from collections import deque import sys from eventlet import event from eventlet import hubs from eventlet import timeout from eventlet.hubs import timer from eventlet.support import greenlets as greenlet, six import warnings __all__ = ['getcurrent', 'sleep', 'spawn', 'spawn_n', 'spawn_after', 'spawn_after_local', 'GreenThread'] getcurrent = greenlet.getcurrent def sleep(seconds=0): """Yield control to another eligible coroutine until at least *seconds* have elapsed. *seconds* may be specified as an integer, or a float if fractional seconds are desired. Calling :func:`~greenthread.sleep` with *seconds* of 0 is the canonical way of expressing a cooperative yield. For example, if one is looping over a large list performing an expensive calculation without calling any socket methods, it's a good idea to call ``sleep(0)`` occasionally; otherwise nothing else will run. """ hub = hubs.get_hub() current = getcurrent() assert hub.greenlet is not current, 'do not call blocking functions from the mainloop' timer = hub.schedule_call_global(seconds, current.switch) try: hub.switch() finally: timer.cancel() def spawn(func, *args, **kwargs): """Create a greenthread to run ``func(*args, **kwargs)``. Returns a :class:`GreenThread` object which you can use to get the results of the call. Execution control returns immediately to the caller; the created greenthread is merely scheduled to be run at the next available opportunity. Use :func:`spawn_after` to arrange for greenthreads to be spawned after a finite delay. """ hub = hubs.get_hub() g = GreenThread(hub.greenlet) hub.schedule_call_global(0, g.switch, func, args, kwargs) return g def spawn_n(func, *args, **kwargs): """Same as :func:`spawn`, but returns a ``greenlet`` object from which it is not possible to retrieve either a return value or whether it raised any exceptions. This is faster than :func:`spawn`; it is fastest if there are no keyword arguments. If an exception is raised in the function, spawn_n prints a stack trace; the print can be disabled by calling :func:`eventlet.debug.hub_exceptions` with False. """ return _spawn_n(0, func, args, kwargs)[1] def spawn_after(seconds, func, *args, **kwargs): """Spawns *func* after *seconds* have elapsed. It runs as scheduled even if the current greenthread has completed. *seconds* may be specified as an integer, or a float if fractional seconds are desired. The *func* will be called with the given *args* and keyword arguments *kwargs*, and will be executed within its own greenthread. The return value of :func:`spawn_after` is a :class:`GreenThread` object, which can be used to retrieve the results of the call. To cancel the spawn and prevent *func* from being called, call :meth:`GreenThread.cancel` on the return value of :func:`spawn_after`. This will not abort the function if it's already started running, which is generally the desired behavior. If terminating *func* regardless of whether it's started or not is the desired behavior, call :meth:`GreenThread.kill`. """ hub = hubs.get_hub() g = GreenThread(hub.greenlet) hub.schedule_call_global(seconds, g.switch, func, args, kwargs) return g def spawn_after_local(seconds, func, *args, **kwargs): """Spawns *func* after *seconds* have elapsed. The function will NOT be called if the current greenthread has exited. *seconds* may be specified as an integer, or a float if fractional seconds are desired. The *func* will be called with the given *args* and keyword arguments *kwargs*, and will be executed within its own greenthread. The return value of :func:`spawn_after` is a :class:`GreenThread` object, which can be used to retrieve the results of the call. To cancel the spawn and prevent *func* from being called, call :meth:`GreenThread.cancel` on the return value. This will not abort the function if it's already started running. If terminating *func* regardless of whether it's started or not is the desired behavior, call :meth:`GreenThread.kill`. """ hub = hubs.get_hub() g = GreenThread(hub.greenlet) hub.schedule_call_local(seconds, g.switch, func, args, kwargs) return g def call_after_global(seconds, func, *args, **kwargs): warnings.warn( "call_after_global is renamed to spawn_after, which" "has the same signature and semantics (plus a bit extra). Please do a" " quick search-and-replace on your codebase, thanks!", DeprecationWarning, stacklevel=2) return _spawn_n(seconds, func, args, kwargs)[0] def call_after_local(seconds, function, *args, **kwargs): warnings.warn( "call_after_local is renamed to spawn_after_local, which" "has the same signature and semantics (plus a bit extra).", DeprecationWarning, stacklevel=2) hub = hubs.get_hub() g = greenlet.greenlet(function, parent=hub.greenlet) t = hub.schedule_call_local(seconds, g.switch, *args, **kwargs) return t call_after = call_after_local def exc_after(seconds, *throw_args): warnings.warn("Instead of exc_after, which is deprecated, use " "Timeout(seconds, exception)", DeprecationWarning, stacklevel=2) if seconds is None: # dummy argument, do nothing return timer.Timer(seconds, lambda: None) hub = hubs.get_hub() return hub.schedule_call_local(seconds, getcurrent().throw, *throw_args) # deprecate, remove TimeoutError = timeout.Timeout with_timeout = timeout.with_timeout def _spawn_n(seconds, func, args, kwargs): hub = hubs.get_hub() g = greenlet.greenlet(func, parent=hub.greenlet) t = hub.schedule_call_global(seconds, g.switch, *args, **kwargs) return t, g class GreenThread(greenlet.greenlet): """The GreenThread class is a type of Greenlet which has the additional property of being able to retrieve the return value of the main function. Do not construct GreenThread objects directly; call :func:`spawn` to get one. """ def __init__(self, parent): greenlet.greenlet.__init__(self, self.main, parent) self._exit_event = event.Event() self._resolving_links = False def wait(self): """ Returns the result of the main function of this GreenThread. If the result is a normal return value, :meth:`wait` returns it. If it raised an exception, :meth:`wait` will raise the same exception (though the stack trace will unavoidably contain some frames from within the greenthread module).""" return self._exit_event.wait() def link(self, func, *curried_args, **curried_kwargs): """ Set up a function to be called with the results of the GreenThread. The function must have the following signature:: def func(gt, [curried args/kwargs]): When the GreenThread finishes its run, it calls *func* with itself and with the `curried arguments `_ supplied at link-time. If the function wants to retrieve the result of the GreenThread, it should call wait() on its first argument. Note that *func* is called within execution context of the GreenThread, so it is possible to interfere with other linked functions by doing things like switching explicitly to another greenthread. """ self._exit_funcs = getattr(self, '_exit_funcs', deque()) self._exit_funcs.append((func, curried_args, curried_kwargs)) if self._exit_event.ready(): self._resolve_links() def unlink(self, func, *curried_args, **curried_kwargs): """ remove linked function set by :meth:`link` Remove successfully return True, otherwise False """ if not getattr(self, '_exit_funcs', None): return False try: self._exit_funcs.remove((func, curried_args, curried_kwargs)) return True except ValueError: return False def main(self, function, args, kwargs): try: result = function(*args, **kwargs) except: self._exit_event.send_exception(*sys.exc_info()) self._resolve_links() raise else: self._exit_event.send(result) self._resolve_links() def _resolve_links(self): # ca and ckw are the curried function arguments if self._resolving_links: return self._resolving_links = True try: exit_funcs = getattr(self, '_exit_funcs', deque()) while exit_funcs: f, ca, ckw = exit_funcs.popleft() f(self, *ca, **ckw) finally: self._resolving_links = False def kill(self, *throw_args): """Kills the greenthread using :func:`kill`. After being killed all calls to :meth:`wait` will raise *throw_args* (which default to :class:`greenlet.GreenletExit`).""" return kill(self, *throw_args) def cancel(self, *throw_args): """Kills the greenthread using :func:`kill`, but only if it hasn't already started running. After being canceled, all calls to :meth:`wait` will raise *throw_args* (which default to :class:`greenlet.GreenletExit`).""" return cancel(self, *throw_args) def cancel(g, *throw_args): """Like :func:`kill`, but only terminates the greenthread if it hasn't already started execution. If the grenthread has already started execution, :func:`cancel` has no effect.""" if not g: kill(g, *throw_args) def kill(g, *throw_args): """Terminates the target greenthread by raising an exception into it. Whatever that greenthread might be doing; be it waiting for I/O or another primitive, it sees an exception right away. By default, this exception is GreenletExit, but a specific exception may be specified. *throw_args* should be the same as the arguments to raise; either an exception instance or an exc_info tuple. Calling :func:`kill` causes the calling greenthread to cooperatively yield. """ if g.dead: return hub = hubs.get_hub() if not g: # greenlet hasn't started yet and therefore throw won't work # on its own; semantically we want it to be as though the main # method never got called def just_raise(*a, **kw): if throw_args: six.reraise(throw_args[0], throw_args[1], throw_args[2]) else: raise greenlet.GreenletExit() g.run = just_raise if isinstance(g, GreenThread): # it's a GreenThread object, so we want to call its main # method to take advantage of the notification try: g.main(just_raise, (), {}) except: pass current = getcurrent() if current is not hub.greenlet: # arrange to wake the caller back up immediately hub.ensure_greenlet() hub.schedule_call_global(0, current.switch) g.throw(*throw_args)