gops/internal/cmd/process.go

// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"fmt"
	"log"
	"math"
	"strconv"
	"strings"
	"time"

	"github.com/shirou/gopsutil/v3/process"
	"github.com/spf13/cobra"
)

// ProcessCommand displays information about a Go process.
func ProcessCommand() *cobra.Command {
	return &cobra.Command{
		Use:     "process",
		Aliases: []string{"pid", "proc"},
		Short:   "Prints information about a Go process.",
		RunE: func(cmd *cobra.Command, args []string) error {
			ProcessInfo(args)
			return nil
		},
	}
}

// ProcessInfo takes arguments starting with pid|:addr and grabs all kinds of
// useful Go process information.
func ProcessInfo(args []string) {
	pid, err := strconv.Atoi(args[0])

	var period time.Duration
	if len(args) >= 2 {
		period, err = time.ParseDuration(args[1])
		if err != nil {
			secs, _ := strconv.Atoi(args[1])
			period = time.Duration(secs) * time.Second
		}
	}

	processInfo(pid, period)
}

func processInfo(pid int, period time.Duration) {
	if period < 0 {
		log.Fatalf("Cannot determine CPU usage for negative duration %v", period)
	}
	p, err := process.NewProcess(int32(pid))
	if err != nil {
		log.Fatalf("Cannot read process info: %v", err)
	}
	if v, err := p.Parent(); err == nil {
		fmt.Printf("parent PID:\t%v\n", v.Pid)
	}
	if v, err := p.NumThreads(); err == nil {
		fmt.Printf("threads:\t%v\n", v)
	}
	if v, err := p.MemoryPercent(); err == nil {
		fmt.Printf("memory usage:\t%.3f%%\n", v)
	}
	if v, err := p.CPUPercent(); err == nil {
		fmt.Printf("cpu usage:\t%.3f%%\n", v)
	}
	if period > 0 {
		if v, err := cpuPercentWithinTime(p, period); err == nil {
			fmt.Printf("cpu usage (%v):\t%.3f%%\n", period, v)
		}
	}
	if v, err := p.Username(); err == nil {
		fmt.Printf("username:\t%v\n", v)
	}
	if v, err := p.Cmdline(); err == nil {
		fmt.Printf("cmd+args:\t%v\n", v)
	}
	if v, err := elapsedTime(p); err == nil {
		fmt.Printf("elapsed time:\t%v\n", v)
	}
	if v, err := p.Connections(); err == nil {
		if len(v) > 0 {
			for _, conn := range v {
				fmt.Printf("local/remote:\t%v:%v <-> %v:%v (%v)\n",
					conn.Laddr.IP, conn.Laddr.Port, conn.Raddr.IP, conn.Raddr.Port, conn.Status)
			}
		}
	}
}

// cpuPercentWithinTime return how many percent of the CPU time this process uses within given time duration
func cpuPercentWithinTime(p *process.Process, t time.Duration) (float64, error) {
	cput, err := p.Times()
	if err != nil {
		return 0, err
	}
	time.Sleep(t)
	cput2, err := p.Times()
	if err != nil {
		return 0, err
	}
	return 100 * (cput2.Total() - cput.Total()) / t.Seconds(), nil
}

// elapsedTime shows the elapsed time of the process indicating how long the
// process has been running for.
func elapsedTime(p *process.Process) (string, error) {
	crtTime, err := p.CreateTime()
	if err != nil {
		return "", err
	}
	etime := time.Since(time.Unix(crtTime/1000, 0))
	return fmtEtimeDuration(etime), nil
}

// fmtEtimeDuration formats etime's duration based on ps' format:
// [[DD-]hh:]mm:ss
// format specification: http://linuxcommand.org/lc3_man_pages/ps1.html
func fmtEtimeDuration(d time.Duration) string {
	days := d / (24 * time.Hour)
	hours := d % (24 * time.Hour)
	minutes := hours % time.Hour
	seconds := math.Mod(minutes.Seconds(), 60)
	var b strings.Builder
	if days > 0 {
		fmt.Fprintf(&b, "%02d-", days)
	}
	if days > 0 || hours/time.Hour > 0 {
		fmt.Fprintf(&b, "%02d:", hours/time.Hour)
	}
	fmt.Fprintf(&b, "%02d:", minutes/time.Minute)
	fmt.Fprintf(&b, "%02.0f", seconds)
	return b.String()
}