ager@chromium.org | 71daaf6 | 2009-04-01 07:22:49 +0000 | [diff] [blame] | 1 | // Copyright 2009 the V8 project authors. All rights reserved. |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 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 | #include "v8.h" |
| 29 | |
| 30 | #include "api.h" |
| 31 | #include "global-handles.h" |
| 32 | |
kasperl@chromium.org | 71affb5 | 2009-05-26 05:44:31 +0000 | [diff] [blame] | 33 | namespace v8 { |
| 34 | namespace internal { |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 35 | |
| 36 | class GlobalHandles::Node : public Malloced { |
| 37 | public: |
| 38 | |
| 39 | void Initialize(Object* object) { |
| 40 | // Set the initial value of the handle. |
| 41 | object_ = object; |
| 42 | state_ = NORMAL; |
| 43 | parameter_or_next_free_.parameter = NULL; |
| 44 | callback_ = NULL; |
| 45 | } |
| 46 | |
| 47 | explicit Node(Object* object) { |
| 48 | Initialize(object); |
| 49 | // Initialize link structure. |
| 50 | next_ = NULL; |
| 51 | } |
| 52 | |
| 53 | ~Node() { |
| 54 | if (state_ != DESTROYED) Destroy(); |
| 55 | #ifdef DEBUG |
| 56 | // Zap the values for eager trapping. |
| 57 | object_ = NULL; |
| 58 | next_ = NULL; |
| 59 | parameter_or_next_free_.next_free = NULL; |
| 60 | #endif |
| 61 | } |
| 62 | |
| 63 | void Destroy() { |
| 64 | if (state_ == WEAK || IsNearDeath()) { |
| 65 | GlobalHandles::number_of_weak_handles_--; |
| 66 | if (object_->IsJSGlobalObject()) { |
| 67 | GlobalHandles::number_of_global_object_weak_handles_--; |
| 68 | } |
| 69 | } |
| 70 | state_ = DESTROYED; |
| 71 | } |
| 72 | |
| 73 | // Accessors for next_. |
| 74 | Node* next() { return next_; } |
| 75 | void set_next(Node* value) { next_ = value; } |
| 76 | Node** next_addr() { return &next_; } |
| 77 | |
| 78 | // Accessors for next free node in the free list. |
| 79 | Node* next_free() { |
| 80 | ASSERT(state_ == DESTROYED); |
| 81 | return parameter_or_next_free_.next_free; |
| 82 | } |
| 83 | void set_next_free(Node* value) { |
| 84 | ASSERT(state_ == DESTROYED); |
| 85 | parameter_or_next_free_.next_free = value; |
| 86 | } |
| 87 | |
| 88 | // Returns a link from the handle. |
| 89 | static Node* FromLocation(Object** location) { |
| 90 | ASSERT(OFFSET_OF(Node, object_) == 0); |
| 91 | return reinterpret_cast<Node*>(location); |
| 92 | } |
| 93 | |
| 94 | // Returns the handle. |
| 95 | Handle<Object> handle() { return Handle<Object>(&object_); } |
| 96 | |
| 97 | // Make this handle weak. |
| 98 | void MakeWeak(void* parameter, WeakReferenceCallback callback) { |
| 99 | LOG(HandleEvent("GlobalHandle::MakeWeak", handle().location())); |
ager@chromium.org | 3bf7b91 | 2008-11-17 09:09:45 +0000 | [diff] [blame] | 100 | ASSERT(state_ != DESTROYED); |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 101 | if (state_ != WEAK && !IsNearDeath()) { |
| 102 | GlobalHandles::number_of_weak_handles_++; |
| 103 | if (object_->IsJSGlobalObject()) { |
| 104 | GlobalHandles::number_of_global_object_weak_handles_++; |
| 105 | } |
| 106 | } |
| 107 | state_ = WEAK; |
| 108 | set_parameter(parameter); |
| 109 | callback_ = callback; |
| 110 | } |
| 111 | |
| 112 | void ClearWeakness() { |
| 113 | LOG(HandleEvent("GlobalHandle::ClearWeakness", handle().location())); |
ager@chromium.org | 3bf7b91 | 2008-11-17 09:09:45 +0000 | [diff] [blame] | 114 | ASSERT(state_ != DESTROYED); |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 115 | if (state_ == WEAK || IsNearDeath()) { |
| 116 | GlobalHandles::number_of_weak_handles_--; |
| 117 | if (object_->IsJSGlobalObject()) { |
| 118 | GlobalHandles::number_of_global_object_weak_handles_--; |
| 119 | } |
| 120 | } |
| 121 | state_ = NORMAL; |
| 122 | set_parameter(NULL); |
| 123 | } |
| 124 | |
| 125 | bool IsNearDeath() { |
| 126 | // Check for PENDING to ensure correct answer when processing callbacks. |
| 127 | return state_ == PENDING || state_ == NEAR_DEATH; |
| 128 | } |
| 129 | |
