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 233 matching lines @@
     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.  However, prologue weak persistent handlers are only weak
+ * when the a garbage collector chooses to invoke the prologue and
+ * epilogue callbacks.

[siva, 2012/03/09 21:48:41]

I like the description you used in the gcl upload comments.

(These handles strongly reference their referent except in those garbage
collection cycles where the prolog/epilog callbacks are called).

[cshapiro, 2012/03/13 23:06:43]

I replaced the comment above with the description from the check-in.  Let me
know if that is okay.

+ *

[siva, 2012/03/09 21:48:41]

Documentation for parameters 'object, peer, callback'.
Also needs to be done for Dart_NewWeakPersistentHandle.

[cshapiro, 2012/03/13 23:06:43]

Done.

+ * 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.
+ */
+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
@@ skipping 1708 matching lines @@
 
 // --- 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_