Because retore roles run as workload in simulation,
they do not know when DB is destroyed by the backup and restore test workload.
So if DB is destroyed earlier than restore master unlocks DB, which is rare,
restore master should abort the unlocking DB step.
An actor is schedulable to run if the current worker has enough resourc, i.e.,
the worker's memory usage is below the threshold;
Exception: If the actor is working on the current version batch, we have to schedule
the actor to run to avoid dead-lock.
Future: When we release the actors that are blocked by memory usage, we should release them
in increasing order of their version batch.
atomicOp has an amplified performance overhead to the cluster,
for example, an ADD operation can be small, but SS has to load
the value to do the operation and the value can be large.
When we pipeline multiple version batches, we should prevent a later
version batch from blocking the earlier version batch by consuming
CPU resources.
To achive the above, we should assign higher priority to actors
in later phases in a version batch.
Because restore master will not invoke an actor at a later phase unless
the actors at the earlier phases have been finished. This priority assignment
will not cause dead lock.
1) Sort logfiles by endVersion
2) Exit program early when restore will not succeed
3) Do not increase nextVersion unncessarily when
calculate version batches.
4) Change assert condition that ensures progress in
calculating version batches.
1) Remove endVersion field because it has been included in RestoreAsset;
2) Ensure endVersion in VersionBatch and RestoreAsset is always exclusive;
3) Revise ASSERT in laoder and applier in situations when the dummy commit version
is endVersion, to avoid false positive ASSERT failure.
1. Review memory use cases and improve:
Ensure state varialble is initialized and
change unnecessary state variable to variable.
2. Remove debug code that is no longer useful;
3. Mute verbose debug.
Meng Xu