initial commit of agent

agent/agent.go

@@ -0,0 +1,59 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package agent provides hooks programs can register to retrieve
+// diagnostics data by using gops.
+package agent
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"os"
+	"runtime"
+)
+
+const (
+	// Stack represents a command to print stack trace.
+	Stack = byte(0x1)
+)
+
+func init() {
+	sock := fmt.Sprintf("/tmp/gops%d.sock", os.Getpid())
+	l, err := net.Listen("unix", sock)
+	if err != nil {
+		log.Fatal(err)
+	}
+	// TODO(jbd): cleanup the socket on shutdown.
+	go func() {
+		buf := make([]byte, 1)
+		for {
+			fd, err := l.Accept()
+			if err != nil {
+				log.Println(err)
+				continue
+			}
+			if _, err := fd.Read(buf); err != nil {
+				log.Println(err)
+				continue
+			}
+			if err := handle(fd, buf); err != nil {
+				log.Println(err)
+				continue
+			}
+			fd.Close()
+		}
+	}()
+}
+
+func handle(conn net.Conn, msg []byte) error {
+	switch msg[0] {
+	case Stack:
+		buf := make([]byte, 1<<16)
+		n := runtime.Stack(buf, true)
+		_, err := conn.Write(buf[:n])
+		return err
+	}
+	return nil
+}