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.
Add flags if memtable contains tombstones. They can be used as a
heuristic to determine if a memtable should be compacted on
flush. It's an intermediate step until we can compact during applying
mutations on a memtable.
clang evaluates function arguments from left to right, while gcc does so
in reverse. Therefore, this code can be correct on clang and incorrect
on gcc:
```
f(x.sth(), std::move(x))
```
This patch fixes one such instance of this bug, in memtable.cc.
Fixes#9605.
Closes#9606
This commit consists of changes, which need to reside in a single
commit, so that the tests pass on each of the commits.
1. Remove do_make_flat_reader which disabled reverse reads by making the
slice a forward one. Remove call to get_ranges which would do
superfluous reversal of clustering ranges.
2. test: cql_query_test: remove expectation that the test_query_limit
fails for reversed queries, since reversed queries no longer require
linear memory wrt. the result size, when paginated.
In this commit, I add the ability to read from partition snapshots in
reverse order. Before these changes, a reverse read from memtable has
been handled as follows:
- A reader higher in the hierarchy of readers performs a read from
memtable in the forward order, which is not aware of the intention to
read in reverse.
- Later, some reader reverses the received mutation fragments.
Memtable decides based on options in `slice`, whether to read forward
or in reverse. Note that previous commit creates a killswitch which
clears the `reverse` option from slice before running the logic of
whether to reverse or not. This is due to the fact, that this commit
doesn't all the required code changes.
The reversing partition snapshot reader maintains two schemas - one that
is the reversed schema (called _query_schema) for the output, and the
other one (forward one, called _snapshot_schema), which is used to
access the memtable tree (which needs to be the same as the schema used
to create memtable).
The `partition_slice` provided by callers is provided in 'half-reversed'
format for reversed queries, where the order of clustering ranges is
reversed, but the ranges themselves are not.
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.
Currently all the code operates on the range_tombstone class.
and many of those places get the range tombstone in question
from the range_tombstone_list. Next patches will make that list
carry (and return) some new object called range_tombstone_entry,
so all the code that expects to see the former one there will
need to patched to get the range_tombstone from the _entry one.
This patch prepares the ground for that by introdusing the
range_tombstone& tombstone() { return *this; }
getter on the range_tombstone itself and patching all future
users of the _entry to call .tombstone() right now.
Next patch will remove those getters together with adding the new
range_tombstone_entry object thus automatically converting all
the patched places into using the entry in a proper way.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Get rid of unused includes of seastar/util/{defer,closeable}.hh
and add a few that are missing from source files.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
It is actually `partition_snapshot_flush_accounter`, as opposed to
`partition_snapshot_read_accounter`.
Signed-off-by: Michael Livshin <michael.livshin@scylladb.com>
Close _delegate if it's engaged both in the close() method
and when ever it is currently reset by _delegate = {}.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Unlike flat_mutation_reader_opt that is defined using
optimized_optional<flat_mutation_reader>, std::optional<T> does not evaluate
to `false` after being moved, only after it is explicitly reset.
Use flat_mutation_reader_opt rather than std::optional<flat_mutation_reader>
to make it easier to check if it was closed before it's destroyed
or being assigned-over.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Message-Id: <20210215101254.480228-6-bhalevy@scylladb.com>
The main motivation for this patchset is to prepare
for adding a async close() method to flat_mutation_reader.
In order to close the reader before destroying it
in all paths we need to make next_partition asynchronous
so it can asynchronously close a current reader before
destoring it, e.g. by reassignment of flat_mutation_reader_opt,
as done in scanning_reader::next_partition.
Test: unit(release, debug)
* git@github.com:bhalevy/scylla.git futurize-next-partition-v1:
flat_mutation_reader: return future from next_partition
multishard_mutation_query: read_context: save_reader: destroy reader_meta from the calling shard
mutation_reader: filtering_reader: fill_buffer: futurize inner loop
flat_mutation_reader::impl: consumer_adapter: futurize handle_result
flat_mutation_reader: consume_pausable/in_thread: futurize_invoke consumer
flat_mutation_reader: FlatMutationReaderConsumer: support also async consumer
flat_mutation_reader:impl: get rid of _consume_done member
This is a revival of #7490.
Quoting #7490:
The managed_bytes class now uses implicit linearization: outside LSA, data is never fragmented, and within LSA, data is linearized on-demand, as long as the code is running within with_linearized_managed_bytes() scope.
We would like to stop linearizing managed_bytes and keep it fragmented at all times, since linearization can require large contiguous chunks. Large contiguous allocations are hard to satisfy and cause latency spikes.
