cf5400bc75
always initialize returned values. the branches which
return these unitiailized returned values handles the
unmatched cases, so this change should not have any
impact on the behavior.
ANTLR3's C++ code generator does not assign any value
to the value, if it runs into failure or encounter
exceptions. for instance, following rule assigns the
value of `isStatic` to `isStaticColumn` only if
nothing goes wrong.
```
cfisStatic returns [bool isStaticColumn]
@init{
bool isStatic = false;
}
: (K_STATIC { isStatic=true; })?
{
$isStaticColumn = isStatic;
}
;
```
as shown in the generated C++ code:
```c++
switch (alt118)
{
case 1:
// build/debug/gen/cql3/Cql.g:989:8: K_STATIC
{
this->matchToken(K_STATIC, &FOLLOW_K_STATIC_in_cfisStatic5870);
if (this->hasException())
{
goto rulecfisStaticEx;
}
if (this->hasFailed())
{
return isStaticColumn;
}
if ( this->get_backtracking()==0 )
{
isStaticColumn=isStatic;
}
}
break;
}
```
when `this->hasException()` or `this->hasFailed()`,
`isStaticColumn` is returned right away without being
initialized, because we don't assign any initial value
to it, neither do we customize the exception handling
for this rule.
and, the parser bails out when its smells something bad
after it tries to match the specified rule. also, the
parser is a stateful tokenizer, its failure state is
carried by the parser itself. also, the matchToken()
*could* fail when trying to find the matched token,
this is the runtime behavior of parser, that's why the
compiler cannot be certain that the error path won't
be taken.
anyway, let's always initialize the values without
default constructor. the return values whose type
is of scoped enum are initialized with zero
initialization, because their types don't provide an
"invalid" value.
this change should silence warnings like:
```
clang++ -MD -MT build/debug/gen/cql3/CqlParser.o -MF build/debug/gen/cql3/CqlParser.o.d -I/home/kefu/dev/scylladb/seastar/include -I/home/kefu/dev/scylladb/build/debug/seastar/gen/include -U_FORTIFY_SOURCE -DSEASTAR_SSTRING -Werror=unused-result -fstack-clash-protection -fsanitize=address -fsanitize=undefined -fno-sanitize=vptr -DSEASTAR_API_LEVEL=7 -DSEASTAR_BUILD_SHARED_LIBS -DSEASTAR_SCHEDULING_GROUPS_COUNT=16 -DSEASTAR_DEBUG -DSEASTAR_DEFAULT_ALLOCATOR -DSEASTAR_SHUFFLE_TASK_QUEUE -DSEASTAR_DEBUG_SHARED_PTR -DSEASTAR_LOGGER_TYPE_STDOUT -DSEASTAR_TYPE_ERASE_MORE -DBOOST_NO_CXX98_FUNCTION_BASE -DFMT_SHARED -I/usr/include/p11-kit-1 -ffile-prefix-map=/home/kefu/dev/scylladb=. -march=westmere -DDEBUG -DSANITIZE -DDEBUG_LSA_SANITIZER -DSCYLLA_ENABLE_ERROR_INJECTION -Og -DSCYLLA_BUILD_MODE=debug -g -gz -iquote. -iquote build/debug/gen --std=gnu++20 -ffile-prefix-map=/home/kefu/dev/scylladb=. -march=westmere -DBOOST_TEST_DYN_LINK -DNOMINMAX -DNOMINMAX -fvisibility=hidden -Wall -Werror -Wextra -Wno-deprecated-copy -Wno-mismatched-tags -Wno-missing-field-initializers -Wno-c++11-narrowing -Wno-ignored-qualifiers -Wno-overloaded-virtual -Wno-unsupported-friend -Wno-unused-parameter -Wno-implicit-int-float-conversion -Wno-error=deprecated-declarations -DXXH_PRIVATE_API -DSEASTAR_TESTING_MAIN -DFMT_DEPRECATED_OSTREAM -Wno-parentheses-equality -O1 -fno-sanitize-address-use-after-scope -c -o build/debug/gen/cql3/CqlParser.o build/debug/gen/cql3/CqlParser.cpp
build/debug/gen/cql3/CqlParser.cpp:26645:28: error: variable 'perm' is uninitialized when used here [-Werror,-Wuninitialized]
return perm;
^~~~
build/debug/gen/cql3/CqlParser.cpp:26616:5: note: variable 'perm' is declared here
auth::permission perm;
^
build/debug/gen/cql3/CqlParser.cpp:52577:28: error: variable 'op' is uninitialized when used here [-Werror,-Wuninitialized]
return op;
^~
build/debug/gen/cql3/CqlParser.cpp:52518:5: note: variable 'op' is declared here
oper_t op;
^
```
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closes scylladb/scylladb#15451
Scylla
What is Scylla?
Scylla is the real-time big data database that is API-compatible with Apache Cassandra and Amazon DynamoDB. Scylla embraces a shared-nothing approach that increases throughput and storage capacity to realize order-of-magnitude performance improvements and reduce hardware costs.
For more information, please see the ScyllaDB web site.
Build Prerequisites
Scylla is fairly fussy about its build environment, requiring very recent versions of the C++20 compiler and of many libraries to build. The document HACKING.md includes detailed information on building and developing Scylla, but to get Scylla building quickly on (almost) any build machine, Scylla offers a frozen toolchain, This is a pre-configured Docker image which includes recent versions of all the required compilers, libraries and build tools. Using the frozen toolchain allows you to avoid changing anything in your build machine to meet Scylla's requirements - you just need to meet the frozen toolchain's prerequisites (mostly, Docker or Podman being available).
Building Scylla
Building Scylla with the frozen toolchain dbuild is as easy as:
$ git submodule update --init --force --recursive
$ ./tools/toolchain/dbuild ./configure.py
$ ./tools/toolchain/dbuild ninja build/release/scylla
For further information, please see:
- Developer documentation for more information on building Scylla.
- Build documentation on how to build Scylla binaries, tests, and packages.
- Docker image build documentation for information on how to build Docker images.
Running Scylla
To start Scylla server, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --workdir tmp --smp 1 --developer-mode 1
This will start a Scylla node with one CPU core allocated to it and data files stored in the tmp directory.
The --developer-mode is needed to disable the various checks Scylla performs at startup to ensure the machine is configured for maximum performance (not relevant on development workstations).
Please note that you need to run Scylla with dbuild if you built it with the frozen toolchain.
For more run options, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --help
Testing
See test.py manual.
Scylla APIs and compatibility
By default, Scylla is compatible with Apache Cassandra and its APIs - CQL and Thrift. There is also support for the API of Amazon DynamoDB™, which needs to be enabled and configured in order to be used. For more information on how to enable the DynamoDB™ API in Scylla, and the current compatibility of this feature as well as Scylla-specific extensions, see Alternator and Getting started with Alternator.
Documentation
Documentation can be found here. Seastar documentation can be found here. User documentation can be found here.
Training
Training material and online courses can be found at Scylla University. The courses are free, self-paced and include hands-on examples. They cover a variety of topics including Scylla data modeling, administration, architecture, basic NoSQL concepts, using drivers for application development, Scylla setup, failover, compactions, multi-datacenters and how Scylla integrates with third-party applications.
Contributing to Scylla
If you want to report a bug or submit a pull request or a patch, please read the contribution guidelines.
If you are a developer working on Scylla, please read the developer guidelines.
Contact
- The community forum and Slack channel are for users to discuss configuration, management, and operations of the ScyllaDB open source.
- The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.