Add metrics the number of running transactions

README.md

@@ -134,6 +134,7 @@ collect.perf_schema.replication_applier_status_by_worker     | 5.7           | C
 collect.slave_status                                         | 5.1           | Collect from SHOW SLAVE STATUS (Enabled by default)
 collect.slave_hosts                                          | 5.1           | Collect from SHOW SLAVE HOSTS
 collect.sys.user_summary                                     | 5.7           | Collect metrics from sys.x$user_summary (disabled by default).
+collect.info_schema.innodb_trx                               | 5.7           | Collect Number of running transactions that have been running for more than the specified time(by --collector.info_schema_innodb_trx.running_time)(disabled by default).
 
 
 ### General Flags

collector/info_schema_innodb_trx.go

@@ -0,0 +1,81 @@
+// Copyright 2018 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.
+
+// Scrape `information_schema.INNODB_TRX`.
+package collector
+
+import (
+	"context"
+	"fmt"
+	"github.com/alecthomas/kingpin/v2"
+	"github.com/go-kit/log"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+const infoSchemaInnodbTRX = `
+	SELECT count(1) FROM information_schema.INNODB_TRX WHERE trx_started < NOW() - INTERVAL %d MINUTE;
+`
+
+// Tunable flags.
+var trxRunningTime = kingpin.Flag(
+	"collector.info_schema_innodb_trx.running_time",
+	"The running time in minutes for which to collect the number of running transactions.",
+).Default("0").Int()
+
+// Metric descriptors.
+var (
+	infoSchemaInnodbTrxDesc = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, informationSchema, "innodb_trx_running_transactions"),
+		"Number of running transactions that have been running for more than the specified time.",
+		nil, nil)
+)
+
+// ScrapeTransaction collects from `information_schema.INNODB_TRX`.
+type ScrapeTransaction struct{}
+
+// Name of the Scraper. Should be unique.
+func (ScrapeTransaction) Name() string { return informationSchema + ".innodb_trx" }
+
+// Help describes the role of the Scraper.
+func (ScrapeTransaction) Help() string {
+	return "Number of running transactions that have been running for more than the specified time."
+}
+
+// Version of MySQL from which scraper is available.
+func (ScrapeTransaction) Version() float64 {
+	return 5.7
+}
+
+func (ScrapeTransaction) Scrape(ctx context.Context, instance *instance, ch chan<- prometheus.Metric, logger log.Logger) error {
+	query := fmt.Sprintf(infoSchemaInnodbTRX, *trxRunningTime)
+	db := instance.getDB()
+	rows, err := db.QueryContext(ctx, query)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+
+	var trxRunning int
+
+	for rows.Next() {
+		if err := rows.Scan(&trxRunning); err != nil {
+			return err
+		}
+	}
+	ch <- prometheus.MustNewConstMetric(infoSchemaInnodbTrxDesc, prometheus.GaugeValue, float64(trxRunning))
+
+	return nil
+}
+
+// check interface
+var _ Scraper = ScrapeTransaction{}

collector/info_schema_innodb_trx_test.go

@@ -0,0 +1,66 @@
+// Copyright 2021 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"
+	"fmt"
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/alecthomas/kingpin/v2"
+	"github.com/go-kit/log"
+	"github.com/prometheus/client_golang/prometheus"
+	dto "github.com/prometheus/client_model/go"
+	"github.com/smartystreets/goconvey/convey"
+	"regexp"
+	"testing"
+)
+
+func TestScrapeTransaction(t *testing.T) {
+	_, err := kingpin.CommandLine.Parse([]string{
+		"--collect.info_schema.processlist.min_time=0",
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	db, mock, err := sqlmock.New()
+	if err != nil {
+		t.Fatalf("error opening a stub database connection: %s", err)
+	}
+	defer db.Close()
+	inst := &instance{db: db}
+	query := fmt.Sprintf(infoSchemaInnodbTRX, 0)
+	columns := []string{"count"}
+	rows := sqlmock.NewRows(columns).AddRow(0)
+	mock.ExpectQuery(regexp.QuoteMeta(query)).WillReturnRows(rows)
+	ch := make(chan prometheus.Metric)
+	go func() {
+		if err = (ScrapeTransaction{}).Scrape(context.Background(), inst, ch, log.NewNopLogger()); err != nil {
+			t.Errorf("error calling scrapeTransaction: %s", err)
+		}
+		close(ch)
+	}()
+
+	expected := []MetricResult{
+		{labels: labelMap{}, value: 0, metricType: dto.MetricType_GAUGE},
+	}
+	convey.Convey("Metrics comparison", t, func() {
+		for _, expect := range expected {
+			got := readMetric(<-ch)
+			convey.So(expect, convey.ShouldResemble, got)
+		}
+	})
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("there were unfulfilled exceptions: %s", err)
+	}
+}

mysqld_exporter.go

@@ -105,6 +105,7 @@ var scrapers = map[collector.Scraper]bool{
 	collector.ScrapeHeartbeat{}:                           false,
 	collector.ScrapeSlaveHosts{}:                          false,
 	collector.ScrapeReplicaHost{}:                         false,
+	collector.ScrapeTransaction{}:                         false,
 }
 
 func filterScrapers(scrapers []collector.Scraper, collectParams []string) []collector.Scraper {