Add diskstats collector for OpenBSD (#1250)

* Add diskstats collector for OpenBSD

Tested on i386 and amd64, OpenBSD 6.4 and -current.

* Refactor diskstats collectors

This moves common descriptors from Linux, Darwin, OpenBSD
diskstats collectors into diskstats_common.go

Signed-off-by: Ralf Horstmann <ralf+github@ackstorm.de>

6 files changed, 162 insertions, 84 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c445503..b3c464d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,6 +15,7 @@ The cpufreq metrics now separate the `cpufreq` and `scaling` data based on what
 * [FEATURE] Add a flag to disable exporter metrics #1148
 * [FEATURE] Add kstat-based Solaris metrics for boottime, cpu and zfs collectors #1197
 * [FEATURE] Add uname collector for FreeBSD #1239
+* [FEATURE] Add diskstats collector for OpenBSD #1250
 
 ## 0.17.0 / 2018-11-30
 
diff --git a/README.md b/README.md
index 187e275..3196ab3 100644
--- a/README.md
+++ b/README.md
@@ -32,7 +32,7 @@ bonding | Exposes the number of configured and active slaves of Linux bonding in
 boottime | Exposes system boot time derived from the `kern.boottime` sysctl. | Darwin, Dragonfly, FreeBSD, NetBSD, OpenBSD, Solaris
 conntrack | Shows conntrack statistics (does nothing if no `/proc/sys/net/netfilter/` present). | Linux
 cpu | Exposes CPU statistics | Darwin, Dragonfly, FreeBSD, Linux, Solaris
-diskstats | Exposes disk I/O statistics. | Darwin, Linux
+diskstats | Exposes disk I/O statistics. | Darwin, Linux, OpenBSD
 edac | Exposes error detection and correction statistics. | Linux
 entropy | Exposes available entropy. | Linux
 exec | Exposes execution statistics. | Dragonfly, FreeBSD
diff --git a/collector/diskstats_common.go b/collector/diskstats_common.go
new file mode 100644
index 0000000..7efb399
--- /dev/null
+++ b/collector/diskstats_common.go
@@ -0,0 +1,73 @@
+// 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 !nodiskstats
+// +build openbsd linux darwin
+
+package collector
+
+import (
+        "github.com/prometheus/client_golang/prometheus"
+)
+
+const (
+        diskSubsystem = "disk"
+)
+
+var (
+        diskLabelNames = []string{"device"}
+
+        readsCompletedDesc = prometheus.NewDesc(
+                prometheus.BuildFQName(namespace, diskSubsystem, "reads_completed_total"),
+                "The total number of reads completed successfully.",
+                diskLabelNames, nil,
+        )
+
+        readBytesDesc = prometheus.NewDesc(
+                prometheus.BuildFQName(namespace, diskSubsystem, "read_bytes_total"),
+                "The total number of bytes read successfully.",
+                diskLabelNames, nil,
+        )
+
+        writesCompletedDesc = prometheus.NewDesc(
+                prometheus.BuildFQName(namespace, diskSubsystem, "writes_completed_total"),
+                "The total number of writes completed successfully.",
+                diskLabelNames, nil,
+        )
+
+        writtenBytesDesc = prometheus.NewDesc(
+                prometheus.BuildFQName(namespace, diskSubsystem, "written_bytes_total"),
+                "The total number of bytes written successfully.",
+                diskLabelNames, nil,
+        )
+
+        ioTimeSecondsDesc = prometheus.NewDesc(
+                prometheus.BuildFQName(namespace, diskSubsystem, "io_time_seconds_total"),
+                "Total seconds spent doing I/Os.",
+                diskLabelNames, nil,
+        )
+
+        readTimeSecondsDesc = prometheus.NewDesc(
+                prometheus.BuildFQName(namespace, diskSubsystem, "read_time_seconds_total"),
+                "The total number of seconds spent by all reads.",
+                diskLabelNames,
+                nil,
+        )
+
+        writeTimeSecondsDesc = prometheus.NewDesc(
+                prometheus.BuildFQName(namespace, diskSubsystem, "write_time_seconds_total"),
+                "This is the total number of seconds spent by all writes.",
+                diskLabelNames,
+                nil,
+        )
+)
diff --git a/collector/diskstats_darwin.go b/collector/diskstats_darwin.go
index a92de52..2c76582 100644
--- a/collector/diskstats_darwin.go
+++ b/collector/diskstats_darwin.go
@@ -22,10 +22,6 @@ import (
         "github.com/prometheus/client_golang/prometheus"
 )
 
