"
The second patch in this series is a mechanical conversion of
reader_concurrency_semaphore to flat_mutation_reader_v2, and caller
updates.
The first patch is needed to pass the test suite, since without it a
real reader version conversion would happen on every entry to and exit
from reader_concurrency_semaphore, which is stressful (for example:
mutation_reader_test.test_multishard_streaming_reader reaches 8191
conversions for a couple of readers, which somehow causes it to catch
SIGSEGV in diverse and seemingly-random places).
Note that in a real workload it is unreasonable to expect readers being
parked in a reader_concurrency_semaphore to be pristine, so
short-circuiting their version conversions will be impossible and this
workaround will not really help.
"
* tag 'rcs-v2-v4' of https://github.com/cmm/scylla:
reader_concurrency_semaphore: convert to flat_mutation_reader_v2
short-circuit flat mutation reader upgrades and downgrades
aba68c8f83