before this change, we rely on `using namespace seastar` to use
`seastar::format()` without qualifying the `format()` with its
namespace. this works fine until we changed the parameter type
of format string `seastar::format()` from `const char*` to
`fmt::format_string<...>`. this change practically invited
`seastar::format()` to the club of `std::format()` and `fmt::format()`,
where all members accept a templated parameter as its `fmt`
parameter. and `seastar::format()` is not the best candidate anymore.
despite that argument-dependent lookup (ADT for short) favors the
function which is in the same namespace as its parameter, but
`using namespace` makes `seastar::format()` more competitive,
so both `std::format()` and `seastar::format()` are considered
as the condidates.
that is what is happening scylladb in quite a few caller sites of
`format()`, hence ADT is not able to tell which function the winner
in the name lookup:
```
/__w/scylladb/scylladb/mutation/mutation_fragment_stream_validator.cc:265:12: error: call to 'format' is ambiguous
265 | return format("{} ({}.{} {})", _name_view, s.ks_name(), s.cf_name(), s.id());
| ^~~~~~
/usr/bin/../lib/gcc/x86_64-redhat-linux/14/../../../../include/c++/14/format:4290:5: note: candidate function [with _Args = <const std::basic_string_view<char> &, const seastar::basic_sstring<char, unsigned int, 15> &, const seastar::basic_sstring<char, unsigned int, 15> &, const utils::tagged_uuid<table_id_tag> &>]
4290 | format(format_string<_Args...> __fmt, _Args&&... __args)
| ^
/__w/scylladb/scylladb/seastar/include/seastar/core/print.hh:143:1: note: candidate function [with A = <const std::basic_string_view<char> &, const seastar::basic_sstring<char, unsigned int, 15> &, const seastar::basic_sstring<char, unsigned int, 15> &, const utils::tagged_uuid<table_id_tag> &>]
143 | format(fmt::format_string<A...> fmt, A&&... a) {
| ^
```
in this change, we
change all `format()` to either `fmt::format()` or `seastar::format()`
with following rules:
- if the caller expects an `sstring` or `std::string_view`, change to
`seastar::format()`
- if the caller expects an `std::string`, change to `fmt::format()`.
because, `sstring::operator std::basic_string` would incur a deep
copy.
we will need another change to enable scylladb to compile with the
latest seastar. namely, to pass the format string as a templated
parameter down to helper functions which format their parameters.
to miminize the scope of this change, let's include that change when
bumping up the seastar submodule. as that change will depend on
the seastar change.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
The reconcilable_result is built as it would be constructed for
forward read queries for tables with reversed order.
Mutations constructed for reversed queries are consumed forward.
Drop overloaded reversed functions that reverse read_command and
reconcilable_result directly and keep only those requiring smart
pointers. They are not used any more.
assert() is traditionally disabled in release builds, but not in
scylladb. This hasn't caused problems so far, but the latest abseil
release includes a commit [1] that causes a 1000 insn/op regression when
NDEBUG is not defined.
Clearly, we must move towards a build system where NDEBUG is defined in
release builds. But we can't just define it blindly without vetting
all the assert() calls, as some were written with the expectation that
they are enabled in release mode.
To solve the conundrum, change all assert() calls to a new SCYLLA_ASSERT()
macro in utils/assert.hh. This macro is always defined and is not conditional
on NDEBUG, so we can later (after vetting Seastar) enable NDEBUG in release
mode.
[1] 66ef711d68Closesscylladb/scylladb#20006
flat_mutation_reader_v2 was introduced in a pair of commits in 2021:
e3309322c3 "Clone flat_mutation_reader related classes into v2 variants"
08b5773c12 "Adapt flat_mutation_reader_v2 to the new version of the API"
as a replacement for flat_mutation_reader, using range_tombstone_change
instead of range_tombstone to represent represent range tombstones. See
those commits for more information.
The transition was incremental; the last use of the original
flat_mutation_reader was removed in 2022 in commit
026f8cc1e7 "db: Use mutation_partition_v2 in mvcc"
In turn, flat_mutation_reader was introduced in 2017 in commit
748205ca75 "Introduce flat_mutation_reader"
To transition from a mutation_reader that nested rows within
a partition in a separate stream, to a flat reader that streamed
partitions and rows in the same stream.
