in IOLoop.start, we may modify
# either the old or new version of self._callbacks, but
# either way will work.
self._callbacks.append(
functools.partial(stack_context.wrap(callback), *args,
**kwargs))
def call_at(self, deadline, callback, *args, **kwargs):
timeout = _Timeout(
deadline,
functools.partial(stack_context.wrap(callback), *args, **kwargs),
self)
heapq.heappush(self._timeouts, timeout)
return timeout
def add_future(self, future, callback):
"""Schedules a callback on the ``IOLoop`` when the given
`.Future` is finished.
The callback is invoked with one argument, the
`.Future`.
"""
assert is_future(future)
callback = stack_context.wrap(callback)
future.add_done_callback(
lambda future: self.add_callback(callback, future))
def wrapper(*args, **kwargs):
future = func(*args, **kwargs)
def final_callback(future):
if future.result() is not None:
raise ReturnValueIgnoredError(
"@gen.engine functions cannot return values: %r" %
(future.result(), ))
# The engine interface doesn't give us any way to return
# errors but to raise them into the stack context.
# Save the stack context here to use when the Future has resolved.
future.add_done_callback(stack_context.wrap(final_callback))
def set_exit_callback(self, callback):
"""Runs ``callback`` when this process exits.
The callback takes one argument, the return code of the process.
This method uses a ``SIGCHLD`` handler, which is a global setting
and may conflict if you have other libraries trying to handle the
same signal. If you are using more than one ``IOLoop`` it may
be necessary to call `Subprocess.initialize` first to designate
one ``IOLoop`` to run the signal handlers.
In many cases a close callback on the stdout or stderr streams
can be used as an alternative to an exit callback if the
signal handler is causing a problem.
"""
self._exit_callback = stack_context.wrap(callback)
Subprocess.initialize(self.io_loop)
Subprocess._waiting[self.pid] = self
Subprocess._try_cleanup_process(self.pid)
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.
future.result()
# 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_callback(self, key):
return stack_context.wrap(
_argument_adapter(functools.partial(self.set_result, key)))
def add_parse_callback(self, callback):
"""Adds a parse callback, to be invoked when option parsing is done."""
self._parse_callbacks.append(stack_context.wrap(callback))
def add_handler(self, fd, handler, events):
fd, obj = self.split_fd(fd)
self._handlers[fd] = (obj, stack_context.wrap(handler))
self._impl.register(fd, events | self.ERROR)