Run only a single trap thread at any given time. Ensure that trap threads are joined after a busy block ends.

lib/vagrant/busy.rb

@@ -12,6 +12,7 @@ module Vagrant
 
     @@busy = false
     @@mutex = Mutex.new
+    @@trap_thread = nil
 
     class << self
       def busy?
@@ -34,6 +35,9 @@ module Vagrant
             # busy back to some sane state.
             Busy.busy = false
 
+            # Make sure that the trap thread completes, if it is running
+            trap_thread.join if trap_thread
+
             # And restore the INT trap to the default
             Signal.trap("INT", "DEFAULT")
           end
@@ -41,7 +45,7 @@ module Vagrant
       end
 
       def wait_for_not_busy(sleeptime=5)
-        Thread.new do
+        @@trap_thread ||= Thread.new do
           # Wait while the app is busy
           loop do
             break unless busy?
@@ -50,9 +54,20 @@ module Vagrant
           end
 
           # Exit out of the entire script
+          logger.info "Exiting vagrant..."
           exit
         end
       end
+
+      # Used for testing
+      def reset_trap_thread!
+        @@trap_thread = nil
+      end
+
+      # Returns the trap thread
+      def trap_thread
+        @@trap_thread
+      end
     end
   end
 end

test/vagrant/busy_test.rb

@@ -2,7 +2,19 @@ require File.join(File.dirname(__FILE__), '..', 'test_helper')
 
 class BusyTest < Test::Unit::TestCase
   context "waiting for not busy" do
-    # TODO: Need to test this method
+    setup do
+      Vagrant::Busy.reset_trap_thread!
+    end
+
+    should "run in a thread" do
+      Thread.expects(:new).once.returns(nil)
+      Vagrant::Busy.wait_for_not_busy
+    end
+
+    should "not start a thread multiple times" do
+      Thread.expects(:new).once.returns("foo")
+      Vagrant::Busy.wait_for_not_busy
+    end
   end
 
   context "during an action in a busy block" do
@@ -27,6 +39,18 @@ class BusyTest < Test::Unit::TestCase
       assert !Vagrant.busy?
     end
 
+    should "complete the trap thread even if an exception occurs" do
+      trap_thread = mock("trap_thread")
+      trap_thread.expects(:join).once
+      Vagrant::Busy.stubs(:trap_thread).returns(trap_thread)
+
+      assert_raise Exception do
+        Vagrant.busy do
+          raise Exception
+        end
+      end
+    end
+
     should "report busy to the outside world regardless of thread" do
       Thread.new do
         Vagrant.busy do