Introduce an API mirroring the gc extension

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 3955 matching lines @@
 
    private:
     Isolate* const isolate_;
 
     // Prevent copying of Scope objects.
     Scope(const Scope&);
     Scope& operator=(const Scope&);
   };
 
   /**
+   * Types of garbage collections that can be requested via
+   * RequestGarbageCollection.
+   */
+  enum GarbageCollectionType {
+    kFullGarbageCollection,
+    kMinorGarbageCollection
+  };
+
+  /**
    * Creates a new isolate.  Does not change the currently entered
    * isolate.
    *
    * When an isolate is no longer used its resources should be freed
    * by calling Dispose().  Using the delete operator is not allowed.
    */
   static Isolate* New();
 
   /**
    * Returns the entered isolate for the current thread or NULL in
@@ skipping 191 matching lines @@
    * Registered |callback| must not reenter interrupted Isolate.
    */
   void RequestInterrupt(InterruptCallback callback, void* data);
 
   /**
    * Clear interrupt request created by |RequestInterrupt|.
    * Can be called from another thread without acquiring a |Locker|.
    */
   void ClearInterrupt();
 
+  /**
+   * Request garbage collection in this Isolate. If |minor| is true, a
+   * minor garbage collection is performed.
+   */
+  void RequestGarbageCollection(GarbageCollectionType type);

[Michael Starzinger, 2014/01/13 10:13:24]

I don't like exposing this through the API at all. This should never be called
in production code. IIUC it is only used to replace the gc-extension for tests.

As discussed offline with Jochen: Using a "ForTesting" postfix in the name would
prevent that. I would strongly argue for renaming it in that way.

Also the comment needs to be adapted saying that this actually tanks performance
and only exists for testing purposes. I was thinking along the lines of ...

/**
 * Request garbage collection in this Isolate. If |minor| is true, a
 * minor garbage collection is performed.
 *
 * This should only be used for testing purposes and not to enforce a garbage
 * collection schedule. It has strong negative impact on the garbage collection
 * performance. Use IdleNotification() or LowMemoryNotification() instead to
 * influence the garbage collection schedule.
 */

(yes, at least four lines saying "don't use this")

+
  private:
   Isolate();
   Isolate(const Isolate&);
   ~Isolate();
   Isolate& operator=(const Isolate&);
   void* operator new(size_t size);
   void operator delete(void*, size_t);
 
   void SetObjectGroupId(internal::Object** object, UniqueId id);
   void SetReferenceFromGroup(UniqueId id, internal::Object** object);
@@ skipping 2231 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_