Add cpu collector for darwin

README.md

@@ -19,7 +19,7 @@ Which collectors are used is controlled by the `--collectors.enabled` flag.
 Name     | Description | OS
 ---------|-------------|----
 conntrack | Shows conntrack statistics (does nothing if no `/proc/sys/net/netfilter/` present). | Linux
-cpu | Exposes CPU statistics | Dragonfly, FreeBSD
+cpu | Exposes CPU statistics | Darwin, Dragonfly, FreeBSD
 diskstats | Exposes disk I/O statistics from `/proc/diskstats`. | Linux
 entropy | Exposes available entropy. | Linux
 filefd | Exposes file descriptor statistics from `/proc/sys/fs/file-nr`. | Linux

collector/cpu_darwin.go

@@ -0,0 +1,119 @@
+// Copyright 2016 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.
+
+// Based on gopsutil/cpu/cpu_darwin_cgo.go @ ae251eb which is licensed under
+// BSD. See https://github.com/shirou/gopsutil/blob/master/LICENSE for details.
+
+// +build !nocpu
+
+package collector
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"strconv"
+	"unsafe"
+
+	"github.com/prometheus/client_golang/prometheus"
+)
+
+/*
+#cgo LDFLAGS:
+#include <stdlib.h>
+#include <sys/sysctl.h>
+#include <sys/mount.h>
+#include <mach/mach_init.h>
+#include <mach/mach_host.h>
+#include <mach/host_info.h>
+#if TARGET_OS_MAC
+#include <libproc.h>
+#endif
+#include <mach/processor_info.h>
+#include <mach/vm_map.h>
+*/
+import "C"
+
+// default value. from time.h
+const ClocksPerSec = float64(128)
+
+type statCollector struct {
+	cpu *prometheus.Desc
+}
+
+func init() {
+	Factories["cpu"] = NewCPUCollector
+}
+
+// Takes a prometheus registry and returns a new Collector exposing
+// CPU stats.
+func NewCPUCollector() (Collector, error) {
+	return &statCollector{
+		cpu: prometheus.NewDesc(
+			prometheus.BuildFQName(Namespace, "", "cpu"),
+			"Seconds the cpus spent in each mode.",
+			[]string{"cpu", "mode"}, nil,
+		),
+	}, nil
+}
+
+func (c *statCollector) Update(ch chan<- prometheus.Metric) error {
+	var (
+		count   C.mach_msg_type_number_t
+		cpuload *C.processor_cpu_load_info_data_t
+		ncpu    C.natural_t
+	)
+
+	status := C.host_processor_info(C.host_t(C.mach_host_self()),
+		C.PROCESSOR_CPU_LOAD_INFO,
+		&ncpu,
+		(*C.processor_info_array_t)(unsafe.Pointer(&cpuload)),
+		&count)
+
+	if status != C.KERN_SUCCESS {
+		return fmt.Errorf("host_processor_info error=%d", status)
+	}
+
+	// jump through some cgo casting hoops and ensure we properly free
+	// the memory that cpuload points to
+	target := C.vm_map_t(C.mach_task_self_)
+	address := C.vm_address_t(uintptr(unsafe.Pointer(cpuload)))
+	defer C.vm_deallocate(target, address, C.vm_size_t(ncpu))
+
+	// the body of struct processor_cpu_load_info
+	// aka processor_cpu_load_info_data_t
+	var cpu_ticks [C.CPU_STATE_MAX]uint32
+
+	// copy the cpuload array to a []byte buffer
+	// where we can binary.Read the data
+	size := int(ncpu) * binary.Size(cpu_ticks)
+	buf := (*[1 << 30]byte)(unsafe.Pointer(cpuload))[:size:size]
+
+	bbuf := bytes.NewBuffer(buf)
+
+	for i := 0; i < int(ncpu); i++ {
+		err := binary.Read(bbuf, binary.LittleEndian, &cpu_ticks)
+		if err != nil {
+			return err
+		}
+		for k, v := range map[string]int{
+			"user":   C.CPU_STATE_USER,
+			"system": C.CPU_STATE_SYSTEM,
+			"nice":   C.CPU_STATE_NICE,
+			"idle":   C.CPU_STATE_IDLE,
+		} {
+			ch <- prometheus.MustNewConstMetric(c.cpu, prometheus.CounterValue, float64(cpu_ticks[v])/ClocksPerSec, "cpu"+strconv.Itoa(i), k)
+		}
+	}
+	return nil
+}