src/api.h

   1 // Copyright 2012 the V8 project authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef V8_API_H_
   6 #define V8_API_H_
   7
   8 #include "src/v8.h"
   9
  10 #include "include/v8-testing.h"
  11 #include "src/contexts.h"
  12 #include "src/factory.h"
  13 #include "src/isolate.h"
  14 #include "src/list-inl.h"
  15
  16 namespace v8 {
  17
  18 // Constants used in the implementation of the API.  The most natural thing
  19 // would usually be to place these with the classes that use them, but
  20 // we want to keep them out of v8.h because it is an externally
  21 // visible file.
  22 class Consts {
  23  public:
  24   enum TemplateType {
  25     FUNCTION_TEMPLATE = 0,
  26     OBJECT_TEMPLATE = 1
  27   };
  28 };
  29
  30
  31 // Utilities for working with neander-objects, primitive
  32 // env-independent JSObjects used by the api.
  33 class NeanderObject {
  34  public:
  35   explicit NeanderObject(v8::internal::Isolate* isolate, int size);
  36   explicit inline NeanderObject(v8::internal::Handle<v8::internal::Object> obj);
  37   explicit inline NeanderObject(v8::internal::Object* obj);
  38   inline v8::internal::Object* get(int index);
  39   inline void set(int index, v8::internal::Object* value);
  40   inline v8::internal::Handle<v8::internal::JSObject> value() { return value_; }
  41   int size();
  42  private:
  43   v8::internal::Handle<v8::internal::JSObject> value_;
  44 };
  45
  46
  47 // Utilities for working with neander-arrays, a simple extensible
  48 // array abstraction built on neander-objects.
  49 class NeanderArray {
  50  public:
  51   explicit NeanderArray(v8::internal::Isolate* isolate);
  52   explicit inline NeanderArray(v8::internal::Handle<v8::internal::Object> obj);
  53   inline v8::internal::Handle<v8::internal::JSObject> value() {
  54     return obj_.value();
  55   }
  56
  57   void add(internal::Isolate* isolate,
  58            v8::internal::Handle<v8::internal::Object> value);
  59
  60   int length();
  61
  62   v8::internal::Object* get(int index);
  63   // Change the value at an index to undefined value. If the index is
  64   // out of bounds, the request is ignored. Returns the old value.
  65   void set(int index, v8::internal::Object* value);
  66  private:
  67   NeanderObject obj_;
  68 };
  69
  70
  71 NeanderObject::NeanderObject(v8::internal::Handle<v8::internal::Object> obj)
  72     : value_(v8::internal::Handle<v8::internal::JSObject>::cast(obj)) { }
  73
  74
  75 NeanderObject::NeanderObject(v8::internal::Object* obj)
  76     : value_(v8::internal::Handle<v8::internal::JSObject>(
  77         v8::internal::JSObject::cast(obj))) { }
  78
  79
  80 NeanderArray::NeanderArray(v8::internal::Handle<v8::internal::Object> obj)
  81     : obj_(obj) { }
  82
  83
  84 v8::internal::Object* NeanderObject::get(int offset) {
  85   DCHECK(value()->HasFastObjectElements());
  86   return v8::internal::FixedArray::cast(value()->elements())->get(offset);
  87 }
  88
  89
  90 void NeanderObject::set(int offset, v8::internal::Object* value) {
  91   DCHECK(value_->HasFastObjectElements());
  92   v8::internal::FixedArray::cast(value_->elements())->set(offset, value);
  93 }
  94
  95
  96 template <typename T> inline T ToCData(v8::internal::Object* obj) {
  97   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
  98   return reinterpret_cast<T>(
  99       reinterpret_cast<intptr_t>(
 100           v8::internal::Foreign::cast(obj)->foreign_address()));
 101 }
 102
 103
 104 template <typename T>
 105 inline v8::internal::Handle<v8::internal::Object> FromCData(
 106     v8::internal::Isolate* isolate, T obj) {
 107   STATIC_ASSERT(sizeof(T) == sizeof(v8::internal::Address));
 108   return isolate->factory()->NewForeign(
 109       reinterpret_cast<v8::internal::Address>(reinterpret_cast<intptr_t>(obj)));