As a first step towards that, we remove all implicitly linearizing accessors and replace them with an explicit linearization accessor, with_linearized().
Some of the linearization happens long before use, by creating a bytes_view of the managed_bytes object and passing it onwards, perhaps storing it for later use. This does not work with with_linearized(), which creates a temporary linearized view, and does not work towards the longer term goal of never linearizing. As a substitute a managed_bytes_view class is introduced that acts as a view for managed_bytes (for interoperability it can also be a view for bytes and is compatible with bytes_view).
By the end of the series, all linearizations are temporary, within the scope of a with_linearized() call and can be converted to fragmented consumption of the data at leisure.
This has limited practical value directly, as current uses of managed_bytes are limited to keys (which are limited to 64k). However, it enables converting the atomic_cell layer back to managed_bytes (so we can remove IMR) and the CQL layer to managed_bytes/managed_bytes_view, removing contiguous allocations from the coordinator.
Closes#7820
* github.com:scylladb/scylla:
test: add hashers_test
memtable: fix accounting of managed_bytes in partition_snapshot_accounter
test: add managed_bytes_test
utils: fragment_range: add a fragment iterator for FragmentedView
keys: update comments after changes and remove an unused method
mutation_test: use the correct preferred_max_contiguous_allocation in measuring_allocator
row_cache: more indentation fixes
utils: remove unused linearization facilities in `managed_bytes` class
misc: fix indentation
treewide: remove remaining `with_linearized_managed_bytes` uses
memtable, row_cache: remove `with_linearized_managed_bytes` uses
utils: managed_bytes: remove linearizing accessors
keys, compound: switch from bytes_view to managed_bytes_view
sstables: writer: add write_* helpers for managed_bytes_view
compound_compat: transition legacy_compound_view from bytes_view to managed_bytes_view
types: change equal() to accept managed_bytes_view
types: add parallel interfaces for managed_bytes_view
types: add to_managed_bytes(const sstring&)
serializer_impl: handle managed_bytes without linearizing
utils: managed_bytes: add managed_bytes_view::operator[]
utils: managed_bytes: introduce managed_bytes_view
utils: fragment_range: add serialization helpers for FragmentedMutableView
bytes: implement std::hash using appending_hash
utils: mutable_view: add substr()
utils: fragment_range: add compare_unsigned
utils: managed_bytes: make the constructors from bytes and bytes_view explicit
utils: managed_bytes: introduce with_linearized()
utils: managed_bytes: constrain with_linearized_managed_bytes()
utils: managed_bytes: avoid internal uses of managed_bytes::data()
utils: managed_bytes: extract do_linearize_pure()
thrift: do not depend on implicit conversion of keys to bytes_view
clustering_bounds_comparator: do not depend on implicit conversion of keys to bytes_view
cql3: expression: linearize get_value_from_mutation() eariler
bytes: add to_bytes(bytes)
cql3: expression: mark do_get_value() as static
managed_bytes has a small overhead per each fragment. Due to that, managed_bytes
containing the same data can have different total memory usage in different
allocators. The smaller the preferred max allocation size setting is, the more
fragments are needed and the greater total per-fragment overhead is.
In particular, managed_bytes allocated in the LSA could grow in
memory usage when copied to the standard allocator, if the standard allocator
had a preferred max allocation setting smaller than the LSA.
partition_snapshot_accounter calculates the amount of memory used by
mutation fragments in the memtable (where they are allocated with LSA) based
on the memory usage after they are copied to the standard allocator.
This could result in an overestimation, as explained above.
But partition_snapshot_accounter must not overestimate the amount of freed
memory, as doing otherwise might result in OOM situations.
This patch prevents the overaccounting by adding minimal_external_memory_usage():
a new version of external_memory_usage(), which ignores allocator-dependent
overhead. In particular, it includes the per-fragment overhead in managed_bytes
only once, no matter how many fragments there are.
The patch fixes indentation issues introduced in previous patches
related to removing `with_linearized_managed_bytes` uses from the
code tree.
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
Since `managed_bytes::data()` is deleted as well as other public
APIs of `managed_bytes` which would linearize stored values except
for explicit `with_linearized`, there is no point
invoking `with_linearized_managed_bytes` hack which would trigger
automatic linearization under the hood of managed_bytes.
Remove useless `with_linearized_managed_bytes` wrapper from
memtable and row_cache code.
