kvserver: replicastats can produce nil ptr on perlocalitydecayingrate #94696
Description
Describe the problem
When calling PerLocalityDecayingRate() can produce a nil ptr panic de-referencing the locality counter for a record.
To Reproduce
TestCCLLogic_multi_region_zone_configs/force_repaving_all_zone_configs
(better reproduction in progress)
* ERROR: a panic has occurred!
* runtime error: invalid memory address or nil pointer dereference
* (1) attached stack trace
* -- stack trace:
* | runtime.gopanic
* | GOROOT/src/runtime/panic.go:884
* | runtime.panicmem
* | GOROOT/src/runtime/panic.go:260
* | runtime.sigpanic
* | GOROOT/src/runtime/signal_unix.go:835
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/replicastats.(*ReplicaStats).PerLocalityDecayingRate
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/replicastats/replica_stats.go:314
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/replicastats.(*ReplicaStats).SnapshotRatedSummary
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/replicastats/replica_stats.go:385
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/load.(*ReplicaLoad).RequestLocalityInfo
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/load/replica_load.go:207
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver.RangeUsageInfoForRepl
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/replicate_queue.go:2193
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*Store).Capacity.func1
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/store.go:2919
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*storeReplicaVisitor).Visit
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/store.go:439
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*Store).Capacity
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/store.go:2914
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*Store).Descriptor
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/store.go:2991
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*Store).updateCapacityGauges
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/store_raft.go:920
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*Store).computeMetrics
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/store.go:3248
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*Store).ComputeMetricsPeriodically
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/store.go:3282
* | github.com/cockroachdb/cockroach/pkg/server.(*Node).computeMetricsPeriodically.func1
* | github.com/cockroachdb/cockroach/pkg/server/node.go:773
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*Stores).VisitStores.func1
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/stores.go:150
* | github.com/cockroachdb/cockroach/pkg/util/syncutil.(*IntMap).Range
* | github.com/cockroachdb/cockroach/pkg/util/syncutil/int_map.go:352
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver.(*Stores).VisitStores
* | github.com/cockroachdb/cockroach/pkg/kv/kvserver/pkg/kv/kvserver/stores.go:149
* | github.com/cockroachdb/cockroach/pkg/server.(*Node).computeMetricsPeriodically
* | github.com/cockroachdb/cockroach/pkg/server/node.go:772
* | github.com/cockroachdb/cockroach/pkg/server.(*Node).startComputePeriodicMetrics.func1
* | github.com/cockroachdb/cockroach/pkg/server/node.go:757
* | github.com/cockroachdb/cockroach/pkg/util/stop.(*Stopper).RunAsyncTaskEx.func2
* | github.com/cockroachdb/cockroach/pkg/util/stop/stopper.go:470
* | runtime.goexit
* | GOROOT/src/runtime/asm_amd64.s:1594
* Wraps: (2) runtime error: invalid memory address or nil pointer dereference
Expected behavior
A nil ptr de-reference doesn't occur in PerLocalityDecayingRate()
Environment:
- CockroachDB version: faf291b
Jira issue: CRDB-23093