WaitableEvent is the replacement for Windows events. Previously in the code, a HANDLE from CreateEvent was used for signaling, both within a process and across processes.

WaitableEvent is the cross platform replacement for this. To convert:
  * HANDLE -> base::WaitableEvent*
  * ScopedHandle -> scoped_ptr<base::WaitableEvent>
  * CreateEvent -> new base::WaitableEvent
  * SetEvent -> base::WaitableEvent::Signal
  * ResetEvent -> base::WaitableEvent::Reset
  * ObjectWatcher -> base::WaitableEventWatcher
  * WaitForMultipleObjects -> static base::WaitableEvent::WaitMany

ObjectWatcher remains for Windows specific code. WaitableEventWatcher has an identical interface save,
  * It uses WaitableEvents, not HANDLEs
  * It returns void from StartWatching and StopWatcher, rather than errors. System internal errors are fatal to the address space

IMPORTANT: There are semantic differences between the different platforms. WaitableEvents on Windows are implemented on top of events. Windows events work across process and this is used mostly for modal dialog support. Windows events can be duplicated with DuplicateHandle.

On other platforms, WaitableEvent works only within a single process. In the future we shall have to replace the current uses of cross-process events with IPCs.

BEWARE: HANDLE, on Windows, is a void *. Since any pointer type coerces to void *, you can pass a WaitableEvent * where a HANDLE is expected without any build-time errors.

Review URL: http://codereview.chromium.org/16554


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@8126 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 9 insertions, 5 deletions

diff --git a/chrome/renderer/render_view.h b/chrome/renderer/render_view.h
index ef0307d..26e3b97 100644
--- a/chrome/renderer/render_view.h
+++ b/chrome/renderer/render_view.h
@@ -48,6 +48,10 @@ class WebPluginDelegate;
 class WebPluginDelegateProxy;
 enum WebRequestCachePolicy;
 
+namespace base {
+class WaitableEvent;
+}
+
 namespace webkit_glue {
 struct FileUploadData;
 }
@@ -85,7 +89,7 @@ class RenderView : public RenderWidget,
   static RenderView* Create(
       RenderThreadBase* render_thread,
       HWND parent_hwnd,
-      HANDLE modal_dialog_event,
+      base::WaitableEvent* modal_dialog_event,  // takes ownership
       int32 opener_id,
       const WebPreferences& webkit_prefs,
       SharedRenderViewCounter* counter,
@@ -108,8 +112,8 @@ class RenderView : public RenderWidget,
     return host_window_;
   }
 
-  HANDLE modal_dialog_event() {
-    return modal_dialog_event_.Get();
+  base::WaitableEvent* modal_dialog_event() {
+    return modal_dialog_event_.get();
   }
 
   // IPC::Channel::Listener
@@ -328,7 +332,7 @@ class RenderView : public RenderWidget,
   // set to 'MSG_ROUTING_NONE' if the true ID is not yet known. In this case,
   // CompleteInit must be called later with the true ID.
   void Init(HWND parent,
-            HANDLE modal_dialog_event,
+            base::WaitableEvent* modal_dialog_event,  // takes ownership
             int32 opener_id,
             const WebPreferences& webkit_prefs,
             SharedRenderViewCounter* counter,
@@ -659,7 +663,7 @@ class RenderView : public RenderWidget,
   // Handle to an event that's set when the page is showing a modal dialog (or
   // equivalent constrained window).  The renderer and any plugin processes
   // check this to know if they should pump messages/tasks then.
-  ScopedHandle modal_dialog_event_;
+  scoped_ptr<base::WaitableEvent> modal_dialog_event_;
 
   // Document width when in print CSS media type. 0 otherwise.
   int printed_document_width_;