Add new stat

Signed-off-by: Matt Lord <[email protected]>

go/vt/vttablet/tabletmanager/vdiff/stats.go

@@ -0,0 +1,62 @@
+/*
+Copyright 2023 The Vitess Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package vdiff
+
+import (
+	"sync"
+
+	"vitess.io/vitess/go/stats"
+)
+
+var (
+	globalStats = &vdiffStats{}
+)
+
+func init() {
+	globalStats.register()
+}
+
+// This is a singleton.
+// vdiffStats exports the stats for Engine. It's a separate structure to
+// prevent potential deadlocks with the mutex in Engine.
+type vdiffStats struct {
+	mu sync.Mutex
+
+	RestartedTableDiffs *stats.CountersWithSingleLabel
+}
+
+func (st *vdiffStats) register() {
+	globalStats.RestartedTableDiffs = stats.NewCountersWithSingleLabel("", "", "Table", "")
+
+	stats.NewGaugesFuncWithMultiLabels(
+		"VDiffRestartedTableDiffsCount",
+		"vdiff table diffs restarted due to max-diff-duration counts per table",
+		[]string{"table_name"},
+		func() map[string]int64 {
+			st.mu.Lock()
+			defer st.mu.Unlock()
+			result := make(map[string]int64)
+			for label, count := range globalStats.RestartedTableDiffs.Counts() {
+				if label == "" {
+					continue
+				}
+				result[label] = count
+			}
+			return result
+		},
+	)
+}

go/vt/vttablet/tabletmanager/vdiff/table_differ.go

@@ -525,6 +525,7 @@ func (td *tableDiffer) diff(ctx context.Context, rowsToCompare int64, debug, onl
 		case <-td.wd.ct.done:
 			return nil, ErrVDiffStoppedByUser
 		case <-stop:
+			globalStats.RestartedTableDiffs.Add(td.table.Name, 1)
 			return nil, ErrMaxDiffDurationExceeded
 		default:
 		}