/usr/share/pyshared/gevent/pool.py is in python-gevent 0.13.6-1ubuntu1.
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"""Managing greenlets in a group.
The :class:`Group` class in this module abstracts a group of running greenlets.
When a greenlet dies, it's automatically removed from the group.
The :class:`Pool` which a subclass of :class:`Group` provides a way to limit
concurrency: its :meth:`spawn <Pool.spawn>` method blocks if the number of
greenlets in the pool has already reached the limit, until there is a free slot.
"""
from gevent.hub import GreenletExit, getcurrent
from gevent.greenlet import joinall, Greenlet
from gevent.timeout import Timeout
from gevent.event import Event
from gevent.coros import Semaphore, DummySemaphore
__all__ = ['Group', 'Pool']
class Group(object):
"""Maintain a group of greenlets that are still running.
Links to each item and removes it upon notification.
"""
greenlet_class = Greenlet
def __init__(self, *args):
assert len(args) <= 1, args
self.greenlets = set(*args)
if args:
for greenlet in args[0]:
greenlet.rawlink(self.discard)
# each item we kill we place in dying, to avoid killing the same greenlet twice
self.dying = set()
self._empty_event = Event()
self._empty_event.set()
def __repr__(self):
try:
classname = self.__class__.__name__
except AttributeError:
classname = 'Group' # XXX check if 2.4 really uses this line
return '<%s at %s %s>' % (classname, hex(id(self)), self.greenlets)
def __len__(self):
return len(self.greenlets)
def __contains__(self, item):
return item in self.greenlets
def __iter__(self):
return iter(self.greenlets)
def add(self, greenlet):
greenlet.rawlink(self.discard)
self.greenlets.add(greenlet)
self._empty_event.clear()
def discard(self, greenlet):
self.greenlets.discard(greenlet)
self.dying.discard(greenlet)
if not self.greenlets:
self._empty_event.set()
def start(self, greenlet):
self.add(greenlet)
greenlet.start()
def spawn(self, *args, **kwargs):
add = self.add
greenlet = self.greenlet_class.spawn(*args, **kwargs)
add(greenlet)
return greenlet
def spawn_link(self, *args, **kwargs):
greenlet = self.spawn(*args, **kwargs)
greenlet.link()
return greenlet
def spawn_link_value(self, *args, **kwargs):
greenlet = self.spawn(*args, **kwargs)
greenlet.link_value()
return greenlet
def spawn_link_exception(self, *args, **kwargs):
greenlet = self.spawn(*args, **kwargs)
greenlet.link_exception()
return greenlet
# def close(self):
# """Prevents any more tasks from being submitted to the pool"""
# self.add = RaiseException("This %s has been closed" % self.__class__.__name__)
def join(self, timeout=None, raise_error=False):
if raise_error:
greenlets = self.greenlets.copy()
self._empty_event.wait(timeout=timeout)
for greenlet in greenlets:
if greenlet.exception is not None:
raise greenlet.exception
else:
self._empty_event.wait(timeout=timeout)
def kill(self, exception=GreenletExit, block=True, timeout=None):
timer = Timeout.start_new(timeout)
try:
try:
while self.greenlets:
for greenlet in list(self.greenlets):
if greenlet not in self.dying:
greenlet.kill(exception, block=False)
self.dying.add(greenlet)
if not block:
break
joinall(self.greenlets)
except Timeout, ex:
if ex is not timer:
raise
finally:
timer.cancel()
def killone(self, greenlet, exception=GreenletExit, block=True, timeout=None):
if greenlet not in self.dying and greenlet in self.greenlets:
greenlet.kill(exception, block=False)
self.dying.add(greenlet)
if block:
greenlet.join(timeout)
def apply(self, func, args=None, kwds=None):
"""Equivalent of the apply() builtin function. It blocks till the result is ready."""
if args is None:
args = ()
if kwds is None:
kwds = {}
if getcurrent() in self:
return func(*args, **kwds)
else:
return self.spawn(func, *args, **kwds).get()
def apply_cb(self, func, args=None, kwds=None, callback=None):
result = self.apply(func, args, kwds)
if callback is not None:
Greenlet.spawn(callback, result)
return result
def apply_async(self, func, args=None, kwds=None, callback=None):
"""A variant of the apply() method which returns a Greenlet object.
