heap: allow allocation in gc prologue/epilogue

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4109 matching lines @@
 
   typedef void (*GCPrologueCallback)(Isolate* isolate,
                                      GCType type,
                                      GCCallbackFlags flags);
   typedef void (*GCEpilogueCallback)(Isolate* isolate,
                                      GCType type,
                                      GCCallbackFlags flags);
 
   /**
    * Enables the host application to receive a notification before a
-   * garbage collection.  Allocations are not allowed in the
-   * callback function, you therefore cannot manipulate objects (set
-   * or delete properties for example) since it is possible such
-   * operations will result in the allocation of objects. It is possible
-   * to specify the GCType filter for your callback. But it is not possible to
-   * register the same callback function two times with different
-   * GCType filters.
+   * garbage collection. Allocations are allowed in the callback function,
+   * but the callback is not re-entrant: if the allocation inside it will
+   * trigger the garbage collection, the callback won't be called again.
+   * It is possible to specify the GCType filter for your callback. But it is
+   * not possible to register the same callback function two times with
+   * different GCType filters.
    */
   void AddGCPrologueCallback(
       GCPrologueCallback callback, GCType gc_type_filter = kGCTypeAll);
 
   /**
    * This function removes callback which was installed by
    * AddGCPrologueCallback function.
    */
   void RemoveGCPrologueCallback(GCPrologueCallback callback);
 
   /**
    * Enables the host application to receive a notification after a
-   * garbage collection.  Allocations are not allowed in the
-   * callback function, you therefore cannot manipulate objects (set
-   * or delete properties for example) since it is possible such
-   * operations will result in the allocation of objects. It is possible
-   * to specify the GCType filter for your callback. But it is not possible to
-   * register the same callback function two times with different
-   * GCType filters.
+   * garbage collection. Allocations are allowed in the callback function,
+   * but the callback is not re-entrant: if the allocation inside it will
+   * trigger the garbage collection, the callback won't be called again.
+   * It is possible to specify the GCType filter for your callback. But it is
+   * not possible to register the same callback function two times with
+   * different GCType filters.
    */
   void AddGCEpilogueCallback(
       GCEpilogueCallback callback, GCType gc_type_filter = kGCTypeAll);
 
   /**
    * This function removes callback which was installed by
    * AddGCEpilogueCallback function.
    */
   void RemoveGCEpilogueCallback(GCEpilogueCallback callback);
 
@@ skipping 2289 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_