4d99cd2055
Add the gossip state for broadcasting the nodes state_id. Implemented the Group0 state broadcaster (based on the gossip) that will broadcast the state id of each node and check the minimal state id for the tombstone GC. When there is a change in the tombstone GC minimal state id, the state broadcaster will update the tombstone GC time for the group0-managed tables. The main component of the change is the newly added `group0_state_id_handler` that keeps track, broadcasts and receives the last group0 state_ids across all nodes and sets the tombstone GC deletion time accordingly: * on each group0 change applied, the state_id handler broadcasts the state_id as a gossip state (only if the value has changed) * the handler checks for the node state ids every refresh period (configurable, 1h by default) * on every check, the handler figures out the lowest state_id (timeuuid), which is state_id that all of the nodes already have * the timestamp of this minimum state_id is then used to set the tombstone GC deletion time * the tombstone GC calculation then uses that deletion time to provide the GC time back to the callers, e.g. when doing the compaction * (as the time for tombstone GC calculation has the 1s granularity we actually deduce 1s from the determined timestamp, because it can happen that there were some newer mutations received in the same second that were not distributed across the nodes yet) This change introduces a new flag to the static schema descriptor (`is_group0_table`) that is being checked for this newly added mode in the tombstone GC. We also add a check (in non-release builds only) on every group0 modification that the table has this flag set. The group0 tombstone GC handling is similar to the "repair" tombstone GC mode in a sense (that the tombstone GC time is determined according to a reconciliation action), however it is not explicitly visible to (nor editable by) the user. And also the tombstone GC calculation is much simpler than the "repair" mode calculation - for example, we always use the whole range (as opposed to the "repair" mode that can have specific repair times set for specific ranges). We use the group0 configuration to determine the set of nodes (both current and previous in case of joint configuration) - we need to make sure that we account for all the group0 nodes (if any node didn't provide the state_id yet, the current check round will be skipped, i.e. no GC will be done until all known nodes provide their state_id timestamp value). Also note that the group0 state_id handling works on all nodes independently, i.e. each node might have its own (possibly different) state depending on the gossip application state propagation. This is however not a problem, as some nodes might be behind, but they will catch up eventually, and this solution has the benefit of being distributed (as opposed to having a central point to handle the state, like for example the topology coordinator that has been considered in the early stages of the design). Fixes: scylladb/scylla#15607 New feature, should not be backported. Closes scylladb/scylladb#20394 * github.com:scylladb/scylladb: raft: add the check for the group0 tables raft: fast tombstone GC for group0-managed tables tombstone_gc: refactor the repair map raft: flag the group0-managed tables gossip: broadcast the group0 state id raft/test: add test for the group0 tombstone GC treewide: code cleanup and refactoring
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/cql-pytest 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.
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.