f5603ad9ca
Test.py uses `ring_delay_ms = 0` by default. CDC creates generation's timestamp by adding `ring_delay_ms` to it.
In this test, nodes are learning about new generations (introduced by upgrade procedure and then by node bootstrap) concurrently with doing writes that should go to these generations.
Because of `ring_delay_ms = 0', the generation could have been committed when it should have already been in use.
This can be seen in the following logs from a node:
```
ERROR 2024-03-22 12:29:55,431 [shard 0:strm] cdc - just learned about a CDC generation newer than the one used the last time streams were retrieved. This generation, or some newer one, should have been used instead (new generation's timestamp: 2024/03/22 12:29:54, last time streams were retrieved: 2024/03/22 12:29:55). The new generation probably arrived too late due to a network partition and we've made a write using the wrong set streams.
```
Creating writes during such a generation can result in assigning them a wrong generation or a failure. Failure may occur if it hits short time window when `generation_service::handle_cdc_generation(cdc::generation_id_v2)` has executed
`svc._cdc_metadata.prepare(...)` but`_cdc_metadata.insert(...)` has not yet been executed. With a nonzero ring_delay_ms it's not a problem, because during this time window, the generation should not be in use.
Write can fail with the following response from a node:
```
cdc: attempted to get a stream from a generation that we know about, but weren't able to retrieve (generation timestamp: 2024/03/22 12:29:54, write timestamp: 2024/03/22 12:29:55). Make sure that the replicas which contain this generation's data are alive and reachable from this node.
```
Set ring_delay_ms to 15000 for the debug mode and 5000 in other modes. Wait for the last generation to be in use and sleep one second to make sure there are writes to the CDC table in this generation.
Fixes scylladb/scylladb#17977
Reapply b4144d14c6.
Closes scylladb/scylladb#17998
* github.com:scylladb/scylladb:
test.py: test_topology_upgrade_basic: make ring_delay_ms nonzero
Reapply "test.py: adjust the test for topology upgrade to write to and read from CDC tables"
Scylla in-source tests.
For details on how to run the tests, see docs/dev/testing.md
Shared C++ utils, libraries are in lib/, for Python - pylib/
alternator - Python tests which connect to a single server and use the DynamoDB API unit, boost, raft - unit tests in C++ cql-pytest - Python tests which connect to a single server and use CQL topology* - tests that set up clusters and add/remove nodes cql - approval tests that use CQL and pre-recorded output rest_api - tests for Scylla REST API Port 9000 scylla-gdb - tests for scylla-gdb.py helper script nodetool - tests for C++ implementation of nodetool
If you can use an existing folder, consider adding your test to it. New folders should be used for new large categories/subsystems, or when the test environment is significantly different from some existing suite, e.g. you plan to start scylladb with different configuration, and you intend to add many tests and would like them to reuse an existing Scylla cluster (clusters can be reused for tests within the same folder).
To add a new folder, create a new directory, and then
copy & edit its suite.ini.