"Histograms are used to collect latency information, in Origin, many of the
operations are timed, this is a potential performance issue. This series adds
an option to sample the operations, where small amount will be timed and the
most will only be counted.
This will give an estimation for the statistics, while keeping an accurate
count of the total events and have neglectible performance impact.
The first to use the modified histogram are the column family for their read
and write."
Conflicts:
database.hh
We can catch most errors when we try to load an sstable. But if the TOC file is
the one missing, we won't try to load the sstable at all. This case is still an
invalid case, but it is way easier for us to treat it by waiting for all files
to be loaded, and then checking if we saw a file during scan_dir, without its
corresponding TOC.
Fixes#114
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Currently, each column family creates a fiber to handle compaction requests
in parallel to the system. If there are N column families, N compactions
could be running in parallel, which is definitely horrible.
To solve that problem, a per-database compaction manager is introduced here.
Compaction manager is a feature used to service compaction requests from N
column families. Parallelism is made available by creating more than one
fiber to service the requests. That being said, N compaction requests will
be served by M fibers.
A compaction request being submitted will go to a job queue shared between
all fibers, and the fiber with the lowest amount of pending jobs will be
signalled.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
With the use of sparse histogram, the read and write counters in the
column_family stats can be used.
The total impact on performanc should be neglectible.
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
ASan does not like commit 05c23c7f73
("database: Add create_keyspace_on_all() helper"):
==8112==WARNING: AddressSanitizer failed to allocate 0x7f88b84fc690 bytes
==8112==AddressSanitizer's allocator is terminating the process instead of returning 0
==8112==If you don't like this behavior set allocator_may_return_null=1
==8112==Sanitizer CHECK failed: ../../../../libsanitizer/sanitizer_common/sanitizer_allocator.cc:147 ((0)) != (0) (0, 0)
I was not able to determine the source of the bug. Make ASan happy by
reverting the code movement and using the "cpu zero" trick we use for
table creation.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Add a create_keyspace_on_all() helper which is needed for sending just
one event notification per created keyspace, not one per shard.
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
"This series improves parallel CQL table creation to validate CF UUID.
This should bring us closer to Origin behavior when there's multiple
cassandra-stress processes started at the same time."
This adds the stats object to column_family.
It set the write counter in the write path and support the pending_flush
counter.
The stats object contains information for switch_count, number of
pending flushes, and counters for read, write, and range.
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
Abillity to enable/disable specific sub-modules - this settings do not
affect system tables which are allways persisted,cached and written to
commitlog
enable-in-memory-data-store marks if tables will be written/read to/from
disk
enable-commitllog marks if tables will be written to commitlog
enable-cache marks if tables will be written/read to/from cache
Please note in-memory-data-store does not change the read path so "old"
sstables are still read and cache may be used to cache their data
Signed-off-by: Shlomi Livne <shlomi@cloudius-systems.com>
So far, automatic compaction was disabled, but now that we support
size-tiered strategy, the default compaction strategy algorithm,
we could definitely enable automatic compaction by default.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Currently, compaction will no longer happen for a column family which
a compaction failed for some unexpected reason.
We want to implement a retry policy that will sleep for a while until
the next compaction attempt. This patch implements retry policy for
compaction using exponential_backoff_retry.
With exponential_backoff_retry, the sleep time grows exponentially
with the number of retries until the maximum sleep time is reached.
For compaction specifically, the base sleep time will be 5 seconds and
the maximum sleeping time will be 300 seconds, i.e. 5 minutes.
If compaction succeeded after a retry, the sleep time will be reset to
the base sleep time.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
We must wait for the system tables to be loaded on all shards before
populating the other keyspaces, or we might miss some keyspaces or column
families. This is hinted at by the fact that we use storage_proxy, which
isn't usable until the system keyspace is ready.
Credit to Tomek for identifying the problem and the fix.
compact_all_sstables is about selecting all available sstables
for compaction and executing a compaction code on them.
This compaction code was moved to a more generic function called
compact_sstables, which will compact a list of given sstables.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
As the name implies, this patch introduces the concept of automatic
compaction for sstables.
Compaction task is triggered whenever a new sstable is written.
Concurrent compaction on the same column family isn't supported, so
compaction may be postponed if there is an ongoing compression.
In addition, seastar::gate is used both to prevent a new compaction
from starting and to wait for an ongoing compaction to finish, when
the system is asked for a shutdown.
This patch also introduces an abstract class for compaction strategy,
which is really useful for supporting multiple strategies.
Currently, null and major compaction strategies are supported.
As the name implies, null compaction strategy does nothing.
Major compaction strategy is about compacting all sstables into one.
This strategy may end up being helpful when adding support to major
compaction via nodetool.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
It should not be called directly: externall callers should be calling flush()
instead.
To be sure it doesn't happen again, make seal_active_memtable private.
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
In much of our column_families APIs, we need to pass a pointer to the database.
The only reason we do that, is so we can properly handle the commit log entries
after we seal the current memtables into sstables.
Now that we store a pointer to the commit log in the CF itself at the time it
is created, we no longer have to do it. As a result, the APIs are a lot
cleaner, with no gratuitous parameters.
My motivation for this was the flush method, but as a result, apply() also gets
cleaner.
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
When we create a column family, we can pass as an extra parameter, the
commitlog - or lack thereof. Because the commitlog is optional to begin with -
it won't exist if we don't call init_commitlog, we can have this to be empty
meaning no commit log.
