import geventdef test_1():print '切换不出去'print '切换出去我不是循环'gevent.sleep(1)def test_2():print '切换'print '切换出去我去'gevent.sleep(3)gevent.spawn(test_1)
gevent.spawn(test_2)
gevent.sleep(1)

result = Waiter()
timer = get_hub().loop.timer(5)
timer.start(result.switch, 'hello from Waiter')
print result.get()

    def get(self):"""If a value/an exception is stored, return/raise it. Otherwise until switch() or throw() is called."""if self._exception is not _NONE:if self._exception is None:return self.valueelse:getcurrent().throw(*self._exception)else:assert self.greenlet is None, 'This Waiter is already used by %r' % (self.greenlet, )self.greenlet = getcurrent()try:return self.hub.switch()finally:self.greenlet = None

    def switch(self):switch_out = getattr(getcurrent(), 'switch_out', None)if switch_out is not None:switch_out()return greenlet.switch(self)

    def run(self):assert self is getcurrent(), 'Do not call Hub.run() directly'while True:loop = self.looploop.error_handler = selftry:loop.run()finally:loop.error_handler = None  # break the refcount cycleself.parent.throw(LoopExit('This operation would block forever'))# this function must never return, as it will cause switch() in the parent greenlet# to return an unexpected value# It is still possible to kill this greenlet with throw. However, in that case# switching to it is no longer safe, as switch will return immediatelly

    def switch(self, value=None):"""Switch to the greenlet if one's available. Otherwise store the value."""greenlet = self.greenletif greenlet is None:self.value = valueself._exception = Noneelse:assert getcurrent() is self.hub, "Can only use Waiter.switch method from the Hub greenlet"switch = greenlet.switchtry:switch(value)except:self.hub.handle_error(switch, *sys.exc_info())

            try:return self.hub.switch()finally:self.greenlet = None

    @classmethoddef spawn(cls, *args, **kwargs):"""Return a new :class:`Greenlet` object, scheduled to start.The arguments are passed to :meth:`Greenlet.__init__`."""g = cls(*args, **kwargs)g.start()return g

    def start(self):"""Schedule the greenlet to run in this loop iteration"""if self._start_event is None:self._start_event = self.parent.loop.run_callback(self.switch)

def sleep(seconds=0, ref=True):"""Put the current greenlet to sleep for at least *seconds*.*seconds* may be specified as an integer, or a float if fractional secondsare desired.If *ref* is false, the greenlet running sleep() will not prevent gevent.wait()from exiting."""hub = get_hub()loop = hub.loopif seconds <= 0:waiter = Waiter()loop.run_callback(waiter.switch)waiter.get()else:hub.wait(loop.timer(seconds, ref=ref))

    def wait(self, watcher):waiter = Waiter()unique = object()watcher.start(waiter.switch, unique)try:result = waiter.get()assert result is unique, 'Invalid switch into %s: %r (expected %r)' % (getcurrent(), result, unique)finally:watcher.stop()

    def get(self):"""If a value/an exception is stored, return/raise it. Otherwise until switch() or throw() is called."""if self._exception is not _NONE:if self._exception is None:return self.valueelse:getcurrent().throw(*self._exception) else: assert self.greenlet is None, 'This Waiter is already used by %r' % (self.greenlet, ) self.greenlet = getcurrent() try: return self.hub.switch() finally: self.greenlet = None

    def switch(self):switch_out = getattr(getcurrent(), 'switch_out', None)if switch_out is not None:switch_out()return greenlet.switch(self)

    def run(self):assert self is getcurrent(), 'Do not call Hub.run() directly'while True:loop = self.looploop.error_handler = selftry:loop.run()finally:loop.error_handler = None  # break the refcount cycleself.parent.throw(LoopExit('This operation would block forever'))# this function must never return, as it will cause switch() in the parent greenlet# to return an unexpected value# It is still possible to kill this greenlet with throw. However, in that case# switching to it is no longer safe, as switch will return immediatelly

    def run(self):try:if self._start_event is None:self._start_event = _dummy_eventelse:self._start_event.stop()try:result = self._run(*self.args, **self.kwargs)except:self._report_error(sys.exc_info())returnself._report_result(result)finally:self.__dict__.pop('_run', None)self.__dict__.pop('args', None)self.__dict__.pop('kwargs', None)