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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
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