collector/cpu: split cpu freq metrics into separate collector (#1253)

The cpu frequency information is not always needed and/or available.
This change allows the cpu frequency metrics to be enabled/disabled
separately from the other cpu metrics, and also prevents a frequency
metric failure (such as a parse error) from failing the main cpu
collector.

Fixes #1241

Signed-off-by: Paul Gier <pgier@redhat.com>

collector/cpufreq_solaris.go

@@ -0,0 +1,95 @@
+// Copyright 2019 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.
+
+// +build solaris
+// +build !nocpu
+
+package collector
+
+import (
+	"fmt"
+	"strconv"
+
+	"github.com/prometheus/client_golang/prometheus"
+	kstat "github.com/siebenmann/go-kstat"
+)
+
+// #include <unistd.h>
+import "C"
+
+type cpuFreqCollector struct {
+	cpuFreq    *prometheus.Desc
+	cpuFreqMax *prometheus.Desc
+}
+
+func init() {
+	registerCollector("cpufreq", defaultEnabled, NewCpuFreqCollector)
+}
+
+func NewFreqCpuCollector() (Collector, error) {
+	return &cpuFreqCollector{
+		cpuFreq: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, cpuCollectorSubsystem, "frequency_hertz"),
+			"Current cpu thread frequency in hertz.",
+			[]string{"cpu"}, nil,
+		),
+		cpuFreqMax: prometheus.NewDesc(
+			prometheus.BuildFQName(namespace, cpuCollectorSubsystem, "frequency_max_hertz"),
+			"Maximum cpu thread frequency in hertz.",
+			[]string{"cpu"}, nil,
+		),
+	}, nil
+}
+
+func (c *cpuCollector) Update(ch chan<- prometheus.Metric) error {
+	ncpus := C.sysconf(C._SC_NPROCESSORS_ONLN)
+
+	tok, err := kstat.Open()
+	if err != nil {
+		return err
+	}
+
+	defer tok.Close()
+
+	for cpu := 0; cpu < int(ncpus); cpu++ {
+		ksCPUInfo, err := tok.Lookup("cpu_info", cpu, fmt.Sprintf("cpu_info%d", cpu))
+		if err != nil {
+			return err
+		}
+		cpuFreqV, err := ksCPUInfo.GetNamed("current_clock_Hz")
+		if err != nil {
+			return err
+		}
+
+		cpuFreqMaxV, err := ksCPUInfo.GetNamed("clock_MHz")
+		if err != nil {
+			return err
+		}
+
+		lcpu := strconv.Itoa(cpu)
+		ch <- prometheus.MustNewConstMetric(
+			c.cpuFreq,
+			prometheus.GaugeValue,
+			float64(cpuFreqV.UintVal),
+			lcpu,
+		)
+		// Multiply by 1e+6 to convert MHz to Hz.
+		ch <- prometheus.MustNewConstMetric(
+			c.cpuFreqMax,
+			prometheus.GaugeValue,
+			float64(cpuFreqMaxV.IntVal)*1e+6,
+			lcpu,
+		)
+	}
+	return nil
+}