asim: simplify logic in history.ShowRecordedValueAt

Previously, we introduced support for showing initial and final metric values in
3da645a, including an additional sorting step.
However, the store metrics were already provided in sorted order. This commit
removes the unnecessary sorting to simplify the logic.

Epic: none
Release note: none

Author: wenyihu6

pkg/kv/kvserver/asim/history/history.go

@@ -8,7 +8,6 @@ package history
 import (
 	"context"
 	"fmt"
-	"sort"
 	"strings"
 
 	"github.com/cockroachdb/cockroach/pkg/kv/kvserver/asim/metrics"
@@ -20,6 +19,10 @@ import (
 // Currently it only contains the store metrics of the run.
 // TODO(kvoli): Add a range log like structure to the history.
 type History struct {
+	// Recorded contains per-store metrics snapshots at each tick. The outer slice
+	// grows over time at each tick, while each inner slice has one StoreMetrics per
+	// store. E.g. Recorded[0] is the first tick, Recorded[0][0] is the first store's
+	// metrics at the first tick.
 	Recorded [][]metrics.StoreMetrics
 	S        state.State
 }
@@ -31,72 +34,30 @@ func (h *History) Listen(ctx context.Context, sms []metrics.StoreMetrics) {
 
 func (h *History) ShowRecordedValueAt(idx int, stat string) string {
 	var buf strings.Builder
-	type storeIDWithStat struct {
-		StoreID int64
-		Value   float64
-	}
-	tick := h.Recorded[idx]
-	orderedStoreIDs := make([]storeIDWithStat, 0, len(tick))
-	values := make([]float64, 0, len(tick))
-	for _, sm := range tick {
-		var value float64
-		switch stat {
-		case "qps":
-			value = float64(sm.QPS)
-		// case "cpu":
-		// 	value = float64(sm.CPU)
-		// case "write_bytes_per_second":
-		// 	value = float64(sm.WriteBytesPerSecond)
-		case "write":
-			value = float64(sm.WriteKeys)
-		case "write_b":
-			value = float64(sm.WriteBytes)
-		case "read":
-			value = float64(sm.ReadKeys)
-		case "read_b":
-			value = float64(sm.ReadBytes)
-		case "replicas":
-			value = float64(sm.Replicas)
-		case "leases":
-			value = float64(sm.Leases)
-		case "lease_moves":
-			value = float64(sm.LeaseTransfers)
-		case "replica_moves":
-			value = float64(sm.Rebalances)
-		case "replica_b_rcvd":
-			value = float64(sm.RebalanceRcvdBytes)
-		case "replica_b_sent":
-			value = float64(sm.RebalanceSentBytes)
-		case "range_splits":
-			value = float64(sm.RangeSplits)
-		case "disk_fraction_used":
-			value = sm.DiskFractionUsed
-		default:
-			return "<unrecognized stat>"
-		}
-		orderedStoreIDs = append(orderedStoreIDs, storeIDWithStat{
-			StoreID: sm.StoreID,
-			Value:   value,
-		})
-		values = append(values, value)
-	}
-	sort.Slice(orderedStoreIDs, func(i, j int) bool {
-		return orderedStoreIDs[i].StoreID < orderedStoreIDs[j].StoreID
-	})
+
+	storeMetricsAtTick := h.Recorded[idx]
+	values := make([]float64, 0, len(storeMetricsAtTick))
+
 	_, _ = fmt.Fprintf(&buf, "[")
-	for i, store := range orderedStoreIDs {
+
+	// Extract values for each store. Note that h.Recorded[idx] is already sorted
+	// by store ID when appending to h.Recorded.
+	for i, sm := range storeMetricsAtTick {
 		if i > 0 {
-			_, _ = fmt.Fprintf(&buf, " ")
+			_, _ = fmt.Fprintf(&buf, ", ")
 		}
+		value := sm.GetMetricValue(stat)
 		if stat == "disk_fraction_used" {
-			_, _ = fmt.Fprintf(&buf, "s%v=%.2f", store.StoreID, store.Value)
+			_, _ = fmt.Fprintf(&buf, "s%v=%.2f", sm.StoreID, value)
 		} else {
-			_, _ = fmt.Fprintf(&buf, "s%v=%.0f", store.StoreID, store.Value)
+			_, _ = fmt.Fprintf(&buf, "s%v=%.0f", sm.StoreID, value)
 		}
+		values = append(values, value)
 	}
 	_, _ = fmt.Fprintf(&buf, "]")
 	stddev, _ := stats.StandardDeviation(values)
+	mean, _ := stats.Mean(values)
 	sum, _ := stats.Sum(values)
-	_, _ = fmt.Fprintf(&buf, " (stddev=%.2f,sum=%.2f)", stddev, sum)
+	_, _ = fmt.Fprintf(&buf, " (stddev=%.2f, mean=%.2f, sum=%.0f)", stddev, mean, sum)
 	return buf.String()
 }

