| // Copyright 2014 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "config.h" |
| #include "platform/heap/CallbackStack.h" |
| |
| namespace blink { |
| |
| void CallbackStack::Block::clear() |
| { |
| m_current = &m_buffer[0]; |
| m_next = nullptr; |
| clearUnused(); |
| } |
| |
| void CallbackStack::Block::invokeEphemeronCallbacks(Visitor* visitor) |
| { |
| // This loop can tolerate entries being added by the callbacks after |
| // iteration starts. |
| for (unsigned i = 0; m_buffer + i < m_current; i++) { |
| Item& item = m_buffer[i]; |
| item.call(visitor); |
| } |
| } |
| |
| #if ENABLE(ASSERT) |
| bool CallbackStack::Block::hasCallbackForObject(const void* object) |
| { |
| for (unsigned i = 0; m_buffer + i < m_current; i++) { |
| Item* item = &m_buffer[i]; |
| if (item->object() == object) |
| return true; |
| } |
| return false; |
| } |
| #endif |
| |
| void CallbackStack::Block::clearUnused() |
| { |
| #if ENABLE(ASSERT) |
| for (size_t i = 0; i < blockSize; i++) |
| m_buffer[i] = Item(0, 0); |
| #endif |
| } |
| |
| CallbackStack::CallbackStack() : m_first(new Block(0)), m_last(m_first) |
| { |
| } |
| |
| CallbackStack::~CallbackStack() |
| { |
| clear(); |
| delete m_first; |
| m_first = nullptr; |
| m_last = nullptr; |
| } |
| |
| void CallbackStack::clear() |
| { |
| Block* next; |
| for (Block* current = m_first->next(); current; current = next) { |
| next = current->next(); |
| delete current; |
| } |
| m_first->clear(); |
| m_last = m_first; |
| } |
| |
| bool CallbackStack::isEmpty() const |
| { |
| return hasJustOneBlock() && m_first->isEmptyBlock(); |
| } |
| |
| CallbackStack::Item* CallbackStack::allocateEntrySlow() |
| { |
| ASSERT(!m_first->allocateEntry()); |
| m_first = new Block(m_first); |
| return m_first->allocateEntry(); |
| } |
| |
| CallbackStack::Item* CallbackStack::popSlow() |
| { |
| ASSERT(m_first->isEmptyBlock()); |
| |
| for (;;) { |
| Block* next = m_first->next(); |
| if (!next) { |
| #if ENABLE(ASSERT) |
| m_first->clear(); |
| #endif |
| return nullptr; |
| } |
| delete m_first; |
| m_first = next; |
| if (Item* item = m_first->pop()) |
| return item; |
| } |
| } |
| |
| void CallbackStack::invokeEphemeronCallbacks(Visitor* visitor) |
| { |
| // The first block is the only one where new ephemerons are added, so we |
| // call the callbacks on that last, to catch any new ephemerons discovered |
| // in the callbacks. |
| // However, if enough ephemerons were added, we may have a new block that |
| // has been prepended to the chain. This will be very rare, but we can |
| // handle the situation by starting again and calling all the callbacks |
| // on the prepended blocks. |
| Block* from = nullptr; |
| Block* upto = nullptr; |
| while (from != m_first) { |
| upto = from; |
| from = m_first; |
| invokeOldestCallbacks(from, upto, visitor); |
| } |
| } |
| |
| void CallbackStack::invokeOldestCallbacks(Block* from, Block* upto, Visitor* visitor) |
| { |
| if (from == upto) |
| return; |
| ASSERT(from); |
| // Recurse first (blockSize at a time) so we get to the newly added entries last. |
| invokeOldestCallbacks(from->next(), upto, visitor); |
| from->invokeEphemeronCallbacks(visitor); |
| } |
| |
| bool CallbackStack::hasJustOneBlock() const |
| { |
| return !m_first->next(); |
| } |
| |
| #if ENABLE(ASSERT) |
| bool CallbackStack::hasCallbackForObject(const void* object) |
| { |
| for (Block* current = m_first; current; current = current->next()) { |
| if (current->hasCallbackForObject(object)) |
| return true; |
| } |
| return false; |
| } |
| #endif |
| |
| } |