Denormalize jobs in AppendAllocs:
AppendAlloc was originally only ever called for inplace upgrades and new
allocations. Both these code paths would remove the job from the
allocation. Now we use this to also add fields such as FollowupEvalID
which did not normalize the job. This is only a performance enhancement.
Ignore terminal allocs:
Failed allocations are annotated with the followup Eval ID when one is
created to replace the failed allocation. However, in the plan applier,
when we check if allocations fit, these terminal allocations were not
filtered. This could result in the plan being rejected if the node would
be overcommited if the terminal allocations resources were considered.
Fixes three issues:
1. Retrieving the latest evaluation index was not properly selecting the
greatest index. This would undermine checks we had to reduce the number
of evaluations created when the latest eval index was greater than any
alloc change
2. Fix an issue where the blocking query code was using the incorrect
index such that the index was higher than necassary.
3. Special case handling of blocked evaluation since the create/snapshot
index is no particularly useful since they can be reblocked.
This is the best of three options
1. Users of stats trackers control polling (old method)
2. Stat tracker is stateful and has start/stop methods (like logging)
3. Stat trackers blindly throttle requests
This is the best option because it means N number of concurrent users of
a stats tracker can request polling without inundating the tracker with
redundant frames (or the network with redundant requests), but they also
don't have to coordinate amongst themselves to determine what state a
tracker should be in.
This solves two problems:
1. redundant trackers making redundant requests
2. trackers being obliterated as soon as the primary metric component
is destroyed
It introduces a new problem where visiting more and more node and
allocation pages adds to an ever-growing list of trackers that can
assume lots of memory, but it solves the problem by using a
least-recently-used cache to limit the number of trackers tracked.
