Implement SharedArrayBuffer

include/v8.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 1902 matching lines @@
    * This is an experimental feature.
    */
   bool IsFloat64Array() const;
 
   /**
    * Returns true if this value is a DataView.
    * This is an experimental feature.
    */
   bool IsDataView() const;
 
+  /**
+   * Returns true if this value is a SharedArrayBuffer.
+   * This is an experimental feature.
+   */
+  bool IsSharedArrayBuffer() const;
+
+
   V8_WARN_UNUSED_RESULT MaybeLocal<Boolean> ToBoolean(
       Local<Context> context) const;
   V8_WARN_UNUSED_RESULT MaybeLocal<Number> ToNumber(
       Local<Context> context) const;
   V8_WARN_UNUSED_RESULT MaybeLocal<String> ToString(
       Local<Context> context) const;
   V8_WARN_UNUSED_RESULT MaybeLocal<String> ToDetailString(
       Local<Context> context) const;
   V8_WARN_UNUSED_RESULT MaybeLocal<Object> ToObject(
       Local<Context> context) const;
@@ skipping 1404 matching lines @@
    * Create a new ArrayBuffer over an existing memory block.
    * The created array buffer is by default immediately in externalized state.
    * The memory block will not be reclaimed when a created ArrayBuffer
    * is garbage-collected.
    */
   static Local<ArrayBuffer> New(
       Isolate* isolate, void* data, size_t byte_length,
       ArrayBufferCreationMode mode = ArrayBufferCreationMode::kExternalized);
 
   /**
-   * Returns true if ArrayBuffer is extrenalized, that is, does not
+   * Returns true if ArrayBuffer is externalized, that is, does not
    * own its memory block.
    */
   bool IsExternal() const;
 
   /**
    * Returns true if this ArrayBuffer may be neutered.
    */
   bool IsNeuterable() const;
 
   /**
@@ skipping 266 matching lines @@
                              size_t byte_offset, size_t length);
   V8_INLINE static DataView* Cast(Value* obj);
 
  private:
   DataView();
   static void CheckCast(Value* obj);
 };
 
 
 /**
+ * TODO(binji): document
+ * An instance of the built-in SharedArrayBuffer constructor (ES6 draft
+ * 15.13.5).
+ * This API is experimental and may change significantly.
+ */
+class V8_EXPORT SharedArrayBuffer : public Object {
+ public:
+  /**
+   * The contents of an |SharedArrayBuffer|. Externalization of
+   * |SharedArrayBuffer| returns an instance of this class, populated, with a
+   * pointer to data and byte length.
+   *
+   * The Data pointer of SharedArrayBuffer::Contents is always allocated with
+   * |ArrayBuffer::Allocator::Allocate| by the allocator specified in
+   * v8::Isolate::CreateParams::shared_array_buffer_allocator.
+   *
+   * This API is experimental and may change significantly.
+   */
+  class V8_EXPORT Contents {  // NOLINT
+   public:
+    Contents() : data_(NULL), byte_length_(0) {}
+
+    void* Data() const { return data_; }
+    size_t ByteLength() const { return byte_length_; }
+
+   private:
+    void* data_;
+    size_t byte_length_;
+
+    friend class SharedArrayBuffer;
+  };
+
+
+  /**
+   * Data length in bytes.
+   */
+  size_t ByteLength() const;
+
+  /**
+   * Create a new SharedArrayBuffer. Allocate |byte_length| bytes.
+   * Allocated memory will be owned by a created SharedArrayBuffer and
+   * will be deallocated when it is garbage-collected,
+   * unless the object is externalized.
+   */
+  static Local<SharedArrayBuffer> New(Isolate* isolate, size_t byte_length);
+
+  /**
+   * Create a new SharedArrayBuffer over an existing memory block.  The created
+   * array buffer is immediately in externalized state unless otherwise
+   * specified. The memory block will not be reclaimed when a created
+   * SharedArrayBuffer is garbage-collected.
+   */
+  static Local<SharedArrayBuffer> New(
+      Isolate* isolate, void* data, size_t byte_length,
+      ArrayBufferCreationMode mode = ArrayBufferCreationMode::kExternalized);
+
+  /**
+   * Returns true if SharedArrayBuffer is externalized, that is, does not
+   * own its memory block.
+   */
+  bool IsExternal() const;
+
+  /**
+   * Make this SharedArrayBuffer external. The pointer to underlying memory
+   * block and byte length are returned as |Contents| structure. After
+   * SharedArrayBuffer had been etxrenalized, it does no longer owns the memory
+   * block. The caller should take steps to free memory when it is no longer
+   * needed.
+   *
+   * The memory block is guaranteed to be allocated with |Allocator::Allocate|
+   * by the allocator specified in
+   * v8::Isolate::CreateParams::shared_array_buffer_allocator.
+   *
+   */
+  Contents Externalize();
+
+  /**
+   * Get a pointer to the ArrayBuffer's underlying memory block without
+   * externalizing it. If the ArrayBuffer is not externalized, this pointer
+   * will become invalid as soon as the ArrayBuffer became garbage collected.
+   *
+   * The embedder should make sure to hold a strong reference to the
+   * ArrayBuffer while accessing this pointer.
+   *
+   * The memory block is guaranteed to be allocated with |Allocator::Allocate|
+   * by the allocator specified in
+   * v8::Isolate::CreateParams::shared_array_buffer_allocator.
+   */
+  Contents GetContents();
+
+  V8_INLINE static SharedArrayBuffer* Cast(Value* obj);
+
+  static const int kInternalFieldCount = V8_ARRAY_BUFFER_INTERNAL_FIELD_COUNT;
+
+ private:
+  SharedArrayBuffer();
+  static void CheckCast(Value* obj);
+};
+
+
+/**
  * An instance of the built-in Date constructor (ECMA-262, 15.9).
  */
 class V8_EXPORT Date : public Object {
  public:
   static V8_DEPRECATE_SOON("Use maybe version.",
                            Local<Value> New(Isolate* isolate, double time));
   static V8_WARN_UNUSED_RESULT MaybeLocal<Value> New(Local<Context> context,
                                                      double time);
 
