removal of need for ps

server/pse_linux.go

@@ -0,0 +1,62 @@
+// Copyright 2015 Apcera Inc. All rights reserved.
+
+package server
+
+/*
+#include <unistd.h>
+*/
+import "C"
+
+import (
+	"bytes"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"syscall"
+)
+
+var procStatFile string
+var ticks int64
+
+const (
+	utimePos = 13
+	stimePos = 14
+	startPos = 21
+	vssPos   = 22
+	rssPos   = 23
+)
+
+func init() {
+	ticks = int64(C.sysconf(C._SC_CLK_TCK))
+	procStatFile = fmt.Sprintf("/proc/%d/stat", os.Getpid())
+}
+
+func procUsage(pcpu *float64, rss, vss *int64) error {
+	contents, err := ioutil.ReadFile(procStatFile)
+	if err != nil {
+		return err
+	}
+	fields := bytes.Fields(contents)
+
+	*rss = (parseInt64(fields[rssPos])) << 12
+	*vss = parseInt64(fields[vssPos])
+
+	startTime := parseInt64(fields[startPos])
+	utime := parseInt64(fields[utimePos])
+	stime := parseInt64(fields[stimePos])
+	totalTime := utime + stime
+
+	sysinfo := syscall.Sysinfo_t{}
+	if err := syscall.Sysinfo(&sysinfo); err != nil {
+		return err
+	}
+
+	seconds := sysinfo.Uptime - (startTime / ticks)
+
+	if seconds > 0 {
+		ipcpu := (totalTime * 1000 / ticks) / seconds
+		*pcpu = float64(ipcpu) / 10.0
+	}
+
+	return nil
+}

server/pse_test.go

@@ -0,0 +1,49 @@
+// Copyright 2015 Apcera Inc. All rights reserved.
+
+package server
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"testing"
+)
+
+func TestPSEmulation(t *testing.T) {
+	var rss, vss, psRss, psVss int64
+	var pcpu, psPcpu float64
+
+	// PS version first
+	pidStr := fmt.Sprintf("%d", os.Getpid())
+	out, err := exec.Command("ps", "o", "pcpu=,rss=,vsz=", "-p", pidStr).Output()
+	if err != nil {
+		t.Fatalf("Failed to execute ps command: %v\n", err)
+	}
+
+	fmt.Sscanf(string(out), "%f %d %d", &psPcpu, &psRss, &psVss)
+	psRss *= 1024 // 1k blocks, want bytes.
+	psVss *= 1024 // 1k blocks, want bytes.
+
+	// Our internal version
+	procUsage(&pcpu, &rss, &vss)
+
+	if pcpu != psPcpu {
+		delta := int64(pcpu - psPcpu)
+		if delta < 0 {
+			delta = -delta
+		}
+		if delta > 5 { // 5%
+			t.Fatalf("CPUs did not match close enough: %f vs %f", pcpu, psPcpu)
+		}
+	}
+	if rss != psRss {
+		delta := rss - psRss
+		if delta < 0 {
+			delta = -delta
+		}
+		t.Logf("delta is %d\n", delta)
+		if delta > 200*1024 { // 200k
+			t.Fatalf("RSSs did not match close enough: %d vs %d", rss, psRss)
+		}
+	}
+}