Read the proc status file when PID is given for metrics purpose.

To measure the MaxRSS memory correctly, read the proc status file
under /proc/<pid>/status and extract the MaxRSS value from it. The
implementation is only available for Linux based distributions.

Bug: b/169453825
Test: go test
Change-Id: I32e3068fee7447f9ef5dfb5a8d8dcb6934e0af23

1 files changed, 128 insertions, 0 deletions

diff --git a/ui/metrics/proc/status.go b/ui/metrics/proc/status.go
new file mode 100644
index 000000000..f8b734c02
--- /dev/null
+++ b/ui/metrics/proc/status.go
@@ -0,0 +1,128 @@
+// package proc contains functionality to read proc status files.
+package proc
+
+import (
+	"strconv"
+	"strings"
+)
+
+// ProcStatus holds information regarding the memory usage of
+// an executing process. The memory sizes in each of the field
+// is in bytes.
+type ProcStatus struct {
+	// Process PID.
+	pid int
+
+	// Peak virtual memory size.
+	VmPeak uint64
+
+	// Virtual memory size.
+	VmSize uint64
+
+	// Locked Memory size.
+	VmLck uint64
+
+	// Pinned memory size.
+	VmPin uint64
+
+	// Peak resident set size.
+	VmHWM uint64
+
+	// Resident set size (sum of RssAnon, RssFile and RssShmem).
+	VmRss uint64
+
+	// Size of resident anonymous memory.
+	RssAnon uint64
+
+	// Size of resident shared memory.
+	RssShmem uint64
+
+	// Size of data segments.
+	VmData uint64
+
+	// Size of stack segments.
+	VmStk uint64
+
+	//Size of text segments.
+	VmExe uint64
+
+	//Shared library code size.
+	VmLib uint64
+
+	// Page table entries size.
+	VmPTE uint64
+
+	// Size of second-level page tables.
+	VmPMD uint64
+
+	// Swapped-out virtual memory size by anonymous private.
+	VmSwap uint64
+
+	// Size of hugetlb memory page size.
+	HugetlbPages uint64
+}
+
+// fillProcStatus takes the key and value, converts the value
+// to the proper size unit and is stored in the ProcStatus.
+func fillProcStatus(s *ProcStatus, key, value string) {
+	v := strToUint64(value)
+	switch key {
+	case "VmPeak":
+		s.VmPeak = v
+	case "VmSize":
+		s.VmSize = v
+	case "VmLck":
+		s.VmLck = v
+	case "VmPin":
+		s.VmPin = v
+	case "VmHWM":
+		s.VmHWM = v
+	case "VmRSS":
+		s.VmRss = v
+	case "RssAnon":
+		s.RssAnon = v
+	case "RssShmem":
+		s.RssShmem = v
+	case "VmData":
+		s.VmData = v
+	case "VmStk":
+		s.VmStk = v
+	case "VmExe":
+		s.VmExe = v
+	case "VmLib":
+		s.VmLib = v
+	case "VmPTE":
+		s.VmPTE = v
+	case "VmPMD":
+		s.VmPMD = v
+	case "VmSwap":
+		s.VmSwap = v
+	case "HugetlbPages":
+		s.HugetlbPages = v
+	}
+}
+
+// strToUint64 takes the string and converts to unsigned 64-bit integer.
+// If the string contains a memory unit such as kB and is converted to
+// bytes.
+func strToUint64(v string) uint64 {
+	// v could be "1024 kB" so scan for the empty space and
+	// split between the value and the unit.
+	var separatorIndex int
+	if separatorIndex = strings.IndexAny(v, " "); separatorIndex < 0 {
+		separatorIndex = len(v)
+	}
+	value, err := strconv.ParseUint(v[:separatorIndex], 10, 64)
+	if err != nil {
+		return 0
+	}
+
+	var scale uint64 = 1
+	switch strings.TrimSpace(v[separatorIndex:]) {
+	case "kB", "KB":
+		scale = 1024
+	case "mB", "MB":
+		scale = 1024 * 1024
+	}
+	return value * scale
+}