When a table is loaded on startup during a vnodes-to-tablets migration
(forward or rollback), the `table_populator` runs a resharding
compaction.
Set the migration virtual task as parent of the resharding task. This
enables users to easily find all node-local resharding tasks related to
a particular migration.
Make `migration_virtual_task::make_task_id()` public so that the
`distributed_loader` can compute the migration's task ID.
Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
Add a virtual task that exposes in-progress vnodes-to-tablets migrations
through the task manager API.
The task is synthesized from the current migration state, so completed
migrations are not shown. Progress is reported as the number of nodes
that currently use tablets: it increases on the forward path and
decreases on rollback. For simplicity, per-node storage modes are not
exposed in the task status; callers that need them should use the
migration status REST endpoint.
Unlike regular tasks that use time-based UUIDs, this task uses
deterministic named UUIDs derived from the keyspace names. This keeps
the implementation simple (no need to persist them) and gives each
keyspace a stable task ID. The downside is that the start time of each
task is unknown and repeated migrations of the same keyspace
(migration -> rollback -> new migration) cannot be distinguished.
Introduce a new task manager module to keep them separate from other
tasks.
Add support for `wait()`. While its practical value is debatable
(migration is a manual procedure, rolling restart will interrupt it), it
keeps the task consistent with the task manager interface.
Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
Add a service::topo::global_topology_request_virtual_task, which
covers the replication factor changes.
Currently, the global_topology_request_virtual_task can be aborted
only if it is paused.
The progress of the rf change isn't counted.
Extend tablet_virtual_task::wait to support resize tasks.
To decide what is a state of a finished resize virtual task (done
or failed), the tablet count is checked. The task state is set to done,
if the tablet count before resize is different than after.
Extend tablet_virtual_task::wait to support migration tasks.
To decide what is a state of a finished migration virtual task
(done or failed), the tablet replicas are checked. The task state
is set to done, if the replicas contain the destination of a tablet
migration.
