From: James McCoy <jamessan@debian.org>
Date: Wed, 1 Aug 2018 20:44:36 -0400
Subject: ruby-test-svnserve-race

Bug #378837: Ruby testsuite: wait for svnserve to start before
Bug #378837: Ruby testsuite: wait for svnserve to start before
connecting to it.  This mainly affects very slow machines - observed
on various arm and m68k builds.

Thanks to Roman Zippel, Kobayashi Noritada, Wouter Verhelst and Martin
Michlmayr.
---
 subversion/bindings/swig/ruby/test/util.rb | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/subversion/bindings/swig/ruby/test/util.rb b/subversion/bindings/swig/ruby/test/util.rb
index 06ae7ba..4f54992 100644
--- a/subversion/bindings/swig/ruby/test/util.rb
+++ b/subversion/bindings/swig/ruby/test/util.rb
@@ -19,6 +19,7 @@
 
 require "fileutils"
 require "pathname"
+require "socket"
 
 # Tale of a hack...
 #
@@ -289,11 +290,7 @@ realm = #{@realm}
                "-d", "--foreground")
         }
         pid, status = Process.waitpid2(@svnserve_pid, Process::WNOHANG)
-        if status and status.exited?
-          if $DEBUG
-            STDERR.puts "port #{port} couldn't be used for svnserve"
-          end
-        else
+        if wait_until_svnserve_gets_available_at(port)
           # svnserve started successfully.  Note port number and cease
           # startup attempts.
           @svnserve_port = port
@@ -359,4 +356,25 @@ exit 1
     include Svnserve
     extend SetupEnvironment
   end
+
+  # Waits until svnserve gets available at port +port+, avoiding the race
+  # condition between starting up a svnserve process and trying to connect
+  # to it (Bug#378837 in Debian's BTS).
+  def wait_until_svnserve_gets_available_at(port)
+    1000.times do |n|
+      begin
+	pid, status = Process.waitpid2(@svnserve_pid, Process::WNOHANG)
+	if status and status.exited?
+	  STDERR.puts "port #{port} couldn't be used for svnserve"
+	  return false
+	end
+	TCPSocket.new(@svnserve_host, port).close
+      rescue Errno::ECONNREFUSED
+	sleep(n < 10 ? 0.2 : 0.5)
+      else
+	return true
+      end
+    end
+    raise "svnserve couldn't get available at port #{port}"
+  end
 end