From 9e56b84c41efcaf3349f82a93c3dc854e172e5c4 Mon Sep 17 00:00:00 2001

From: Kamil Dudka <kdudka@redhat.com>

Date: Fri, 9 Aug 2013 16:22:08 +0200

Subject: [PATCH 4/5] partially revert "window_size: explicit adjustments only"

This partially reverts commit 03ca9020756a4e16f0294e5b35e9826ee6af2364

in order to fix extreme slowdown when uploading to localhost via SFTP.

I was able to repeat the issue on RHEL-7 on localhost only.  It did not

occur when uploading via network and it did not occur on a RHEL-6 box

with the same version of libssh2.

The problem was that sftp_read() used a read-ahead logic to figure out

the window_size, but sftp_packet_read() called indirectly from

sftp_write() did not use any read-ahead logic.

---

 src/channel.c |   29 +++++++++++++++++++++++++++++

 1 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/src/channel.c b/src/channel.c

index 4f41e1f..d4ffdce 100644

--- a/src/channel.c

+++ b/src/channel.c

@@ -1759,6 +1759,15 @@ ssize_t _libssh2_channel_read(LIBSSH2_CHANNEL *channel, int stream_id,

         channel->read_state = libssh2_NB_state_created;

     }

+    /*

+     * =============================== NOTE ===============================

+     * I know this is very ugly and not a really good use of "goto", but

+     * this case statement would be even uglier to do it any other way

+     */

+    if (channel->read_state == libssh2_NB_state_jump1) {

+        goto channel_read_window_adjust;

+    }

+

     rc = 1; /* set to >0 to let the while loop start */

     /* Process all pending incoming packets in all states in order to "even

@@ -1867,6 +1876,26 @@ ssize_t _libssh2_channel_read(LIBSSH2_CHANNEL *channel, int stream_id,

            more off the network again */

         channel->read_state = libssh2_NB_state_created;

+    if(channel->remote.window_size < (LIBSSH2_CHANNEL_WINDOW_DEFAULT*30)) {

+        /* the window is getting too narrow, expand it! */

+

+      channel_read_window_adjust:

+        channel->read_state = libssh2_NB_state_jump1;

+        /* the actual window adjusting may not finish so we need to deal with

+           this special state here */

+        rc = _libssh2_channel_receive_window_adjust(channel,

+                                                    (LIBSSH2_CHANNEL_WINDOW_DEFAULT*60), 0, NULL);

+        if (rc)

+            return rc;

+

+        _libssh2_debug(session, LIBSSH2_TRACE_CONN,

+                       "channel_read() filled %d adjusted %d",

+                       bytes_read, buflen);

+        /* continue in 'created' state to drain the already read packages

+           first before starting to empty the socket further */

+        channel->read_state = libssh2_NB_state_created;

+    }

+

     return bytes_read;

 }

-- 

1.7.1