In a later commit, we want to use sstables/consumer.hh
to implement a parser of BTI row index headers read
from Rows.db.
Partition tombstones in this file have an encoding which
uses the first bit of the first byte to determine if
the tombstone is live or not. If yes, then the timestamp
is in the remaining 7 bits of the first byte, and the next
7 bytes, and the deletion_time is in the 4 bytes after that.
So I need some way to read 1 byte, and then, depending on its
value, maybe read the next 7 bytes and then 4 bytes. This commits
adds a helper for reading a 7-byte int.
Now that I'm typing this out, maybe that's not the smartest idea.
Maybe I should just "manually" read the 11 bytes as 8, 2, 1.
But I've already written this, so I might as well post it,
it can always be replaced later.
C++20 introduced two new attributes--likely and unlikely--that
function as a built-in replacement for __builtin_expect implemented
in various compilers. Since it makes code easier to read and it's
an integral part of the language, there's no reason to not use it
instead.
Closesscylladb/scylladb#24786
So parse errors on corrupt SSTables don't result in crashes, instead
just aborting the read in process.
There are a lot of SCYLLA_ASSERT() usages remaining in sstables/. This
patch tried to focus on those usages which are in the read path. Some
places not only used on the read path may have been converted too, where
the usage of said method is not clear.
'static inline' is always wrong in headers - if the same header is
included multiple times, and the function happens not to be inlined,
then multiple copies of it will be generated.
Fix by mechanically changing '^static inline' to 'inline'.
Currently, parsers work with temporary_buffer<char>. This is unsafe
when invoked by bsearch_clustered_cursor, which reuses some of the
parsers, and passes temporary_buffer<char> which is a view onto LSA
buffer which comes from the index file page cache. This view is stable
only around consume(). If parsing requires more than one page, it will
continue with a different input buffer. The old buffer will be
invalid, and it's unsafe for the parser to store and access
it. Unfortunetly, the temporary_buffer API allows sharing the buffer
via the share() method, which shares the underlying memory area. This
is not correct when the underlying is managed by LSA, because storage
may move. Parser uses this sharing when parsing blobs, e.g. clustering
key components. When parsing resumes in the next page, parser will try
to access the stored shared buffers pointing to the previous page,
which may result in use-after-free on the memory area.
In prearation for fixing the problem, parametrize parsers to work with
different kinds of buffers. This will allow us to instantiate them
with a buffer kind which supports sharing of LSA buffers properly in a
safe way.
It's not purely mechanical work. Some parts of the parsing state
machine still works with temporary_buffer<char>, and allocate buffers
internally, when reading into linearized destination buffer. They used
to store this destination in _read_bytes vector, same field which is
used to store the shared buffers. Now it's not possible, since shared
buffer type may be different than temporary_buffer<char>. So those
paths were changed to use a new field: _read_bytes_buf.
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
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
in C++20, compiler generate operator!=() if the corresponding
operator==() is already defined, the language now understands
that the comparison is symmetric in the new standard.
fortunately, our operator!=() is always equivalent to
`! operator==()`, this matches the behavior of the default
generated operator!=(). so, in this change, all `operator!=`
are removed.
in addition to the defaulted operator!=, C++20 also brings to us
the defaulted operator==() -- it is able to generated the
operator==() if the member-wise lexicographical comparison.
under some circumstances, this is exactly what we need. so,
in this change, if the operator==() is also implemented as
a lexicographical comparison of all memeber variables of the
class/struct in question, it is implemented using the default
generated one by removing its body and mark the function as
`default`. moreover, if the class happen to have other comparison
operators which are implemented using lexicographical comparison,
the default generated `operator<=>` is used in place of
the defaulted `operator==`.
sometimes, we fail to mark the operator== with the `const`
specifier, in this change, to fulfil the need of C++ standard,
and to be more correct, the `const` specifier is added.
also, to generate the defaulted operator==, the operand should
be `const class_name&`, but it is not always the case, in the
class of `version`, we use `version` as the parameter type, to
fulfill the need of the C++ standard, the parameter type is
changed to `const version&` instead. this does not change
the semantic of the comparison operator. and is a more idiomatic
way to pass non-trivial struct as function parameters.
please note, because in C++20, both operator= and operator<=> are
symmetric, some of the operators in `multiprecision` are removed.
they are the symmetric form of the another variant. if they were
not removed, compiler would, for instance, find ambiguous
overloaded operator '=='.
this change is a cleanup to modernize the code base with C++20
features.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closes#13687
A separate method for callers of make_tracked_temporary_buffer() who
are creating new empty tracked buffers of a certain size.
make_tracked_temporary_buffer() is about to be changed to be more
targeted at callers who call it with pre-consumed memory units.
The primitive_consumer method templates overcomplicate the
declaration of the fact that one of the method arguments is
the sub-type of a template argument
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
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
When skipping bytes at the end of a continuous_data_consumer range,
the position of the consumer is moved after the skipped bytes, but
the position of the underlying input_stream is not.
This patch adds skipping of the underlying input_stream, to make
its position consistent with the position of the consumer.