The creation of a column family should be always done through
add_column_family. And if that is the case, we have the database's commitlog
right there and can get the pointer through the db. Only tests are not creating
the column family this way, and for them, it is fine.
We want to do that, because some column family operations will use the commit log.
Right now, they are forcing us to add parameters to APIs that would be much cleaner
without it. So while separation is good, this level of coupling is a net win as it
allows us to clean up some visible APIs.
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Mutation query differs from data query in that returns information
needed to reconcile data slice with that retruned by other data
sources.
There is a generic mutation_query() algorithm introduced, which can
work with any mutation_source.
database::query_mutations() is a shard-local interface for mutation
queries.
The reconcilable_result is introduced as a medium for mutation query
results. It piggy backs on frozen_mutation as a medium for
reconcilable data.
We will have to flush it from other places as well, so wrap the flushing code
into a method - specially because the current code has issues and it will be
easier to deal with it if it is in a single place.
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
This patch bootstraps the keyspaces found in system sstables and make
our in-memory structures reflect them. It tries to reuse as much code
as we can from db::legacy_system_tables, but keeping everything local
and without applying any mutations to the database - since the latter
would only unnecessarily complicate the write path.
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
In order for us to call some function from db::legacy_schema_tables, we need
a working storage proxy. We will use those functions in order to leverage the
work done in keyspace / table creation from mutations
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
get_config returns a const reference to the configuration object inside
the database object because it returns a const referent it could be
const. This is helpful when the call is made from a const reference to the
database.
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
This is an example of how to use the low-level compact_sstable() function
to compact all the sstables of one column family into one. It is not a
full-fledged "compaction strategy" but the real ones can be based on this
example.
Among the things that this code doesn't do yet is to delete the old
sstables. In the future, this should happen automatically in the sstable
destructor when all the references to the sstable get deleted.
Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
There is only one user in tree, and as Tomek pointed out, it is buggy. The
reason is that ksm is a shard-local structure, and it is currently used
indiscriminately by all shards which can easily lead to problems.
We could fix it with some tricks, but it is way better and safer to make sure
the callers are doing it right instead. There is only one caller, so let's fix
that.
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
"This is the current patchset to flush and persist schema changes to disk.
It is not perfect, in the sense that older changes still in flight won't be
waited for. But as we discussed - at this moment we'll just note that, and
leave the fix for later"
By doing this, it is possible to synchronously wait for the seal to complete by
waiting on this future. This is useful in situations where we want to
synchronously flush data to disk.
Existing callers will not be patched, and this keeps their current behavior,
alas, asynchronously initiating a write, is preserved.
TODO: A better interface would guarantee that all writes before this one are
also complete
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
Snitch class semantics defined to be per-Node. To make it so we
introduce here a static member in an i_endpoint_snitch class that
has to contain the pointer to the relevant snitch class instance.
Since the snitch contents are not always pure const it has to be per
shard, therefore we'll make it a "distributed". All the I/O is going
to take place on a single shard and if there are changes - they are going
to be propagated to the rest of the shards.
The application is responsible to initialize this distributed<shnitch>
before it's used for the first time.
This patch effectively reverts most of the "locator: futurize
snitch creation" a2594015f9 patch - the part that modifies the
code that was creating the snitch instance. Since snitch is
created explicitly by the application and all the rest of the code
simply assumes that the above global is initialized we won't need
all those changes any more and the code will get back to be nice and simple
as it was before the patch above.
So, to summarize, this patch does the following:
- Reverts the changes introduced by a2594015f9 related to the fact that
every time a replication strategy was created there should have been created
a snitch that would have been stored in this strategy object. More specifically,
methods like keyspace::create_replication_strategy() do not return a future<>
any more and this allows to simplify the code that calls it significantly.
- Introduce the global distributed<snitch_ptr> object:
- It belongs to the i_endpoint_snitch class.
- There has been added a corresponding interface to access both global and
shard-local instances.
- locator::abstract_replication_strategy::create_replication_strategy() does
not accept snitch_ptr&& - it'll get and pass the corresponding shard-local
instance of the snitch to the replication strategy's constructor by itself.
- Adjusted the existing snitch infrastructure to the new semantics:
- Modified the create_snitch() to create and start all per-shard snitch
instances and update the global variable.
- Introduced a static i_endpoint_snitch::stop_snitch() function that properly
stops the global distributed snitch.
- Added the code to the gossiping_property_file_snitch that distributes the
changed data to all per-shard snitch objects.
- Made all existing snitches classes properly maintain their state in order
to be able to shut down cleanly.
- Patched both urchin and cql_query_test to initialize a snitch instance before
all other services.
Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
New in v6:
- Rebased to the current master.
- Extended a commit message a little - the summary.
New in v5:
- database::create_keyspace(): added a missing _keyspaces.emplace()
New in v4:
- Kept the database::create_keyspace() to return future<> by Glauber's request
and added a description to this method that needs to be changed when Glauber
adds his bits that require this interface.
To support initialization of system tables keyspace replication_strategy
without the need of having snitch creation.
Signed-off-by: Shlomi Livne <shlomi@cloudius-systems.com>
We need to do that in order to close the database cleanly, flushing all pending
data before we do.
Signed-off-by: Glauber Costa <glommer@cloudius-systems.com>
This change abstracts reading from on-disk data sources behind a single
reader which is then composed with memtable readers. This change also
abstracts all data sources behind a single reader obtained via
column_family::make_reader(). That reader is then used by algorithms
like column_family::for_all_partitions() or
column_family::query(). Having those abstractions will make it easier
to add row cache, because it will be encapsulated in a single place.
