Bug#504063: Bug#511708: aptitude: [etch upgrade] TUI consistently blocks after doing one set of operations

[Daniel Burrows]

  This is for everyone who can reproduce the bug.

  Could you build a libcwidget3 with the attached patch and see what's
produced in /tmp/cwidget.input.log when you reproduce the bug?  If I
start aptitude, run dpkg once, and exit, I get this:

Starting input thread
Creating new input thread
Input thread created
Stopping input thread
Destroying existing input thread
Input thread destroyed
Starting input thread
Creating new input thread
Input thread created
Stopping input thread
Destroying existing input thread
Input thread destroyed

  Daniel

diff --git a/src/cwidget/toplevel.cc b/src/cwidget/toplevel.cc
index 7cfd048..486fb00 100644
--- a/src/cwidget/toplevel.cc
+++ b/src/cwidget/toplevel.cc
@@ -58,6 +58,8 @@
 #include <fcntl.h>
 #include <sys/types.h>
 
+#include <fstream>
+
 namespace cwidget
 {
   std::string version()
@@ -425,22 +427,34 @@ namespace cwidget
     public:
       static void start()
       {
+	std::ofstream out("/tmp/cwidget.input.log", std::ios::app);
+	out << "Starting input thread" << std::endl;
+
 	threads::mutex::lock l(instance_mutex);
 
 	if(instancet == NULL)
-	  instancet = new threads::thread(threads::make_bootstrap_proxy(&instance));
+	  {
+	    out << "Creating new input thread" << std::endl;
+	    instancet = new threads::thread(threads::make_bootstrap_proxy(&instance));
+	    out << "Input thread created" << std::endl;
+	  }
       }
 
       static void stop()
       {
+	std::ofstream out("/tmp/cwidget.input.log", std::ios::app);
+	out << "Stopping input thread" << std::endl;
+
 	threads::mutex::lock l(instance_mutex);
 
 	if(instancet != NULL)
 	  {
+	    out << "Destroying existing input thread" << std::endl;
 	    instancet->cancel();
 	    instancet->join();
 	    delete instancet;
 	    instancet = NULL;
+	    out << "Input thread destroyed" << std::endl;
 	  }
       }