The poll loop used condition_variable::wait(timeout) to sleep between
iterations. On every normal timeout expiry, this threw a
condition_variable_timed_out exception, which incremented the C++
exception metric and triggered false alerts for support.
Replace the timed wait with a seastar::timer that broadcasts the
condition variable on expiry, combined with an untimed wait(). The
timer is cancelled automatically on scope exit when the wait is woken
early by trigger_poll() or abort.
Fixes SCYLLADB-1477
Closesscylladb/scylladb#29438
Introduce the `subscribe` method to disk_space_monitor, allowing clients to
register callbacks triggered when disk utilization crosses a configurable
threshold.
The API supports flexible trigger options, including notifications on threshold
crossing and direction (above/below). This enables more granular and efficient
disk space monitoring for consumers.
Register the current space_source_fn in an RAII
object that resets monitor._space_source to the
previous function when the RAII object is destroyed.
Use space_source_registration in database_test::
mutation_dump_generated_schema_deterministic_id_version
to prevent use-after-stack-return in the test.
Fixes#24314
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Closesscylladb/scylladb#24342
Intended for testing, or hot-fixing out-of-space issues in production.
Tablet load balancer uses this information for determining per-shard load
so reducing capacity will cause tablets to be migrated away from the node.
Instantiated only on shard 0.
Currently, only subscribe from unit test
Manual unit test using loop mount was added.
Note that the test requires sudo access
and root access to /dev/loop, so it cannot
run in rootless podman instance, and it'd
fail with Permission denied.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Closesscylladb/scylladb#21523