-const (
-        diskSubsystem = "disk"
-)
-
 type typedDescFunc struct {
         typedDesc
         value func(stat *iostat.DriveStats) float64
@@ -47,12 +43,7 @@ func NewDiskstatsCollector() (Collector, error) {
                 descs: []typedDescFunc{
                         {
                                 typedDesc: typedDesc{
-                                        desc: prometheus.NewDesc(
-                                                prometheus.BuildFQName(namespace, diskSubsystem, "reads_completed_total"),
-                                                "The total number of reads completed successfully.",
-                                                diskLabelNames,
-                                                nil,
-                                        ),
+                                        desc:      readsCompletedDesc,
                                         valueType: prometheus.CounterValue,
                                 },
                                 value: func(stat *iostat.DriveStats) float64 {
@@ -75,12 +66,7 @@ func NewDiskstatsCollector() (Collector, error) {
                         },
                         {
                                 typedDesc: typedDesc{
-                                        desc: prometheus.NewDesc(
-                                                prometheus.BuildFQName(namespace, diskSubsystem, "read_time_seconds_total"),
-                                                "The total number of seconds spent by all reads.",
-                                                diskLabelNames,
-                                                nil,
-                                        ),
+                                        desc:      readTimeSecondsDesc,
                                         valueType: prometheus.CounterValue,
                                 },
                                 value: func(stat *iostat.DriveStats) float64 {
@@ -89,12 +75,7 @@ func NewDiskstatsCollector() (Collector, error) {
                         },
                         {
                                 typedDesc: typedDesc{
-                                        desc: prometheus.NewDesc(
-                                                prometheus.BuildFQName(namespace, diskSubsystem, "writes_completed_total"),
-                                                "The total number of writes completed successfully.",
-                                                diskLabelNames,
-                                                nil,
-                                        ),
+                                        desc:      writesCompletedDesc,
                                         valueType: prometheus.CounterValue,
                                 },
                                 value: func(stat *iostat.DriveStats) float64 {
@@ -117,12 +98,7 @@ func NewDiskstatsCollector() (Collector, error) {
                         },
                         {
                                 typedDesc: typedDesc{
-                                        desc: prometheus.NewDesc(
-                                                prometheus.BuildFQName(namespace, diskSubsystem, "write_time_seconds_total"),
-                                                "This is the total number of seconds spent by all writes.",
-                                                diskLabelNames,
-                                                nil,
-                                        ),
+                                        desc:      writeTimeSecondsDesc,
                                         valueType: prometheus.CounterValue,
                                 },
                                 value: func(stat *iostat.DriveStats) float64 {
@@ -131,12 +107,7 @@ func NewDiskstatsCollector() (Collector, error) {
                         },
                         {
                                 typedDesc: typedDesc{
-                                        desc: prometheus.NewDesc(
-                                                prometheus.BuildFQName(namespace, diskSubsystem, "read_bytes_total"),
-                                                "The total number of bytes read successfully.",
-                                                diskLabelNames,
-                                                nil,
-                                        ),
+                                        desc:      readBytesDesc,
                                         valueType: prometheus.CounterValue,
                                 },
                                 value: func(stat *iostat.DriveStats) float64 {
@@ -145,12 +116,7 @@ func NewDiskstatsCollector() (Collector, error) {
                         },
                         {
                                 typedDesc: typedDesc{
-                                        desc: prometheus.NewDesc(
-                                                prometheus.BuildFQName(namespace, diskSubsystem, "written_bytes_total"),
-                                                "The total number of bytes written successfully.",
-                                                diskLabelNames,
-                                                nil,
-                                        ),
+                                        desc:      writtenBytesDesc,
                                         valueType: prometheus.CounterValue,
                                 },
                                 value: func(stat *iostat.DriveStats) float64 {
diff --git a/collector/diskstats_linux.go b/collector/diskstats_linux.go
index 8efffd9..1d39f2b 100644
--- a/collector/diskstats_linux.go
+++ b/collector/diskstats_linux.go
@@ -30,7 +30,6 @@ import (
 )
 