If callback is specified then it should be a callable which accepts a single argument. When the result becomes ready
callback is applied to it (unless the call failed)."""
if args is None:
args = ()
if kwds is None:
kwds = {}
if self.full():
# cannot call spawn() directly because it will block
return Greenlet.spawn(self.apply_cb, func, args, kwds, callback)
else:
greenlet = self.spawn(func, *args, **kwds)
if callback is not None:
greenlet.link(pass_value(callback))
return greenlet
def map(self, func, iterable):
greenlets = [self.spawn(func, item) for item in iterable]
return [greenlet.get() for greenlet in greenlets]
def map_cb(self, func, iterable, callback=None):
result = self.map(func, iterable)
if callback is not None:
callback(result)
return result
def map_async(self, func, iterable, callback=None):
"""
A variant of the map() method which returns a Greenlet object.
If callback is specified then it should be a callable which accepts a
single argument.
"""
return Greenlet.spawn(self.map_cb, func, iterable, callback)
def imap(self, func, iterable):
"""An equivalent of itertools.imap()
**TODO**: Fix this.
"""
return iter(self.map(func, iterable))
def imap_unordered(self, func, iterable):
"""The same as imap() except that the ordering of the results from the
returned iterator should be considered in arbitrary order."""
return IMapUnordered.spawn(self.spawn, func, iterable)
def full(self):
return False
def wait_available(self):
pass
class IMapUnordered(Greenlet):
def __init__(self, spawn, func, iterable):
from gevent.queue import Queue
Greenlet.__init__(self)
self.spawn = spawn
self.func = func
self.iterable = iterable
self.queue = Queue()
self.count = 0
def __iter__(self):
return self.queue
def _run(self):
try:
func = self.func
for item in self.iterable:
self.count += 1
self.spawn(func, item).rawlink(self._on_result)
finally:
self.__dict__.pop('spawn', None)
self.__dict__.pop('func', None)
self.__dict__.pop('iterable', None)
def _on_result(self, greenlet):
self.count -= 1
if greenlet.successful():
self.queue.put(greenlet.value)
if self.ready() and self.count <= 0:
self.queue.put(StopIteration)
def GreenletSet(*args, **kwargs):
import warnings
warnings.warn("gevent.pool.GreenletSet was renamed to gevent.pool.Group since version 0.13.0", DeprecationWarning, stacklevel=2)
return Group(*args, **kwargs)
class Pool(Group):
def __init__(self, size=None, greenlet_class=None):
if size is not None and size < 1:
raise ValueError('Invalid size for pool (positive integer or None required): %r' % (size, ))
Group.__init__(self)
self.size = size
if greenlet_class is not None:
self.greenlet_class = greenlet_class
if size is None:
self._semaphore = DummySemaphore()
else:
self._semaphore = Semaphore(size)
def wait_available(self):
self._semaphore.wait()
def full(self):
return self.free_count() <= 0
def free_count(self):
if self.size is None:
return 1
return max(0, self.size - len(self))
def start(self, greenlet):
self._semaphore.acquire()
try:
self.add(greenlet)
except:
self._semaphore.release()
raise
greenlet.start()
def spawn(self, *args, **kwargs):
self._semaphore.acquire()
try:
greenlet = self.greenlet_class.spawn(*args, **kwargs)
self.add(greenlet)
except:
self._semaphore.release()
raise
return greenlet
def spawn_link(self, *args, **kwargs):
self._semaphore.acquire()
try:
greenlet = self.greenlet_class.spawn_link(*args, **kwargs)
self.add(greenlet)
except:
self._semaphore.release()
raise
return greenlet
def spawn_link_value(self, *args, **kwargs):
self._semaphore.acquire()
try:
greenlet = self.greenlet_class.spawn_link_value(*args, **kwargs)
self.add(greenlet)
except:
self._semaphore.release()
raise
return greenlet
def spawn_link_exception(self, *args, **kwargs):
self._semaphore.acquire()
try:
greenlet = self.greenlet_class.spawn_link_exception(*args, **kwargs)
self.add(greenlet)
except:
self._semaphore.release()
raise
return greenlet
def discard(self, greenlet):
Group.discard(self, greenlet)
self._semaphore.release()
def get_values(greenlets):
joinall(greenlets)
return [x.value for x in greenlets]
class pass_value(object):
__slots__ = ['callback']
def __init__(self, callback):
self.callback = callback
def __call__(self, source):
if source.successful():
self.callback(source.value)
def __hash__(self):
return hash(self.callback)
def __eq__(self, other):
return self.callback == getattr(other, 'callback', other)
def __str__(self):
return str(self.callback)
def __repr__(self):
return repr(self.callback)
def __getattr__(self, item):
assert item != 'callback'
return getattr(self.callback, item)
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