Test a source crashing after an entrust.

This adds a test for destination behaviour, in that if a source crashes
after sending an entrust message but before the destination can reply,
the destination must allow the source to reconnect and retry the mirror.

src/mirror.c

@@ -239,8 +239,16 @@ void mirror_give_control( struct mirror_status * mirror )
 	 * requests while the response was in flight, and if the
 	 * response went astray we'd have two servers claiming
 	 * responsibility for the same data.
+	 *
+	 * The meaning of these is as follows:
+	 * The entrust signifies that all the data has been sent, and
+	 * the client is currently paused but not disconnected.
+	 * The disconnect signifies that the client has been
+	 * safely disconnected.
+	 * TODO: Disconnect the client!
 	 */
 	socket_nbd_entrust( mirror->client );
+	debug("TODO: The client *should* be disconnected here, but isn't yet");
 	socket_nbd_disconnect( mirror->client );
 }
 

tests/acceptance/fakes/source/close_after_entrust.rb

@@ -0,0 +1,34 @@
+#!/usr/bin/env ruby
+
+# Connect, send a migration, entrust then *immediately* disconnect.
+# This simulates a client which fails while the client is blocked.
+#
+# We attempt to reconnect immediately afterwards to prove that we can
+# retry the mirroring.
+
+require 'flexnbd/fake_source'
+include FlexNBD
+
+addr, port, srv_pid = *ARGV
+
+client = FakeSource.new( addr, port, "Timed out connecting" )
+client.read_hello
+client.write_write_request( 0, 8 )
+client.write_data( "12345678" )
+
+# Use system "kill" rather than Process.kill because Process.kill
+# doesn't seem to work
+system "kill -STOP #{srv_pid}"
+
+client.write_entrust_request
+client.close
+
+system "kill -CONT #{srv_pid}"
+
+
+sleep(0.25)
+
+client2 = FakeSource.new( addr, port, "Timed out reconnecting" )
+client2.close
+
+exit(0)

tests/acceptance/fakes/source/close_after_write_data.rb

@@ -27,7 +27,7 @@ Process.kill( "CONT", srv_pid.to_i )
 sleep(0.25)
 
 # ...and can we reconnect?
-client2 = FakeSource.new( addr, port, "Timed out connecting" )
+client2 = FakeSource.new( addr, port, "Timed out reconnecting" )
 client2.close
 
 exit(0)

tests/acceptance/flexnbd/fake_source.rb

@@ -29,22 +29,34 @@ module FlexNBD
     end
 
 
-    def write_write_request( from, len, handle="myhandle" )
+    def send_request( type, handle="myhandle", from=0, len=0 )
       fail "Bad handle" unless handle.length == 8
 
       @sock.write( "\x25\x60\x95\x13" )
-      @sock.write( "\x00\x00\x00\x01" )
+      @sock.write( [type].pack( 'N' ) )
       @sock.write( handle )
       @sock.write( "\x0"*4 )
       @sock.write( [from].pack( 'N' ) )
       @sock.write( [len ].pack( 'N' ) )
     end
 
+
+    def write_write_request( from, len, handle="myhandle" )
+      send_request( 1, handle, from, len )
+    end
+
+
+    def write_entrust_request( handle="myhandle" )
+      send_request( 65536, handle )
+    end
+
+
     def write_data( data )
       @sock.write( data )
     end
 
 
+
     def read_response
       magic = @sock.read(4)
       error_s = @sock.read(4)

tests/acceptance/test_dest_error_handling.rb

@@ -54,6 +54,10 @@ class TestDestErrorHandling  < Test::Unit::TestCase
     run_fake( "source/close_after_write" )
   end
 
+  def test_disconnect_before_entrust_reply_causes_error
+    run_fake( "source/close_after_entrust" )
+  end
+
 
   def test_disconnect_before_write_reply_causes_error
     # Note that this is an odd case: writing the reply doesn't fail.