 const (
-        diskSubsystem     = "disk"
         diskSectorSize    = 512
         diskstatsFilename = "diskstats"
 )
@@ -70,12 +69,7 @@ func NewDiskstatsCollector() (Collector, error) {
                 ignoredDevicesPattern: regexp.MustCompile(*ignoredDevices),
                 descs: []typedFactorDesc{
                         {
-                                desc: prometheus.NewDesc(
-                                        prometheus.BuildFQName(namespace, diskSubsystem, "reads_completed_total"),
-                                        "The total number of reads completed successfully.",
-                                        diskLabelNames,
-                                        nil,
-                                ), valueType: prometheus.CounterValue,
+                                desc: readsCompletedDesc, valueType: prometheus.CounterValue,
                         },
                         {
                                 desc: prometheus.NewDesc(
@@ -86,30 +80,15 @@ func NewDiskstatsCollector() (Collector, error) {
                                 ), valueType: prometheus.CounterValue,
                         },
                         {
-                                desc: prometheus.NewDesc(
-                                        prometheus.BuildFQName(namespace, diskSubsystem, "read_bytes_total"),
-                                        "The total number of bytes read successfully.",
-                                        diskLabelNames,
-                                        nil,
-                                ), valueType: prometheus.CounterValue,
+                                desc: readBytesDesc, valueType: prometheus.CounterValue,
                                 factor: diskSectorSize,
                         },
                         {
-                                desc: prometheus.NewDesc(
-                                        prometheus.BuildFQName(namespace, diskSubsystem, "read_time_seconds_total"),
-                                        "The total number of seconds spent by all reads.",
-                                        diskLabelNames,
-                                        nil,
-                                ), valueType: prometheus.CounterValue,
+                                desc: readTimeSecondsDesc, valueType: prometheus.CounterValue,
                                 factor: .001,
                         },
                         {
-                                desc: prometheus.NewDesc(
-                                        prometheus.BuildFQName(namespace, diskSubsystem, "writes_completed_total"),
-                                        "The total number of writes completed successfully.",
-                                        diskLabelNames,
-                                        nil,
-                                ), valueType: prometheus.CounterValue,
+                                desc: writesCompletedDesc, valueType: prometheus.CounterValue,
                         },
                         {
                                 desc: prometheus.NewDesc(
@@ -120,21 +99,11 @@ func NewDiskstatsCollector() (Collector, error) {
                                 ), valueType: prometheus.CounterValue,
                         },
                         {
-                                desc: prometheus.NewDesc(
-                                        prometheus.BuildFQName(namespace, diskSubsystem, "written_bytes_total"),
-                                        "The total number of bytes written successfully.",
-                                        diskLabelNames,
-                                        nil,
-                                ), valueType: prometheus.CounterValue,
+                                desc: writtenBytesDesc, valueType: prometheus.CounterValue,
                                 factor: diskSectorSize,
                         },
                         {
-                                desc: prometheus.NewDesc(
-                                        prometheus.BuildFQName(namespace, diskSubsystem, "write_time_seconds_total"),
-                                        "This is the total number of seconds spent by all writes.",
-                                        diskLabelNames,
-                                        nil,
-                                ), valueType: prometheus.CounterValue,
+                                desc: writeTimeSecondsDesc, valueType: prometheus.CounterValue,
                                 factor: .001,
                         },
                         {
@@ -146,12 +115,7 @@ func NewDiskstatsCollector() (Collector, error) {
                                 ), valueType: prometheus.GaugeValue,
                         },
                         {
-                                desc: prometheus.NewDesc(
-                                        prometheus.BuildFQName(namespace, diskSubsystem, "io_time_seconds_total"),
-                                        "Total seconds spent doing I/Os.",
-                                        diskLabelNames,
-                                        nil,
-                                ), valueType: prometheus.CounterValue,
+                                desc: ioTimeSecondsDesc, valueType: prometheus.CounterValue,
                                 factor: .001,
                         },
                         {
diff --git a/collector/diskstats_openbsd.go b/collector/diskstats_openbsd.go
new file mode 100644
index 0000000..f17e2a8
--- /dev/null
+++ b/collector/diskstats_openbsd.go
@@ -0,0 +1,74 @@
+// 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 !nodiskstats
+
+package collector
+
+import (
+        "unsafe"
+
+        "github.com/prometheus/client_golang/prometheus"
+        "golang.org/x/sys/unix"
+)
+
+/*
+#include <sys/types.h>
+#include <sys/disk.h>
+*/
+import "C"
+
+type diskstatsCollector struct {
+        rxfer  typedDesc
+        rbytes typedDesc
+        wxfer  typedDesc
+        wbytes typedDesc
+        time   typedDesc
+}
+
+func init() {
+        registerCollector("diskstats", defaultEnabled, NewDiskstatsCollector)
+}
+
+// NewDiskstatsCollector returns a new Collector exposing disk device stats.
+func NewDiskstatsCollector() (Collector, error) {
+        return &diskstatsCollector{
+                rxfer:  typedDesc{readsCompletedDesc, prometheus.CounterValue},
+                rbytes: typedDesc{readBytesDesc, prometheus.CounterValue},
+                wxfer:  typedDesc{writesCompletedDesc, prometheus.CounterValue},
+                wbytes: typedDesc{writtenBytesDesc, prometheus.CounterValue},
+                time:   typedDesc{ioTimeSecondsDesc, prometheus.CounterValue},
+        }, nil
+}
+
+func (c *diskstatsCollector) Update(ch chan<- prometheus.Metric) (err error) {
+        diskstatsb, err := unix.SysctlRaw("hw.diskstats")
+        if err != nil {
+                return err
+        }
+
+        ndisks := len(diskstatsb) / C.sizeof_struct_diskstats
+        diskstats := *(*[]C.struct_diskstats)(unsafe.Pointer(&diskstatsb))
+
+        for i := 0; i < ndisks; i++ {
+                diskname := C.GoString(&diskstats[i].ds_name[0])
+
+                ch <- c.rxfer.mustNewConstMetric(float64(diskstats[i].ds_rxfer), diskname)
+                ch <- c.rbytes.mustNewConstMetric(float64(diskstats[i].ds_rbytes), diskname)
+                ch <- c.wxfer.mustNewConstMetric(float64(diskstats[i].ds_wxfer), diskname)
+                ch <- c.wbytes.mustNewConstMetric(float64(diskstats[i].ds_wbytes), diskname)
+                time := float64(diskstats[i].ds_time.tv_sec) + float64(diskstats[i].ds_time.tv_usec)/1000000
+                ch <- c.time.mustNewConstMetric(time, diskname)
+        }
+        return nil
+}