pkg/kv/kvserver/asim/metrics/tracker.go

@@ -40,6 +40,44 @@ type StoreMetrics struct {
 	DiskFractionUsed   float64
 }
 
+// GetMetricValue extracts the requested metric value from StoreMetrics.
+func (sm *StoreMetrics) GetMetricValue(stat string) float64 {
+	switch stat {
+	case "qps":
+		return float64(sm.QPS)
+	// case "cpu":
+	// 	value = float64(sm.CPU)
+	// case "write_bytes_per_second":
+	// 	value = float64(sm.WriteBytesPerSecond)
+	case "write":
+		return float64(sm.WriteKeys)
+	case "write_b":
+		return float64(sm.WriteBytes)
+	case "read":
+		return float64(sm.ReadKeys)
+	case "read_b":
+		return float64(sm.ReadBytes)
+	case "replicas":
+		return float64(sm.Replicas)
+	case "leases":
+		return float64(sm.Leases)
+	case "lease_moves":
+		return float64(sm.LeaseTransfers)
+	case "replica_moves":
+		return float64(sm.Rebalances)
+	case "replica_b_rcvd":
+		return float64(sm.RebalanceRcvdBytes)
+	case "replica_b_sent":
+		return float64(sm.RebalanceSentBytes)
+	case "range_splits":
+		return float64(sm.RangeSplits)
+	case "disk_fraction_used":
+		return sm.DiskFractionUsed
+	default:
+		return 0
+	}
+}
+
 // the MetricsTracker to report new store metrics for a tick.
 type StoreMetricsListener interface {
 	Listen(context.Context, []StoreMetrics)

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_add_node

@@ -52,7 +52,7 @@ plot stat=replicas sample=1
   20 ┤ ╭──╯
    0 ┼─╯
                                           replicas
-initial store values: [s1=301 s2=0 s3=0] (stddev=141.89,sum=301.00)
-last store values: [s1=300 s2=301 s3=300] (stddev=0.47,sum=901.00)
+initial store values: [s1=301, s2=0, s3=0] (stddev=141.89, mean=100.33, sum=301)
+last store values: [s1=300, s2=301, s3=300] (stddev=0.47, mean=300.33, sum=901)
 
 # vim:ft=sh

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_fulldisk

@@ -36,8 +36,8 @@ plot stat=replicas
  164 ┤                                                         ╰─╯ ╰──╮╭─────╮╭╮
  151 ┤                                                                ╰╯     ╰╯╰─────
                                           replicas
-initial store values: [s1=300 s2=300 s3=300 s4=300 s5=300] (stddev=0.00,sum=1500.00)
-last store values: [s1=342 s2=338 s3=339 s4=334 s5=156] (stddev=72.94,sum=1509.00)
+initial store values: [s1=300, s2=300, s3=300, s4=300, s5=300] (stddev=0.00, mean=300.00, sum=1500)
+last store values: [s1=342, s2=338, s3=339, s4=334, s5=156] (stddev=72.94, mean=301.80, sum=1509)
 
 # Plot the % of disk storage capacity used. We should see s5 hovering right
 # around 92.5-95% (the storage capacity threshold value).
@@ -60,5 +60,5 @@ plot stat=disk_fraction_used
  0.07 ┤
  0.00 ┼───────────────────────────────────────────────────────────────────────────────
                                       disk_fraction_used
-initial store values: [s1=0.00 s2=0.00 s3=0.00 s4=0.00 s5=0.83] (stddev=0.33,sum=0.83)
-last store values: [s1=0.00 s2=0.00 s3=0.00 s4=0.00 s5=0.94] (stddev=0.38,sum=0.94)
+initial store values: [s1=0.00, s2=0.00, s3=0.00, s4=0.00, s5=0.83] (stddev=0.33, mean=0.17, sum=1)
+last store values: [s1=0.00, s2=0.00, s3=0.00, s4=0.00, s5=0.94] (stddev=0.38, mean=0.19, sum=1)

