these warnings are found by Clang-17 after removing
`-Wno-unused-lambda-capture` and '-Wno-unused-variable' from
the list of disabled warnings in `configure.py`.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Move mutation-related files to a new mutation/ directory. The names
are kept in the global namespace to reduce churn; the names are
unambiguous in any case.
mutation_reader remains in the readers/ module.
mutation_partition_v2.cc was missing from CMakeLists.txt; it's added in this
patch.
This is a step forward towards librarization or modularization of the
source base.
Closes#12788
Said method calls `compact_mutation_state::start_new_page()` which
requires the kind of the next fragment in the reader. When there is no
fragment (reader is at EOS), we use partition-end. This was a poor
choice: if the reader is at EOS, partition-kind was the last fragment
kind, if the stream were to continue the next fragment would be a
partition-start.
When querier read page with tombstones more than `tombstone_warn_threshold` limit - warning message appeared in logs.
If `tombstone_warn_threshold:0` feature disabled.
Refs scylladb#11410
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>
Instead of a separate partition key and position-in-partition.
This continues the recently started effort to standardize storing of
full positions on `full_position`.
This patch is also a hidden preparation for read_context::save_readers()
multishard_mutation_query.cc) no longer being able to get partition key
from compaction state in the future.
This reverts commit c3bad157e5, reversing
changes made to e66809d051. The checks it
adds are triggered by some dtests. While it's possible the check is
triggered due to an existing problem, better to investigate it out-of-tree.
Fixes#11169.
Instead of a separate partition key and position-in-partition.
This continues the recently started effort to standardize storing of
full positions on `full_position`.
This patch is also a hidden preparation for read_context::save_readers()
multishard_mutation_query.cc) no longer being able to get partition key
from compaction state in the future.
Now that we use emit_only_live_rows::no everywhere we can remove this
template parameters. Only the template parameter is removed, the
internal logic around it is left in place (will be removed in a next
patch), by hard-wiring `only_live()`.
emit_only_live_rows is a convenience so downstream consumers of the
mutation compactors don't have to check the `bool is_live` already
passed to them. This convenience however causes a template parameter and
additional logic for the compactor. As the most prominent of these
consumers (the query result builder) will soon have to switch to
emit_only_live_rows::no for other reasons anyway (it will want to count
tombstones), we take the opportunity to switch everybody to ::no. This
can be done with very little additional complexity to these consumer --
basically an additional if or two.
This prepares the ground for removing this template parameter and the
associate logic from the compactor.
Soon, the currently two distinct types of queriers will be merged, as
the template parameter differentiating them will be gone. This will make
using type based overload for insert() impossible, as 2 out of the 3
types will be the same. Use different names instead.
The change is mostly mechanical: update all compactor instances to the
_v2 variant and update all call-sites, of which there is not that many.
As a consequence of this patch, queries -- both single-partition and
range-scans -- now do the v2->v1 conversion in the consumers, instead of
in the compactor.
Mostly mechanical transformation. The main difference is in the detached
compaction state, from which we now get the range tombstone change,
instead of the range tombstone list. The code around this is a bit
awkward, will become simpler when compactor drops v1 support.
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
The shard_mutation_querier is left using a v1 reader in its API as the
multishard query code is not ready yet. When saving this reader it is
upgraded to v2 and on lookup it is downgraded to v1. This should cancel
out thanks to upgrade/downgrade unwrapping.
Said wrapper was conceived to make unmovable `compact_mutation` because
readers wanted movable consumers. But `compact_mutation` is movable for
years now, as all its unmovable bits were moved into an
`lw_shared_ptr<>` member. So drop this unnecessary wrapper and its
unnecessary usages.
