make msg_store responsible for sync'ing

The API to the msg_store has changed: now instead of asking whether a
sync is needed for a set of msg ids, and subsequently requesting a
sync, we request a sync for a set of msg ids and supply a callback
that is invoked when that sync is done. That way the msg_store can
make its own decisions on when to sync, and less logic is required by
callers.

During queue deletion we must remove *all* queue messages from the
store, including those that are part of committed transactions for
which the disk_queue has not yet received the sync callback. To do
that we keep a record of these messages in a dict in the state. The
dict also ensures that we do not act on a sync callback involving a
queue which has since been deleted and perhaps recreated.

0 files changed, 0 insertions, 0 deletions