Here, we reclaim the original name and rename the awkward
flat_mutation_reader_v2 to mutation_reader.
Note that mutation_fragment_v2 remains since we still use the original
for compatibilty, sometimes.
Some notes about the transition:
- files were also renamed. In one case (flat_mutation_reader_test.cc), the
rename target already existed, so we rename to
mutation_reader_another_test.cc.
- a namespace 'mutation_reader' with two definitions existed (in
mutation_reader_fwd.hh). Its contents was folded into the mutation_reader
class. As a result, a few #includes had to be adjusted.
Closesscylladb/scylladb#19356
in theory, std::result_of_t should have been removed in C++20. and
std::invoke_result_t is available since C++17. thanks to libstdc++,
the tree is compiling. but we should not rely on this.
so, in this change, we replace all `std::result_of_t` with
`std::invoke_result_t`. actually, clang + libstdc++ is already warning
us like:
```
In file included from /home/runner/work/scylladb/scylladb/multishard_mutation_query.cc:9:
In file included from /home/runner/work/scylladb/scylladb/schema/schema_registry.hh:11:
In file included from /usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/unordered_map:38:
Warning: /usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/type_traits:2624:5: warning: 'result_of<void (noop_compacted_fragments_consumer::*(noop_compacted_fragments_consumer &))()>' is deprecated: use 'std::invoke_result' instead [-Wdeprecated-declarations]
2624 | using result_of_t = typename result_of<_Tp>::type;
| ^
/home/runner/work/scylladb/scylladb/mutation/mutation_compactor.hh:518:43: note: in instantiation of template type alias 'result_of_t' requested here
518 | if constexpr (std::is_same_v<std::result_of_t<decltype(&GCConsumer::consume_end_of_stream)(GCConsumer&)>, void>) {
|
```
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#18835
when compiling with clang-tidy, it warngs:
```
[6/9] Building CXX object readers/CMakeFiles/readers.dir/multishard.cc.o
/home/kefu/dev/scylladb/readers/multishard.cc:84:53: warning: 'fut_and_result' used after it was moved [bugprone-use-after-move]
84 | auto result = std::get<1>(std::move(fut_and_result));
| ^
/home/kefu/dev/scylladb/readers/multishard.cc:79:34: note: move occurred here
79 | _read_ahead_future = std::get<0>(std::move(fut_and_result));
| ^
```
but this warning is but a false alarm, as we are not really moving away
the *whole* tuple, we are just move away an element from it. but
clang-tidy cannot tell which element we are actually moving. so, silence
both places of `std::move()`.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#18363
When the reader is currently paused, it is resumed, fast-forwarded, then
paused again. The fast forwarding part can throw and this will lead to
destroying the reader without it being closed first.
Add a try-catch surrounding this part in the code. Also mark
`maybe_pause()` and `do_pause()` as noexcept, to make it clear why
that part doesn't need to be in the try-catch.
Fixes: #16606Closesscylladb/scylladb#16630
Fixes some typos as found by codespell run on the code.
In this commit, I was hoping to fix only comments, not user-visible alerts, output, etc.
Follow-up commits will take care of them.
Refs: https://github.com/scylladb/scylladb/issues/16255
Signed-off-by: Yaniv Kaul <yaniv.kaul@scylladb.com>
The evictable reader must ensure that each buffer fill makes forward
progress, i.e. the last fragment in the buffer has a position larger
than the last fragment from the previous buffer-fill. Otherwise, the
reader could get stuck in an infinite loop between buffer fills, if the
reader is evicted in-between.
The code guranteeing this forward progress had a bug: the comparison
between the position after the last buffer-fill and the current
last fragment position was done in the wrong direction.
So if the condition that we wanted to achieve was already true, we would
continue filling the buffer until partition end which may lead to OOMs
such as in #13491.
There was already a fix in this area to handle `partition_start`
fragments correctly - #13563 - but it missed that the position
comparison was done in the wrong order.
Fix the comparison and adjust one of the tests (added in #13563) to
detect this case.
Fixes#13491
This is not strictly necessary, as the multishard reader will be later
avoided altogether for tablet-based tables, but it is a step towards
converting all code to use the erm->get_sharder() instead of
schema::get_sharder().