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
Tracking both min and max timestamp will be required for memtable flush
to short-circuit interposer consumer if needed.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Require a schema and an operation name to be given to each permit when
created. The schema is of the table the read is executed against, and
the operation name, which is some name identifying the operation the
permit is part of. Ideally this should be different for each site the
permit is created at, to be able to discern not only different kind of
reads, but different code paths the read took.
As not all read can be associated with one schema, the schema is allowed
to be null.
The name will be used for debugging purposes, both for coredump
debugging and runtime logging of permit-related diagnostics.
The main user of this method, the one which required this method to
return the collective buffer size of the entire reader tree, is now
gone. The remaining two users just use it to check the size of the
reader instance they are working with.
So de-virtualize this method and reduce its responsibility to just
returning the buffer size of the current reader instance.
Not used yet, this patch does all the churn of propagating a permit
to each impl.
In the next patch we will use it to track to track the memory
consumption of `_buffer`.
The change is the same as with row-cache -- use B+ with int64_t token
as key and array of memtable_entry-s inside it.
The changes are:
Similar to those for row_cache:
- compare() goes away, new collection uses ring_position_comparator
- insertion and removal happens with the help of double_decker, most
of the places are about slightly changed semantics of it
- flags are added to memtable_entry, this makes its size larger than
it could be, but still smaller than it was before
Memtable-specific:
- when the new entry is inserted into tree iterators _might_ get
invalidated by double-decker inner array. This is easy to check
when it happens, so the invalidation is avoided when possible
- the size_in_allocator_without_rows() is now not very precise. This
is because after the patch memtable_entries are not allocated
individually as they used to. They can be squashed together with
those having token conflict and asking allocator for the occupied
memory slot is not possible. As the closest (lower) estimate the
size of enclosing B+ data node is used
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
All reader are soon going to require a valid permit, so make sure we
have a valid permit which we can pass to the delegate reader when
creating it. This means `memtable::make_flat_reader()` now also requires
a permit to be passed to it.
Internally the permit is stored in `scanning_reader`, which is used both
for flushes and normal reads. In the former case a permit is not
required.
We typically use `std::bad_function_call` to throw from
mandatory-to-implement virtual functions, that cannot have a meaningful
implementation in the derived class. The problem with
`std::bad_function_call` is that it carries absolutely no information
w.r.t. where was it thrown from.
I originally wanted to replace `std::bad_function_call` in our codebase
with a custom exception type that would allow passing in the name of the
function it is thrown from to be included in the exception message.
However after I ended up also including a backtrace, Benny Halevy
pointed out that I might as well just throw `std:bad_function_call` with
a backtrace instead. So this is what this patch does.
All users are various unimplemented methods of the
`flat_mutation_reader::impl` interface.
Signed-off-by: Botond Dénes <bdenes@scylladb.com>
Message-Id: <20200408075801.701416-1-bdenes@scylladb.com>
and replace all dht::global_partitioner().decorate_key
with dht::decorate_key
It is an improvement because dht::decorate_key takes schema
and uses it to obtain partitioner instead of using global
partitioner as it was before.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
The former was never really more than a reader_permit with one
additional method. Currently using it doesn't even save one from any
includes. Now that readers will be using reader_permit we would have to
pass down both to mutation_source. Instead get rid of
reader_resource_tracker and just use reader_permit. Instead of making it
a last and optional parameter that is easy to ignore, make it a
first class parameter, right after schema, to signify that permits are
now a prominent part of the reader API.
This -- mostly mechanical -- patch essentially refactors mutation_source
to ask for the reader_permit instead of reader_resource_tracking and
updates all usage sites.
Adds per-table metrics for counting partition and row reuse
in memtables. New metrics are as follows:
- memtable_partition_writes - number of write operations performed
on partitions in memtables,
- memtable_partition_hits - number of write operations performed
on partitions that previously existed in a memtable,
- memtable_row_writes - number of row write operations performed
in memtables,
- memtable_row_hits - number of row write operations that ovewrote
rows previously present in a memtable.
Tests: unit(release)
`collection_type_impl::serialize_mutation_form`
became `collection_mutation(_view)_description::serialize`.
Previously callers had to cast their data_type down to collection_type
to use serialize_mutation_form. Now it's done inside `serialize`.
In the future `serialize` will be generalized to handle UDTs.
`collection_type_impl::deserialize_mutation_form`
became a free standing function `deserialize_collection_mutation`
with similiar benefits. Actually, noone needs to call this function
manually because of the next paragraph.
