Implement a garbage collection prologue and epilogue callback mechanism.

runtime/vm/dart_api_impl.cc

Index: runtime/vm/dart_api_impl.cc
diff --git a/runtime/vm/dart_api_impl.cc b/runtime/vm/dart_api_impl.cc
index 048ee57d4f133bcb0d51319acf39d03b9c3eb074..97b2a2f5e535ebb42f4b6760182dba3c21b29254 100644
--- a/runtime/vm/dart_api_impl.cc
+++ b/runtime/vm/dart_api_impl.cc
@@ -490,6 +490,80 @@ DART_EXPORT Dart_Handle Dart_NewWeakReferenceSet(Dart_Handle* keys,
   return Api::Success();
 }
 
+
+// --- Garbage Collection Callbacks --
+
+
+DART_EXPORT Dart_Handle Dart_NewGcPrologueCallback(
+    Dart_GcPrologueCallback callback) {
+  Isolate* isolate = Isolate::Current();
+  CHECK_ISOLATE(isolate);
+  ApiState* state = isolate->api_state();

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

You could permissibly move these callback lists to the isolate itself.  Doesn't
matter much, but it is where I would have probably put them.

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

Done.  I will move the weak references in a follow-up change.

+  ASSERT(state != NULL);
+  GcPrologueCallbacks& callbacks = state->gc_prologue_callbacks();
+  if (callbacks.Contains(callback)) {
+    return Api::NewError(
+        "%s permits only one instance of 'callback' to be present in the "
+        "prologue callback list.",
+        CURRENT_FUNC);
+  }
+  state->gc_prologue_callbacks().Add(callback);
+  return Api::Success();
+}
+
+
+DART_EXPORT Dart_Handle Dart_DeleteGcPrologueCallback(
+    Dart_GcPrologueCallback callback) {
+  Isolate* isolate = Isolate::Current();
+  CHECK_ISOLATE(isolate);
+  ApiState* state = isolate->api_state();
+  ASSERT(state != NULL);
+  GcPrologueCallbacks& callbacks = state->gc_prologue_callbacks();
+  if (!callbacks.Contains(callback)) {
+    return Api::NewError(
+        "%s expects 'callback' to be present in the prologue callback list.",
+        CURRENT_FUNC);
+  }
+  state->gc_prologue_callbacks().Remove(callback);
+  return Api::Success();
+}
+
+
+DART_EXPORT Dart_Handle Dart_NewGcEpilogueCallback(
+    Dart_GcEpilogueCallback callback) {
+  Isolate* isolate = Isolate::Current();
+  CHECK_ISOLATE(isolate);
+  ApiState* state = isolate->api_state();
+  ASSERT(state != NULL);
+  GcEpilogueCallbacks& callbacks = state->gc_epilogue_callbacks();
+  if (callbacks.Contains(callback)) {
+    return Api::NewError(
+        "%s permits only one instance of 'callback' to be present in the "
+        "epilogue callback list.",
+        CURRENT_FUNC);
+  }
+  callbacks.Add(callback);
+  return Api::Success();
+}
+
+
+DART_EXPORT Dart_Handle Dart_DeleteGcEpilogueCallback(
+    Dart_GcEpilogueCallback callback) {
+  Isolate* isolate = Isolate::Current();
+  CHECK_ISOLATE(isolate);
+  ApiState* state = isolate->api_state();
+  ASSERT(state != NULL);
+  GcEpilogueCallbacks& callbacks = state->gc_epilogue_callbacks();
+  if (!callbacks.Contains(callback)) {
+    return Api::NewError(
+        "%s expects 'callback' to be present in the epilogue callback list.",
+        CURRENT_FUNC);
+  }
+  callbacks.Remove(callback);
+  return Api::Success();
+}
+
+
 // --- Initialization and Globals ---