Add BSD exec statistics collector (#457)

* First pass of a sysctl_bsd source, exec_bsd + exec metrics

* Incorportate PR feedback, including removing pre-build descriptions, unit conversion callback.

* Remove redundant cached_description field, per PR feedback

* Incorporate PR feedback

README.md

@@ -26,6 +26,7 @@ cpu | Exposes CPU statistics | Darwin, Dragonfly, FreeBSD
 diskstats | Exposes disk I/O statistics from `/proc/diskstats`. | Linux
 edac | Exposes error detection and correction statistics. | Linux
 entropy | Exposes available entropy. | Linux
+exec | Exposes execution statistics. | Dragonfly, FreeBSD
 filefd | Exposes file descriptor statistics from `/proc/sys/fs/file-nr`. | Linux
 filesystem | Exposes filesystem statistics, such as disk space used. | Darwin, Dragonfly, FreeBSD, Linux, OpenBSD
 hwmon | Expose hardware monitoring and sensor data from `/sys/class/hwmon/`. | Linux

collector/exec_bsd.go

@@ -0,0 +1,98 @@
+// 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.
+
+// +build freebsd dragonfly
+// +build !noexec
+
+package collector
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+type execCollector struct {
+	sysctls []bsdSysctl
+}
+
+func init() {
+	Factories["exec"] = NewExecCollector
+}
+
+// NewExecCollector returns a new Collector exposing system execution statistics
+func NewExecCollector() (Collector, error) {
+	// From sys/vm/vm_meter.c:
+	// All are of type CTLTYPE_UINT.
+	//
+	// vm.stats.sys.v_swtch: Context switches
+	// vm.stats.sys.v_trap: Traps
+	// vm.stats.sys.v_syscall: System calls
+	// vm.stats.sys.v_intr: Device interrupts
+	// vm.stats.sys.v_soft: Software interrupts
+	// vm.stats.vm.v_forks: Number of fork() calls
+
+	return &execCollector{
+		sysctls: []bsdSysctl{
+			{
+				name:        "context_switches_total",
+				description: "Context switches since system boot.  Resets at architeture unsigned integer.",
+				mib:         "vm.stats.sys.v_swtch",
+			},
+			{
+				name:        "traps_total",
+				description: "Traps since system boot.  Resets at architeture unsigned integer.",
+				mib:         "vm.stats.sys.v_trap",
+			},
+			{
+				name:        "system_calls_total",
+				description: "System calls since system boot.  Resets at architeture unsigned integer.",
+				mib:         "vm.stats.sys.v_syscall",
+			},
+			{
+				name:        "device_interrupts_total",
+				description: "Device interrupts since system boot.  Resets at architeture unsigned integer.",
+				mib:         "vm.stats.sys.v_intr",
+			},
+			{
+				name:        "software_interrupts_total",
+				description: "Software interrupts since system boot.  Resets at architeture unsigned integer.",
+				mib:         "vm.stats.sys.v_soft",
+			},
+			{
+				name:        "forks_total",
+				description: "Number of fork() calls since system boot.  Resets at architeture unsigned integer.",
+				mib:         "vm.stats.vm.v_forks",
+			},
+		},
+	}, nil
+}
+
+// Update pushes exec statistics onto ch
+func (c *execCollector) Update(ch chan<- prometheus.Metric) (err error) {
+	for _, m := range c.sysctls {
+		v, err := m.Value()
+		if err != nil {
+			return err
+		}
+
+		// We "know" all of our sysctls are CounterValues, let's skip
+		// parsing them
+		ch <- prometheus.MustNewConstMetric(
+			prometheus.NewDesc(
+				prometheus.BuildFQName(Namespace, "exec", m.name),
+				m.description,
+				nil, nil,
+			), prometheus.CounterValue, v)
+	}
+
+	return nil
+}

collector/sysctl_bsd.go

@@ -0,0 +1,70 @@
+// 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.
+
+// +build freebsd dragonfly
+// +build !nomeminfo
+
+package collector
+
+import (
+	"github.com/prometheus/client_golang/prometheus"
+	"golang.org/x/sys/unix"
+)
+
+type bsdSysctlType uint8
+
+// BSD-specific sysctl value types.  There is an impedience mismatch between
+// native C types, e.g. int vs long, and the golang unix.Sysctl variables
+
+const (
+	// Default to uint32.
+	bsdSysctlTypeUint32 bsdSysctlType = iota
+	bsdSysctlTypeUint64
+)
+
+// Contains all the info needed to map a single bsd-sysctl to a prometheus value.
+type bsdSysctl struct {
+	// Prometheus name
+	name string
+
+	// Simple prometheus description
+	description string
+
+	// Prometheus type
+	valueType prometheus.ValueType
+
+	// Sysctl name
+	mib string
+
+	// Sysctl data-type
+	dataType bsdSysctlType
+}
+
+func (b bsdSysctl) Value() (float64, error) {
+	var tmp32 uint32
+	var tmp64 uint64
+	var err error
+
+	switch b.dataType {
+	case bsdSysctlTypeUint32:
+		tmp32, err = unix.SysctlUint32(b.mib)
+		tmp64 = uint64(tmp32)
+	case bsdSysctlTypeUint64:
+		tmp64, err = unix.SysctlUint64(b.mib)
+	}
+	if err != nil {
+		return 0, err
+	}
+
+	return float64(tmp64), nil
+}

node_exporter.go

@@ -32,7 +32,7 @@ import (
 )
 
 const (
-	defaultCollectors = "conntrack,cpu,diskstats,entropy,edac,filefd,filesystem,hwmon,infiniband,loadavg,mdadm,meminfo,netdev,netstat,sockstat,stat,textfile,time,uname,vmstat,wifi,zfs"
+	defaultCollectors = "conntrack,cpu,diskstats,entropy,edac,exec,filefd,filesystem,hwmon,infiniband,loadavg,mdadm,meminfo,netdev,netstat,sockstat,stat,textfile,time,uname,vmstat,wifi,zfs"
 )
 
 var (