The only user is the tests of downgrade_to_v1(), which uses it through
mutation source. To avoid any new users popping up, we make it a private
method of the latter. In the process the pass-through optimization is
dropped, it is not needed for tests anyway.
The only user is row level repair: it is replaced with
downgrade_to_v1(make_empty_flat_reader_v2()). The row level reader has
lots of downgrade_to_v1() calls, we will deal with these later all at
once.
Another use is the empty mutation source, this is trivially converted to
use the v2 variant.
"
cache_flat_mutation_reader gets a native v2 implementation. The
underlying mutation representation is not changed: range deletions are
still stored as v1 range_tombstones in mutation_partition. These are
converted to range tombstone changes during reading.
This allows for separating the change of a native v2 reader
implementation and a native v2 in-memory storage format, enabling the
two to be done at separate times and incrementally.
This means there is still conversion ingoing when reading from cache and
when populating, but when reading from underlying, the stream can now be
passed through as-is without conversions.
Also, any future v2 related changes to the in-memory storage will now be
limited to the cache reader implementation itself.
In the process, the non-forwarding reader, whose only user is the cache,
is also converted to v2.
"
Performance results reported by Botond:
"
build/release/test/perf/perf_simple_query -c1 -m2G --flush --
duration=20
BEFORE
median 130421.76 tps ( 71.1 allocs/op, 12.1 tasks/op, 47462
insns/op)
median absolute deviation: 319.64
maximum: 131028.33
minimum: 127502.55
AFTER
median 133297.41 tps ( 64.1 allocs/op, 12.2 tasks/op, 45406
insns/op)
median absolute deviation: 2964.24
maximum: 137581.56
minimum: 123739.4
Getting rid of those upgrade/downgrade was good for allocs and ops.
Curiously there is a 0.1 rise in number of tasks though.
"
* 'row-cache-readers-v2/v1' of https://github.com/denesb/scylla:
row_cache: update reader implementations to v2
range_tombstone_change_generator: flush(): add end_of_range
readers/nonforwardable: convert to v2
read_context: fix indentation
read_context: coroutinize move_to_next_partition()
row_cache: cache_entry::read(): return v2 reader
row_cache: return v2 readers from make_reader*()
readers/delegating_v2: s/make_delegating_reader_v2/make_delegating_reader/
It has a single user, the row cache, which for now has to
upgrade/downgrade around the nonforwardable reader, but this will go
away in the next patches when the row cache readers are converted to v2
proper.
Extract the common parts of the single mutation reader
and the vector-based variant into mutation_reader_base
and reuse from both readers.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
slice_mutations() is currently used only by readers/mutation_readers.cc
so there's no need to expose it.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
There are at least 1 actual and 1 potential users for it; this
change converts the existing one.
Signed-off-by: Michael Livshin <michael.livshin@scylladb.com>
"
First migrate all users to the v2 variant, all of which are tests.
However, to be able to properly migrate all tests off it, a v2 variant
of the restricted reader is also needed. All restricted reader users are
then migrated to the freshly introduced v2 variant and the v1 variant is
removed.
Users include:
* replica::table::make_reader_v2()
* streaming_virtual_table::as_mutation_source()
* sstables::make_reader()
* tests
This allows us to get rid of a bunch of conversions on the query path,
which was mostly v2 already.
With a few tests we did kick the can down the road by wrapping the v2
reader in `downgrade_to_v1()`, but this series is long enough already.
Tests: unit(dev), unit(boost/flat_mutation_reader_test:debug)
"
* 'remove-reader-from-mutations-v1/v3' of https://github.com/denesb/scylla:
readers: remove now unused v1 reader from mutations
test: move away from v1 reader from mutations
test/boost/mutation_reader_test: use fragment_scatterer
test/boost/mutation_fragment_test: extract fragment_scatterer into a separate hh
test/boost: mutation_fragment_test: refactor fragment_scatterer
readers: remove now unused v1 reversing reader
test/boost/flat_mutation_reader_test: convert to v2
frozen_mutation: fragment_and_freeze(): convert to v2
frozen_mutation: coroutinize fragment_and_freeze()
readers: migrate away from v1 reversing reader
db/virtual_table: use v2 variant of reversing and forwardable readers
replica/table: use v2 variant of reversing reader
sstables/sstable: remove unused make_crawling_reader_v1()
sstables/sstable: remove make_reader_v1()
readers: add v2 variant of reversing reader
readers/reversing: remove FIXME
readers: reader from mutations: use mutation's own schema when slicing
The only internal user is the v1 make reader from mutations, we use a
downgrade/upgrade to be able to use the v2 reversing reader there. This
is ugly but the v1 reader from mutations is going away soon too, so not
a real problem.
The v2 format allows for a much simpler reversing mechanism since
clustering fragments can simply be reversed as they are read. Fragments
are directly pushed in the reader's buffer eliminating a separate move
phase.
Existing reverse reader unit tests are converted to test the v2 one.
Instead of the schema that is used for the reader. The schema of
individual mutations might be different (albeit compatible) and in debug
mode this can trigger an assert in mutation partition.
By folding the former to the latter. Now that all the readers are nicely
co-located in the same folder, no point in having two distinct logger
for them.
In most files it was unused. We should move these to the patch which
moved out the last interesting reader from mutation_reader.hh (and added
the corresponding new header include) but its probably not worth the
effort.
Some other files still relied on mutation_reader.hh to provide reader
concurrency semaphore and some other misc reader related definitions.
"
The only real user is view building, which is converted to v2 and then
the v1 version of the mutation from fragments reader is removed.
Tests: unit(dev, release)
"
* 'v2-only-from-fragments-mutations/v1' of https://github.com/denesb/scylla:
readers: remove now unused v1 reader from fragments
test/boost: flat_mutation_reader_test: remove reader from fragments test
replica/table: migrate generate_and_propagate_view_updates() to v2
replica/table: migrate populate_views() to v2
db/view: convert view_update_builder interface to v2
db/view: migrate view_update_builder to v2
Adaptor converts the
`noncopyable_function<future<mutation_fragment_opt>>` to the v2
equivalent, so we can have a single generating reader implementation.
The adaptor uses the upgrading_consumer reusable upgrade component to
implement the actual upgrade.
std::function<> requires the functor it wraps to be copyable, which is
an unnecessarily strict requirement. To relax this, we use
noncopyable_function<> instead. Since the former seems to lack some
disambiguation magic of the latter, we add `_v1` and `_v2` postfixes to
manually disambiguate.
The flat_mutation_reader files were conflated and contained multiple
readers, which were not strictly necessary. Splitting optimizes both
iterative compilation times, as touching rarely used readers doesn't
recompile large chunks of codebase. Total compilation times are also
improved, as the size of flat_mutation_reader.hh and
flat_mutation_reader_v2.hh have been reduced and those files are
included by many file in the codebase.
With changes
real 29m14.051s
user 168m39.071s
sys 5m13.443s
Without changes
real 30m36.203s
user 175m43.354s
sys 5m26.376s
Closes#10194
