Re: [PATCH] git-web--browser: avoid errors in terminal when running Firefox on Windows

On Fri, Jan 25, 2013 at 06:44:13PM +0400, Alexey Shumkin wrote:

 test_web_browse () {
-	# browser=$1 url=$2
+	# browser=$1 url=$2 sleep_timeout=$3
+	sleep_timeout="$3"
 	git web--browse --browser="$1" "$2" >actual &&
+	# if $3 is set
+	# as far as Firefox is run in background (it is run with &)
+	# we trying to avoid race condition
+	# by waiting for "$sleep_timeout" seconds of timeout for 'fake_browser_ran' file appearance
+	(test -z "$sleep_timeout" || (
+	    for timeout in $(seq 1 $sleep_timeout); do
+			test -f fake_browser_ran && break
+			sleep 1
+		done
+		test $timeout -ne $sleep_timeout
+		)
+	) &&
 	tr -d '\015' <actual >text &&

Gross, but I don't really see another way to handle the asynchronous
nature of spawning background browsers.

Two things, though:

  1. Should test_web_browse just delete fake_browser_ran for us? Then
     later tests do not have to remember to do so.

  2. Seeing fake_browser_ran appeared, we know that the script has
     started.  But there is still a race condition in which it may not
     have written anything to "actual" yet.

In this implementation:

+	cat >"fake browser" <<-\EOF &&
+	#!/bin/sh
+
+	: > fake_browser_ran
+	if test "$1" = "-version"; then
+		echo Fake Firefox browser version 1.2.3
+	else
+		# Firefox (in contrast to w3m) is run in background (with &)
+		# so redirect output to "actual"
+		echo fake: "$@" > actual
+	fi
+	EOF

There is a period where fake_browser_ran exists, but nothing is in
actual. You can solve it by setting fake_browser_ran at the end rather
than the beginning.

Or you can drop fake_browser_ran entirely, and just atomically move
actual into place, like:

  echo "fake: $*" >actual.tmp
  mv actual.tmp actual

and then test_web_browse can just spin waiting for "actual" to appear.

-Peff