Patch: Improve HTTP time by sending Connection:close

[Walter Huf]

GRUB's HTTP module declares support for HTTP/1.1, which defaults to Connection:keepalive. At the end of the content, the server holds the TCP connection open waiting for the next request.

It seems that grub_net_poll_cards() is watching for the HTTP module to set net->stall, and otherwise waits the full 400ms GRUB_NET_INTERVAL to return to processing. However, HTTP module only sets that flag in specific conditions:

• parse_line detects that we are at the end of downloading a chunked Transfer-Encoding
• http_err detects a problem with the underlying TCP connection
• http_receive has queued 20 netbuffer packets for processing

If the file is small and takes less than 20 packets, and the server is not using chunked encoding, grub_net_poll_cards() will wait the full 400ms before continuing to process and finish the file download.

This patch sets Connection:close, which will tell the server to close the connection as soon as it has finished sending the file. GRUB closes any connections that are left open (in http_seek), so it does not change performance. When the server disconnects, I think it triggers http_err and then quits out of grub_net_poll_cards early.

---

diff --git a/grub-core/net/http.c b/grub-core/net/http.c

index 5aa4ad3..a5d64f6 100644

--- a/grub-core/net/http.c

+++ b/grub-core/net/http.c

@@ -318,6 +318,7 @@ http_establish (struct grub_file *file, grub_off_t offset, int initial)

    + grub_strlen (data->filename)

    + sizeof (" HTTP/1.1\r\nHost: ") - 1

    + grub_strlen (file->device->net->server)

+   + sizeof ("\r\nConnection: close") - 1

    + sizeof ("\r\nUser-Agent: " PACKAGE_STRING

      "\r\n") - 1

    + sizeof ("Range: bytes=XXXXXXXXXXXXXXXXXXXX"

@@ -366,6 +367,17 @@ http_establish (struct grub_file *file, grub_off_t offset, int initial)

        grub_strlen (file->device->net->server));

 

   ptr = nb->tail;

+  err = grub_netbuff_put (nb,

+  sizeof ("\r\nConnection: close")

+  - 1);

+  if (err)

+    {

+      grub_netbuff_free (nb);

+      return err;

+    }

+  grub_memcpy (ptr, "\r\nConnection: close",

+       sizeof ("\r\nConnection: close") - 1);

+  ptr = nb->tail;

   err = grub_netbuff_put (nb, 

   sizeof ("\r\nUser-Agent: " PACKAGE_STRING "\r\n")

   - 1);