Implement prologue weak persistent handles.

runtime/include/dart_api.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef INCLUDE_DART_API_H_
 #define INCLUDE_DART_API_H_
 
 /** \mainpage Dart Embedding API Reference
  *
  * Dart is a class-based programming language for creating structured
@@ skipping 220 matching lines @@
  */
 DART_EXPORT void Dart_DeletePersistentHandle(Dart_Handle object);
 
 /**
  * Allocates a weak persistent handle for an object.
  *
  * This handle has the lifetime of the current isolate unless it is
  * explicitly deallocated by calling Dart_DeletePersistentHandle.
  *
  * Requires there to be a current isolate.
+ *
+ * \param object An object.
+ * \param peer A pointer to a native object or NULL.  This value is
+ *   provided to callback when it is invoked.
+ * \param callback A function pointer that will be invoked sometime
+ *   after the object is garbage collected.
+ *
+ * \return Success if the weak persistent handle was
+ *   created. Otherwise, returns an error.
  */
 DART_EXPORT Dart_Handle Dart_NewWeakPersistentHandle(
     Dart_Handle object,
     void* peer,
     Dart_WeakPersistentHandleFinalizer callback);
 
 /**
  * Is this object a weak persistent handle?
  *
  * Requires there to be a current isolate.
  */
 DART_EXPORT bool Dart_IsWeakPersistentHandle(Dart_Handle object);
 
+/**
+ * Allocates a prologue weak persistent handle for an object.
+ *
+ * Prologue weak persistent handles are similar to weak persistent
+ * handles but exhibit different behavior during garbage collections
+ * that invoke the prologue and epilogue callbacks.  While weak
+ * persistent handles always weakly reference their referents,
+ * prologue weak persistent handles weakly reference their referents
+ * only during a garbage collection that invokes the prologue and
+ * epilogue callbacks.  During all other garbage collections, prologue
+ * weak persistent handles strongly reference their referents.
+ *
+ * This handle has the lifetime of the current isolate unless it is
+ * explicitly deallocated by calling Dart_DeletePersistentHandle.
+ *
+ * Requires there to be a current isolate.
+ *
+ * \param object An object.
+ * \param peer A pointer to a native object or NULL.  This value is
+ *   provided to callback when it is invoked.
+ * \param callback A function pointer that will be invoked sometime
+ *   after the object is garbage collected.
+ *
+ * \return Success if the prologue weak persistent handle was created.
+ *   Otherwise, returns an error.
+ */
+DART_EXPORT Dart_Handle Dart_NewPrologueWeakPersistentHandle(
+    Dart_Handle object,
+    void* peer,
+    Dart_WeakPersistentHandleFinalizer callback);
+
+/**
+ * Is this object a prologue weak persistent handle?
+ *
+ * Requires there to be a current isolate.
+ */
+DART_EXPORT bool Dart_IsPrologueWeakPersistentHandle(Dart_Handle object);
 
 /**
  * Constructs a set of weak references from the Cartesian product of
  * the objects in the key set and the objects in values set.
  *
  * \param keys A set of object references.  These references will be
  *   considered weak by the garbage collector.
  * \param num_keys the number of objects in the keys set.
  * \param values A set of object references.  These references will be
  *   considered weak by garbage collector unless any object reference
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 // --- Profiling support ----
 
 // External pprof support for gathering and dumping symbolic
 // information that can be used for better profile reports for
 // dynamically generated code.
 DART_EXPORT void Dart_InitPprofSupport();
 DART_EXPORT void Dart_GetPprofSymbolInfo(void** buffer, int* buffer_size);
 
 #endif  // INCLUDE_DART_API_H_