| 130 | bool IsWeak() { |
| 131 | return state_ == WEAK; |
| 132 | } |
| 133 | |
| 134 | // Returns the id for this weak handle. |
| 135 | void set_parameter(void* parameter) { |
| 136 | ASSERT(state_ != DESTROYED); |
| 137 | parameter_or_next_free_.parameter = parameter; |
| 138 | } |
| 139 | void* parameter() { |
| 140 | ASSERT(state_ != DESTROYED); |
| 141 | return parameter_or_next_free_.parameter; |
| 142 | } |
| 143 | |
| 144 | // Returns the callback for this weak handle. |
| 145 | WeakReferenceCallback callback() { return callback_; } |
| 146 | |
sgjesse@chromium.org | c81c894 | 2009-08-21 10:54:26 +0000 | [diff] [blame] | 147 | bool PostGarbageCollectionProcessing() { |
| 148 | if (state_ != Node::PENDING) return false; |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 149 | LOG(HandleEvent("GlobalHandle::Processing", handle().location())); |
| 150 | void* par = parameter(); |
| 151 | state_ = NEAR_DEATH; |
| 152 | set_parameter(NULL); |
| 153 | // The callback function is resolved as late as possible to preserve old |
| 154 | // behavior. |
| 155 | WeakReferenceCallback func = callback(); |
sgjesse@chromium.org | c81c894 | 2009-08-21 10:54:26 +0000 | [diff] [blame] | 156 | if (func == NULL) return false; |
| 157 | |
| 158 | v8::Persistent<v8::Object> object = ToApi<v8::Object>(handle()); |
| 159 | { |
| 160 | // Forbid reuse of destroyed nodes as they might be already deallocated. |
| 161 | // It's fine though to reuse nodes that were destroyed in weak callback |
| 162 | // as those cannot be deallocated until we are back from the callback. |
| 163 | set_first_free(NULL); |
| 164 | // Leaving V8. |
| 165 | VMState state(EXTERNAL); |
| 166 | func(object, par); |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 167 | } |
sgjesse@chromium.org | c81c894 | 2009-08-21 10:54:26 +0000 | [diff] [blame] | 168 | return true; |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 169 | } |
| 170 | |
| 171 | // Place the handle address first to avoid offset computation. |
| 172 | Object* object_; // Storage for object pointer. |
| 173 | |
| 174 | // Transition diagram: |
| 175 | // NORMAL <-> WEAK -> PENDING -> NEAR_DEATH -> { NORMAL, WEAK, DESTROYED } |
| 176 | enum State { |
| 177 | NORMAL, // Normal global handle. |
| 178 | WEAK, // Flagged as weak but not yet finalized. |
| 179 | PENDING, // Has been recognized as only reachable by weak handles. |
| 180 | NEAR_DEATH, // Callback has informed the handle is near death. |
| 181 | DESTROYED |
| 182 | }; |
| 183 | State state_; |
| 184 | |
| 185 | private: |
| 186 | // Handle specific callback. |
| 187 | WeakReferenceCallback callback_; |
| 188 | // Provided data for callback. In DESTROYED state, this is used for |
| 189 | // the free list link. |
| 190 | union { |
| 191 | void* parameter; |
| 192 | Node* next_free; |
| 193 | } parameter_or_next_free_; |
| 194 | |
| 195 | // Linkage for the list. |
| 196 | Node* next_; |
| 197 | |
| 198 | public: |
| 199 | TRACK_MEMORY("GlobalHandles::Node") |
| 200 | }; |
| 201 | |
| 202 | |
| 203 | Handle<Object> GlobalHandles::Create(Object* value) { |
| 204 | Counters::global_handles.Increment(); |
| 205 | Node* result; |
| 206 | if (first_free() == NULL) { |
| 207 | // Allocate a new node. |
| 208 | result = new Node(value); |
| 209 | result->set_next(head()); |
| 210 | set_head(result); |
| 211 | } else { |
| 212 | // Take the first node in the free list. |
| 213 | result = first_free(); |
| 214 | set_first_free(result->next_free()); |
| 215 | result->Initialize(value); |
| 216 | } |
| 217 | return result->handle(); |
| 218 | } |
| 219 | |
| 220 | |
| 221 | void GlobalHandles::Destroy(Object** location) { |
| 222 | Counters::global_handles.Decrement(); |
| 223 | if (location == NULL) return; |
| 224 | Node* node = Node::FromLocation(location); |
| 225 | node->Destroy(); |
| 226 | // Link the destroyed. |
| 227 | node->set_next_free(first_free()); |
