add experimental plugin system

util/timeoutlistener.go

@@ -0,0 +1,86 @@
+package util
+
+import (
+	"net"
+	"sync/atomic"
+	"time"
+)
+
+type listener struct {
+	net.Listener
+	ReadTimeout  time.Duration
+	WriteTimeout time.Duration
+}
+
+func (l *listener) Accept() (net.Conn, error) {
+	c, err := l.Listener.Accept()
+	if err != nil {
+		return nil, err
+	}
+	tc := &Conn{
+		Conn:                     c,
+		ReadTimeout:              l.ReadTimeout,
+		WriteTimeout:             l.WriteTimeout,
+		ReadThreshold:            int32((l.ReadTimeout * 1024) / time.Second),
+		WriteThreshold:           int32((l.WriteTimeout * 1024) / time.Second),
+		BytesReadFromDeadline:    0,
+		BytesWrittenFromDeadline: 0,
+	}
+	return tc, nil
+}
+
+// Conn wraps a net.Conn, and sets a deadline for every read
+// and write operation.
+type Conn struct {
+	net.Conn
+	ReadTimeout              time.Duration
+	WriteTimeout             time.Duration
+	ReadThreshold            int32
+	WriteThreshold           int32
+	BytesReadFromDeadline    int32
+	BytesWrittenFromDeadline int32
+}
+
+func (c *Conn) Read(b []byte) (n int, err error) {
+	if atomic.LoadInt32(&c.BytesReadFromDeadline) > c.ReadThreshold {
+		atomic.StoreInt32(&c.BytesReadFromDeadline, 0)
+		// we set both read and write deadlines here otherwise after the request
+		// is read writing the response fails with an i/o timeout error
+		err = c.Conn.SetDeadline(time.Now().Add(c.ReadTimeout))
+		if err != nil {
+			return 0, err
+		}
+	}
+	n, err = c.Conn.Read(b)
+	atomic.AddInt32(&c.BytesReadFromDeadline, int32(n))
+	return
+}
+
+func (c *Conn) Write(b []byte) (n int, err error) {
+	if atomic.LoadInt32(&c.BytesWrittenFromDeadline) > c.WriteThreshold {
+		atomic.StoreInt32(&c.BytesWrittenFromDeadline, 0)
+		// we extend the read deadline too, not sure it's necessary,
+		// but it doesn't hurt
+		err = c.Conn.SetDeadline(time.Now().Add(c.WriteTimeout))
+		if err != nil {
+			return
+		}
+	}
+	n, err = c.Conn.Write(b)
+	atomic.AddInt32(&c.BytesWrittenFromDeadline, int32(n))
+	return
+}
+
+func newListener(network, addr string, readTimeout, writeTimeout time.Duration) (net.Listener, error) {
+	l, err := net.Listen(network, addr)
+	if err != nil {
+		return nil, err
+	}
+
+	tl := &listener{
+		Listener:     l,
+		ReadTimeout:  readTimeout,
+		WriteTimeout: writeTimeout,
+	}
+	return tl, nil
+}