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_io_overload

@@ -35,8 +35,8 @@ plot stat=replicas
   33 ┤  ╭───╯
    0 ┼───────────────────────────────────────────────────────────────────────────────
                                           replicas
-initial store values: [s1=500 s2=500 s3=500 s4=0 s5=0] (stddev=244.95,sum=1500.00)
-last store values: [s1=372 s2=381 s3=371 s4=376 s5=0] (stddev=150.04,sum=1500.00)
+initial store values: [s1=500, s2=500, s3=500, s4=0, s5=0] (stddev=244.95, mean=300.00, sum=1500)
+last store values: [s1=372, s2=381, s3=371, s4=376, s5=0] (stddev=150.04, mean=300.00, sum=1500)
 
 plot stat=leases
 ----
@@ -57,5 +57,5 @@ plot stat=leases
   33 ┤     ╭─────────╯                                  ╭╭────────────╯
    0 ┼───────────────────────────────────────────────────────────────────────────────
                                            leases
-initial store values: [s1=500 s2=0 s3=0 s4=0 s5=0] (stddev=200.00,sum=500.00)
-last store values: [s1=230 s2=98 s3=67 s4=105 s5=0] (stddev=74.86,sum=500.00)
+initial store values: [s1=500, s2=0, s3=0, s4=0, s5=0] (stddev=200.00, mean=100.00, sum=500)
+last store values: [s1=230, s2=98, s3=67, s4=105, s5=0] (stddev=74.86, mean=100.00, sum=500)

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_liveness

@@ -50,8 +50,8 @@ plot stat=replicas
   29 ┤                          ╰───╮                           ╰───────╮
    0 ┤                              ╰────────────────────────────────────────────────
                                           replicas
-initial store values: [s1=300 s2=300 s3=300 s4=300 s5=300 s6=300 s7=300] (stddev=0.00,sum=2100.00)
-last store values: [s1=430 s2=428 s3=409 s4=414 s5=419 s6=0 s7=0] (stddev=189.86,sum=2100.00)
+initial store values: [s1=300, s2=300, s3=300, s4=300, s5=300, s6=300, s7=300] (stddev=0.00, mean=300.00, sum=2100)
+last store values: [s1=430, s2=428, s3=409, s4=414, s5=419, s6=0, s7=0] (stddev=189.86, mean=300.00, sum=2100)
 
 # Both nodes should begin losing leases immediately after their liveness status
 # is changed to dead or decommissioning (5 minutes later).
@@ -74,7 +74,7 @@ plot stat=leases
   10 ┤                            ╰──╮                        ╰──╮
    0 ┤                               ╰───────────────────────────────────────────────
                                            leases
-initial store values: [s1=100 s2=100 s3=100 s4=100 s5=100 s6=100 s7=100] (stddev=0.00,sum=700.00)
-last store values: [s1=135 s2=147 s3=140 s4=141 s5=137 s6=0 s7=0] (stddev=63.34,sum=700.00)
+initial store values: [s1=100, s2=100, s3=100, s4=100, s5=100, s6=100, s7=100] (stddev=0.00, mean=100.00, sum=700)
+last store values: [s1=135, s2=147, s3=140, s4=141, s5=137, s6=0, s7=0] (stddev=63.34, mean=100.00, sum=700)
 
 # vim:ft=sh

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_multi_store

@@ -40,5 +40,5 @@ plot stat=leases
   0.93 ┤ ╭─╯────────────╭──────────────────────────────────────────────────────────────
   0.00 ┼────────────────╯───────────────────────────────╯
                                              leases
-initial store values: [s1=14 s2=0 s3=0 s4=0 s5=0 s6=0 s7=0 s8=0 s9=0 s10=0 s11=0 s12=0 s13=0 s14=0] (stddev=3.61,sum=14.00)
-last store values: [s1=1 s2=1 s3=1 s4=1 s5=1 s6=1 s7=1 s8=1 s9=1 s10=1 s11=1 s12=1 s13=1 s14=1] (stddev=0.00,sum=14.00)
+initial store values: [s1=14, s2=0, s3=0, s4=0, s5=0, s6=0, s7=0, s8=0, s9=0, s10=0, s11=0, s12=0, s13=0, s14=0] (stddev=3.61, mean=1.00, sum=14)
+last store values: [s1=1, s2=1, s3=1, s4=1, s5=1, s6=1, s7=1, s8=1, s9=1, s10=1, s11=1, s12=1, s13=1, s14=1] (stddev=0.00, mean=1.00, sum=14)