In that level no io_priority_class-es exist. Instead, all the IO happens
in the context of current sched-group. File API no longer accepts prio
class argument (and makes io_intent arg mandatory to impls).
So the change consists of
- removing all usage of io_priority_class
- patching file_impl's inheritants to updated API
- priority manager goes away altogether
- IO bandwidth update is performed on respective sched group
- tune-up scylla-gdb.py io_queues command
The first change is huge and was made semi-autimatically by:
- grep io_priority_class | default_priority_class
- remove all calls, found methods' args and class' fields
Patching file_impl-s is smaller, but also mechanical:
- replace io_priority_class& argument with io_intent* one
- pass intent to lower file (if applicatble)
Dropping the priority manager is:
- git-rm .cc and .hh
- sed out all the #include-s
- fix configure.py and cmakefile
The scylla-gdb.py update is a bit hairry -- it needs to use task queues
list for IO classes names and shares, but to detect it should it checks
for the "commitlog" group is present.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closes#13963
In https://github.com/scylladb/scylladb/pull/13482 we renamed the reader permit states to more descriptive names. That PR however only covered only the states themselves and their usages, as well as the documentation in `docs/dev`.
This PR is a followup to said PR, completing the name changes: renaming all symbols, names, comments etc, so all is consistent and up-to-date.
Closes#13573
* github.com:scylladb/scylladb:
reader_concurrency_semaphore: misc updates w.r.t. recent permit state name changes
reader_concurrency_semaphore: update permit members w.r.t. recent permit state name changes
reader_concurrency_semaphore: update RAII state guard classes w.r.t. recent permit state name changes
reader_concurrency_semaphore: update API w.r.t. recent permit state name changes
reader_concurrency_semaphore: update stats w.r.t. recent permit state name changes
The evictable reader must ensure that each buffer fill makes forward
progress, i.e. the last fragment in the buffer has a position larger
than the last fragment from the last buffer-fill. Otherwise, the reader
could get stuck in an infinite loop between buffer fills, if the reader
is evicted in-between.
The code guranteeing this forward change has a bug: when the next
expected position is a partition-start (another partition), the code
would loop forever, effectively reading all there is from the underlying
reader.
To avoid this, add a special case to ignore the progress guarantee loop
altogether when the next expected position is a partition start. In this
case, progress is garanteed anyway, because there is exactly one
partition-start fragment in each partition.
Fixes: #13491Closes#13563
When creating the reader, the lifecycle policy might return one that was
saved on the last page and survived in the cache. This reader might have
skipped some fast-forwarding ranges while sitting in the cache. To avoid
using a reader reading a stale range (from the read's POV), check its
read range and fast forward it if necessary.
And propagate it down to where it is created. This will be used to add
trace points for semaphore related events, but this will come in the
next patches.
Schema related files are moved there. This excludes schema files that
also interact with mutations, because the mutation module depends on
the schema. Those files will have to go into a separate module.
Closes#12858
Timouts are benign, especially on a read-ahead that turned out to be not
needed at all. They just introduce noise in the logs, so silence them.
Fixes: #12435Closes#12441
This fixes a long standing bug related to handling of non-full
clustering keys, issue #1446.
after_key() was creating a position which is after all keys prefixed
by a non-full key, rather than a position which is right after that
key.
This will issue will be caught by cql_query_test::test_compact_storage
in debug mode when mutation_partition_v2 merging starts inserting
sentinels at position after_key() on preemption.
It probably already causes problems for such keys.
do_full_buffer() is an eclectic mix of coroutines and continuations.
That makes it hard to follow what is running sequentially and
concurrently.
Convert it into a pure coroutine by changing internal continuations
to lambda coroutines. These lambda coroutines are guarded with
seastar::coroutine::lambda. Furthermore, a future that is co_awaited
is converted to immediate co_await (without an intermediate future),
since seastar::coroutine::lambda only works if the coroutine is awaited
in the same statement it is defined on.
Commit 8ab57aa added a yield to the buffer-copy loop, which means that
the copy can yield before done and the multishard reader might see the
half-copied buffer and consider the reader done (because
`_end_of_stream` is already set) resulting in the dropping the remaining
part of the buffer and in an invalid stream if the last copied fragment
wasn't a partition-end.
Fixes: #11561
