Fix Request.connectionCloseFast bugs

See https://github.com/valyala/fasthttp/pull/265
and https://github.com/valyala/fasthttp/issues/220
and https://github.com/valyala/fasthttp/issues/264

header.go

@@ -157,12 +157,6 @@ func (h *RequestHeader) ConnectionClose() bool {
 	return h.connectionClose
 }
 
-func (h *RequestHeader) connectionCloseFast() bool {
-	// h.parseRawHeaders() isn't called for performance reasons.
-	// Use ConnectionClose for triggering raw headers parsing.
-	return h.connectionClose
-}
-
 // SetConnectionClose sets 'Connection: close' header.
 func (h *RequestHeader) SetConnectionClose() {
 	// h.parseRawHeaders() isn't called for performance reasons.

header_test.go

@@ -431,9 +431,6 @@ func TestRequestHeaderHTTP10ConnectionClose(t *testing.T) {
 		t.Fatalf("unexpected error: %s", err)
 	}
 
-	if !h.connectionCloseFast() {
-		t.Fatalf("expecting 'Connection: close' request header")
-	}
 	if !h.ConnectionClose() {
 		t.Fatalf("expecting 'Connection: close' request header")
 	}

server.go

@@ -1746,7 +1746,7 @@ func (s *Server) serveConn(c net.Conn) error {
 			}
 		}
 
-		connectionClose = s.DisableKeepalive || ctx.Request.Header.connectionCloseFast()
+		connectionClose = s.DisableKeepalive || ctx.Request.Header.ConnectionClose()
 		isHTTP11 = ctx.Request.Header.IsHTTP11()
 
 		if serverName != nil {
@@ -1785,9 +1785,7 @@ func (s *Server) serveConn(c net.Conn) error {
 			lastWriteDeadlineTime = s.updateWriteDeadline(c, ctx, lastWriteDeadlineTime)
 		}
 
-		// Verify Request.Header.connectionCloseFast() again,
-		// since request handler might trigger full headers' parsing.
-		connectionClose = connectionClose || ctx.Request.Header.connectionCloseFast() || ctx.Response.ConnectionClose()
+		connectionClose = connectionClose || ctx.Response.ConnectionClose()
 		if connectionClose {
 			ctx.Response.Header.SetCanonical(strConnection, strClose)
 		} else if !isHTTP11 {