 110 }
 111
 112
 113 class ApiFunction {
 114  public:
 115   explicit ApiFunction(v8::internal::Address addr) : addr_(addr) { }
 116   v8::internal::Address address() { return addr_; }
 117  private:
 118   v8::internal::Address addr_;
 119 };
 120
 121
 122
 123 class RegisteredExtension {
 124  public:
 125   explicit RegisteredExtension(Extension* extension);
 126   static void Register(RegisteredExtension* that);
 127   static void UnregisterAll();
 128   Extension* extension() { return extension_; }
 129   RegisteredExtension* next() { return next_; }
 130   static RegisteredExtension* first_extension() { return first_extension_; }
 131  private:
 132   Extension* extension_;
 133   RegisteredExtension* next_;
 134   static RegisteredExtension* first_extension_;
 135 };
 136
 137
 138 #define OPEN_HANDLE_LIST(V)                  \
 139   V(Template, TemplateInfo)                  \
 140   V(FunctionTemplate, FunctionTemplateInfo)  \
 141   V(ObjectTemplate, ObjectTemplateInfo)      \
 142   V(Signature, FunctionTemplateInfo)         \
 143   V(AccessorSignature, FunctionTemplateInfo) \
 144   V(TypeSwitch, TypeSwitchInfo)              \
 145   V(Data, Object)                            \
 146   V(RegExp, JSRegExp)                        \
 147   V(Object, JSObject)                        \
 148   V(Array, JSArray)                          \
 149   V(ArrayBuffer, JSArrayBuffer)              \
 150   V(ArrayBufferView, JSArrayBufferView)      \
 151   V(TypedArray, JSTypedArray)                \
 152   V(Uint8Array, JSTypedArray)                \
 153   V(Uint8ClampedArray, JSTypedArray)         \
 154   V(Int8Array, JSTypedArray)                 \
 155   V(Uint16Array, JSTypedArray)               \
 156   V(Int16Array, JSTypedArray)                \
 157   V(Uint32Array, JSTypedArray)               \
 158   V(Int32Array, JSTypedArray)                \
 159   V(Float32Array, JSTypedArray)              \
 160   V(Float64Array, JSTypedArray)              \
 161   V(DataView, JSDataView)                    \
 162   V(SharedArrayBuffer, JSArrayBuffer)        \
 163   V(Name, Name)                              \
 164   V(String, String)                          \
 165   V(Symbol, Symbol)                          \
 166   V(Script, JSFunction)                      \
 167   V(UnboundScript, SharedFunctionInfo)       \
 168   V(Function, JSFunction)                    \
 169   V(Message, JSMessageObject)                \
 170   V(Context, Context)                        \
 171   V(External, Object)                        \
 172   V(StackTrace, JSArray)                     \
 173   V(StackFrame, JSObject)                    \
 174   V(NativeWeakMap, JSWeakMap)
 175
 176 class Utils {
 177  public:
 178   static inline bool ApiCheck(bool condition,
 179                               const char* location,
 180                               const char* message) {
 181     if (!condition) Utils::ReportApiFailure(location, message);
 182     return condition;
 183   }
 184
 185   static Local<FunctionTemplate> ToFunctionTemplate(NeanderObject obj);
 186   static Local<ObjectTemplate> ToObjectTemplate(NeanderObject obj);
 187
 188   static inline Local<Context> ToLocal(
 189       v8::internal::Handle<v8::internal::Context> obj);
 190   static inline Local<Value> ToLocal(
 191       v8::internal::Handle<v8::internal::Object> obj);
 192   static inline Local<Function> ToLocal(
 193       v8::internal::Handle<v8::internal::JSFunction> obj);
 194   static inline Local<Name> ToLocal(
 195       v8::internal::Handle<v8::internal::Name> obj);
 196   static inline Local<String> ToLocal(
 197       v8::internal::Handle<v8::internal::String> obj);
 198   static inline Local<Symbol> ToLocal(
 199       v8::internal::Handle<v8::internal::Symbol> obj);
