From d7cb4dcaca5de2f245d20f4a4aa643cfdd3c317d Mon Sep 17 00:00:00 2001
From: Derek Parker <parkerderek86@gmail.com>
Date: Wed, 14 Jan 2015 08:58:32 -0600
Subject: [PATCH] Remove parseProcessStatus and only report stop

Currently there is no need for the other items in the ProcessStatus
struct, we really only care if the process is not running, so we can
avoid sending signals to it.
---
 proctl/proctl.go             | 31 ++++---------------------------
 proctl/proctl_linux_amd64.go | 25 ++++++++++++++++++-------
 2 files changed, 22 insertions(+), 34 deletions(-)

diff --git a/proctl/proctl.go b/proctl/proctl.go
index 0124559b..8a8ac893 100644
--- a/proctl/proctl.go
+++ b/proctl/proctl.go
@@ -39,21 +39,6 @@ func (mse ManualStopError) Error() string {
 	return "Manual stop requested"
 }
 
-// ProcessStatus is the result of parsing the data from
-// the /proc/<pid>/stats psuedo file.
-type ProcessStatus struct {
-	pid   int
-	comm  string
-	state rune
-	ppid  int
-}
-
-const (
-	STATUS_SLEEPING   = 'S'
-	STATUS_RUNNING    = 'R'
-	STATUS_TRACE_STOP = 't'
-)
-
 var (
 	breakpointIDCounter = 0
 )
@@ -215,8 +200,7 @@ func (dbp *DebuggedProcess) FindLocation(str string) (uint64, error) {
 func (dbp *DebuggedProcess) RequestManualStop() {
 	dbp.halt = true
 	for _, th := range dbp.Threads {
-		ps, _ := parseProcessStatus(th.Id)
-		if ps.state == STATUS_TRACE_STOP {
+		if stopped(th.Id) {
 			continue
 		}
 		syscall.Tgkill(dbp.Pid, th.Id, syscall.SIGSTOP)
@@ -493,21 +477,14 @@ func stopTheWorld(dbp *DebuggedProcess) error {
 	// are inactive. We send SIGSTOP and ensure all
 	// threads are in in signal-delivery-stop mode.
 	for _, th := range dbp.Threads {
-		ps, err := parseProcessStatus(th.Id)
-		if err != nil {
-			return err
-		}
-
-		if ps.state == STATUS_TRACE_STOP {
+		if stopped(th.Id) {
 			continue
 		}
-
-		err = syscall.Tgkill(dbp.Pid, th.Id, syscall.SIGSTOP)
+		err := syscall.Tgkill(dbp.Pid, th.Id, syscall.SIGSTOP)
 		if err != nil {
 			return err
 		}
-
-		pid, _, err := wait(th.Id, 0)
+		pid, _, err := wait(th.Id, syscall.WNOHANG)
 		if err != nil {
 			return fmt.Errorf("wait err %s %d", err, pid)
 		}
diff --git a/proctl/proctl_linux_amd64.go b/proctl/proctl_linux_amd64.go
index db9a2e93..3575bfa3 100644
--- a/proctl/proctl_linux_amd64.go
+++ b/proctl/proctl_linux_amd64.go
@@ -11,6 +11,12 @@ import (
 	"github.com/derekparker/delve/dwarf/frame"
 )
 
+const (
+	STATUS_SLEEPING   = 'S'
+	STATUS_RUNNING    = 'R'
+	STATUS_TRACE_STOP = 't'
+)
+
 func (dbp *DebuggedProcess) addThread(tid int) (*ThreadContext, error) {
 	err := syscall.PtraceSetOptions(tid, syscall.PTRACE_O_TRACECLONE)
 	if err == syscall.ESRCH {
@@ -33,18 +39,23 @@ func (dbp *DebuggedProcess) addThread(tid int) (*ThreadContext, error) {
 	return dbp.Threads[tid], nil
 }
 
-func parseProcessStatus(pid int) (*ProcessStatus, error) {
-	var ps ProcessStatus
-
+func stopped(pid int) bool {
 	f, err := os.Open(fmt.Sprintf("/proc/%d/stat", pid))
 	if err != nil {
-		return nil, err
+		return false
 	}
 	defer f.Close()
 
-	fmt.Fscanf(f, "%d %s %c %d", &ps.pid, &ps.comm, &ps.state, &ps.ppid)
-
-	return &ps, nil
+	var (
+		p     int
+		comm  string
+		state rune
+	)
+	fmt.Fscanf(f, "%d %s %c", &p, &comm, &state)
+	if state == STATUS_TRACE_STOP {
+		return true
+	}
+	return false
 }
 
 // Finds the executable from /proc/<pid>/exe and then