Per-isolate v8::Locker and v8::Unlocker

include/v8.h

 // Copyright 2007-2009 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 3295 matching lines @@
 
  private:
   friend class Value;
   friend class Script;
   friend class Object;
   friend class Function;
 };
 
 
 /**
  * Multiple threads in V8 are allowed, but only one thread at a time

[Vitaly Repeshko, 2011/04/15 00:29:39]

This comment needs to be updated to make it clear that using lockers is actually
required for multi-threaded access and we also need some examples with isolates.

  * is allowed to use any given V8 isolate. See Isolate class
  * comments. The definition of 'using V8 isolate' includes
  * accessing handles or holding onto object pointers obtained
  * from V8 handles while in the particular V8 isolate.  It is up
  * to the user of V8 to ensure (perhaps with locking) that this
  * constraint is not violated.
  *
  * More then one thread and multiple V8 isolates can be used
  * without any locking if each isolate is created and accessed
  * by a single thread only. For example, one thread can use
@@ skipping 60 matching lines @@
  *     // V8 locked again (2 levels).
  *   }
  *   // V8 still locked (1 level).
  * }
  * // V8 Now no longer locked.
  * \endcode
  */
 class V8EXPORT Unlocker {
  public:
   Unlocker();
+  explicit Unlocker(Isolate* isolate);
   ~Unlocker();
+ private:
+  void Init();
+  internal::Isolate* isolate_;
 };
 
 
 class V8EXPORT Locker {
  public:
   Locker();
+  explicit Locker(Isolate* isolate);

[Dmitry Titov, 2011/04/13 00:45:10]

Consider: If it was:
explicit Locker(Isolate* isolate = NULL);
then there would be only 1 ctor, 1 IsLocked and no Init() method in this
API-specifying file... Same for Unlocker.
See TerminateExecution() in this file for precedent.

[Dmitry Lomov, 2011/04/13 00:54:12]

Yes, this sounds reasonable to me
On 2011/04/13 00:45:10, Dmitry Titov wrote:

[Dmitry Lomov, 2011/04/19 01:50:47]

Done.

   ~Locker();
 
   /**
    * Start preemption.
    *
    * When preemption is started, a timer is fired every n milli seconds
    * that will switch between multiple threads that are in contention
    * for the V8 lock.
    */
   static void StartPreemption(int every_n_ms);
 
   /**
    * Stop preemption.
    */
   static void StopPreemption();
 
   /**
-   * Returns whether or not the locker is locked by the current thread.
+   * Returns whether or not the locker for current isolate is locked by
+   * the current thread.
    */
   static bool IsLocked();
 
   /**
+   * Returns whether or not the locker for a given isolate is locked by the current thread.

[Vitaly Repeshko, 2011/04/15 00:29:39]

nit: Long line.

[Dmitry Lomov, 2011/04/19 01:50:47]

Done.

+   */
+  static bool IsLocked(Isolate * isolate);

[Vitaly Repeshko, 2011/04/15 00:29:39]

nit: Drop space before '*'.

[Dmitry Lomov, 2011/04/19 01:50:47]

Done.

+
+  /**
    * Returns whether v8::Locker is being used by this V8 instance.
    */
   static bool IsActive() { return active_; }
 
  private:
+  void Init();
+
   bool has_lock_;
   bool top_level_;
+  internal::Isolate* isolate_;
 
   static bool active_;
 
   // Disallow copying and assigning.
   Locker(const Locker&);
   void operator=(const Locker&);
 };
 
 
 /**
@@ skipping 548 matching lines @@
 
 
 }  // namespace v8
 
 
 #undef V8EXPORT
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_