Reland r17907 - Make it possible to add more than one piece of embedder data to isolates"

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index 13ec7470dbf29b553a2d99d1e3333cb4bec5bc23..df82352703664bd2019d1fb3727df7d638af9cbc 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -4054,17 +4054,37 @@ class V8_EXPORT Isolate {
   void Dispose();
 
   /**
-   * Associate embedder-specific data with the isolate
+   * Associate embedder-specific data with the isolate. This legacy method
+   * puts the data in the 0th slot. It will be deprecated soon.
    */
   V8_INLINE void SetData(void* data);
 
   /**
-   * Retrieve embedder-specific data from the isolate.
+   * Associate embedder-specific data with the isolate. |slot| has to be
+   * between 0 and GetNumberOfDataSlots() - 1.
+   */
+  V8_INLINE void SetData(uint32_t slot, void* data);
+
+  /**
+   * Retrieve embedder-specific data from the isolate. This legacy method
+   * retrieves the data from slot 0. It will be deprecated soon.
    * Returns NULL if SetData has never been called.
    */
   V8_INLINE void* GetData();
 
   /**
+   * Retrieve embedder-specific data from the isolate.
+   * Returns NULL if SetData has never been called for the given |slot|.
+   */
+  V8_INLINE void* GetData(uint32_t slot);
+
+  /**
+   * Returns the maximum number of available embedder data slots. Valid slots
+   * are in the range of 0 - GetNumberOfDataSlots() - 1.
+   */
+  V8_INLINE static uint32_t GetNumberOfDataSlots();
+
+  /**
    * Get statistics about the heap memory usage.
    */
   void GetHeapStatistics(HeapStatistics* heap_statistics);
@@ -5448,8 +5468,8 @@ class Internals {
   static const int kExternalTwoByteRepresentationTag = 0x02;
   static const int kExternalAsciiRepresentationTag = 0x06;
 
-  static const int kIsolateEmbedderDataOffset = 1 * kApiPointerSize;
-  static const int kIsolateRootsOffset = 3 * kApiPointerSize;
+  static const int kIsolateEmbedderDataOffset = 0 * kApiPointerSize;
+  static const int kIsolateRootsOffset = 5 * kApiPointerSize;
   static const int kUndefinedValueRootIndex = 5;
   static const int kNullValueRootIndex = 7;
   static const int kTrueValueRootIndex = 8;
@@ -5473,6 +5493,8 @@ class Internals {
   static const int kUndefinedOddballKind = 5;
   static const int kNullOddballKind = 3;
 
+  static const uint32_t kNumIsolateDataSlots = 4;
+
   V8_EXPORT static void CheckInitializedImpl(v8::Isolate* isolate);
   V8_INLINE static void CheckInitialized(v8::Isolate* isolate) {
 #ifdef V8_ENABLE_CHECKS
@@ -5536,15 +5558,17 @@ class Internals {
     *addr = static_cast<uint8_t>((*addr & ~kNodeStateMask) | value);
   }
 
-  V8_INLINE static void SetEmbedderData(v8::Isolate* isolate, void* data) {
-    uint8_t* addr = reinterpret_cast<uint8_t*>(isolate) +
-        kIsolateEmbedderDataOffset;
+  V8_INLINE static void SetEmbedderData(v8::Isolate *isolate,
+                                        uint32_t slot,
+                                        void *data) {
+    uint8_t *addr = reinterpret_cast<uint8_t *>(isolate) +
+                    kIsolateEmbedderDataOffset + slot * kApiPointerSize;
     *reinterpret_cast<void**>(addr) = data;
   }
 
-  V8_INLINE static void* GetEmbedderData(v8::Isolate* isolate) {
+  V8_INLINE static void* GetEmbedderData(v8::Isolate* isolate, uint32_t slot) {
     uint8_t* addr = reinterpret_cast<uint8_t*>(isolate) +
-        kIsolateEmbedderDataOffset;
+        kIsolateEmbedderDataOffset + slot * kApiPointerSize;
     return *reinterpret_cast<void**>(addr);
   }
 
@@ -6470,13 +6494,31 @@ Handle<Boolean> False(Isolate* isolate) {
 
 void Isolate::SetData(void* data) {
   typedef internal::Internals I;
-  I::SetEmbedderData(this, data);
+  I::SetEmbedderData(this, 0, data);
 }
 
 
 void* Isolate::GetData() {
   typedef internal::Internals I;
-  return I::GetEmbedderData(this);
+  return I::GetEmbedderData(this, 0);
+}
+
+
+void Isolate::SetData(uint32_t slot, void* data) {
+  typedef internal::Internals I;
+  I::SetEmbedderData(this, slot, data);
+}
+
+
+void* Isolate::GetData(uint32_t slot) {
+  typedef internal::Internals I;
+  return I::GetEmbedderData(this, slot);
+}
+
+
+uint32_t Isolate::GetNumberOfDataSlots() {
+  typedef internal::Internals I;
+  return I::kNumIsolateDataSlots;
 }