 200   static inline Local<RegExp> ToLocal(
 201       v8::internal::Handle<v8::internal::JSRegExp> obj);
 202   static inline Local<Object> ToLocal(
 203       v8::internal::Handle<v8::internal::JSObject> obj);
 204   static inline Local<Array> ToLocal(
 205       v8::internal::Handle<v8::internal::JSArray> obj);
 206   static inline Local<ArrayBuffer> ToLocal(
 207       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 208   static inline Local<ArrayBufferView> ToLocal(
 209       v8::internal::Handle<v8::internal::JSArrayBufferView> obj);
 210   static inline Local<DataView> ToLocal(
 211       v8::internal::Handle<v8::internal::JSDataView> obj);
 212
 213   static inline Local<TypedArray> ToLocal(
 214       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 215   static inline Local<Uint8Array> ToLocalUint8Array(
 216       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 217   static inline Local<Uint8ClampedArray> ToLocalUint8ClampedArray(
 218       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 219   static inline Local<Int8Array> ToLocalInt8Array(
 220       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 221   static inline Local<Uint16Array> ToLocalUint16Array(
 222       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 223   static inline Local<Int16Array> ToLocalInt16Array(
 224       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 225   static inline Local<Uint32Array> ToLocalUint32Array(
 226       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 227   static inline Local<Int32Array> ToLocalInt32Array(
 228       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 229   static inline Local<Float32Array> ToLocalFloat32Array(
 230       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 231   static inline Local<Float64Array> ToLocalFloat64Array(
 232       v8::internal::Handle<v8::internal::JSTypedArray> obj);
 233
 234   static inline Local<SharedArrayBuffer> ToLocalShared(
 235       v8::internal::Handle<v8::internal::JSArrayBuffer> obj);
 236
 237   static inline Local<Message> MessageToLocal(
 238       v8::internal::Handle<v8::internal::Object> obj);
 239   static inline Local<Promise> PromiseToLocal(
 240       v8::internal::Handle<v8::internal::JSObject> obj);
 241   static inline Local<StackTrace> StackTraceToLocal(
 242       v8::internal::Handle<v8::internal::JSArray> obj);
 243   static inline Local<StackFrame> StackFrameToLocal(
 244       v8::internal::Handle<v8::internal::JSObject> obj);
 245   static inline Local<Number> NumberToLocal(
 246       v8::internal::Handle<v8::internal::Object> obj);
 247   static inline Local<Integer> IntegerToLocal(
 248       v8::internal::Handle<v8::internal::Object> obj);
 249   static inline Local<Uint32> Uint32ToLocal(
 250       v8::internal::Handle<v8::internal::Object> obj);
 251   static inline Local<FunctionTemplate> ToLocal(
 252       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 253   static inline Local<ObjectTemplate> ToLocal(
 254       v8::internal::Handle<v8::internal::ObjectTemplateInfo> obj);
 255   static inline Local<Signature> SignatureToLocal(
 256       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 257   static inline Local<AccessorSignature> AccessorSignatureToLocal(
 258       v8::internal::Handle<v8::internal::FunctionTemplateInfo> obj);
 259   static inline Local<TypeSwitch> ToLocal(
 260       v8::internal::Handle<v8::internal::TypeSwitchInfo> obj);
 261   static inline Local<External> ExternalToLocal(
 262       v8::internal::Handle<v8::internal::JSObject> obj);
 263   static inline Local<NativeWeakMap> NativeWeakMapToLocal(
 264       v8::internal::Handle<v8::internal::JSWeakMap> obj);
 265
 266 #define DECLARE_OPEN_HANDLE(From, To) \
 267   static inline v8::internal::Handle<v8::internal::To> \
