From 02a91378b87edda73af43a660ade7b73386f875b Mon Sep 17 00:00:00 2001
From: Shirou WAKAYAMA <shirou.faw@gmail.com>
Date: Thu, 1 May 2014 18:27:43 +0900
Subject: [PATCH] implements Process.IOCounters on linux.

---
 README.rst       |  2 +-
 process_linux.go | 33 ++++++++++++++++++++++++++++++++-
 process_test.go  | 31 +++++++++++++++++++++++++------
 3 files changed, 58 insertions(+), 8 deletions(-)

diff --git a/README.rst b/README.rst
index c14eb62..e1870a3 100644
--- a/README.rst
+++ b/README.rst
@@ -87,6 +87,7 @@ Current Status
     - uids (linux, freebsd)
     - gids (linux, freebsd)
     - terminal (linux, freebsd)
+    - io_counters (linux)
     - nice (linux)
     - num_fds (linux)
     - num_threads (linux, freebsd, windows)
@@ -111,7 +112,6 @@ Current Status
     - username
     - ionice
     - rlimit
-    - io_counters
     - num_ctx_switches
     - num_handlers
     - threads
diff --git a/process_linux.go b/process_linux.go
index fbd7e39..96d65c5 100644
--- a/process_linux.go
+++ b/process_linux.go
@@ -129,7 +129,7 @@ func (p *Process) Rlimit() ([]RlimitStat, error) {
 	return nil, errors.New("not implemented yet")
 }
 func (p *Process) IOCounters() (*IOCountersStat, error) {
-	return nil, errors.New("not implemented yet")
+	return p.fillFromIO()
 }
 func (p *Process) NumCtxSwitches() (int32, error) {
 	return 0, errors.New("not implemented yet")
@@ -335,6 +335,37 @@ func (p *Process) fillFromCmdline() (string, error) {
 	return ret, nil
 }
 
+// Get IO status from /proc/(pid)/io
+func (p *Process) fillFromIO() (*IOCountersStat, error) {
+	pid := p.Pid
+	ioPath := filepath.Join("/", "proc", strconv.Itoa(int(pid)), "io")
+	ioline, err := ioutil.ReadFile(ioPath)
+	if err != nil {
+		return nil, err
+	}
+	lines := strings.Split(string(ioline), "\n")
+	ret := &IOCountersStat{}
+
+	for _, line := range lines {
+		field := strings.Split(line, ":")
+		if len(field) < 2 {
+			continue
+		}
+		switch field[0] {
+		case "rchar":
+			ret.ReadCount = parseInt32(strings.Trim(field[1], " \t"))
+		case "wchar":
+			ret.WriteCount = parseInt32(strings.Trim(field[1], " \t"))
+		case "read_bytes":
+			ret.ReadBytes = parseInt32(strings.Trim(field[1], " \t"))
+		case "write_bytes":
+			ret.WriteBytes = parseInt32(strings.Trim(field[1], " \t"))
+		}
+	}
+
+	return ret, nil
+}
+
 // Get memory info from /proc/(pid)/statm
 func (p *Process) fillFromStatm() (*MemoryInfoStat, *MemoryInfoExStat, error) {
 	pid := p.Pid
diff --git a/process_test.go b/process_test.go
index e8364a3..7612144 100644
--- a/process_test.go
+++ b/process_test.go
@@ -8,6 +8,15 @@ import (
 	"testing"
 )
 
+func test_getProcess() Process {
+	checkPid := os.Getpid()
+	if runtime.GOOS == "windows" {
+		checkPid = 7960
+	}
+	ret, _ := NewProcess(int32(checkPid))
+	return *ret
+}
+
 func Test_Pids(t *testing.T) {
 	ret, err := Pids()
 	if err != nil {
@@ -68,13 +77,9 @@ func Test_Process_memory_maps(t *testing.T) {
 }
 
 func Test_Process_Ppid(t *testing.T) {
-	checkPid := os.Getpid()
-	if runtime.GOOS == "windows" {
-		checkPid = 7960
-	}
-	ret, err := NewProcess(int32(checkPid))
+	p := test_getProcess()
 
-	v, err := ret.Ppid()
+	v, err := p.Ppid()
 	if err != nil {
 		t.Errorf("geting ppid error %v", err)
 	}
@@ -83,3 +88,17 @@ func Test_Process_Ppid(t *testing.T) {
 	}
 
 }
+
+func Test_Process_IOCounters(t *testing.T) {
+	p := test_getProcess()
+
+	v, err := p.IOCounters()
+	if err != nil {
+		t.Errorf("geting ppid error %v", err)
+	}
+	fmt.Println(v)
+	if v.ReadCount == 0 {
+		t.Errorf("return value is 0 %v", v)
+	}
+
+}