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_rebalancing

@@ -59,8 +59,8 @@ plot stat=qps sample=2
   335 ┤ │││ │                       │                         │
     0 ┼─────────────────────────────╯─────────────────────────╯
                                              qps
-initial store values: [s1=0 s2=0 s3=0 s4=0 s5=0 s6=0 s7=0] (stddev=0.00,sum=0.00)
-last store values: [s1=996 s2=997 s3=996 s4=1000 s5=1000 s6=1005 s7=1001] (stddev=3.01,sum=6995.00)
+initial store values: [s1=0, s2=0, s3=0, s4=0, s5=0, s6=0, s7=0] (stddev=0.00, mean=0.00, sum=0)
+last store values: [s1=996, s2=997, s3=996, s4=1000, s5=1000, s6=1005, s7=1001] (stddev=3.01, mean=999.29, sum=6995)
 
 # The cluster settings and simulation variables can be modified to examine how
 # allocation behaves during uncommon scenarios. Update the gossip delay to be
@@ -97,8 +97,8 @@ plot stat=qps sample=3
   467 ┤ │    │││    ││  │       │      ││               │
     0 ┼─────────────────────────────────╯───────────────╯
                                              qps
-initial store values: [s1=0 s2=0 s3=0 s4=0 s5=0 s6=0 s7=0] (stddev=0.00,sum=0.00)
-last store values: [s1=1003 s2=997 s3=1002 s4=1003 s5=999 s6=994 s7=999] (stddev=3.11,sum=6997.00)
+initial store values: [s1=0, s2=0, s3=0, s4=0, s5=0, s6=0, s7=0] (stddev=0.00, mean=0.00, sum=0)
+last store values: [s1=1003, s2=997, s3=1002, s4=1003, s5=999, s6=994, s7=999] (stddev=3.11, mean=999.57, sum=6997)
 
 # Plot the replica movements for the same sample, we should see a steadily
 # increasing counter for each store; indicating that rebalancing activity is
@@ -122,7 +122,7 @@ plot stat=replica_moves sample=3
   0.93 ┤     │╭╭╯────│  ╭──────╯                        ╭──────────────────────────────
   0.00 ┼────────────────────────────────────────────────╯
                                          replica_moves
-initial store values: [s1=0 s2=0 s3=0 s4=0 s5=0 s6=0 s7=0] (stddev=0.00,sum=0.00)
-last store values: [s1=14 s2=6 s3=5 s4=5 s5=5 s6=2 s7=1] (stddev=3.89,sum=38.00)
+initial store values: [s1=0, s2=0, s3=0, s4=0, s5=0, s6=0, s7=0] (stddev=0.00, mean=0.00, sum=0)
+last store values: [s1=14, s2=6, s3=5, s4=5, s5=5, s6=2, s7=1] (stddev=3.89, mean=5.43, sum=38)
 
 # vim:ft=sh

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_splitting

@@ -46,15 +46,15 @@ plot stat=replicas sample=2
  1.33 ┤   │
  1.00 ┼───╯
                                            replicas
-initial store values: [s1=1] (stddev=0.00,sum=1.00)
-last store values: [s1=6] (stddev=0.00,sum=6.00)
+initial store values: [s1=1] (stddev=0.00, mean=1.00, sum=1)
+last store values: [s1=6] (stddev=0.00, mean=6.00, sum=6)
 