 268       OpenHandle(const From* that, bool allow_empty_handle = false);
 269
 270 OPEN_HANDLE_LIST(DECLARE_OPEN_HANDLE)
 271
 272 #undef DECLARE_OPEN_HANDLE
 273
 274   template<class From, class To>
 275   static inline Local<To> Convert(v8::internal::Handle<From> obj) {
 276     DCHECK(obj.is_null() || !obj->IsTheHole());
 277     return Local<To>(reinterpret_cast<To*>(obj.location()));
 278   }
 279
 280   template <class T>
 281   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 282       const v8::Persistent<T>& persistent) {
 283     return v8::internal::Handle<v8::internal::Object>(
 284         reinterpret_cast<v8::internal::Object**>(persistent.val_));
 285   }
 286
 287   template <class T>
 288   static inline v8::internal::Handle<v8::internal::Object> OpenPersistent(
 289       v8::Persistent<T>* persistent) {
 290     return OpenPersistent(*persistent);
 291   }
 292
 293   template <class From, class To>
 294   static inline v8::internal::Handle<To> OpenHandle(v8::Local<From> handle) {
 295     return OpenHandle(*handle);
 296   }
 297
 298  private:
 299   static void ReportApiFailure(const char* location, const char* message);
 300 };
 301
 302
 303 template <class T>
 304 v8::internal::Handle<T> v8::internal::Handle<T>::EscapeFrom(
 305     v8::EscapableHandleScope* scope) {
 306   v8::internal::Handle<T> handle;
 307   if (!is_null()) {
 308     handle = *this;
 309   }
 310   return Utils::OpenHandle(*scope->Escape(Utils::ToLocal(handle)), true);
 311 }
 312
 313
 314 template <class T>
 315 inline T* ToApi(v8::internal::Handle<v8::internal::Object> obj) {
 316   return reinterpret_cast<T*>(obj.location());
 317 }
 318
 319 template <class T>
 320 inline v8::Local<T> ToApiHandle(
 321     v8::internal::Handle<v8::internal::Object> obj) {
 322   return Utils::Convert<v8::internal::Object, T>(obj);
 323 }
 324
 325
 326 template <class T>
 327 inline bool ToLocal(v8::internal::MaybeHandle<v8::internal::Object> maybe,
 328                     Local<T>* local) {
 329   v8::internal::Handle<v8::internal::Object> handle;
 330   if (maybe.ToHandle(&handle)) {
 331     *local = Utils::Convert<v8::internal::Object, T>(handle);
 332     return true;
 333   }
 334   return false;
 335 }
 336
 337
 338 // Implementations of ToLocal
 339
 340 #define MAKE_TO_LOCAL(Name, From, To)                                       \
 341   Local<v8::To> Utils::Name(v8::internal::Handle<v8::internal::From> obj) { \
 342     return Convert<v8::internal::From, v8::To>(obj);  \
 343   }
 344
 345
 346 #define MAKE_TO_LOCAL_TYPED_ARRAY(Type, typeName, TYPE, ctype, size)  \
 347   Local<v8::Type##Array> Utils::ToLocal##Type##Array(                 \
 348       v8::internal::Handle<v8::internal::JSTypedArray> obj) {         \
 349     DCHECK(obj->type() == v8::internal::kExternal##Type##Array);      \
 350     return Convert<v8::internal::JSTypedArray, v8::Type##Array>(obj); \
 351   }
 352
 353
 354 MAKE_TO_LOCAL(ToLocal, Context, Context)
 355 MAKE_TO_LOCAL(ToLocal, Object, Value)
 356 MAKE_TO_LOCAL(ToLocal, JSFunction, Function)
 357 MAKE_TO_LOCAL(ToLocal, Name, Name)
 358 MAKE_TO_LOCAL(ToLocal, String, String)
 359 MAKE_TO_LOCAL(ToLocal, Symbol, Symbol)
 360 MAKE_TO_LOCAL(ToLocal, JSRegExp, RegExp)
 361 MAKE_TO_LOCAL(ToLocal, JSObject, Object)
 362 MAKE_TO_LOCAL(ToLocal, JSArray, Array)
 363 MAKE_TO_LOCAL(ToLocal, JSArrayBuffer, ArrayBuffer)
 364 MAKE_TO_LOCAL(ToLocal, JSArrayBufferView, ArrayBufferView)
 365 MAKE_TO_LOCAL(ToLocal, JSDataView, DataView)
 366 MAKE_TO_LOCAL(ToLocal, JSTypedArray, TypedArray)
 367 MAKE_TO_LOCAL(ToLocalShared, JSArrayBuffer, SharedArrayBuffer)
 368
 369 TYPED_ARRAYS(MAKE_TO_LOCAL_TYPED_ARRAY)
 370
 371 MAKE_TO_LOCAL(ToLocal, FunctionTemplateInfo, FunctionTemplate)
 372 MAKE_TO_LOCAL(ToLocal, ObjectTemplateInfo, ObjectTemplate)
