sprint() recently became more strict, throwing on sprint("%s", 5). Replace
with the more modern format().
Mechanically converted with https://github.com/avikivity/unsprint.
The calculation consists of several parts with preemption point between
them, so a table can be added while calculation is ongoing. Do not
assume that table exists in intermediate data structure.
Fixes#3636
Message-Id: <20180801093147.GD23569@scylladb.com>
The code filters CFs by name to not include system keyspace, but v3
schema added yet another system namespace. Better filter according to
replication strategy to accommodate for schema v4 adding even more
system keyspaces.
Fixes: #2516
Message-Id: <20170621073816.GB3944@scylladb.com>
When a node start it does not have any information about cache temperature
of other nodes in the cluster and it is hard (if not impossible) to make
right guess. During cluster startup all nodes have cold caches, so there
is no point to redirect reads to other nodes even though local cache it
cold, but if only that node restarted than other nodes have populated
cache and reads should be redirected.
The node will get up-to-date information about other nodes caches,
but only after receiving first reply, until then it does not have the
information to make right decisions which may cause unwanted spikes
immediately after restart. Having cache temperature in gossiper helps
to solve the problem.
This patch adds new class cache_hitrate_calculator whose responsibility
is to periodically calculate average cache hit rates between all shards
for each CF.
