node_exporter/collector/sysctl_bsd.go

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// 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 openbsd netbsd darwin
// +build !nomeminfo
package collector
import (
"fmt"
"syscall"
"unsafe"
"github.com/prometheus/client_golang/prometheus"
"golang.org/x/sys/unix"
)
// #include <sys/types.h>
import "C"
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
bsdSysctlTypeStructTimeval
bsdSysctlTypeCLong
)
// 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
// Post-retrieval conversion hooks
conversion func(float64) float64
}
func (b bsdSysctl) Value() (float64, error) {
var tmp32 uint32
var tmp64 uint64
var tmpf64 float64
var err error
switch b.dataType {
case bsdSysctlTypeUint32:
tmp32, err = unix.SysctlUint32(b.mib)
tmpf64 = float64(tmp32)
case bsdSysctlTypeUint64:
tmp64, err = unix.SysctlUint64(b.mib)
tmpf64 = float64(tmp64)
case bsdSysctlTypeStructTimeval:
tmpf64, err = b.getStructTimeval()
case bsdSysctlTypeCLong:
tmpf64, err = b.getCLong()
}
if err != nil {
return 0, err
}
if b.conversion != nil {
return b.conversion(tmpf64), nil
}
return tmpf64, nil
}
func (b bsdSysctl) getStructTimeval() (float64, error) {
raw, err := unix.SysctlRaw(b.mib)
if err != nil {
return 0, err
}
if len(raw) != int(unsafe.Sizeof(syscall.Timeval{})) {
// Shouldn't get here.
return 0, fmt.Errorf(
"length of bytes received from sysctl (%d) does not match expected bytes (%d)",
len(raw),
unsafe.Sizeof(syscall.Timeval{}),
)
}
tv := *(*syscall.Timeval)(unsafe.Pointer(&raw[0]))
// This conversion maintains the usec precision. Using the time
// package did not.
return (float64(tv.Sec) + (float64(tv.Usec) / float64(1000*1000))), nil
}
func (b bsdSysctl) getCLong() (float64, error) {
raw, err := unix.SysctlRaw(b.mib)
if err != nil {
return 0, err
}
if len(raw) == C.sizeof_long {
return float64(*(*C.long)(unsafe.Pointer(&raw[0]))), nil
}
if len(raw) == C.sizeof_int {
// This is valid for at least vfs.bufspace, and the default
// long handler - which can clamp longs to 32-bits:
// https://github.com/freebsd/freebsd/blob/releng/10.3/sys/kern/vfs_bio.c#L338
// https://github.com/freebsd/freebsd/blob/releng/10.3/sys/kern/kern_sysctl.c#L1062
return float64(*(*C.int)(unsafe.Pointer(&raw[0]))), nil
}
return 0, fmt.Errorf(
"length of bytes received from sysctl (%d) does not match expected bytes (long: %d), (int: %d)",
len(raw),
C.sizeof_long,
C.sizeof_int,
)
}