The reader_lifecycle_policy API was created around the idea of shard
readers (optionally) being saved and reused on the next page. To do
this, the lifecycle policy has to also be able to control the lifecycle
of by-reference parameters of readers: the slice and the range. This was
possible from day 1, as the readers are created through the lifecycle
policy, which can intercept and replace the said parameters with copies
that are created in stable storage. There was one whole in the design
though: fast-forwarding, which can change the range of the read, without
the lifecycle policy knowing about this. In practice this results in
fast-forwarded readers being saved together with the wrong range, their
range reference becoming stale. The only lifecycle implementation prone
to this is the one in `multishard_mutation_query.cc`, as it is the only
one actually saving readers. It will fast-forward its reader when the
query happens over multiple ranges. There were no problems related to
this so far because no one passes more than one range to said functions,
but this is incidental.
This patch solves this by adding an `update_read_range()` method to the
lifecycle policy, allowing the shard reader to update the read range
when being fast forwarded. To allow the shard reader to also have
control over the lifecycle of this range, a shared pointer is used. This
control is required because when an `evictable_reader` is the top-level
reader on the shard, it can invoke `create_reader()` with an edited
range after `update_read_range()`, replacing the fast-forwarded-to
range with a new one, yanking it out from under the feet of the
evictable reader itself. By using a shared pointer here, we can ensure
the range stays alive while it is the current one.
Push down reversing to the mutation-sources proper, instead of doing it
on the querier level. This will allow us to test reverse reads on the
mutation source level.
The `max_size` parameter of `consume_page()` is now unused but is not
removed in this patch, it will be removed in a follow-up to reduce
churn.
Add the content of the compaction stats introduced in the previous patch
to the tracing data. This will help diagnose query performance related
problems caused by tombstones.
We define the native reverse format as a reversed mutation fragment
stream that is identical to one that would be emitted by a table with
the same schema but with reversed clustering order. The main difference
to the current format is how range tombstones are handled: instead of
looking at their start or end bound depending on the order, we always
use them as-usual and the reversing reader swaps their bounds to
facilitate this. This allows us to treat reversed streams completely
transparently: just pass along them a reversed schema and all the
reader, compacting and result building code is happily ignorant about
the fact that it is a reversed stream.
The querier cache refuses to cache queriers that read in reverse. These
queriers are also not closed, with the caller having no way to determine
whether the querier it just moved into `insert()` needs a close
afterwards or not, requiring a `close()` on the moved-from querier just
to be sure.
Avoid this by consistently closing all passed-in queriers, including
those the cache refuses to save. For this, the internal
`insert_querier()` methods has to be made a member to be able to use the
closing gate.
Close the _closing_gate to wait on background
close of dropped queries, and close all remaining queriers.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Make sure to close the dropped querier before it's destroyed.
The operation is moved to the background so not to penelize
the common path.
A following patch will add a querier_cache::close() method
that will close _closing_gate to wait on the querier close
(among other things it needs to wait on :)).
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
In preparation to closing the querier in the background
before dropping it.
With that, stats need not be passed as a parameter,
but rather the _stats member can be used directly.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Depening on the variant _reader contents, either close
the reader or unregister the inactive reader and close it.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
We don't own _source therefore do not close it.
That said, we still need to make sure that the reversing reader
itself is closed to calm down the check when it's destroyed.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
"
Currently inactive readers are stored in two different places:
* reader concurrency semaphore
* querier cache
With the latter registering its inactive readers with the former. This
is an unnecessarily complex (and possibly surprising) setup that we want
to move away from. This series solves this by moving the responsibility
if storing of inactive reads solely to the reader concurrency semaphore,
including all supported eviction policies. The querier cache is now only
responsible for indexing queriers and maintaining relevant stats.
This makes the ownership of the inactive readers much more clear,
hopefully making Benny's work on introducing close() and abort() a
little bit easier.
