Merge daa2cb1689 into 2ce65c324c

collector/pg_archiver.go

@@ -0,0 +1,81 @@
+// 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"
+
+	"github.com/go-kit/log"
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+func init() {
+	registerCollector("archiver", defaultDisabled, NewPGArchiverCollector)
+}
+
+type PGArchiverCollector struct {
+	log log.Logger
+}
+
+const archiverSubsystem = "archiver"
+
+func NewPGArchiverCollector(config collectorConfig) (Collector, error) {
+	return &PGArchiverCollector{log: config.logger}, nil
+}
+
+var (
+	pgArchiverPendingWalCount = prometheus.NewDesc(
+		prometheus.BuildFQName(namespace, archiverSubsystem, "pending_wals"),
+		"Number of WAL files waiting to be archived",
+		[]string{}, prometheus.Labels{},
+	)
+
+	pgArchiverQuery = `
+	WITH
+      current_wal_file AS (
+         SELECT CASE WHEN NOT pg_is_in_recovery() THEN pg_walfile_name(pg_current_wal_insert_lsn()) ELSE NULL END pg_walfile_name
+      ),
+      current_wal AS (
+        SELECT
+          ('x'||substring(pg_walfile_name,9,8))::bit(32)::int log,
+          ('x'||substring(pg_walfile_name,17,8))::bit(32)::int seg,
+          pg_walfile_name
+        FROM current_wal_file
+      ),
+      archive_wal AS(
+        SELECT
+          ('x'||substring(last_archived_wal,9,8))::bit(32)::int log,
+          ('x'||substring(last_archived_wal,17,8))::bit(32)::int seg,
+          last_archived_wal
+        FROM pg_stat_archiver
+      )
+    SELECT coalesce(((cw.log - aw.log) * 256) + (cw.seg-aw.seg),'NaN'::float) as pending_wal_count FROM current_wal cw, archive_wal aw
+	`
+)
+
+func (c *PGArchiverCollector) Update(ctx context.Context, instance *instance, ch chan<- prometheus.Metric) error {
+	db := instance.getDB()
+	row := db.QueryRowContext(ctx,
+		pgArchiverQuery)
+	var pendingWalCount float64
+	err := row.Scan(&pendingWalCount)
+	if err != nil {
+		return err
+	}
+	ch <- prometheus.MustNewConstMetric(
+		pgArchiverPendingWalCount,
+		prometheus.GaugeValue,
+		pendingWalCount,
+	)
+	return nil
+}

collector/pg_archiver_test.go

@@ -0,0 +1,96 @@
+// 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"
+	"math"
+	"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 TestPgArchiverCollector(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}
+	mock.ExpectQuery(sanitizeQuery(pgArchiverQuery)).WillReturnRows(sqlmock.NewRows([]string{"pending_wal_count"}).
+		AddRow(5))
+
+	ch := make(chan prometheus.Metric)
+	go func() {
+		defer close(ch)
+		c := PGArchiverCollector{}
+
+		if err := c.Update(context.Background(), inst, ch); err != nil {
+			t.Errorf("Error calling PGArchiverCollector.Update: %s", err)
+		}
+	}()
+
+	expected := []MetricResult{
+		{labels: labelMap{}, value: 5, metricType: dto.MetricType_GAUGE},
+	}
+	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 TestPgArchiverNaNCollector(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}
+	mock.ExpectQuery(sanitizeQuery(pgArchiverQuery)).WillReturnRows(sqlmock.NewRows([]string{"pending_wal_count"}).
+		AddRow(math.NaN()))
+
+	ch := make(chan prometheus.Metric)
+	go func() {
+		defer close(ch)
+		c := PGArchiverCollector{}
+
+		if err := c.Update(context.Background(), inst, ch); err != nil {
+			t.Errorf("Error calling PGArchiverCollector.Update: %s", err)
+		}
+	}()
+
+	expected := []MetricResult{
+		{labels: labelMap{}, value: math.NaN(), metricType: dto.MetricType_GAUGE},
+	}
+	convey.Convey("Metrics comparison", t, func() {
+		for _, expect := range expected {
+			m := readMetric(<-ch)
+			convey.So(expect.labels, convey.ShouldResemble, m.labels)
+			convey.So(math.IsNaN(m.value), convey.ShouldResemble, math.IsNaN(expect.value))
+			convey.So(expect.metricType, convey.ShouldEqual, m.metricType)
+		}
+	})
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("there were unfulfilled exceptions: %s", err)
+	}
+}