105 lines
2.9 KiB
Python
105 lines
2.9 KiB
Python
|
"""Synchronization primitives."""
|
||
|
|
from .abstract import Thenable
|
||
|
|
from .promises import promise
|
||
|
|
|
||
|
|
__all__ = ['barrier']
|
||
|
|
|
||
|
|
|
||
|
|
class barrier:
|
||
|
|
"""Barrier.
|
||
|
|
|
||
|
|
Synchronization primitive to call a callback after a list
|
||
|
|
of promises have been fulfilled.
|
||
|
|
|
||
|
|
Example:
|
||
|
|
|
||
|
|
.. code-block:: python
|
||
|
|
|
||
|
|
# Request supports the .then() method.
|
||
|
|
p1 = http.Request('http://a')
|
||
|
|
p2 = http.Request('http://b')
|
||
|
|
p3 = http.Request('http://c')
|
||
|
|
requests = [p1, p2, p3]
|
||
|
|
|
||
|
|
def all_done():
|
||
|
|
pass # all requests complete
|
||
|
|
|
||
|
|
b = barrier(requests).then(all_done)
|
||
|
|
|
||
|
|
# oops, we forgot we want another request
|
||
|
|
b.add(http.Request('http://d'))
|
||
|
|
|
||
|
|
Note that you cannot add new promises to a barrier after
|
||
|
|
the barrier is fulfilled.
|
||
|
|
"""
|
||
|
|
|
||
|
|
def __init__(self, promises=None, args=None, kwargs=None,
|
||
|
|
callback=None, size=None):
|
||
|
|
self.p = promise()
|
||
|
|
self.args = args or ()
|
||
|
|
self.kwargs = kwargs or {}
|
||
|
|
self._value = 0
|
||
|
|
self.size = size or 0
|
||
|
|
if not self.size and promises:
|
||
|
|
# iter(l) calls len(l) so generator wrappers
|
||
|
|
# can only return NotImplemented in the case the
|
||
|
|
# generator is not fully consumed yet.
|
||
|
|
plen = promises.__len__()
|
||
|
|
if plen is not NotImplemented:
|
||
|
|
self.size = plen
|
||
|
|
self.ready = self.failed = False
|
||
|
|
self.reason = None
|
||
|
|
self.cancelled = False
|
||
|
|
self.finalized = False
|
||
|
|
|
||
|
|
[self.add_noincr(p) for p in promises or []]
|
||
|
|
self.finalized = bool(promises or self.size)
|
||
|
|
if callback:
|
||
|
|
self.then(callback)
|
||
|
|
|
||
|
|
__slots__ = ( # noqa
|
||
|
|
'p', 'args', 'kwargs', '_value', 'size',
|
||
|
|
'ready', 'reason', 'cancelled', 'finalized',
|
||
|
|
'__weakref__',
|
||
|
|
# adding '__dict__' to get dynamic assignment
|
||
|
|
"__dict__",
|
||
|
|
)
|
||
|
|
|
||
|
|
def __call__(self, *args, **kwargs):
|
||
|
|
if not self.ready and not self.cancelled:
|
||
|
|
self._value += 1
|
||
|
|
if self.finalized and self._value >= self.size:
|
||
|
|
self.ready = True
|
||
|
|
self.p(*self.args, **self.kwargs)
|
||
|
|
|
||
|
|
def finalize(self):
|
||
|
|
if not self.finalized and self._value >= self.size:
|
||
|
|
self.p(*self.args, **self.kwargs)
|
||
|
|
self.finalized = True
|
||
|
|
|
||
|
|
def cancel(self):
|
||
|
|
self.cancelled = True
|
||
|
|
self.p.cancel()
|
||
|
|
|
||
|
|
def add_noincr(self, p):
|
||
|
|
if not self.cancelled:
|
||
|
|
if self.ready:
|
||
|
|
raise ValueError('Cannot add promise to full barrier')
|
||
|
|
p.then(self)
|
||
|
|
|
||
|
|
def add(self, p):
|
||
|
|
if not self.cancelled:
|
||
|
|
self.add_noincr(p)
|
||
|
|
self.size += 1
|
||
|
|
|
||
|
|
def then(self, callback, errback=None):
|
||
|
|
self.p.then(callback, errback)
|
||
|
|
|
||
|
|
def throw(self, *args, **kwargs):
|
||
|
|
if not self.cancelled:
|
||
|
|
self.p.throw(*args, **kwargs)
|
||
|
|
throw1 = throw
|
||
|
|
|
||
|
|
|
||
|
|
Thenable.register(barrier)
|