Gitlab Collector: User Index io stats collector and test (#845)

* User Index io stats collector and test

---------

Signed-off-by: Felix Yuan <felix.yuan@reddit.com>

collector/pg_statio_user_indexes.go

@@ -0,0 +1,118 @@
+// Copyright 2023 The Prometheus 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 collector
+
+import (
+	"context"
+	"database/sql"
+
+	"github.com/go-kit/log"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func init() {
+	registerCollector(statioUserIndexesSubsystem, defaultDisabled, NewPGStatioUserIndexesCollector)
+}
+
+type PGStatioUserIndexesCollector struct {
+	log log.Logger
+}
+
+const statioUserIndexesSubsystem = "statio_user_indexes"
+
+func NewPGStatioUserIndexesCollector(config collectorConfig) (Collector, error) {
+	return &PGStatioUserIndexesCollector{log: config.logger}, nil
+}
+
+var (
+	statioUserIndexesIdxBlksRead = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, statioUserIndexesSubsystem, "idx_blks_read_total"),
+		"Number of disk blocks read from this index",
+		[]string{"schemaname", "relname", "indexrelname"},
+		prometheus.Labels{},
+	)
+	statioUserIndexesIdxBlksHit = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, statioUserIndexesSubsystem, "idx_blks_hit_total"),
+		"Number of buffer hits in this index",
+		[]string{"schemaname", "relname", "indexrelname"},
+		prometheus.Labels{},
+	)
+
+	statioUserIndexesQuery = `
+	SELECT
+		schemaname,
+		relname,
+		indexrelname,
+		idx_blks_read,
+		idx_blks_hit
+	FROM pg_statio_user_indexes
+	`
+)
+
+func (c *PGStatioUserIndexesCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
+	db := instance.getDB()
+	rows, err := db.QueryContext(ctx,
+		statioUserIndexesQuery)
+
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+	for rows.Next() {
+		var schemaname, relname, indexrelname sql.NullString
+		var idxBlksRead, idxBlksHit sql.NullFloat64
+
+		if err := rows.Scan(&schemaname, &relname, &indexrelname, &idxBlksRead, &idxBlksHit); err != nil {
+			return err
+		}
+		schemanameLabel := "unknown"
+		if schemaname.Valid {
+			schemanameLabel = schemaname.String
+		}
+		relnameLabel := "unknown"
+		if relname.Valid {
+			relnameLabel = relname.String
+		}
+		indexrelnameLabel := "unknown"
+		if indexrelname.Valid {
+			indexrelnameLabel = indexrelname.String
+		}
+		labels := []string{schemanameLabel, relnameLabel, indexrelnameLabel}
+
+		idxBlksReadMetric := 0.0
+		if idxBlksRead.Valid {
+			idxBlksReadMetric = idxBlksRead.Float64
+		}
+		ch <- prometheus.MustNewConstMetric(
+			statioUserIndexesIdxBlksRead,
+			prometheus.CounterValue,
+			idxBlksReadMetric,
+			labels...,
+		)
+
+		idxBlksHitMetric := 0.0
+		if idxBlksHit.Valid {
+			idxBlksHitMetric = idxBlksHit.Float64
+		}
+		ch <- prometheus.MustNewConstMetric(
+			statioUserIndexesIdxBlksHit,
+			prometheus.CounterValue,
+			idxBlksHitMetric,
+			labels...,
+		)
+	}
+	if err := rows.Err(); err != nil {
+		return err
+	}
+	return nil
+}

collector/pg_statio_user_indexes_test.go

@@ -0,0 +1,109 @@
+// Copyright 2023 The Prometheus 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 collector
+
+import (
+	"context"
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+	"github.com/smartystreets/goconvey/convey"
+)
+
+func TestPgStatioUserIndexesCollector(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	if err != nil {
+		t.Fatalf("Error opening a stub db connection: %s", err)
+	}
+	defer db.Close()
+	inst := &instance{db: db}
+	columns := []string{
+		"schemaname",
+		"relname",
+		"indexrelname",
+		"idx_blks_read",
+		"idx_blks_hit",
+	}
+	rows := sqlmock.NewRows(columns).
+		AddRow("public", "pgtest_accounts", "pgtest_accounts_pkey", 8, 9)
+
+	mock.ExpectQuery(sanitizeQuery(statioUserIndexesQuery)).WillReturnRows(rows)
+
+	ch := make(chan prometheus.Metric)
+	go func() {
+		defer close(ch)
+		c := PGStatioUserIndexesCollector{}
+
+		if err := c.Update(context.Background(), inst, ch); err != nil {
+			t.Errorf("Error calling PGStatioUserIndexesCollector.Update: %s", err)
+		}
+	}()
+	expected := []MetricResult{
+		{labels: labelMap{"schemaname": "public", "relname": "pgtest_accounts", "indexrelname": "pgtest_accounts_pkey"}, value: 8, metricType: dto.MetricType_COUNTER},
+		{labels: labelMap{"schemaname": "public", "relname": "pgtest_accounts", "indexrelname": "pgtest_accounts_pkey"}, value: 9, metricType: dto.MetricType_COUNTER},
+	}
+	convey.Convey("Metrics comparison", t, func() {
+		for _, expect := range expected {
+			m := readMetric(<-ch)
+			convey.So(expect, convey.ShouldResemble, m)
+		}
+	})
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("there were unfulfilled exceptions: %s", err)
+	}
+}
+
+func TestPgStatioUserIndexesCollectorNull(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	if err != nil {
+		t.Fatalf("Error opening a stub db connection: %s", err)
+	}
+	defer db.Close()
+	inst := &instance{db: db}
+	columns := []string{
+		"schemaname",
+		"relname",
+		"indexrelname",
+		"idx_blks_read",
+		"idx_blks_hit",
+	}
+	rows := sqlmock.NewRows(columns).
+		AddRow(nil, nil, nil, nil, nil)
+
+	mock.ExpectQuery(sanitizeQuery(statioUserIndexesQuery)).WillReturnRows(rows)
+
+	ch := make(chan prometheus.Metric)
+	go func() {
+		defer close(ch)
+		c := PGStatioUserIndexesCollector{}
+
+		if err := c.Update(context.Background(), inst, ch); err != nil {
+			t.Errorf("Error calling PGStatioUserIndexesCollector.Update: %s", err)
+		}
+	}()
+	expected := []MetricResult{
+		{labels: labelMap{"schemaname": "unknown", "relname": "unknown", "indexrelname": "unknown"}, value: 0, metricType: dto.MetricType_COUNTER},
+		{labels: labelMap{"schemaname": "unknown", "relname": "unknown", "indexrelname": "unknown"}, value: 0, metricType: dto.MetricType_COUNTER},
+	}
+	convey.Convey("Metrics comparison", t, func() {
+		for _, expect := range expected {
+			m := readMetric(<-ch)
+			convey.So(expect, convey.ShouldResemble, m)
+		}
+	})
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("there were unfulfilled exceptions: %s", err)
+	}
+}