Make psutil a submodule of resources, remove default psutil

resources/psutil/process_linux.go

@@ -0,0 +1,97 @@
+//go:build linux
+// +build linux
+
+package psutil
+
+import (
+	"bytes"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/tklauser/go-sysconf"
+)
+
+// Extracted from "github.com/shirou/gopsutil/v3/process/process_linux.go"
+// We only need the CPU times. p.proc.Times() calls a function that is
+// doing more than we actually need.
+
+var clockTicks = 100 // default value
+
+func init() {
+	clkTck, err := sysconf.Sysconf(sysconf.SC_CLK_TCK)
+	// ignore errors
+	if err == nil {
+		clockTicks = int(clkTck)
+	}
+}
+
+func (p *process) cpuTimes() (*cpuTimesStat, error) {
+	value := os.Getenv("HOST_PROC")
+	if value == "" {
+		value = "/proc"
+	}
+
+	path := filepath.Join(value, strconv.FormatInt(int64(p.pid), 10), "stat")
+
+	contents, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	// Indexing from one, as described in `man proc` about the file /proc/[pid]/stat
+	fields := splitProcStat(contents)
+
+	utime, err := strconv.ParseFloat(fields[14], 64)
+	if err != nil {
+		return nil, err
+	}
+
+	stime, err := strconv.ParseFloat(fields[15], 64)
+	if err != nil {
+		return nil, err
+	}
+
+	// There is no such thing as iotime in stat file.  As an approximation, we
+	// will use delayacct_blkio_ticks (aggregated block I/O delays, as per Linux
+	// docs).  Note: I am assuming at least Linux 2.6.18
+	var iotime float64
+	if len(fields) > 42 {
+		iotime, err = strconv.ParseFloat(fields[42], 64)
+		if err != nil {
+			iotime = 0 // Ancient linux version, most likely
+		}
+	} else {
+		iotime = 0 // e.g. SmartOS containers
+	}
+
+	userTime := utime / float64(clockTicks)
+	systemTime := stime / float64(clockTicks)
+	iowaitTime := iotime / float64(clockTicks)
+
+	s := &cpuTimesStat{
+		total:  userTime + systemTime + iowaitTime,
+		system: systemTime,
+		user:   userTime,
+		other:  iowaitTime,
+	}
+
+	if s.other < 0.0001 {
+		s.other = 0
+	}
+
+	return s, nil
+}
+
+func splitProcStat(content []byte) []string {
+	nameStart := bytes.IndexByte(content, '(')
+	nameEnd := bytes.LastIndexByte(content, ')')
+	restFields := strings.Fields(string(content[nameEnd+2:])) // +2 skip ') '
+	name := content[nameStart+1 : nameEnd]
+	pid := strings.TrimSpace(string(content[:nameStart]))
+	fields := make([]string, 3, len(restFields)+3)
+	fields[1] = string(pid)
+	fields[2] = string(name)
+	fields = append(fields, restFields...)
+	return fields
+}