Merge pull request #17 from sokurenko/master

avoid costly process info extraction if unnecessary

netstat/netstat_linux.go

@@ -153,7 +153,7 @@ func parseSocktab(r io.Reader, accept AcceptFn) ([]SockTabEntry, error) {
 		}
 		e.UID = uint32(u)
 		e.ino = fields[9]
-        extractProcInfo(&e)
+		extractProcInfo(&e)
 		if accept(&e) {
 			tab = append(tab, e)
 		}
@@ -201,29 +201,29 @@ func (p *procFd) iterFdDir() {
 			continue
 		}
 
-			sk := p.sktab
-			ss := sockPrefix + sk.ino + "]"
-			if ss != lname {
-				continue
+		sk := p.sktab
+		ss := sockPrefix + sk.ino + "]"
+		if ss != lname {
+			continue
+		}
+		if p.p == nil {
+			stat, err := os.Open(path.Join(p.base, "stat"))
+			if err != nil {
+				return
 			}
-			if p.p == nil {
-				stat, err := os.Open(path.Join(p.base, "stat"))
-				if err != nil {
-					return
-				}
-				if stat != nil {
-					defer stat.Close()
-				}
-				n, err := stat.Read(buf[:])
-				if err != nil {
-					return
-				}
-				z := bytes.SplitN(buf[:n], []byte(" "), 3)
-				name := getProcName(z[1])
-				p.p = &Process{p.pid, name}
-				stat.Close()
+			if stat != nil {
+				defer stat.Close()
 			}
-			sk.Process = p.p
+			n, err := stat.Read(buf[:])
+			if err != nil {
+				return
+			}
+			z := bytes.SplitN(buf[:n], []byte(" "), 3)
+			name := getProcName(z[1])
+			p.p = &Process{p.pid, name}
+			stat.Close()
+		}
+		sk.Process = p.p
 	}
 }
 
@@ -262,7 +262,11 @@ func doNetstat(path string, fn AcceptFn) ([]SockTabEntry, error) {
 	if err != nil {
 		return nil, err
 	}
-	//extractProcInfo(tabs)
+
+	if len(tabs) != 0 {
+		extractProcInfo(tabs)
+	}
+
 	return tabs, nil
 }