Implement a garbage collection prologue and epilogue callback mechanism.

runtime/include/dart_api.h

Index: runtime/include/dart_api.h
diff --git a/runtime/include/dart_api.h b/runtime/include/dart_api.h
index 48b4a4718b2fd9a99b13f11fc5d30b86c7ede05a..3df6cbeb5fb1281d403448c4543c225845102480 100755
--- a/runtime/include/dart_api.h
+++ b/runtime/include/dart_api.h
@@ -272,6 +272,61 @@ DART_EXPORT Dart_Handle Dart_NewWeakReferenceSet(Dart_Handle* keys,
                                                  Dart_Handle* values,
                                                  intptr_t num_values);
 
+// --- Garbage Collection Callbacks --

[turnidge, 2012/03/07 00:25:16]

Could add general comment here (see other sections).

[cshapiro, 2012/03/07 03:06:10]

Done.

+
+typedef void (*Dart_GcPrologueCallback)();
+typedef void (*Dart_GcEpilogueCallback)();

[turnidge, 2012/03/07 00:25:16]

Comment these in a way similar to other function typedefs.

[cshapiro, 2012/03/07 03:06:10]

Done.

+
+/**
+ * Adds a garbage collection prologue callback.
+ *
+ * \param callback A function pointer to a prologue callback function.
+ *   This function must not have been previously added as a prologue
+ *   callback.
+ *
+ * \return Success if the callback was added.  Otherwise, returns an
+ *   error handle.
+ */
+DART_EXPORT Dart_Handle Dart_NewGcPrologueCallback(

[turnidge, 2012/03/07 00:25:16]

Consider s/New/add? 

[cshapiro, 2012/03/07 03:06:10]

I've make the switch.  These are now the only add and remove functions in the
API.  Let me know how it looks.  I can go either way.

+    Dart_GcPrologueCallback callback);
+
+/**
+ * Removes a garbage collection prologue callback.
+ *
+ * \param callback A function pointer to a prologue callback function.
+ *   This function must have been added as a prologue callback.
+ *
+ * \return Success if the callback was removed.  Otherwise, returns an
+ *   error handle.
+ */
+DART_EXPORT Dart_Handle Dart_DeleteGcPrologueCallback(

[turnidge, 2012/03/07 00:25:16]

s/Delete/Remove?

[cshapiro, 2012/03/07 03:06:10]

See above.

+    Dart_GcPrologueCallback callback);
+
+/**
+ * Adds a garbage collection epilogue callback.
+ *
+ * \param callback A function pointer to an epilogue callback
+ *   function.  This function must not have been previously added as
+ *   an epilogue callback.
+ *
+ * \return Success if the callback was added.  Otherwise, returns an
+ *   error handle.
+ */
+DART_EXPORT Dart_Handle Dart_NewGcEpilogueCallback(
+    Dart_GcEpilogueCallback callback);
+
+/**
+ * Removes a garbage collection epilogue callback.
+ *
+ * \param callback A function pointer to an epilogue callback
+ *   function.  This function must have been added as an epilogue
+ *   callback.
+ *
+ * \return Success if the callback was removed.  Otherwise, returns an
+ *   error handle.
+ */
+DART_EXPORT Dart_Handle Dart_DeleteGcEpilogueCallback(
+    Dart_GcEpilogueCallback callback);
 
 // --- Initialization and Globals ---