| 228 | set_first_free(node); |
| 229 | } |
| 230 | |
| 231 | |
| 232 | void GlobalHandles::MakeWeak(Object** location, void* parameter, |
| 233 | WeakReferenceCallback callback) { |
| 234 | ASSERT(callback != NULL); |
| 235 | Node::FromLocation(location)->MakeWeak(parameter, callback); |
| 236 | } |
| 237 | |
| 238 | |
| 239 | void GlobalHandles::ClearWeakness(Object** location) { |
| 240 | Node::FromLocation(location)->ClearWeakness(); |
| 241 | } |
| 242 | |
| 243 | |
| 244 | bool GlobalHandles::IsNearDeath(Object** location) { |
| 245 | return Node::FromLocation(location)->IsNearDeath(); |
| 246 | } |
| 247 | |
| 248 | |
| 249 | bool GlobalHandles::IsWeak(Object** location) { |
| 250 | return Node::FromLocation(location)->IsWeak(); |
| 251 | } |
| 252 | |
| 253 | |
| 254 | void GlobalHandles::IterateWeakRoots(ObjectVisitor* v) { |
| 255 | // Traversal of GC roots in the global handle list that are marked as |
| 256 | // WEAK or PENDING. |
| 257 | for (Node* current = head_; current != NULL; current = current->next()) { |
| 258 | if (current->state_ == Node::WEAK |
| 259 | || current->state_ == Node::PENDING |
| 260 | || current->state_ == Node::NEAR_DEATH) { |
| 261 | v->VisitPointer(¤t->object_); |
| 262 | } |
| 263 | } |
| 264 | } |
| 265 | |
| 266 | |
christian.plesner.hansen@gmail.com | 9d58c2b | 2009-10-16 11:48:38 +0000 | [diff] [blame^] | 267 | void GlobalHandles::IterateWeakRoots(WeakReferenceGuest f, |
| 268 | WeakReferenceCallback callback) { |
| 269 | for (Node* current = head_; current != NULL; current = current->next()) { |
| 270 | if (current->IsWeak() && current->callback() == callback) { |
| 271 | f(current->object_, current->parameter()); |
| 272 | } |
| 273 | } |
| 274 | } |
| 275 | |
| 276 | |
ager@chromium.org | 9085a01 | 2009-05-11 19:22:57 +0000 | [diff] [blame] | 277 | void GlobalHandles::IdentifyWeakHandles(WeakSlotCallback f) { |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 278 | for (Node* current = head_; current != NULL; current = current->next()) { |
| 279 | if (current->state_ == Node::WEAK) { |
| 280 | if (f(¤t->object_)) { |
| 281 | current->state_ = Node::PENDING; |
| 282 | LOG(HandleEvent("GlobalHandle::Pending", current->handle().location())); |
| 283 | } |
| 284 | } |
| 285 | } |
| 286 | } |
| 287 | |
| 288 | |
sgjesse@chromium.org | c81c894 | 2009-08-21 10:54:26 +0000 | [diff] [blame] | 289 | int post_gc_processing_count = 0; |
| 290 | |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 291 | void GlobalHandles::PostGarbageCollectionProcessing() { |
| 292 | // Process weak global handle callbacks. This must be done after the |
| 293 | // GC is completely done, because the callbacks may invoke arbitrary |
| 294 | // API functions. |
v8.team.kasperl | 727e995 | 2008-09-02 14:56:44 +0000 | [diff] [blame] | 295 | // At the same time deallocate all DESTROYED nodes |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 296 | ASSERT(Heap::gc_state() == Heap::NOT_IN_GC); |
sgjesse@chromium.org | c81c894 | 2009-08-21 10:54:26 +0000 | [diff] [blame] | 297 | const int initial_post_gc_processing_count = ++post_gc_processing_count; |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 298 | Node** p = &head_; |
| 299 | while (*p != NULL) { |
sgjesse@chromium.org | c81c894 | 2009-08-21 10:54:26 +0000 | [diff] [blame] | 300 | if ((*p)->PostGarbageCollectionProcessing()) { |
| 301 | if (initial_post_gc_processing_count != post_gc_processing_count) { |
| 302 | // Weak callback triggered another GC and another round of |
| 303 | // PostGarbageCollection processing. The current node might |
| 304 | // have been deleted in that round, so we need to bail out (or |
| 305 | // restart the processing). |
| 306 | break; |
| 307 | } |
| 308 | } |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 309 | if ((*p)->state_ == Node::DESTROYED) { |
| 310 | // Delete the link. |
| 311 | Node* node = *p; |
| 312 | *p = node->next(); // Update the link. |
