bug#23864: 25.1.50; Poor network responsivenes using open-network-stream

[Paul Eggert <eggert@cs.ucla.edu>]

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On 07/04/2016 04:35 PM, Eli Zaretskii wrote:
> Do you consider these changes safe for back-porting to emacs-25?

Yes. Propose patch to emacs-25 attached.

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From ea23b4519698c9695a851508c3455f36ff94115b Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 5 Jul 2016 20:40:40 +0200
Subject: [PATCH] Fix open-network-stream responsiveness

Problem reported by Christer Ekholm (Bug#23864).
Backport from master.
* src/process.c (wait_reading_process_output):
Fix typo introduced in 2015-07-06T02:19:13Z!eggert@cs.ucla.edu
when wait == INFINITY and got_output_end_time is invalid.
In this case the code should break, not continue.
---
 src/process.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/process.c b/src/process.c
index 14d7b6d..0593429 100644
--- a/src/process.c
+++ b/src/process.c
@@ -4911,16 +4911,22 @@ wait_reading_process_output (intmax_t time_limit, int nsecs, int read_kbd,
              haven't lowered our timeout due to timers or SIGIO and
              have waited a long amount of time due to repeated
              timers.  */
+	  struct timespec huge_timespec
+	    = make_timespec (TYPE_MAXIMUM (time_t), 2 * TIMESPEC_RESOLUTION);
+	  struct timespec cmp_time = huge_timespec;
 	  if (wait < TIMEOUT)
 	    break;
-	  struct timespec cmp_time
-	    = (wait == TIMEOUT
-	       ? end_time
-	       : (!process_skipped && got_some_output > 0
-		  && (timeout.tv_sec > 0 || timeout.tv_nsec > 0))
-	       ? got_output_end_time
-	       : invalid_timespec ());
-	  if (timespec_valid_p (cmp_time))
+	  if (wait == TIMEOUT)
+	    cmp_time = end_time;
+	  if (!process_skipped && got_some_output > 0
+	      && (timeout.tv_sec > 0 || timeout.tv_nsec > 0))
+	    {
+	      if (!timespec_valid_p (got_output_end_time))
+		break;
+	      if (timespec_cmp (got_output_end_time, cmp_time) < 0)
+		cmp_time = got_output_end_time;
+	    }
+	  if (timespec_cmp (cmp_time, huge_timespec) < 0)
 	    {
 	      now = current_timespec ();
 	      if (timespec_cmp (cmp_time, now) <= 0)
-- 
2.5.5