Attributes are unmaintained and unused.
They have become more of a liability than a benefit.
This change eliminates them from the codebase.
The only user-visible change (assuming that attrs are not used) is that the attrs field will no longer appear in row JSON.
A while back we started just polling the reported cluster state of one node
when starting a cluster for tests. This works fine if we're doing fresh
new etcd queries for every single operation -- but that's insanely
expensive, it turns out.
When we use the watcher, some nodes will report stale data for "a
while", where "a while" appears to be easily a couple dozen milliseconds.
This is probably irrelevant in most real-world cases, because the common
case (detecting a node going down) means that we have at least five
seconds after a node goes down before etcd notices the lease expiring,
and a few milliseconds more or less won't matter.
But we have tests that assume either that node 0 is always the
coordinator (wrong) or that waiting for node 0 to think the cluster
is up means that every node in the cluster thinks the cluster is up,
or at least that it means that the coordinator thinks the cluster is
up. We retried later operations but not the initial ones against
the coordinator.
In fact, we probably want to wait for the entire cluster to think
it's up before we start trying things on clusters.
We also replace the "CheckClusterState" function with the existing
AwaitState call, or a new AssertState which errors out since that's
the way we usually use AwaitState anyway.
In the AwaitPrimaryState function, which used to be
AwaitCoordinatorState in a different long-lost revision, we have
to delay until a primary node is available, or fail if one does
not become available, to avoid a panic. This probably shouldn't
happen anymore, because of the last change:
Also, rovide dummy topology.Node entries before metadata is read.
During initial startup, we want to be able to do things like determine
which node is the primary, even before we've read metadata from them.
To do this, we populate the node list with dummy entries that just have
the ID (the only part we need to sort our list), and a node state of
UNKNOWN.
This breaks the fancy logic for determining whether or not to update
the node data, because the initial status of UNKNOWN matches what we
get from SetMetadata giving us new data so we end up not realizing
that this was actually a meaningful change. But actually, that's
a pretty niche optimization; we usually only get state changes when
there's an actual change in state. The updates here are cheap
and only happen after a write (or on the first query) so it's not
worth making the logic a lot fancier to make it work, when we can
just do the simple thing and update any time the dirty flag is set.
We also standardize on a 50ms delay, because 1ms delays were
really expensive when each check was hitting etcd multiple times,
and 50ms is Usually Long Enough.
this doesn't quite work as-is, but I verified that it reproduced/fixed
the issue by adding a panic where the problem log statement
is. There's a follow up ticket to fix the test... it's just a bit open
ended as to the best way to do that.
etcd runs a LOT more goroutines during server startup. Fix a
goroutine/for loop bug causing us to run four 7-node clusters
instead of 1/3/4/7-node clusters, also have the test/cluster
code reduce import workers. We can't do much about the spamminess
of the Raft stuff, but this should tone it down some.
