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Rewire the ProcessingQueue to ensure that we can exhaust it completely and don't get stuck

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This commit is contained in:
croneter 2020-02-15 17:46:48 +01:00
parent 73ffb706f8
commit 51d1538f95
2 changed files with 34 additions and 54 deletions
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82
resources/lib/backgroundthread.py
View file

@ -123,7 +123,7 @@ class ProcessingQueue(Queue.Queue, object):
Put tuples (count, item) into this queue, with count being the respective
position of the item in the queue, starting with 0 (zero).
(None, None) is the sentinel for a single queue being exhausted, added by
put_sentinel()
add_sentinel()
"""
def _init(self, maxsize):
self.queue = deque()
@ -131,6 +131,7 @@ class ProcessingQueue(Queue.Queue, object):
self._queues = deque()
self._current_section = None
self._current_queue = None
# Item-index for the currently active queue
self._counter = 0
def _qsize(self):
@ -140,15 +141,9 @@ class ProcessingQueue(Queue.Queue, object):
return sum(q._qsize() for q in self._queues) if self._queues else 0
def put(self, item, block=True, timeout=None):
"""Put an item into the queue.
If optional args 'block' is true and 'timeout' is None (the default),
block if necessary until a free slot is available. If 'timeout' is
a non-negative number, it blocks at most 'timeout' seconds and raises
the Full exception if no free slot was available within that time.
Otherwise ('block' is false), put an item on the queue if a free slot
is immediately available, else raise the Full exception ('timeout'
is ignored in that case).
"""
PKC customization of Queue.put. item needs to be the tuple
(count [int], {'section': [Section], 'xml': [etree xml]})
"""
self.not_full.acquire()
try:
@ -168,73 +163,46 @@ class ProcessingQueue(Queue.Queue, object):
if remaining <= 0.0:
raise Queue.Full
self.not_full.wait(remaining)
if self._put(item) == 0:
# Only notify one waiting thread if this item is put into the
# current queue
self.not_empty.notify()
else:
# Be sure to signal not_empty only once!
self._unlock_after_section_change()
self._put(item)
self.unfinished_tasks += 1
self.not_empty.notify()
finally:
self.not_full.release()
def _put(self, item):
"""
Returns the index of the section in whose subqueue we need to put the
item into
"""
for i, section in enumerate(self._sections):
if item[1]['section'] == section:
self._queues[i]._put(item)
break
else:
raise RuntimeError('Could not find section for item %s' % item[1])
return i
def _unlock_after_section_change(self):
"""
Ugly work-around if we expected more items to be synced, but we had
to lower our section.number_of_items because PKC decided that nothing
changed and we don't need to sync the respective item(s).
get() thus might block indefinitely
"""
while (self._current_section and
self._counter == self._current_section.number_of_items):
LOG.debug('Signaling completion of current section')
self._init_next_section()
if self._current_queue and self._current_queue._qsize():
LOG.debug('Signaling not_empty')
self.not_empty.notify()
def put_sentinel(self, section):
def add_sentinel(self, section):
"""
Adds a new empty section as a sentinel. Call with an empty Section()
object.
object. Call this method immediately after having added all sections
with add_section().
Once the get()-method returns None, you've received the sentinel and
you've thus exhausted the queue
"""
self.not_empty.acquire()
self.not_full.acquire()
try:
section.number_of_items = 1
self._add_section(section)
# Add the actual sentinel to the queue we just added
self._queues[-1]._put((None, None))
self.unfinished_tasks += 1
if len(self._queues) == 1:
# queue was already exhausted!
self._activate_next_section()
self._counter = 0
self.not_empty.notify()
else:
self._unlock_after_section_change()
self.not_empty.notify()
finally:
self.not_empty.release()
self.not_full.release()
def add_section(self, section):
"""
Be sure to add all sections first before starting to pop items off this
queue or adding them to the queue
Add a new Section() to this Queue. Each section will be entirely
processed before moving on to the next section.
Be sure to set section.number_of_items correctly as it will signal
when processing is completely done for a specific section!
"""
self.mutex.acquire()
try:
@ -251,12 +219,24 @@ class ProcessingQueue(Queue.Queue, object):
self._activate_next_section()
def _init_next_section(self):
"""
Call only when a section has been completely exhausted
"""
# Might have some items left if we lowered section.number_of_items
leftover = self._current_queue._qsize()
if leftover:
LOG.warn('Still have %s items in the current queue', leftover)
self.unfinished_tasks -= leftover
if self.unfinished_tasks == 0:
self.all_tasks_done.notify_all()
elif self.unfinished_tasks < 0:
raise RuntimeError('Got negative number of unfinished_tasks')
self._sections.popleft()
self._queues.popleft()
self._counter = 0
self._activate_next_section()
def _activate_next_section(self):
self._counter = 0
self._current_section = self._sections[0] if self._sections else None
self._current_queue = self._queues[0] if self._queues else None

6
resources/lib/library_sync/full_sync.py
View file

@ -101,9 +101,6 @@ class FullSync(common.LibrarySyncMixin, bg.KillableThread):
for t in metadata_threads:
t.join()
LOG.debug('Download metadata threads finished')
# Sentinel for the process_thread once we added everything else
processing_queue.put_sentinel(sections.Section())
LOG.debug('Put sentinel into queue, waiting for processing thread')
process_thread.join()
self.successful = process_thread.successful
LOG.debug('threads finished work. successful: %s', self.successful)
@ -181,7 +178,10 @@ class FullSync(common.LibrarySyncMixin, bg.KillableThread):
except Exception:
utils.ERROR(notify=True)
finally:
# Sentinel for the section queue
section_queue.put(None)
# Sentinel for the process_thread once we added everything else
processing_queue.add_sentinel(sections.Section())
LOG.debug('Exiting threaded_get_generators')
def full_library_sync(self):