Tests: unit(release, debug:v1)
"
* 'unify-inactive-readers/v2' of https://github.com/denesb/scylla:
reader_concurrency_semaphore: store inactive readers directly
querier_cache: store readers in the reader concurrency semaphore directly
querier_cache: retire memory based cache eviction
querier_cache: delegate expiry to the reader_concurrency_semaphore
reader_concurrency_semaphore: introduce ttl for inactive reads
querier_cache: use new eviction notify mechanism to maintain stats
reader_concurrency_semaphore: add eviction notification facility
reader_concurrency_semaphore: extract evict code into method evict()
The querier cache has a memory limit it enforces on cached queriers. For
determining how much memory each querier uses, it currently uses
`flat_mutation_reader::buffer_size()`. However, we now have a much more
complete accounting of the memory each read consumes, in the form of the
reader permit, which also happens to be handy in the queriers. So use it
instead of the not very well maintained `buffer_size()`.
Currently, we cannot select more than 2^32 rows from a table because we are limited by types of
variables containing the numbers of rows. This patch changes these types and sets new limits.
The new limits take effect while selecting all rows from a table - custom limits of rows in a result
stay the same (2^32-1).
In classes which are being serialized and used in messaging, in order to be able to process queries
originating from older nodes, the top 32 bits of new integers are optional and stay at the end
of the class - if they're absent we assume they equal 0.
The backward compatibility was tested by querying an older node for a paged selection, using the
received paging_state with the same select statement on an upgraded node, and comparing the returned
rows with the result generated for the same query by the older node, additionally checking if the
paging_state returned by the upgraded node contained new fields with correct values. Also verified
if the older node simply ignores the top 32 bits of the remaining rows number when handling a query
with a paging_state originating from an upgraded node by generating and sending such a query to
an older node and checking the paging_state in the reply(using python driver).
Fixes#5101.
We want to switch from using a single limit to a dual soft/hard limit.
As a first step we switch the limit field of `query_class_config` to use
the recently introduced type for this. As this field has a single user
at the moment -- reverse queries (and not a lot of propagation) -- we
update it in this same patch to use the soft/hard limit: warn on
reaching the soft limit and abort on the hard limit (the previous
behaviour).
The querier cache expects all querier objects it stores to have certain
methods. To avoid accessing these via `std::visit()` (the querier object
is stored in an `std::variant`), we move all the stuff that is common to
all querier types into a base class. The querier cache now accesses the
members via a reference to this common base. Additionally the variant is
eliminated completely and the cache entry stores an
`std::unique_ptr<querier_base>` instead.
Tests: unit(dev)
Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <20200603152544.83704-1-bdenes@scylladb.com>
Seastar recently lost support for the experimental Concepts Technical
Specification (TS) and gained support for C++20 concepts. Re-enable
concepts in Scylla by updating our use of concepts to the C++20
standard.
This change:
- peels off uses of the GCC6_CONCEPT macro
- removes inclusions of <seastar/gcc6-concepts.hh>
- replaces function-style concepts (no longer supported) with
equation-style concepts
- semicolons added and removed as needed
- deprecated std::is_pod replaced by recommended replacement
- updates return type constraints to use concepts instead of
type names (either std::same_as or std::convertible_to, with
std::same_as chosen when possible)
No attempt is made to improve the concepts; this is a specification
update only.
Message-Id: <20200531110254.2555854-1-avi@scylladb.com>
Currently the `querier_cache` is passed a semaphore during its
construction and it uses this semaphore to do all the inactive reader
registering/unregistering. This is inaccurate as in theory cached reads
could belong to different semaphores (although currently this is not yet
the case). As all queriers store a valid permit now, use this
permit to obtain the semaphore the querier is associated with, and
register the inactive read with this semaphore.
In preparation of a valid permit being required to be passed to all
mutation sources, create a permit before creating the shard readers and
pass it to the mutation source when doing so. The permit is also
persisted in the `shard_mutation_querier` object when saving the reader,
which is another forward looking change, to allow the querier-cache to
use it to obtain the semaphore the read is actually registered with.
In preparation of a valid permit being required to be passed to all
mutation sources, also add a permit to the querier object, which is then
passed to the source when it is used to create a reader.
