- Fix table drop blocking for the full client timeout when in-flight writes can't reach quorum
- Handle unhandled timeout exception in the wait-for-leader loop during group startup
When a strongly consistent table is dropped, `schedule_raft_group_deletion`() calls `g->close()` which waits for all in-flight operations to release their gate holders. But other nodes may have already destroyed their raft servers for this group, so an in-flight write on the leader cannot reach quorum and hangs until the client timeout expires (~seconds), unnecessarily delaying group deletion.
Additionally, the wait-for-leader loop in groups_manager::update() uses abort_on_expiry with a 60-second timeout but never catches the exception if it fires, leaving the group in an indeterminate state.
SCYLLADB-2080 fix:
- Reorder `schedule_raft_group_deletion`: initiate gate close (prevents new operations), then abort the raft server (unblocks stuck writes by causing `raft::stopped_error`), then await the gate future (resolves immediately since holders are released).
- Handle `raft::stopped_error` in the coordinator's top-level catch blocks (both write and read paths): if the table no longer exists, return `no_such_column_family` (CQL layer converts to InvalidRequest: unconfigured table). Otherwise fall through to the default timeout handling.
- Replace gate->hold() with try_hold() + on_internal_error in acquire_server, with a comment explaining why the gate can never be closed at that point (table removal in `schema_applier::commit_on_shard` precedes gate closure, with no scheduling point in between).
Timeout handling fix:
- Use `coroutine::as_future` in the wait-for-leader loop to catch timeout exceptions gracefully — log a warning and break out instead of propagating unhandled.
Includes a cluster test reproducer (test_drop_table_unblocks_stuck_write) that:
1. Pauses a write on the leader before add_entry
2. Drops the table (follower destroys its group immediately)
3. Resumes the write — verifies it fails promptly with InvalidRequest ("unconfigured table") instead of hanging for 15 seconds
backport: no need, strong consistency is not released yet
Fixes: SCYLLADB-2080
Closesscylladb/scylladb#30105
* github.com:scylladb/scylladb:
strong consistency/groups_manager: handle timeout in update() wait-for-leader loop
strong consistency: abort raft server before gate close when dropping a table
test/cluster: rewrite test_queries_while_dropping_table for SCYLLADB-2080
8dfd455001