Define table_id as a distinct utils::tagged_uuid modeled after raft
tagged_id, so it can be differentiated from other uuid-class types,
in particular from table_schema_version.
Fixes#11207
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
This patch avoids unncessary CACHE_HITRATES updates through gossip.
After this patch:
Publish CACHE_HITRATES in case:
- We haven't published it at all
- The diff is bigger than 1% and we haven't published in the last 5 seconds
- The diff is really big 10%
Note: A peer node can know the cache hitrate through read_data
read_mutation_data and read_digest RPC verbs which have cache_temperature in
the response. So there is no need to update CACHE_HITRATES through gossip in
high frequency.
We do the recalculation faster if the diff is bigger than 0.01. It is useful to
do the calculation even if we do not publish the CACHE_HITRATES though gossip,
since the recalculation will call the table->set_global_cache_hit_rate to set
the hitrate.
Fixes#5971Closes#11079
After fcb8d040 ("treewide: use Software Package Data Exchange
(SPDX) license identifiers"), many dual-licensed files were
left with empty comments on top. Remove them to avoid visual
noise.
Closes#10562
Instead of lengthy blurbs, switch to single-line, machine-readable
standardized (https://spdx.dev) license identifiers. The Linux kernel
switched long ago, so there is strong precedent.
Three cases are handled: AGPL-only, Apache-only, and dual licensed.
For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0),
reasoning that our changes are extensive enough to apply our license.
The changes we applied mechanically with a script, except to
licenses/README.md.
Closes#9937
Move replica-oriented classes to the replica namespace. The main
classes moved are ::database, ::keyspace, and ::table, but a few
ancillary classes are also moved. There are certainly classes that
should be moved but aren't (like distributed_loader) but we have
to start somewhere.
References are adjusted treewide. In many cases, it is obvious that
a call site should not access the replica (but the data_dictionary
instead), but that is left for separate work.
scylla-gdb.py is adjusted to look for both the new and old names.
The database, keyspace, and table classes represent the replica-only
part of the objects after which they are named. Reading from a table
doesn't give you the full data, just the replica's view, and it is not
consistent since reconciliation is applied on the coordinator.
As a first step in acknowledging this, move the related files to
a replica/ subdirectory.
recalculate_hitrates() is defined to return future<lowres_clock::duration>
but actually returns future<std::chrono::milliseconds>. This fails
if the two types are not the same.
Fix by returning the declared type.
The calculator needs to update its app-state on gossiper. Keeping
a reference is safe -- gossiper starts early, the calculator -- at
the very very end, stop in reverse.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Returning a function parameter guarantees copy elision and does not
require a std::move(). Enable -Wredundant-move to warn us that the
move is unneeded, and gain slightly more readable code. A few violations
are trivially adjusted.
Closes#9004
Eliminate not used includes and replace some more includes
with forward declarations where appropriate.
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
The database.hh is the central recursive-headers knot -- it has ~50
includes. This patch leaves only 34 (it remains the champion though).
Similar thing for database.cc.
Both changes help the latter compile ~4% faster :)
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Message-Id: <20210414183107.30374-1-xemul@scylladb.com>
The blacklog of current and max in VIEW_BACKLOG is not update but the
nodes are updating VIEW_BACKLOG all the time. For example:
```
INFO 2020-03-06 17:13:46,761 [shard 0] storage_service - Update system.peers table: endpoint=127.0.0.3, app_state=VIEW_BACKLOG, versioned_value=Value(0:18446744073709551615:1583486026590,718)
INFO 2020-03-06 17:13:46,821 [shard 0] storage_service - Update system.peers table: endpoint=127.0.0.2, app_state=VIEW_BACKLOG, versioned_value=Value(0:18446744073709551615:1583486026531,742)
INFO 2020-03-06 17:13:47,765 [shard 0] storage_service - Update system.peers table: endpoint=127.0.0.3, app_state=VIEW_BACKLOG, versioned_value=Value(0:18446744073709551615:1583486027590,721)
INFO 2020-03-06 17:13:47,825 [shard 0] storage_service - Update system.peers table: endpoint=127.0.0.2, app_state=VIEW_BACKLOG, versioned_value=Value(0:18446744073709551615:1583486027531,745)
INFO 2020-03-06 17:13:48,772 [shard 0] storage_service - Update system.peers table: endpoint=127.0.0.3, app_state=VIEW_BACKLOG, versioned_value=Value(0:18446744073709551615:1583486028590,726)
INFO 2020-03-06 17:13:48,833 [shard 0] storage_service - Update system.peers table: endpoint=127.0.0.2, app_state=VIEW_BACKLOG, versioned_value=Value(0:18446744073709551615:1583486028531,750)
INFO 2020-03-06 17:13:49,772 [shard 0] storage_service - Update system.peers table: endpoint=127.0.0.3, app_state=VIEW_BACKLOG, versioned_value=Value(0:18446744073709551615:1583486029590,729)
INFO 2020-03-06 17:13:49,832 [shard 0] storage_service - Update system.peers table: endpoint=127.0.0.2, app_state=VIEW_BACKLOG, versioned_value=Value(0:18446744073709551615:1583486029531,753)
```
The downside of such updates:
- Introduces more gossip exchange traffic
- Updates system.peers all the time
The extra unnecessary gossip traffic is fine to a cluster in a good
shape but when some of the nodes or shards are loaded, such messages and
the handling of such messages can make the system even busy.
