openstack/zaqar
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Merge "Why do we increment the counter after the insert?"

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Jenkins 2014-11-19 21:10:03 +00:00 committed by Gerrit Code Review
commit f5c42c7b0f
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7
zaqar/queues/storage/mongodb/messages.py
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@ -514,6 +514,13 @@ class MessageController(storage.Message):
collection = self._collection(queue_name, project)
# Set the next basis marker for the first attempt.
#
# Note that we don't increment the counter right away because
# if 2 concurrent posts happen and the one with the higher counter
# ends before the one with the lower counter, there's a window
# where a client paging through the queue may get the messages
# with the higher counter and skip the previous ones. This would
# make our FIFO guarantee unsound.
next_marker = self._queue_ctrl._get_counter(queue_name, project)
# Unique transaction ID to facilitate atomic batch inserts