| 313 | delete node; |
| 314 | } else { |
| 315 | p = (*p)->next_addr(); |
| 316 | } |
| 317 | } |
| 318 | set_first_free(NULL); |
| 319 | } |
| 320 | |
| 321 | |
| 322 | void GlobalHandles::IterateRoots(ObjectVisitor* v) { |
| 323 | // Traversal of global handles marked as NORMAL or NEAR_DEATH. |
| 324 | for (Node* current = head_; current != NULL; current = current->next()) { |
| 325 | if (current->state_ == Node::NORMAL) { |
| 326 | v->VisitPointer(¤t->object_); |
| 327 | } |
| 328 | } |
| 329 | } |
| 330 | |
| 331 | void GlobalHandles::TearDown() { |
| 332 | // Delete all the nodes in the linked list. |
| 333 | Node* current = head_; |
| 334 | while (current != NULL) { |
| 335 | Node* n = current; |
| 336 | current = current->next(); |
| 337 | delete n; |
| 338 | } |
| 339 | // Reset the head and free_list. |
| 340 | set_head(NULL); |
| 341 | set_first_free(NULL); |
| 342 | } |
| 343 | |
| 344 | |
| 345 | int GlobalHandles::number_of_weak_handles_ = 0; |
| 346 | int GlobalHandles::number_of_global_object_weak_handles_ = 0; |
| 347 | |
| 348 | GlobalHandles::Node* GlobalHandles::head_ = NULL; |
| 349 | GlobalHandles::Node* GlobalHandles::first_free_ = NULL; |
| 350 | |
| 351 | #ifdef DEBUG |
| 352 | |
| 353 | void GlobalHandles::PrintStats() { |
| 354 | int total = 0; |
| 355 | int weak = 0; |
| 356 | int pending = 0; |
| 357 | int near_death = 0; |
| 358 | int destroyed = 0; |
| 359 | |
| 360 | for (Node* current = head_; current != NULL; current = current->next()) { |
| 361 | total++; |
| 362 | if (current->state_ == Node::WEAK) weak++; |
| 363 | if (current->state_ == Node::PENDING) pending++; |
| 364 | if (current->state_ == Node::NEAR_DEATH) near_death++; |
| 365 | if (current->state_ == Node::DESTROYED) destroyed++; |
| 366 | } |
| 367 | |
| 368 | PrintF("Global Handle Statistics:\n"); |
| 369 | PrintF(" allocated memory = %dB\n", sizeof(Node) * total); |
| 370 | PrintF(" # weak = %d\n", weak); |
| 371 | PrintF(" # pending = %d\n", pending); |
| 372 | PrintF(" # near_death = %d\n", near_death); |
| 373 | PrintF(" # destroyed = %d\n", destroyed); |
| 374 | PrintF(" # total = %d\n", total); |
| 375 | } |
| 376 | |
| 377 | void GlobalHandles::Print() { |
| 378 | PrintF("Global handles:\n"); |
| 379 | for (Node* current = head_; current != NULL; current = current->next()) { |
| 380 | PrintF(" handle %p to %p (weak=%d)\n", current->handle().location(), |
| 381 | *current->handle(), current->state_ == Node::WEAK); |
| 382 | } |
| 383 | } |
| 384 | |
| 385 | #endif |
| 386 | |
ager@chromium.org | 8bb6058 | 2008-12-11 12:02:20 +0000 | [diff] [blame] | 387 | List<ObjectGroup*>* GlobalHandles::ObjectGroups() { |
| 388 | // Lazily initialize the list to avoid startup time static constructors. |
| 389 | static List<ObjectGroup*> groups(4); |
| 390 | return &groups; |
| 391 | } |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 392 | |
ager@chromium.org | 8bb6058 | 2008-12-11 12:02:20 +0000 | [diff] [blame] | 393 | void GlobalHandles::AddGroup(Object*** handles, size_t length) { |
| 394 | ObjectGroup* new_entry = new ObjectGroup(length); |
| 395 | for (size_t i = 0; i < length; ++i) |
| 396 | new_entry->objects_.Add(handles[i]); |
| 397 | ObjectGroups()->Add(new_entry); |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 398 | } |
| 399 | |
| 400 | |
| 401 | void GlobalHandles::RemoveObjectGroups() { |
ager@chromium.org | 8bb6058 | 2008-12-11 12:02:20 +0000 | [diff] [blame] | 402 | List<ObjectGroup*>* object_groups = ObjectGroups(); |
| 403 | for (int i = 0; i< object_groups->length(); i++) { |
| 404 | delete object_groups->at(i); |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 405 | } |
ager@chromium.org | 8bb6058 | 2008-12-11 12:02:20 +0000 | [diff] [blame] | 406 | object_groups->Clear(); |
christian.plesner.hansen | 43d26ec | 2008-07-03 15:10:15 +0000 | [diff] [blame] | 407 | } |
| 408 | |
| 409 | |
| 410 | } } // namespace v8::internal |