1 // Copyright 2006-2008 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 // 28 29 #ifndef V8_HANDLES_INL_H_ 30 #define V8_HANDLES_INL_H_ 31 32 #include "api.h" 33 #include "apiutils.h" 34 #include "handles.h" 35 #include "heap.h" 36 #include "isolate.h" 37 38 namespace v8 { 39 namespace internal { 40 41 template<typename T> 42 Handle<T>::Handle(T* obj) { 43 ASSERT(!obj->IsFailure()); 44 location_ = HandleScope::CreateHandle(obj->GetIsolate(), obj); 45 } 46 47 48 template<typename T> 49 Handle<T>::Handle(T* obj, Isolate* isolate) { 50 ASSERT(!obj->IsFailure()); 51 location_ = HandleScope::CreateHandle(isolate, obj); 52 } 53 54 55 template <typename T> 56 inline bool Handle<T>::is_identical_to(const Handle<T> other) const { 57 ASSERT(location_ == NULL || !(*location_)->IsFailure()); 58 if (location_ == other.location_) return true; 59 if (location_ == NULL || other.location_ == NULL) return false; 60 // Dereferencing deferred handles to check object equality is safe. 61 SLOW_ASSERT(IsDereferenceAllowed(NO_DEFERRED_CHECK) && 62 other.IsDereferenceAllowed(NO_DEFERRED_CHECK)); 63 return *location_ == *other.location_; 64 } 65 66 67 template <typename T> 68 inline T* Handle<T>::operator*() const { 69 ASSERT(location_ != NULL && !(*location_)->IsFailure()); 70 SLOW_ASSERT(IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK)); 71 return *BitCast<T**>(location_); 72 } 73 74 template <typename T> 75 inline T** Handle<T>::location() const { 76 ASSERT(location_ == NULL || !(*location_)->IsFailure()); 77 SLOW_ASSERT(location_ == NULL || 78 IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK)); 79 return location_; 80 } 81 82 #ifdef DEBUG 83 template <typename T> 84 bool Handle<T>::IsDereferenceAllowed(DereferenceCheckMode mode) const { 85 ASSERT(location_ != NULL); 86 Object* object = *BitCast<T**>(location_); 87 if (object->IsSmi()) return true; 88 HeapObject* heap_object = HeapObject::cast(object); 89 Heap* heap = heap_object->GetHeap(); 90 Object** handle = reinterpret_cast<Object**>(location_); 91 Object** roots_array_start = heap->roots_array_start(); 92 if (roots_array_start <= handle && 93 handle < roots_array_start + Heap::kStrongRootListLength && 94 heap->RootCanBeTreatedAsConstant( 95 static_cast<Heap::RootListIndex>(handle - roots_array_start))) { 96 return true; 97 } 98 if (!AllowHandleDereference::IsAllowed()) return false; 99 if (mode == INCLUDE_DEFERRED_CHECK && 100 !AllowDeferredHandleDereference::IsAllowed()) { 101 // Accessing maps and internalized strings is safe. 102 if (heap_object->IsMap()) return true; 103 if (heap_object->IsInternalizedString()) return true; 104 return !heap->isolate()->IsDeferredHandle(handle); 105 } 106 return true; 107 } 108 #endif 109 110 111 112 HandleScope::HandleScope(Isolate* isolate) { 113 v8::ImplementationUtilities::HandleScopeData* current = 114 isolate->handle_scope_data(); 115 isolate_ = isolate; 116 prev_next_ = current->next; 117 prev_limit_ = current->limit; 118 current->level++; 119 } 120 121 122 HandleScope::~HandleScope() { 123 CloseScope(isolate_, prev_next_, prev_limit_); 124 } 125 126 127 void HandleScope::CloseScope(Isolate* isolate, 128 Object** prev_next, 129 Object** prev_limit) { 130 v8::ImplementationUtilities::HandleScopeData* current = 131 isolate->handle_scope_data(); 132 133 std::swap(current->next, prev_next); 134 current->level--; 135 if (current->limit != prev_limit) { 136 current->limit = prev_limit; 137 DeleteExtensions(isolate); 138 #ifdef ENABLE_HANDLE_ZAPPING 139 ZapRange(current->next, prev_limit); 140 } else { 141 ZapRange(current->next, prev_next); 142 #endif 143 } 144 } 145 146 147 template <typename T> 148 Handle<T> HandleScope::CloseAndEscape(Handle<T> handle_value) { 149 v8::ImplementationUtilities::HandleScopeData* current = 150 isolate_->handle_scope_data(); 151 152 T* value = *handle_value; 153 // Throw away all handles in the current scope. 154 CloseScope(isolate_, prev_next_, prev_limit_); 155 // Allocate one handle in the parent scope. 156 ASSERT(current->level > 0); 157 Handle<T> result(CreateHandle<T>(isolate_, value)); 158 // Reinitialize the current scope (so that it's ready 159 // to be used or closed again). 160 prev_next_ = current->next; 161 prev_limit_ = current->limit; 162 current->level++; 163 return result; 164 } 165 166 167 template <typename T> 168 T** HandleScope::CreateHandle(Isolate* isolate, T* value) { 169 ASSERT(AllowHandleAllocation::IsAllowed()); 170 v8::ImplementationUtilities::HandleScopeData* current = 171 isolate->handle_scope_data(); 172 173 internal::Object** cur = current->next; 174 if (cur == current->limit) cur = Extend(isolate); 175 // Update the current next field, set the value in the created 176 // handle, and return the result. 177 ASSERT(cur < current->limit); 178 current->next = cur + 1; 179 180 T** result = reinterpret_cast<T**>(cur); 181 *result = value; 182 return result; 183 } 184 185 186 #ifdef DEBUG 187 inline SealHandleScope::SealHandleScope(Isolate* isolate) : isolate_(isolate) { 188 // Make sure the current thread is allowed to create handles to begin with. 189 CHECK(AllowHandleAllocation::IsAllowed()); 190 v8::ImplementationUtilities::HandleScopeData* current = 191 isolate_->handle_scope_data(); 192 // Shrink the current handle scope to make it impossible to do 193 // handle allocations without an explicit handle scope. 194 limit_ = current->limit; 195 current->limit = current->next; 196 level_ = current->level; 197 current->level = 0; 198 } 199 200 201 inline SealHandleScope::~SealHandleScope() { 202 // Restore state in current handle scope to re-enable handle 203 // allocations. 204 v8::ImplementationUtilities::HandleScopeData* current = 205 isolate_->handle_scope_data(); 206 ASSERT_EQ(0, current->level); 207 current->level = level_; 208 ASSERT_EQ(current->next, current->limit); 209 current->limit = limit_; 210 } 211 212 #endif 213 214 } } // namespace v8::internal 215 216 #endif // V8_HANDLES_INL_H_ 217
