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189 lines
5.1 KiB
Go
189 lines
5.1 KiB
Go
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// Copyright 2018 The Prometheus Authors
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package procfs
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import (
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"bytes"
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"fmt"
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"io/ioutil"
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"os"
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)
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// Originally, this USER_HZ value was dynamically retrieved via a sysconf call
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// which required cgo. However, that caused a lot of problems regarding
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// cross-compilation. Alternatives such as running a binary to determine the
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// value, or trying to derive it in some other way were all problematic. After
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// much research it was determined that USER_HZ is actually hardcoded to 100 on
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// all Go-supported platforms as of the time of this writing. This is why we
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// decided to hardcode it here as well. It is not impossible that there could
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// be systems with exceptions, but they should be very exotic edge cases, and
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// in that case, the worst outcome will be two misreported metrics.
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//
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// See also the following discussions:
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//
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// - https://github.com/prometheus/node_exporter/issues/52
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// - https://github.com/prometheus/procfs/pull/2
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// - http://stackoverflow.com/questions/17410841/how-does-user-hz-solve-the-jiffy-scaling-issue
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const userHZ = 100
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// ProcStat provides status information about the process,
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// read from /proc/[pid]/stat.
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type ProcStat struct {
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// The process ID.
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PID int
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// The filename of the executable.
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Comm string
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// The process state.
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State string
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// The PID of the parent of this process.
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PPID int
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// The process group ID of the process.
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PGRP int
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// The session ID of the process.
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Session int
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// The controlling terminal of the process.
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TTY int
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// The ID of the foreground process group of the controlling terminal of
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// the process.
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TPGID int
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// The kernel flags word of the process.
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Flags uint
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// The number of minor faults the process has made which have not required
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// loading a memory page from disk.
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MinFlt uint
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// The number of minor faults that the process's waited-for children have
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// made.
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CMinFlt uint
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// The number of major faults the process has made which have required
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// loading a memory page from disk.
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MajFlt uint
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// The number of major faults that the process's waited-for children have
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// made.
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CMajFlt uint
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// Amount of time that this process has been scheduled in user mode,
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// measured in clock ticks.
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UTime uint
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// Amount of time that this process has been scheduled in kernel mode,
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// measured in clock ticks.
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STime uint
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// Amount of time that this process's waited-for children have been
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// scheduled in user mode, measured in clock ticks.
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CUTime uint
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// Amount of time that this process's waited-for children have been
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// scheduled in kernel mode, measured in clock ticks.
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CSTime uint
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// For processes running a real-time scheduling policy, this is the negated
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// scheduling priority, minus one.
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Priority int
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// The nice value, a value in the range 19 (low priority) to -20 (high
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// priority).
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Nice int
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// Number of threads in this process.
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NumThreads int
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// The time the process started after system boot, the value is expressed
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// in clock ticks.
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Starttime uint64
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// Virtual memory size in bytes.
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VSize int
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// Resident set size in pages.
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RSS int
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fs FS
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}
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// NewStat returns the current status information of the process.
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func (p Proc) NewStat() (ProcStat, error) {
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f, err := os.Open(p.path("stat"))
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if err != nil {
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return ProcStat{}, err
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}
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defer f.Close()
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data, err := ioutil.ReadAll(f)
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if err != nil {
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return ProcStat{}, err
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}
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var (
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ignore int
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s = ProcStat{PID: p.PID, fs: p.fs}
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l = bytes.Index(data, []byte("("))
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r = bytes.LastIndex(data, []byte(")"))
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)
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if l < 0 || r < 0 {
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return ProcStat{}, fmt.Errorf(
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"unexpected format, couldn't extract comm: %s",
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data,
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)
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}
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s.Comm = string(data[l+1 : r])
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_, err = fmt.Fscan(
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bytes.NewBuffer(data[r+2:]),
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&s.State,
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&s.PPID,
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&s.PGRP,
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&s.Session,
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&s.TTY,
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&s.TPGID,
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&s.Flags,
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&s.MinFlt,
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&s.CMinFlt,
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&s.MajFlt,
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&s.CMajFlt,
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&s.UTime,
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&s.STime,
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&s.CUTime,
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&s.CSTime,
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&s.Priority,
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&s.Nice,
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&s.NumThreads,
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&ignore,
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&s.Starttime,
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&s.VSize,
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&s.RSS,
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)
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if err != nil {
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return ProcStat{}, err
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}
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return s, nil
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}
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// VirtualMemory returns the virtual memory size in bytes.
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func (s ProcStat) VirtualMemory() int {
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return s.VSize
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}
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// ResidentMemory returns the resident memory size in bytes.
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func (s ProcStat) ResidentMemory() int {
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return s.RSS * os.Getpagesize()
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}
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// StartTime returns the unix timestamp of the process in seconds.
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func (s ProcStat) StartTime() (float64, error) {
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stat, err := s.fs.NewStat()
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if err != nil {
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return 0, err
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}
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return float64(stat.BootTime) + (float64(s.Starttime) / userHZ), nil
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}
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// CPUTime returns the total CPU user and system time in seconds.
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func (s ProcStat) CPUTime() float64 {
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return float64(s.UTime+s.STime) / userHZ
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}
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