With this patch, VIEW_BACKLOG is updated only when the backlog is really
updated.
Btw, we can even make the update only when the change of the backlog is
great than a threshold, e.g., 5%, which can reduce the traffic even
further.
Fixes#5970
The new guarantees are a bit better IMHO:
Once a subscriber is removed, it is never notified. This was not true
in the old code since it would iterate over a copy that would still
have that subscriber.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
load_broadcaster::stop_broadcasting uses shared_from_this(). Since
that is the only reference that the produced shared_ptr knows of, it
is deleted immediately. Fix that by also using a shared_ptr in
load_meter.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
This simplifies the storage_service API and fixes the
complain about shared_ptr usage instead of unique_ptr.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
There's a lonely get_load_map() call on storage_service that
needs only load broadcaster, always runs on shard 0 and that's it.
Next patch will move this whole stuff into its own helper no-shard
container and this is preparation for this.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The class in question wants to run its own instances on different
shards, for this sake it keeps reference on sharded self to call
invoke_on() on. There's a handy peering_sharded_service<> in seastar
for the same, using it makes the code nicer and shorter.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Message-Id: <20191226112401.23960-1-xemul@scylladb.com>
This patches silences the remaining discarded future warnings, those
where it cannot be determined with reasonable confidence that this was
indeed the actual intent of the author, or that the discarding of the
future could lead to problems. For all those places a FIXME is added,
with the intent that these will be soon followed-up with an actual fix.
I deliberately haven't fixed any of these, even if the fix seems
trivial. It is too easy to overlook a bad fix mixed in with so many
mechanical changes.
This patch silences those future discard warnings where it is clear that
discarding the future was actually the intent of the original author,
*and* they did the necessary precautions (handling errors). The patch
also adds some trivial error handling (logging the error) in some
places, which were lacking this, but otherwise look ok. No functional
changes.
We should wait for a future returned from add_local_application_state() to
resolve before issuing new calculation, otherwise two
add_local_application_state() may run simultaneously for the same state.
Fixes#4838.
Message-Id: <20190812082158.GE17984@scylladb.com>
The calculation is done in a non preemptable loop over all tables, so if
numbers of tables is very large it may take a while since we also build
a string for gossiper state. Make the loop preemtable and also make
the string calculation more efficient by preallocating memory for it.
Message-Id: <20190516132748.6469-3-gleb@scylladb.com>
invoke_on_all() copies provided function for each shard it is executed
on, so by moving stats map into the capture we copy it for each shard
too. Avoid it by putting it into the top level object which is already
captured by reference.
Message-Id: <20190516132748.6469-2-gleb@scylladb.com>
Currently stop returns ready future immediately. This is not a problem
since calculation loop holds a shared pointer to the local service, so
it will not be destroyed until calculation completes and global database
object db, that also used by the calculation, is never destroyed. But the
later is just a workaround for a shutdown sequence that cannot handle
it and will be changed one day. Make cache hitrate calculation service
ready for it.
Message-Id: <20190422113538.GR21208@scylladb.com>
non_system_filter lambda is defined static which means it is initialized
only once, so the 'this' that is will capture will belong to a shard
where the function runs first. During service destruction the function
may run on different shard and access already other's shard service that
may be already freed.
Fixed#4425
Message-Id: <20190421152139.GN21208@scylladb.com>
This header, which is easily replaced with a forward declaration,
introduces a dependency on database.hh everywhere. Remove it and scatter
includes of database.hh in source files that really need it.
This patch introduces the view_update_backlog_broker class, which is
responsible for periodically updating the local gossip state with the
current node's view update backlog. It also registers to updates from
other nodes, and updates the local coordinator's view of their view
update backlogs.
We consider the view update backlog received from a peer through the
mutation_done verb to be always fresh, but we consider the one received
through gossip to be fresh only if it has a higher timestamp than what
we currently have recorded.
This is because a node only updates its gossip state periodically, and
also because a node can transitively receive gossip state about a third
node with outdated information.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
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.