A common pattern consisting of linearizing data inside a `collection_mutation_view`
followed by calling `deserialize_mutation_form` has been abstracted out
as a `with_deserialized` method inside collection_mutation_view.
serialize_mutation_form_only_live was removed,
because it hadn't been used anywhere.
Merged patch series from Avi Kivity:
The static row can be rare: many tables don't have them, and tables
that do will often have mutations without them (if the static row
is rarely updated, it may be present in the cache and in readers,
but absent in memtable mutations). However, it always consumes ~100
bytes of memory, even if it not present, due to row's overhead.
Change it to be optional by allocating it as an external object rather
than inlined into mutation_partition. This adds overhead when the
static row is present (17 bytes for the reference, back reference,
and lsa allocator overhead).
perf_simple_query appears to marginally (2%) faster. Footprint is
reduced by ~9% for a cache entry, 12% in memtables. More details are
provided in the patch commitlog.
Tests: unit (debug)
Avi Kivity (4):
managed_ref: add get() accessor
managed_ref: add external_memory_usage()
mutation_partition: introduce lazy_row
mutation_partition: make static_row optional to reduce memory
footprint
cell_locking.hh | 2 +-
converting_mutation_partition_applier.hh | 4 +-
mutation_partition.hh | 284 ++++++++++++++++++++++-
partition_builder.hh | 4 +-
utils/managed_ref.hh | 12 +
flat_mutation_reader.cc | 2 +-
memtable.cc | 2 +-
mutation_partition.cc | 45 +++-
mutation_partition_serializer.cc | 2 +-
partition_version.cc | 4 +-
tests/multishard_mutation_query_test.cc | 2 +-
tests/mutation_source_test.cc | 2 +-
tests/mutation_test.cc | 12 +-
tests/sstable_mutation_test.cc | 10 +-
14 files changed, 355 insertions(+), 32 deletions(-)
The static row can be rare: many tables don't have them, and tables
that do will often have mutations without them (if the static row
is rarely updated, it may be present in the cache and in readers,
but absent in memtable mutations). However, it always consumes ~100
bytes of memory, even if it not present, due to row's overhead.
Change it to be optional by using lazy_row instead of row. Some call
sites treewide were adjusted to deal with the extra indirection.
perf_simple_query appears to improve by 2%, from 163krps to 165 krps,
though it's hard to be sure due to noisy measurements.
memory_footprint comparisons (before/after):
mutation footprint: mutation footprint:
- in cache: 1096 - in cache: 992
- in memtable: 854 - in memtable: 750
- in sstable: 351 - in sstable: 351
- frozen: 540 - frozen: 540
- canonical: 827 - canonical: 827
- query result: 342 - query result: 342
sizeof(cache_entry) = 112 sizeof(cache_entry) = 112
-- sizeof(decorated_key) = 36 -- sizeof(decorated_key) = 36
-- sizeof(cache_link_type) = 32 -- sizeof(cache_link_type) = 32
-- sizeof(mutation_partition) = 200 -- sizeof(mutation_partition) = 96
-- -- sizeof(_static_row) = 112 -- -- sizeof(_static_row) = 8
-- -- sizeof(_rows) = 24 -- -- sizeof(_rows) = 24
-- -- sizeof(_row_tombstones) = 40 -- -- sizeof(_row_tombstones) = 40
sizeof(rows_entry) = 232 sizeof(rows_entry) = 232
sizeof(lru_link_type) = 16 sizeof(lru_link_type) = 16
sizeof(deletable_row) = 168 sizeof(deletable_row) = 168
sizeof(row) = 112 sizeof(row) = 112
sizeof(atomic_cell_or_collection) = 8 sizeof(atomic_cell_or_collection) = 8
Tests: unit (dev)
Replace stdx::optional and stdx::string_view with the C++ std
counterparts.
Some instances of boost::variant were also replaced with std::variant,
namely those that called seastar::visit.
Scylla now requires GCC 8 to compile.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20190108111141.5369-1-duarte@scylladb.com>
Single-partition reader is less expensive than the one that accepts any
range of partitions, but it doesn't support fast-forwarding to another
partition range properly and therefore cannot be used if that option is
enabled.
After the new in-memory representation of cells was introduced there was
a regression in atomic_cell_or_collection::operator<< which stopped
printing the content of the cell. This makes debugging more incovenient
are time-consuming. This patch fixes the problem. Schema is propagated
to the atomic_cell_or_collection printer and the full content of the
cell is printed.
Fixes#3571.
Message-Id: <20181024095413.10736-1-pdziepak@scylladb.com>