 373 MAKE_TO_LOCAL(SignatureToLocal, FunctionTemplateInfo, Signature)
 374 MAKE_TO_LOCAL(AccessorSignatureToLocal, FunctionTemplateInfo, AccessorSignature)
 375 MAKE_TO_LOCAL(ToLocal, TypeSwitchInfo, TypeSwitch)
 376 MAKE_TO_LOCAL(MessageToLocal, Object, Message)
 377 MAKE_TO_LOCAL(PromiseToLocal, JSObject, Promise)
 378 MAKE_TO_LOCAL(StackTraceToLocal, JSArray, StackTrace)
 379 MAKE_TO_LOCAL(StackFrameToLocal, JSObject, StackFrame)
 380 MAKE_TO_LOCAL(NumberToLocal, Object, Number)
 381 MAKE_TO_LOCAL(IntegerToLocal, Object, Integer)
 382 MAKE_TO_LOCAL(Uint32ToLocal, Object, Uint32)
 383 MAKE_TO_LOCAL(ExternalToLocal, JSObject, External)
 384 MAKE_TO_LOCAL(NativeWeakMapToLocal, JSWeakMap, NativeWeakMap)
 385
 386 #undef MAKE_TO_LOCAL_TYPED_ARRAY
 387 #undef MAKE_TO_LOCAL
 388
 389
 390 // Implementations of OpenHandle
 391
 392 #define MAKE_OPEN_HANDLE(From, To)                                             \
 393   v8::internal::Handle<v8::internal::To> Utils::OpenHandle(                    \
 394       const v8::From* that, bool allow_empty_handle) {                         \
 395     DCHECK(allow_empty_handle || that != NULL);                                \
 396     DCHECK(that == NULL ||                                                     \
 397            (*reinterpret_cast<v8::internal::Object* const*>(that))->Is##To()); \
 398     return v8::internal::Handle<v8::internal::To>(                             \
 399         reinterpret_cast<v8::internal::To**>(const_cast<v8::From*>(that)));    \
 400   }
 401
 402 OPEN_HANDLE_LIST(MAKE_OPEN_HANDLE)
 403
 404 #undef MAKE_OPEN_HANDLE
 405 #undef OPEN_HANDLE_LIST
 406
 407
 408 namespace internal {
 409
 410 // Tracks string usage to help make better decisions when
 411 // externalizing strings.
 412 //
 413 // Implementation note: internally this class only tracks fresh
 414 // strings and keeps a single use counter for them.
 415 class StringTracker {
 416  public:
 417   // Records that the given string's characters were copied to some
 418   // external buffer. If this happens often we should honor
 419   // externalization requests for the string.
 420   void RecordWrite(Handle<String> string) {
 421     Address address = reinterpret_cast<Address>(*string);
 422     Address top = isolate_->heap()->NewSpaceTop();
 423     if (IsFreshString(address, top)) {
 424       IncrementUseCount(top);
 425     }
 426   }
 427
 428   // Estimates freshness and use frequency of the given string based
 429   // on how close it is to the new space top and the recorded usage
 430   // history.
 431   inline bool IsFreshUnusedString(Handle<String> string) {
 432     Address address = reinterpret_cast<Address>(*string);
 433     Address top = isolate_->heap()->NewSpaceTop();
 434     return IsFreshString(address, top) && IsUseCountLow(top);
 435   }
 436
 437  private:
 438   StringTracker() : use_count_(0), last_top_(NULL), isolate_(NULL) { }
 439
 440   static inline bool IsFreshString(Address string, Address top) {
 441     return top - kFreshnessLimit <= string && string <= top;
 442   }
 443
 444   inline bool IsUseCountLow(Address top) {
 445     if (last_top_ != top) return true;
 446     return use_count_ < kUseLimit;
 447   }
 448
 449   inline void IncrementUseCount(Address top) {
 450     if (last_top_ != top) {
 451       use_count_ = 0;
 452       last_top_ = top;
 453     }
 454     ++use_count_;
 455   }
 456
 457   // Single use counter shared by all fresh strings.
 458   int use_count_;
 459
 460   // Last new space top when the use count above was valid.
 461   Address last_top_;
 462
 463   Isolate* isolate_;
 464
 465   // How close to the new space top a fresh string has to be.
 466   static const int kFreshnessLimit = 1024;
 467
 468   // The number of uses required to consider a string useful.
