* cell_entry destructor may be called when the former is unlinked
* update pointer to schema in partition_entry on schema upgrade
* use correct bucket count when creating a new hash table
The comparator constructor took schema by value instead of const l-ref
and, consequently, later tried to access object that has been destroyed
long time ago.
Message-Id: <20170202135853.8190-1-pdziepak@scylladb.com>
The leader receives counter update in a form of deltas which need to be
transformed to counter shards. In order to do that the node needs to
read its current state of the modified counter cells. Since this is
essentially a read-modify-write opertation an appropriate locking
mechanism is needed.
Counter cell locker introduced in this patch uses a hashtable of
partition entry each containing a hashtable of cell entries. Inside a
cell entry there is a semaphore used for synchronization. Once no longer
needed cell entries and partition entries are removed.
In order to avoid deadlocks cell entries are always locked in the same
order which is the lexicographical order of (clustering key, column id)
pairs. Note that schema changes are not a difficulty since they do not
make it possible to change ordering of such pairs.
