process_info.go

// This file is licensed under the MIT License.
// This product includes software developed at Datadog (https://www.datadoghq.com/).
// Copyright © 2015 Kentaro Kuribayashi <kentarok@gmail.com>
// Copyright 2014-present Datadog, Inc.

//go:build linux || darwin

// Package gops extracts the information on running processes from gopsutil
package gops

import (
	"fmt"
	"runtime"

	// 3p
	log "github.com/cihub/seelog"

	// project
	"github.com/shirou/gopsutil/v3/mem"
	"github.com/shirou/gopsutil/v3/process"
)

// ProcessInfo contains information about a single process
type ProcessInfo struct {
	PID      int32
	PPID     int32
	Name     string
	RSS      uint64
	PctMem   float64
	VMS      uint64
	Username string
}

// GetProcesses returns a slice of all the processes that are running
func GetProcesses() ([]*ProcessInfo, error) {
	processInfos := make([]*ProcessInfo, 0, 10)

	virtMemStat, err := mem.VirtualMemory()
	if err != nil {
		err = fmt.Errorf("error fetching system memory stats: %w", err)
		return nil, err
	}
	totalMem := float64(virtMemStat.Total)

	pids, err := process.Pids()
	if err != nil {
		err = fmt.Errorf("error fetching PIDs: %w", err)
		return nil, err
	}

	for _, pid := range pids {
		p, err := process.NewProcess(pid)
		if err != nil {
			// an error can occur here only if the process has disappeared,
			log.Debugf("Process with pid %d disappeared while scanning: %w", pid, err)
			continue
		}
		processInfo, err := newProcessInfo(p, totalMem)
		if err != nil {
			log.Debugf("Error fetching info for pid %d: %w", pid, err)
			continue
		}

		processInfos = append(processInfos, processInfo)
	}

	// platform-specific post-processing on the collected info
	postProcess(processInfos)

	return processInfos, nil
}

// Make a new ProcessInfo from a Process from gopsutil
func newProcessInfo(p *process.Process, totalMem float64) (*ProcessInfo, error) {
	memInfo, err := p.MemoryInfo()
	if err != nil {
		return nil, err
	}
	pid := p.Pid
	ppid, err := p.Ppid()
	if err != nil {
		return nil, err
	}

	name, err := p.Name()
	if err != nil {
		return nil, err
	}

	pctMem := 100. * float64(memInfo.RSS) / totalMem

	var username string
	if runtime.GOOS != "android" {
		username, err = p.Username()
		if err != nil {
			return nil, err
		}
	}

	return &ProcessInfo{pid, ppid, name, memInfo.RSS, pctMem, memInfo.VMS, username}, nil
}