 469   static const int kUseLimit = 32;
 470
 471   friend class Isolate;
 472
 473   DISALLOW_COPY_AND_ASSIGN(StringTracker);
 474 };
 475
 476
 477 class DeferredHandles {
 478  public:
 479   ~DeferredHandles();
 480
 481  private:
 482   DeferredHandles(Object** first_block_limit, Isolate* isolate)
 483       : next_(NULL),
 484         previous_(NULL),
 485         first_block_limit_(first_block_limit),
 486         isolate_(isolate) {
 487     isolate->LinkDeferredHandles(this);
 488   }
 489
 490   void Iterate(ObjectVisitor* v);
 491
 492   List<Object**> blocks_;
 493   DeferredHandles* next_;
 494   DeferredHandles* previous_;
 495   Object** first_block_limit_;
 496   Isolate* isolate_;
 497
 498   friend class HandleScopeImplementer;
 499   friend class Isolate;
 500 };
 501
 502
 503 // This class is here in order to be able to declare it a friend of
 504 // HandleScope.  Moving these methods to be members of HandleScope would be
 505 // neat in some ways, but it would expose internal implementation details in
 506 // our public header file, which is undesirable.
 507 //
 508 // An isolate has a single instance of this class to hold the current thread's
 509 // data. In multithreaded V8 programs this data is copied in and out of storage
 510 // so that the currently executing thread always has its own copy of this
 511 // data.
 512 class HandleScopeImplementer {
 513  public:
 514   explicit HandleScopeImplementer(Isolate* isolate)
 515       : isolate_(isolate),
 516         blocks_(0),
 517         entered_contexts_(0),
 518         saved_contexts_(0),
 519         spare_(NULL),
 520         call_depth_(0),
 521         last_handle_before_deferred_block_(NULL) { }
 522
 523   ~HandleScopeImplementer() {
 524     DeleteArray(spare_);
 525   }
 526
 527   // Threading support for handle data.
 528   static int ArchiveSpacePerThread();
 529   char* RestoreThread(char* from);
 530   char* ArchiveThread(char* to);
 531   void FreeThreadResources();
 532
 533   // Garbage collection support.
 534   void Iterate(v8::internal::ObjectVisitor* v);
 535   static char* Iterate(v8::internal::ObjectVisitor* v, char* data);
 536
 537
 538   inline internal::Object** GetSpareOrNewBlock();
 539   inline void DeleteExtensions(internal::Object** prev_limit);
 540
 541   inline void IncrementCallDepth() {call_depth_++;}
 542   inline void DecrementCallDepth() {call_depth_--;}
 543   inline bool CallDepthIsZero() { return call_depth_ == 0; }
 544
 545   inline void EnterContext(Handle<Context> context);
 546   inline void LeaveContext();
 547   inline bool LastEnteredContextWas(Handle<Context> context);
 548
 549   // Returns the last entered context or an empty handle if no
 550   // contexts have been entered.
 551   inline Handle<Context> LastEnteredContext();
 552
 553   inline void SaveContext(Context* context);
 554   inline Context* RestoreContext();
 555   inline bool HasSavedContexts();
 556
 557   inline List<internal::Object**>* blocks() { return &blocks_; }
 558   Isolate* isolate() const { return isolate_; }
 559
 560   void ReturnBlock(Object** block) {
 561     DCHECK(block != NULL);
 562     if (spare_ != NULL) DeleteArray(spare_);
 563     spare_ = block;
 564   }
 565
 566  private:
 567   void ResetAfterArchive() {
 568     blocks_.Initialize(0);
 569     entered_contexts_.Initialize(0);
 570     saved_contexts_.Initialize(0);
 571     spare_ = NULL;
 572     last_handle_before_deferred_block_ = NULL;
 573     call_depth_ = 0;
 574   }
 575
 576   void Free() {
 577     DCHECK(blocks_.length() == 0);
 578     DCHECK(entered_contexts_.length() == 0);
 579     DCHECK(saved_contexts_.length() == 0);
 580     blocks_.Free();
 581     entered_contexts_.Free();
 582     saved_contexts_.Free();
 583     if (spare_ != NULL) {
 584       DeleteArray(spare_);
 585       spare_ = NULL;
 586     }
 587     DCHECK(call_depth_ == 0);
 588   }
 589
 590   void BeginDeferredScope();
 591   DeferredHandles* Detach(Object** prev_limit);
 592
 593   Isolate* isolate_;
 594   List<internal::Object**> blocks_;
 595   // Used as a stack to keep track of entered contexts.
 596   List<Context*> entered_contexts_;
 597   // Used as a stack to keep track of saved contexts.
