def feed(self):
"""(Greedy) Returns this FeedTask's feed (list of wrappers).
The first access of this property triggers a GET of the feed if it has
not already been fetched, so use this only if you need the
EntryWrappers outside of the execution itself.
"""
if self._feed is None:
self._feed = self._getter.get()
if len(self._feed) == 0:
raise ex.FeedTaskEmptyFeed()
# Do we need to refresh the feed based on having been run?
# If we haven't replicated WrapperTasks yet, there's no chance we're
# out of sync - and we don't want to trigger GET/replication.
if self._tx_by_uuid:
# Rebuild the entire feed from the WrapperTasks' .wrappers.
# TAG_WRAPPER_SYNC
# Note that, if this happens while the WrapperTasks are running,
# we may be grabbing the wrapper from a WrapperTask "while" it is
# being changed as the result of an update(). This is threadsafe as
# long as the assignment (by WrapperTask.execute) and the accessor
# (WrapperTask.wrapper) remain atomic by using simple =/return.
for wrap in self._feed:
if self.get_wrapper(wrap.uuid).etag != wrap.etag:
# Refresh needed
self._feed = [tx.wrapper for tx in
self.wrapper_tasks.values()]
break
return self._feed
def __init__(self,
name,
feed_or_getter,
max_workers=10,
update_timeout=-1):
"""Create a FeedTask with a FeedGetter (preferred) or existing feed.
:param name: A descriptive string name. This will be used along with
each wrapper's UUID to generate the name for that
wrapper's WrapperTask.
:param feed_or_getter: pypowervm.wrappers.entry_wrapper.FeedGetter or
an already-fetched feed (list of EntryWrappers)
over which to operate.
:param max_workers: (Optional) Integer indicating the maximum number of
worker threads to run in parallel within the .flow
or by the .execute method. See
concurrent.futures.ThreadPoolExecutor(max_workers).
:param update_timeout: (Optional) Integer number of seconds after which
to time each WrapperTask's POST request. -1,
the default, causes the request to use the
timeout value configured on the Session
belonging to the Adapter.
"""
super(FeedTask, self).__init__(name)
if isinstance(feed_or_getter, ewrap.FeedGetter):
self._feed = None
self._getter = feed_or_getter
elif isinstance(feed_or_getter, list):
# Make sure the feed has something in it.
if len(feed_or_getter) == 0:
raise ex.FeedTaskEmptyFeed()
# Make sure it's a list of EntryWrapper
if [
i for i in feed_or_getter
if not isinstance(i, ewrap.EntryWrapper)
]:
raise ValueError("List must contain EntryWrappers "
"exclusively.")
self._feed = feed_or_getter
self._getter = None
else:
raise ValueError(
_("Must supply either a list of EntryWrappers or "
"a FeedGetter."))
# Max WrapperTasks to run in parallel
self.max_workers = max_workers
self.update_timeout = update_timeout
# Map of {uuid: WrapperTask}. We keep this empty until we need the
# individual WraperTasks. This is triggered by .wrapper_tasks and
# .get_wrapper(uuid) (and obviously executing).
self._tx_by_uuid = {}
# Until we *need* individual WrapperTasks, save subtasks in one place.
# EntryWrapperGetter is a cheat to allow us to build the WrapperTask.
self._common_tx = WrapperTask(
'internal', ewrap.EntryWrapperGetter(None, ewrap.Wrapper, None))
self._post_exec = []