15fa1c1c7e
Applying lazy evaluation to the BTI encoding of clustering keys was probably a bad default. The possible benefits are dubious (because it's quite likely that the laziness won't allow us to avoid that much work), but the overhead needed to implement the laziness is large and immediate. In this patch we get rid of the laziness. We rewrite lazy_comparable_bytes_from_clustering_position and lazy_comparable_bytes_from_ring_position so that they performs the key translation eagerly, all components to a single bytes_ostream in one synchronous call. perf_bti_key_translation (microbenchmark added in this series, 1 iteration is 100 translations of a clustering key with 8 cells of int32_type): ``` Before: test iterations median mad min max allocs tasks inst cycles lcb_mismatch_test.lcb_mismatch 9233 109.930us 0.000ns 109.930us 109.930us 4356.000 0.000 2615394.3 614709.6 After: test iterations median mad min max allocs tasks inst cycles lcb_mismatch_test.lcb_mismatch 50952 19.487us 0.000ns 19.487us 19.487us 198.000 0.000 603120.1 109042.9 ``` Enhancement, backport not required. Closes scylladb/scylladb#26302 * github.com:scylladb/scylladb: sstables/trie: BTI-translate the entire partition key at once sstables/trie: avoid an unnecessary allocation of std::generator in last_block_offset() sstables/trie: perform the BTI-encoding of position_in_partition eagerly types/comparable_bytes: add comparable_bytes_from_compound test/perf: add perf_bti_key_translation
Scylla unit tests using C++ and the Boost test framework
The source files in this directory are Scylla unit tests written in C++ using the Boost.Test framework. These unit tests come in three flavors:
-
Some simple tests that check stand-alone C++ functions or classes use Boost's
BOOST_AUTO_TEST_CASE. -
Some tests require Seastar features, and need to be declared with Seastar's extensions to Boost.Test, namely
SEASTAR_TEST_CASE. -
Even more elaborate tests require not just a functioning Seastar environment but also a complete (or partial) Scylla environment. Those tests use the
do_with_cql_env()ordo_with_cql_env_thread()function to set up a mostly-functioning environment behaving like a single-node Scylla, in which the test can run.
While we have many tests of the third flavor, writing new tests of this type should be reserved to white box tests - tests where it is necessary to inspect or control Scylla internals that do not have user-facing APIs such as CQL. In contrast, black-box tests - tests that can be written only using user-facing APIs, should be written in one of newer test frameworks that we offer - such as test/cqlpy or test/alternator (in Python, using the CQL or DynamoDB APIs respectively) or test/cql (using textual CQL commands), or - if more than one Scylla node is needed for a test - using the test/topology* framework.
Running tests
Because these are C++ tests, they need to be compiled before running.
To compile a single test executable row_cache_test, use a command like
ninja build/dev/test/boost/row_cache_test
You can also use ninja dev-test to build all C++ tests, or use
ninja deb-build to build the C++ tests and also the full Scylla executable
(however, note that full Scylla executable isn't needed to run Boost tests).
Replace "dev" by "debug" or "release" in the examples above and below to use the "debug" build mode (which, importantly, compiles the test with ASAN and UBSAN enabling on and helps catch difficult-to-catch use-after-free bugs) or the "release" build mode (optimized for run speed).
To run an entire test file row_cache_test, including all its test
functions, use a command like:
build/dev/test/boost/row_cache_test -- -c1 -m1G
to run a single test function test_reproduce_18045() from the longer test
file, use a command like:
build/dev/test/boost/row_cache_test -t test_reproduce_18045 -- -c1 -m1G
In these command lines, the parameters before the -- are passed to
Boost.Test, while the parameters after the -- are passed to the test code,
and in particular to Seastar. In this example Seastar is asked to run on one
CPU (-c1) and use 1G of memory (-m1G) instead of hogging the entire
machine. The Boost.Test option -t test_reproduce_18045 asks it to run just
this one test function instead of all the test functions in the executable.
Unfortunately, interrupting a running test with control-C while doesn't
work. This is a known bug (#5696). Kill a test with SIGKILL (-9) if you
need to kill it while it's running.
Boost tests can also be run using test.py - which is a script that provides a uniform way to run all tests in scylladb.git - C++ tests, Python tests, etc.
Execution with pytest
To run all tests with pytest execute
pytest test/boost
To execute all tests in one file, provide the path to the source filename as a parameter
pytest test/boost/aggregate_fcts_test.cc
Since it's a normal path, autocompletion works in the terminal out of the box.
To execute only one test function, provide the path to the source file and function name
pytest --mode dev test/boost/aggregate_fcts_test.cc::test_aggregate_avg
To provide a specific mode, use the next parameter --mode dev,
if parameter isn't provided pytest tries to use ninja mode_list to find out the compiled modes.
Parallel execution is controlled by pytest-xdist and the parameter -n auto.
This command starts tests with the number of workers equal to CPU cores.
The useful command to discover the tests in the file or directory is
pytest --collect-only -q --mode dev test/boost/aggregate_fcts_test.cc
That will return all test functions in the file.
To execute only one function from the test, you can invoke the output from the previous command.
However, suffix for mode should be skipped.
For example,
output shows in the terminal something like this test/boost/aggregate_fcts_test.cc::test_aggregate_avg.dev.
So to execute this specific test function, please use the next command
pytest --mode dev test/boost/aggregate_fcts_test.cc::test_aggregate_avg
Writing tests
Because of the large build time and build size of each separate test executable, it is recommended to put test functions into relatively large source files. But not too large - to keep compilation time of a single source file (during development) at reasonable levels.
When adding new source files in test/boost, don't forget to list the new source file in configure.py and also in CMakeLists.txt. The former is needed by our CI, but the latter is preferred by some developers.