Add Bus::ShutdownOnDBusThreadAndBlock() and remove bus::Shutdown()

    
This function is intended to use at the the very end of the browser shutdown,
where it it makes more sense to shut down the bus synchronously, than trying
to make it asynchronous.

Remove Bus::Shutdown() as we are unlikely to need it for the production code.

BUG=chromium:90036
TEST=dbus_unittests


Review URL: http://codereview.chromium.org/7830009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@99331 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 20 insertions, 14 deletions

diff --git a/dbus/bus.h b/dbus/bus.h
index 792eb83..5be6ddc 100644
--- a/dbus/bus.h
+++ b/dbus/bus.h
@@ -14,6 +14,7 @@
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/waitable_event.h"
 #include "base/threading/platform_thread.h"
 #include "base/tracked_objects.h"
 
@@ -61,9 +62,9 @@ class ObjectProxy;
 //
 // SHUTDOWN
 //
-// The Bus object must be shut down manually by Shutdown() or
-// ShutdownAndBlock(). We require the manual shutdown as we should not
-// issue blocking calls in the destructor.
+// The Bus object must be shut down manually by ShutdownAndBlock() and
+// friends. We require the manual shutdown to make the operation explicit
+// rather than doing it silently in the destructor.
 //
 // EXAMPLE USAGE:
 //
@@ -119,8 +120,8 @@ class ObjectProxy;
 // WHY IS THIS A REF COUNTED OBJECT?
 //
 // Bus is a ref counted object, to ensure that |this| of the object is
-// alive when callbacks referencing |this| are called. However, after
-// Shutdown() is called, |connection_| can be NULL. Hence, callbacks should
+// alive when callbacks referencing |this| are called. However, after the
+// bus is shut down, |connection_| can be NULL. Hence, callbacks should
 // not rely on that |connection_| is alive.
 class Bus : public base::RefCountedThreadSafe<Bus> {
  public:
@@ -163,9 +164,6 @@ class Bus : public base::RefCountedThreadSafe<Bus> {
     base::Thread* dbus_thread;  // NULL by default.
   };
 
-  // Called when shutdown is done. Used for Shutdown().
-  typedef base::Callback<void ()> OnShutdownCallback;
-
   // Creates a Bus object. The actual connection will be established when
   // Connect() is called.
   explicit Bus(const Options& options);
@@ -219,11 +217,17 @@ class Bus : public base::RefCountedThreadSafe<Bus> {
   // BLOCKING CALL.
   virtual void ShutdownAndBlock();
 
-  // Shuts down the bus in the D-Bus thread. |callback| will be called in
-  // the origin thread.
+  // Similar to ShutdownAndBlock(), but this function is used to
+  // synchronously shut down the bus that uses the D-Bus thread. This
+  // function is intended to be used at the very end of the browser
+  // shutdown, where it makes more sense to shut down the bus
+  // synchronously, than trying to make it asynchronous.
   //
-  // Must be called in the origin thread.
-  virtual void Shutdown(OnShutdownCallback callback);
+  // BLOCKING CALL, but must be called in the origin thread.
+  virtual void ShutdownOnDBusThreadAndBlock();
+
+  // Returns true if the shutdown has been completed.
+  bool shutdown_completed() { return shutdown_completed_; }
 
   //
   // The public functions below are not intended to be used in client
@@ -381,8 +385,8 @@ class Bus : public base::RefCountedThreadSafe<Bus> {
  private:
   friend class base::RefCountedThreadSafe<Bus>;
 
-  // Helper function used for Shutdown().
-  void ShutdownInternal(OnShutdownCallback callback);
+  // Helper function used for ShutdownOnDBusThreadAndBlock().
+  void ShutdownOnDBusThreadAndBlockInternal();
 
   // Processes the all incoming data to the connection, if any.
   //
@@ -427,6 +431,7 @@ class Bus : public base::RefCountedThreadSafe<Bus> {
   const BusType bus_type_;
   const ConnectionType connection_type_;
   base::Thread* dbus_thread_;
+  base::WaitableEvent on_shutdown_;
   DBusConnection* connection_;
 
   MessageLoop* origin_loop_;
@@ -455,6 +460,7 @@ class Bus : public base::RefCountedThreadSafe<Bus> {
   ExportedObjectTable exported_object_table_;
 
   bool async_operations_set_up_;
+  bool shutdown_completed_;
 
   // Counters to make sure that OnAddWatch()/OnRemoveWatch() and
   // OnAddTimeout()/OnRemoveTimeou() are balanced.