 598   List<Context*> saved_contexts_;
 599   Object** spare_;
 600   int call_depth_;
 601   Object** last_handle_before_deferred_block_;
 602   // This is only used for threading support.
 603   HandleScopeData handle_scope_data_;
 604
 605   void IterateThis(ObjectVisitor* v);
 606   char* RestoreThreadHelper(char* from);
 607   char* ArchiveThreadHelper(char* to);
 608
 609   friend class DeferredHandles;
 610   friend class DeferredHandleScope;
 611
 612   DISALLOW_COPY_AND_ASSIGN(HandleScopeImplementer);
 613 };
 614
 615
 616 const int kHandleBlockSize = v8::internal::KB - 2;  // fit in one page
 617
 618
 619 void HandleScopeImplementer::SaveContext(Context* context) {
 620   saved_contexts_.Add(context);
 621 }
 622
 623
 624 Context* HandleScopeImplementer::RestoreContext() {
 625   return saved_contexts_.RemoveLast();
 626 }
 627
 628
 629 bool HandleScopeImplementer::HasSavedContexts() {
 630   return !saved_contexts_.is_empty();
 631 }
 632
 633
 634 void HandleScopeImplementer::EnterContext(Handle<Context> context) {
 635   entered_contexts_.Add(*context);
 636 }
 637
 638
 639 void HandleScopeImplementer::LeaveContext() {
 640   entered_contexts_.RemoveLast();
 641 }
 642
 643
 644 bool HandleScopeImplementer::LastEnteredContextWas(Handle<Context> context) {
 645   return !entered_contexts_.is_empty() && entered_contexts_.last() == *context;
 646 }
 647
 648
 649 Handle<Context> HandleScopeImplementer::LastEnteredContext() {
 650   if (entered_contexts_.is_empty()) return Handle<Context>::null();
 651   return Handle<Context>(entered_contexts_.last());
 652 }
 653
 654
 655 // If there's a spare block, use it for growing the current scope.
 656 internal::Object** HandleScopeImplementer::GetSpareOrNewBlock() {
 657   internal::Object** block = (spare_ != NULL) ?
 658       spare_ :
 659       NewArray<internal::Object*>(kHandleBlockSize);
 660   spare_ = NULL;
 661   return block;
 662 }
 663
 664
 665 void HandleScopeImplementer::DeleteExtensions(internal::Object** prev_limit) {
 666   while (!blocks_.is_empty()) {
 667     internal::Object** block_start = blocks_.last();
 668     internal::Object** block_limit = block_start + kHandleBlockSize;
 669
 670     // SealHandleScope may make the prev_limit to point inside the block.
 671     if (block_start <= prev_limit && prev_limit <= block_limit) {
 672 #ifdef ENABLE_HANDLE_ZAPPING
 673       internal::HandleScope::ZapRange(prev_limit, block_limit);
 674 #endif
 675       break;
 676     }
 677
 678     blocks_.RemoveLast();
 679 #ifdef ENABLE_HANDLE_ZAPPING
 680     internal::HandleScope::ZapRange(block_start, block_limit);
 681 #endif
 682     if (spare_ != NULL) {
 683       DeleteArray(spare_);
 684     }
 685     spare_ = block_start;
 686   }
 687   DCHECK((blocks_.is_empty() && prev_limit == NULL) ||
 688          (!blocks_.is_empty() && prev_limit != NULL));
 689 }
 690
 691
 692 // Interceptor functions called from generated inline caches to notify
 693 // CPU profiler that external callbacks are invoked.
 694 void InvokeAccessorGetterCallback(
 695     v8::Local<v8::Name> property,
 696     const v8::PropertyCallbackInfo<v8::Value>& info,
 697     v8::AccessorNameGetterCallback getter);
 698
 699 void InvokeFunctionCallback(const v8::FunctionCallbackInfo<v8::Value>& info,
 700                             v8::FunctionCallback callback);
 701
 702 class Testing {
 703  public:
 704   static v8::Testing::StressType stress_type() { return stress_type_; }
 705   static void set_stress_type(v8::Testing::StressType stress_type) {
 706     stress_type_ = stress_type;
 707   }
 708
 709  private:
 710   static v8::Testing::StressType stress_type_;
 711 };
 712
 713 } }  // namespace v8::internal
 714
 715 #endif  // V8_API_H_