Fixes#9024
Signed-off-by: Wojciech Mitros <wojciech.mitros@scylladb.com>
We'd like that to simplify the soon-to-be-introduced
sstable_mutation_reader::close error handling path.
close_index_list can be marked noexcept since parallel_for_each is,
with that index_reader::close can be marked noexcept too.
Note that since reader close can not fail
both lower and upper bounds are closed (since
closing lower_bound cannot fail).
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
When we want to parse a linearized buffer of bytes, we're copying them
into the first and only element of the _read_bytes vector. Thus
_read_bytes often contains only one element, which makes a small_vector
a better alternative.
Signed-off-by: Wojciech Mitros <wojciech.mitros@scylladb.com>
Currently, the primitive_consumer parses all values in contiguous buffers.
A string of bytes may be very long, so parsing it in a single buffer
can cause a big allocation. This patch allows parsing into
fragmented_temporary_buffers instead of temporary_buffers.
Signed-off-by: Wojciech Mitros <wojciech.mitros@scylladb.com>
Based on heap profiling, buffers used for storing half-parsed fields are
a major contributor to the overall memory consumption of reads. This
memory was completely "under the radar" before. Track it by using
tracked `temporary_buffer` instances everywhere in
`continuous_data_consumer`. As `continuous_data_consumer` is the basis
for parsing all index and data files, adding the tracing here
automatically covers all data, index and promoted index parsing.
I'm almost convinced that there is a better place to store the `permit`
then the three places now, but so far I was unable to completely
decipher the our data/index file parsing class hierarchy.
vint deserialiser can be more performant if it is allowed to do an
overread (i.e. read more memory than the value it is deserialising).
In case of sstable reads those vints are going to be usually in a middle
of a much larger buffer so lets pass the whole length of the buffer and
enable this optimisation.
Deserialisation function returns a structure containing both the value
and its length in the input buffer. In the vast majority of the cases
the caller will already know the length and having this structure will
make it harder for the compiler to emit good code, especially if the
function is not inlined.
In practice I've seen the structure causing register pressure problems
that lead to spilling variables to memory.
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>
Will allow state_processor to know its position in the
stream.
Currently position() is meaningless inside process_state() because in
some cases it points to the position after the buffer and in some
cases before it. This patch standardizes on the former. This is more
useful than the latter because process_state() trims from the front of
the buffer as it consumes, so the position inside the stream can be
obtained by subtracting the remaining buffer size from position(),
without introducing any new variables.
do_process_buffer had two unreachable default cases and a long
if-else-if chain.
This converts the the if-else-if chain to a switch and a helper
function.
This moves the error checking from run time to compile time. If we
were to add a 128 bit integer for example, gcc would complain about it
missing from the switch.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
Message-Id: <20181125221451.106067-1-espindola@scylladb.com>
* seastar d59fcef...b924495 (2):
> build: Fix protobuf generation rules
> Merge "Restructure files" from Jesse
Includes fixup patch from Jesse:
"
Update Seastar `#include`s to reflect restructure
All Seastar header files are now prefixed with "seastar" and the
configure script reflects the new locations of files.
Signed-off-by: Jesse Haber-Kucharsky <jhaberku@scylladb.com>
Message-Id: <5d22d964a7735696fb6bb7606ed88f35dde31413.1542731639.git.jhaberku@scylladb.com>
"
Before it was depending on byteorder.hh that just happend
to be included in all compilation units that were using consumer.hh
This change makes the header compile when used in new compilation units.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
All of the adjustments to _remain already ensure it is greater than 0,
and indeed a negative _remain doesn't make sense.
Switching to an unsigne types allows us to re-enable -Wsign-compare.
Tests: unit (release)
Message-Id: <20180212121636.10463-1-avi@scylladb.com>
Remove redundant input parameter as continuous_data_consumer derivatives
would only use themselves as a context. So take it internally and make
the function regular (non-template) and having no parameters.
Signed-off-by: Vladimir Krivopalov <vladimir@scylladb.com>
Callers, like compactions, will be able to know at any time the current
progress of a read.
As we do that, the currently unimplemented position() method of
data_consume_context becomes redundant and is removed.
Signed-off-by: Glauber Costa <glauber@scylladb.com>
If sstable Summary is not present Scylla does not refuses to boot but
instead creates summary information on the fly. There is a bug in this
code though. Summary files is a map between keys and offsets into Index
file, but the code creates map between keys and Data file offsets
instead. Fix it by keeping offset of an index entry in index_entry
structure and use it during Summary file creation.
Reviewed-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20161116165421.GA22296@scylladb.com>
After state_processor().process_state() returns proceed::no the upper
layer should have a chance to act before more data is pushed to the
consumer. This means that in case of proceed::no verify_end_state()
should not be called immediately since it may invoke
consume_end_partition().
Fixes#1605.
Signed-off-by: Paweł Dziepak <pdziepak@scylladb.com>
Message-Id: <1471943032-7290-1-git-send-email-pdziepak@scylladb.com>
unaligned_cast violates strict aliasing, and causes code misgeneration on
gcc 6. Replace it with read_be/write_be, which are nicer anyway.
Message-Id: <1469122850-7511-1-git-send-email-avi@scylladb.com>
