added tsdb/head mint maxt metrics (#4888)

added the head metrics with the correct suffix.

Signed-off-by: Krasi Georgiev <kgeorgie@redhat.com>

storage/tsdb/tsdb.go

@@ -124,6 +124,46 @@ type Options struct {
 	NoLockfile bool
 }
 
+var (
+	startTime   prometheus.GaugeFunc
+	headMaxTime prometheus.GaugeFunc
+	headMinTime prometheus.GaugeFunc
+)
+
+func registerMetrics(db *tsdb.DB, r prometheus.Registerer) {
+
+	startTime = prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+		Name: "prometheus_tsdb_lowest_timestamp_seconds",
+		Help: "Lowest timestamp value stored in the database.",
+	}, func() float64 {
+		bb := db.Blocks()
+		if len(bb) == 0 {
+			return float64(db.Head().MinTime()) / 1000
+		}
+		return float64(db.Blocks()[0].Meta().MinTime) / 1000
+	})
+	headMinTime = prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+		Name: "prometheus_tsdb_head_min_time_seconds",
+		Help: "Minimum time bound of the head block.",
+	}, func() float64 {
+		return float64(db.Head().MinTime()) / 1000
+	})
+	headMaxTime = prometheus.NewGaugeFunc(prometheus.GaugeOpts{
+		Name: "prometheus_tsdb_head_max_time_seconds",
+		Help: "Maximum timestamp of the head block.",
+	}, func() float64 {
+		return float64(db.Head().MaxTime()) / 1000
+	})
+
+	if r != nil {
+		r.MustRegister(
+			startTime,
+			headMaxTime,
+			headMinTime,
+		)
+	}
+}
+
 // Open returns a new storage backed by a TSDB database that is configured for Prometheus.
 func Open(path string, l log.Logger, r prometheus.Registerer, opts *Options) (*tsdb.DB, error) {
 	if opts.MinBlockDuration > opts.MaxBlockDuration {
@@ -149,6 +189,8 @@ func Open(path string, l log.Logger, r prometheus.Registerer, opts *Options) (*t
 	if err != nil {
 		return nil, err
 	}
+	registerMetrics(db, r)
+
 	return db, nil
 }
 

storage/tsdb/tsdb_export_test.go

@@ -0,0 +1,21 @@
+// Copyright 2017 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 tsdb
+
+// Export the internal variables only for tests.
+var (
+	StartTime   = &startTime
+	HeadMaxTime = &headMaxTime
+	HeadMinTime = &headMinTime
+)

storage/tsdb/tsdb_test.go

@@ -0,0 +1,63 @@
+// Copyright 2017 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 tsdb_test
+
+import (
+	"testing"
+
+	dto "github.com/prometheus/client_model/go"
+	"github.com/prometheus/common/model"
+	"github.com/prometheus/prometheus/pkg/labels"
+	"github.com/prometheus/prometheus/storage/tsdb"
+	"github.com/prometheus/prometheus/util/testutil"
+)
+
+func TestMetrics(t *testing.T) {
+	db := testutil.NewStorage(t)
+	defer db.Close()
+
+	metrics := &dto.Metric{}
+	startTime := *tsdb.StartTime
+	headMinTime := *tsdb.HeadMinTime
+	headMaxTime := *tsdb.HeadMaxTime
+
+	// Check initial values.
+	testutil.Ok(t, startTime.Write(metrics))
+	testutil.Equals(t, float64(model.Latest)/1000, metrics.Gauge.GetValue())
+
+	testutil.Ok(t, headMinTime.Write(metrics))
+	testutil.Equals(t, float64(model.Latest)/1000, metrics.Gauge.GetValue())
+
+	testutil.Ok(t, headMaxTime.Write(metrics))
+	testutil.Equals(t, float64(model.Earliest)/1000, metrics.Gauge.GetValue())
+
+	app, err := db.Appender()
+	testutil.Ok(t, err)
+
+	app.Add(labels.FromStrings(model.MetricNameLabel, "a"), 1, 1)
+	app.Add(labels.FromStrings(model.MetricNameLabel, "a"), 2, 1)
+	app.Add(labels.FromStrings(model.MetricNameLabel, "a"), 3, 1)
+	testutil.Ok(t, app.Commit())
+
+	// Check after adding some samples.
+	testutil.Ok(t, startTime.Write(metrics))
+	testutil.Equals(t, 0.001, metrics.Gauge.GetValue())
+
+	testutil.Ok(t, headMinTime.Write(metrics))
+	testutil.Equals(t, 0.001, metrics.Gauge.GetValue())
+
+	testutil.Ok(t, headMaxTime.Write(metrics))
+	testutil.Equals(t, 0.003, metrics.Gauge.GetValue())
+
+}