From 6b59f51b312f06d9420d34c09fa408c658aac6d2 Mon Sep 17 00:00:00 2001
From: Nicolas Pitre <nico@fluxnic.net>
Date: Wed, 11 Nov 2009 17:24:42 -0500
Subject: give priority to progress messages

In theory it is possible for sideband channel #2 to be delayed if
pack data is quick to come up for sideband channel #1.  And because
data for channel #2 is read only 128 bytes at a time while pack data
is read 8192 bytes at a time, it is possible for many pack blocks to
be sent to the client before the progress message fifo is emptied,
making the situation even worse.  This would result in totally garbled
progress display on the client's console as local progress gets mixed
with partial remote progress lines.

Let's prevent such situations by giving transmission priority to
progress messages over pack data at all times.

Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-upload-archive.c b/builtin-upload-archive.c
index f6c4c0f..58f6b8f 100644
--- a/builtin-upload-archive.c
+++ b/builtin-upload-archive.c
@@ -132,7 +132,6 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 
 	while (1) {
 		struct pollfd pfd[2];
-		ssize_t processed[2] = { 0, 0 };
 		int status;
 
 		pfd[0].fd = fd1[0];
@@ -147,15 +146,14 @@ int cmd_upload_archive(int argc, const char **argv, const char *prefix)
 			}
 			continue;
 		}
-		if (pfd[0].revents & POLLIN)
-			/* Data stream ready */
-			processed[0] = process_input(pfd[0].fd, 1);
 		if (pfd[1].revents & POLLIN)
 			/* Status stream ready */
-			processed[1] = process_input(pfd[1].fd, 2);
-		/* Always finish to read data when available */
-		if (processed[0] || processed[1])
-			continue;
+			if (process_input(pfd[1].fd, 2))
+				continue;
+		if (pfd[0].revents & POLLIN)
+			/* Data stream ready */
+			if (process_input(pfd[0].fd, 1))
+				continue;
 
 		if (waitpid(writer, &status, 0) < 0)
 			error_clnt("%s", lostchild);
diff --git a/upload-pack.c b/upload-pack.c
index b98b1d6..8734f1d 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -218,6 +218,23 @@ static void create_pack_file(void)
 			}
 			continue;
 		}
+		if (0 <= pe && (pfd[pe].revents & (POLLIN|POLLHUP))) {
+			/* Status ready; we ship that in the side-band
+			 * or dump to the standard error.
+			 */
+			sz = xread(pack_objects.err, progress,
+				  sizeof(progress));
+			if (0 < sz)
+				send_client_data(2, progress, sz);
+			else if (sz == 0) {
+				close(pack_objects.err);
+				pack_objects.err = -1;
+			}
+			else
+				goto fail;
+			/* give priority to status messages */
+			continue;
+		}
 		if (0 <= pu && (pfd[pu].revents & (POLLIN|POLLHUP))) {
 			/* Data ready; we keep the last byte to ourselves
 			 * in case we detect broken rev-list, so that we
@@ -255,21 +272,6 @@ static void create_pack_file(void)
 			if (sz < 0)
 				goto fail;
 		}
-		if (0 <= pe && (pfd[pe].revents & (POLLIN|POLLHUP))) {
-			/* Status ready; we ship that in the side-band
-			 * or dump to the standard error.
-			 */
-			sz = xread(pack_objects.err, progress,
-				  sizeof(progress));
-			if (0 < sz)
-				send_client_data(2, progress, sz);
-			else if (sz == 0) {
-				close(pack_objects.err);
-				pack_objects.err = -1;
-			}
-			else
-				goto fail;
-		}
 	}
 
 	if (finish_command(&pack_objects)) {
-- 
cgit v0.10.2-6-g49f6