mirror of
https://github.com/ceph/ceph
synced 2024-12-15 07:56:12 +00:00
84 lines
2.2 KiB
Python
84 lines
2.2 KiB
Python
import logging
|
|
|
|
import gevent.pool
|
|
import gevent.queue
|
|
|
|
log = logging.getLogger(__name__)
|
|
|
|
class parallel(object):
|
|
"""
|
|
This class is a context manager for running functions in parallel.
|
|
|
|
You add functions to be run with the spawn method::
|
|
|
|
with parallel() as p:
|
|
for foo in bar:
|
|
p.spawn(quux, foo, baz=True)
|
|
|
|
You can iterate over the results (which are in arbitrary order)::
|
|
|
|
with parallel() as p:
|
|
for foo in bar:
|
|
p.spawn(quux, foo, baz=True)
|
|
for result in p:
|
|
print result
|
|
|
|
If one of the spawned functions throws an exception, it will be thrown
|
|
when iterating over the results, or when the with block ends.
|
|
|
|
At the end of the with block, the main thread waits until all
|
|
spawned functions have completed, or, if one exited with an exception,
|
|
kills the rest and raises the exception.
|
|
"""
|
|
|
|
def __init__(self):
|
|
self.group = gevent.pool.Group()
|
|
self.results = gevent.queue.Queue()
|
|
self.count = 0
|
|
self.any_spawned = False
|
|
|
|
def spawn(self, func, *args, **kwargs):
|
|
self.count += 1
|
|
self.any_spawned = True
|
|
greenlet = self.group.spawn(func, *args, **kwargs)
|
|
greenlet.link(self._finish)
|
|
|
|
def __enter__(self):
|
|
return self
|
|
|
|
def __exit__(self, type_, value, traceback):
|
|
if value is not None:
|
|
self.group.kill(block=True)
|
|
return False
|
|
|
|
try:
|
|
# raises if any greenlets exited with an exception
|
|
for result in self:
|
|
log.debug('result is %s', repr(result))
|
|
pass
|
|
except:
|
|
self.group.kill(block=True)
|
|
raise
|
|
return True
|
|
|
|
def __iter__(self):
|
|
return self
|
|
|
|
def next(self):
|
|
if not self.any_spawned:
|
|
raise StopIteration()
|
|
result = self.results.get()
|
|
if isinstance(result, BaseException):
|
|
raise result
|
|
return result
|
|
|
|
def _finish(self, greenlet):
|
|
if greenlet.successful():
|
|
self.results.put(greenlet.value)
|
|
else:
|
|
self.results.put(greenlet.exception)
|
|
|
|
self.count -= 1
|
|
if self.count <= 0:
|
|
self.results.put(StopIteration())
|