 # Update the load generator to use a zipfian distribution instead of a uniform.
 # Now the load based splitter must find a split key from a skewed distribution
 # repeatedly - if the load split algorithm is good, we should expect the same
 # number of splits as the uniform workload. However, that is not the case as we
 # require more splits with a zipfian distribution.
-gen_load rate=10000 rw_ratio=1 access_skew=true replace=true
+gen_load rate=10000 rw_ratio=1 access_skew=true
 ----
 
 eval duration=5m samples=2 seed=42
@@ -63,24 +63,24 @@ OK
 
 plot stat=replicas sample=4
 ----
- 9.00 ┤                          ╭────────────────────────────────────────────────────
- 8.47 ┤                          │
- 7.93 ┤                      ╭───╯
- 7.40 ┤                      │
- 6.87 ┤                   ╭──╯
- 6.33 ┤                   │
- 5.80 ┤               ╭───╯
- 5.27 ┤               │
- 4.73 ┤            ╭──╯
- 4.20 ┤         ╭──╯
- 3.67 ┤         │
- 3.13 ┤      ╭──╯
- 2.60 ┤      │
- 2.07 ┤   ╭──╯
- 1.53 ┤   │
- 1.00 ┼───╯
-                                           replicas
-initial store values: [s1=1] (stddev=0.00,sum=1.00)
-last store values: [s1=9] (stddev=0.00,sum=9.00)
+ 15.00 ┤                                ╭──────────────────────────────────────────────
+ 14.07 ┤                             ╭──╯
+ 13.13 ┤                         ╭───╯
+ 12.20 ┤                      ╭──╯
+ 11.27 ┤                   ╭──╯
+ 10.33 ┤                ╭──╯
+  9.40 ┤            ╭───╯
+  8.47 ┤         ╭──╯
+  7.53 ┤         │
+  6.60 ┤         │
+  5.67 ┤         │
+  4.73 ┤         │
+  3.80 ┤      ╭──╯
+  2.87 ┤      │
+  1.93 ┤   ╭──╯
+  1.00 ┼───╯
+                                            replicas
+initial store values: [s1=1] (stddev=0.00, mean=1.00, sum=1)
+last store values: [s1=15] (stddev=0.00, mean=15.00, sum=15)
 
 # vim:ft=sh

pkg/kv/kvserver/asim/tests/testdata/non_rand/example_zone_config

@@ -70,5 +70,5 @@ plot stat=replicas
   3.47 ┤         ╰╰╰╰───────╮─╮
   0.00 ┤          ╰──╰╰──╰──╰──────────────────────────────────────────────────────────
                                             replicas
-initial store values: [s1=17 s2=17 s3=17 s4=17 s5=17 s6=16 s7=16 s8=17 s9=17 s10=17 s11=17 s12=17 s13=16 s14=16 s15=16 s16=16 s17=17 s18=17 s19=17 s20=16 s21=17 s22=16 s23=17 s24=17 s25=17 s26=17 s27=17 s28=16 s29=17 s30=16 s31=17 s32=17 s33=16 s34=16 s35=17 s36=17] (stddev=0.47,sum=600.00)
-last store values: [s1=50 s2=49 s3=50 s4=50 s5=51 s6=49 s7=50 s8=50 s9=52 s10=49 s11=50 s12=50 s13=0 s14=0 s15=0 s16=0 s17=0 s18=0 s19=0 s20=0 s21=0 s22=0 s23=0 s24=0 s25=0 s26=0 s27=0 s28=0 s29=0 s30=0 s31=0 s32=0 s33=0 s34=0 s35=0 s36=0] (stddev=23.57,sum=600.00)
+initial store values: [s1=17, s2=17, s3=17, s4=17, s5=17, s6=16, s7=16, s8=17, s9=17, s10=17, s11=17, s12=17, s13=16, s14=16, s15=16, s16=16, s17=17, s18=17, s19=17, s20=16, s21=17, s22=16, s23=17, s24=17, s25=17, s26=17, s27=17, s28=16, s29=17, s30=16, s31=17, s32=17, s33=16, s34=16, s35=17, s36=17] (stddev=0.47, mean=16.67, sum=600)
+last store values: [s1=50, s2=49, s3=50, s4=50, s5=51, s6=49, s7=50, s8=50, s9=52, s10=49, s11=50, s12=50, s13=0, s14=0, s15=0, s16=0, s17=0, s18=0, s19=0, s20=0, s21=0, s22=0, s23=0, s24=0, s25=0, s26=0, s27=0, s28=0, s29=0, s30=0, s31=0, s32=0, s33=0, s34=0, s35=0, s36=0] (stddev=23.57, mean=16.67, sum=600)