def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
python类coroutine()的实例源码
def _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
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 _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
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 _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
def _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
def _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
def _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
def _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
def _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
def _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
def _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
def _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def sleep(duration):
"""Return a `.Future` that resolves after the given number of seconds.
When used with ``yield`` in a coroutine, this is a non-blocking
analogue to `time.sleep` (which should not be used in coroutines
because it is blocking)::
yield gen.sleep(0.5)
Note that calling this function on its own does nothing; you must
wait on the `.Future` it returns (usually by yielding it).
.. versionadded:: 4.1
"""
f = Future()
IOLoop.current().call_later(duration, lambda: f.set_result(None))
return f
def _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
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 _argument_adapter(callback):
"""Returns a function that when invoked runs ``callback`` with one arg.
If the function returned by this function is called with exactly
one argument, that argument is passed to ``callback``. Otherwise
the args tuple and kwargs dict are wrapped in an `Arguments` object.
"""
def wrapper(*args, **kwargs):
if kwargs or len(args) > 1:
callback(Arguments(args, kwargs))
elif args:
callback(args[0])
else:
callback(None)
return wrapper
# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded.
def _value_from_stopiteration(e):
try:
# StopIteration has a value attribute beginning in py33.
# So does our Return class.
return e.value
except AttributeError:
pass
try:
# Cython backports coroutine functionality by putting the value in
# e.args[0].
return e.args[0]
except (AttributeError, IndexError):
return None
def engine(func):
"""Callback-oriented decorator for asynchronous generators.
This is an older interface; for new code that does not need to be
compatible with versions of Tornado older than 3.0 the
`coroutine` decorator is recommended instead.
This decorator is similar to `coroutine`, except it does not
return a `.Future` and the ``callback`` argument is not treated
specially.
In most cases, functions decorated with `engine` should take
a ``callback`` argument and invoke it with their result when
they are finished. One notable exception is the
`~tornado.web.RequestHandler` :ref:`HTTP verb methods <verbs>`,
which use ``self.finish()`` in place of a callback argument.
"""
func = _make_coroutine_wrapper(func, replace_callback=False)
@functools.wraps(func)
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))
return wrapper
def coroutine(func, replace_callback=True):
"""Decorator for asynchronous generators.
Any generator that yields objects from this module must be wrapped
in either this decorator or `engine`.
Coroutines may "return" by raising the special exception
`Return(value) <Return>`. In Python 3.3+, it is also possible for
the function to simply use the ``return value`` statement (prior to
Python 3.3 generators were not allowed to also return values).
In all versions of Python a coroutine that simply wishes to exit
early may use the ``return`` statement without a value.
Functions with this decorator return a `.Future`. Additionally,
they may be called with a ``callback`` keyword argument, which
will be invoked with the future's result when it resolves. If the
coroutine fails, the callback will not be run and an exception
will be raised into the surrounding `.StackContext`. The
``callback`` argument is not visible inside the decorated
function; it is handled by the decorator itself.
From the caller's perspective, ``@gen.coroutine`` is similar to
the combination of ``@return_future`` and ``@gen.engine``.
.. warning::
When exceptions occur inside a coroutine, the exception
information will be stored in the `.Future` object. You must
examine the result of the `.Future` object, or the exception
may go unnoticed by your code. This means yielding the function
if called from another coroutine, using something like
`.IOLoop.run_sync` for top-level calls, or passing the `.Future`
to `.IOLoop.add_future`.
"""
return _make_coroutine_wrapper(func, replace_callback=True)
