Sending with sendfile: use chunks so MHD will be able to process other connections too.

src/microhttpd/connection.c

@@ -238,12 +238,18 @@ sendfile_adapter (struct MHD_Connection *connection)
 #else  /* HAVE_SENDFILE64 */
   off64_t offset;
 #endif /* HAVE_SENDFILE64 */
+  const bool used_thr_p_c = (0 != (daemon->options & MHD_USE_THREAD_PER_CONNECTION));
+  size_t send_size;
   mhd_assert (MHD_resp_sender_sendfile == connection->resp_sender);
 
   offsetu64 = connection->response_write_position + connection->response->fd_off;
   left = connection->response->total_size - connection->response_write_position;
-  if (left > SSIZE_MAX)
-    left = SSIZE_MAX;
+  /* Do not allow system to stick sending on single fast connection:
+   * use 128KiB chunks (2MiB for thread-per-connection). */
+  if (!used_thr_p_c)
+    send_size = (left > 0x20000) ? 0x20000 : (size_t) left;
+  else
+    send_size = (left > 0x200000) ? 0x200000 : (size_t) left;
 #ifndef HAVE_SENDFILE64
   if ((uint64_t)OFF_T_MAX < offsetu64)
     { /* Retry to send with standard 'send()'. */
@@ -254,7 +260,7 @@ sendfile_adapter (struct MHD_Connection *connection)
     ret = sendfile (connection->socket_fd,
                     file_fd,
                     &offset,
-                    left);
+                    send_size);
 #else  /* HAVE_SENDFILE64 */
   if ((uint64_t)OFF64_T_MAX < offsetu64)
     { /* Retry to send with standard 'send()'. */
@@ -265,7 +271,7 @@ sendfile_adapter (struct MHD_Connection *connection)
     ret = sendfile64 (connection->socket_fd,
                       file_fd,
                       &offset,
-                      left);
+                      send_size);
 #endif /* HAVE_SENDFILE64 */
   if (0 > ret)
     {
@@ -292,7 +298,7 @@ sendfile_adapter (struct MHD_Connection *connection)
       return MHD_ERR_AGAIN_;
     }
 #ifdef EPOLL_SUPPORT
-  else if (left > (uint64_t)ret)
+  else if (send_size > (size_t)ret)
         connection->epoll_state &= ~MHD_EPOLL_STATE_WRITE_READY;
 #endif /* EPOLL_SUPPORT */
   return ret;