From 32cae67a75434ef5487c70b9f8f42e233f8ba31d Mon Sep 17 00:00:00 2001
From: nick <nick@bytemark.co.uk>
Date: Tue, 25 Sep 2012 11:47:44 +0100
Subject: [PATCH] flexnbd: Move building the allocation map to before server
 socket bind()

Building the allocation map takes time, which scales with the size of the disc
being presented. By building that map in the space between bind() and accept(),
we leave the process in a useless state after the only good signal we have for
"we are ready" and the state where it is actually ready. This was breaking
migrations of large files.
---
 src/serve.c                             |  2 +-
 tests/acceptance/flexnbd.rb             | 17 ++++++++++++-
 tests/acceptance/flexnbd/fake_source.rb | 32 ++++++++++++++++++++-----
 3 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/src/serve.c b/src/serve.c
index 91f2569..e720be0 100644
--- a/src/serve.c
+++ b/src/serve.c
@@ -816,8 +816,8 @@ int do_serve(struct server* params)
 	int has_control;
 
 	error_set_handler((cleanup_handler*) serve_cleanup, params);
-	serve_open_server_socket(params);
 	serve_init_allocation_map(params);
+	serve_open_server_socket(params);
 	serve_accept_loop(params);
 	has_control = params->has_control;
 	serve_cleanup(params, 0);
diff --git a/tests/acceptance/flexnbd.rb b/tests/acceptance/flexnbd.rb
index 1262982..887e7d8 100644
--- a/tests/acceptance/flexnbd.rb
+++ b/tests/acceptance/flexnbd.rb
@@ -314,9 +314,16 @@ module FlexNBD
 
       while !File.socket?(ctrl)
         pid, status = Process.wait2(@pid, Process::WNOHANG)
-        raise "server did not start (#{cmd})" if pid
+        raise "server did not start (#{cmd}) - UNIX socket didn't appear" if pid
         sleep 0.1
       end
+
+      while !socket_open?
+        pid, status = Process.wait2(@pid, Process::WNOHANG)
+        raise "server did not start (#{cmd}) - TCP socket didn't appear" if pid
+        sleep 0.1
+      end
+
       at_exit { kill }
     end
     private :run_serve_cmd
@@ -511,7 +518,15 @@ module FlexNBD
       hsh
     end
 
+    def socket_open?
+      sock = (TCPSocket.new(@ip, @port) rescue nil)
+      !!sock
+    ensure
+      sock.close rescue nil if sock
+    end
+
 
   end
 
 end
+
diff --git a/tests/acceptance/flexnbd/fake_source.rb b/tests/acceptance/flexnbd/fake_source.rb
index 1f14719..5d4c91a 100644
--- a/tests/acceptance/flexnbd/fake_source.rb
+++ b/tests/acceptance/flexnbd/fake_source.rb
@@ -8,16 +8,35 @@ module FlexNBD
   class FakeSource
 
     def initialize( addr, port, err_msg, source_addr=nil, source_port=0 )
-      timing_out( 2, err_msg ) do
-        @sock = if source_addr
-          TCPSocket.new( addr, port, source_addr, source_port )
-        else 
-          TCPSocket.new( addr, port )
-        end
+      timing_out( 10, err_msg ) {
+        @sock = wait_for_server_socket( addr, port, source_addr, source_port )
+      }
+    end
+
+
+    def wait_for_server_socket(addr, port, saddr = nil, sport = 0)
+      sock = nil
+
+      loop do
+        sock = try_get_server_socket( addr, port, saddr, sport )
+        break if sock
+        sleep 0.1
+      end
+
+      sock
+    end
+
+    def try_get_server_socket(addr, port, saddr = nil, sport = 0)
+      if saddr
+        TCPSocket.new( addr, port, saddr, sport ) rescue nil
+      else
+        TCPSocket.new( addr, port ) rescue nil
       end
     end
 
 
+
+
     def close
       @sock.close
     end
@@ -137,3 +156,4 @@ module FlexNBD
 
   end # class FakeSource
 end # module FlexNBD
+