   /**
@@ skipping 1355 matching lines @@
    * Initial configuration parameters for a new Isolate.
    */
   struct CreateParams {
     CreateParams()
         : entry_hook(NULL),
           code_event_handler(NULL),
           snapshot_blob(NULL),
           counter_lookup_callback(NULL),
           create_histogram_callback(NULL),
           add_histogram_sample_callback(NULL),
-          array_buffer_allocator(NULL) {}
+          array_buffer_allocator(NULL),
+          shared_array_buffer_allocator(NULL) {}
 
     /**
      * The optional entry_hook allows the host application to provide the
      * address of a function that's invoked on entry to every V8-generated
      * function.  Note that entry_hook is invoked at the very start of each
      * generated function. Furthermore, if an  entry_hook is given, V8 will
      * always run without a context snapshot.
      */
     FunctionEntryHook entry_hook;
 
@@ skipping 27 matching lines @@
      * function.
      */
     CreateHistogramCallback create_histogram_callback;
     AddHistogramSampleCallback add_histogram_sample_callback;
 
     /**
      * The ArrayBuffer::Allocator to use for allocating and freeing the backing
      * store of ArrayBuffers.
      */
     ArrayBuffer::Allocator* array_buffer_allocator;
+
+    /**
+     * The ArrayBuffer::Allocator to use for allocating and freeing the backing
+     * store of SharedArrayBuffers.
+     */
+    ArrayBuffer::Allocator* shared_array_buffer_allocator;

[jochen (gone - plz use gerrit), 2015/05/22 08:37:47]

why do we need a separate allocator?

[binji, 2015/05/22 09:27:34]

We probably don't. Removed.

   };
 
 
   /**
    * Stack-allocated class which sets the isolate for all operations
    * executed within a local scope.
    */
   class V8_EXPORT Scope {
    public:
     explicit Scope(Isolate* isolate) : isolate_(isolate) {
@@ skipping 1672 matching lines @@
   static const int kHeapObjectMapOffset = 0;
   static const int kMapInstanceTypeAndBitFieldOffset =
       1 * kApiPointerSize + kApiIntSize;
   static const int kStringResourceOffset = 3 * kApiPointerSize;
 
   static const int kOddballKindOffset = 3 * kApiPointerSize;
   static const int kForeignAddressOffset = kApiPointerSize;
   static const int kJSObjectHeaderSize = 3 * kApiPointerSize;
   static const int kFixedArrayHeaderSize = 2 * kApiPointerSize;
   static const int kContextHeaderSize = 2 * kApiPointerSize;
-  static const int kContextEmbedderDataIndex = 78;
+  static const int kContextEmbedderDataIndex = 79;
   static const int kFullStringRepresentationMask = 0x07;
   static const int kStringEncodingMask = 0x4;
   static const int kExternalTwoByteRepresentationTag = 0x02;
   static const int kExternalOneByteRepresentationTag = 0x06;
 
   static const int kIsolateEmbedderDataOffset = 0 * kApiPointerSize;
   static const int kAmountOfExternalAllocatedMemoryOffset =
       4 * kApiPointerSize;
   static const int kAmountOfExternalAllocatedMemoryAtLastGlobalGCOffset =
       kAmountOfExternalAllocatedMemoryOffset + kApiInt64Size;
@@ skipping 1050 matching lines @@
 
 
 DataView* DataView::Cast(v8::Value* value) {
 #ifdef V8_ENABLE_CHECKS
   CheckCast(value);
 #endif
   return static_cast<DataView*>(value);
 }
 
 
+SharedArrayBuffer* SharedArrayBuffer::Cast(v8::Value* value) {
+#ifdef V8_ENABLE_CHECKS
+  CheckCast(value);
+#endif
+  return static_cast<SharedArrayBuffer*>(value);
+}
+
+
 Function* Function::Cast(v8::Value* value) {
 #ifdef V8_ENABLE_CHECKS
   CheckCast(value);
 #endif
   return static_cast<Function*>(value);
 }
 
 
 External* External::Cast(v8::Value* value) {
 #ifdef V8_ENABLE_CHECKS
@@ skipping 285 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // V8_H_