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..786a3515024efabe2c958df84cb5a39277dfe8c3 100755
--- a/runtime/include/dart_api.h
+++ b/runtime/include/dart_api.h
@@ -272,6 +272,75 @@ DART_EXPORT Dart_Handle Dart_NewWeakReferenceSet(Dart_Handle* keys,
                                                  Dart_Handle* values,
                                                  intptr_t num_values);
 
+// --- Garbage Collection Callbacks --
+
+/**
+ * Callbacks signal the beginning and end of a garbage collection.
+ *
+ * These signals are intended to be used by the embedder to manage the
+ * lifetime of native objects with a managed object peer.
+ */
+
+/**
+ * A callback invoked at the beginning of a garbage collection.
+ */
+typedef void (*Dart_GcPrologueCallback)();
+
+/**
+ * A callback invoked at the end of a garbage collection.
+ */
+typedef void (*Dart_GcEpilogueCallback)();
+
+/**
+ * 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_AddGcPrologueCallback(
+    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_RemoveGcPrologueCallback(
+    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_AddGcEpilogueCallback(
+    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_RemoveGcEpilogueCallback(
+    Dart_GcEpilogueCallback callback);
 
 // --- Initialization and Globals ---