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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/Badge.h>
#include <AK/HashTable.h>
#include <LibJS/Heap.h>
#include <LibJS/HeapBlock.h>
#include <LibJS/Interpreter.h>
#include <LibJS/Object.h>
#define HEAP_DEBUG
namespace JS {
Heap::Heap(Interpreter& interpreter)
: m_interpreter(interpreter)
{
}
Heap::~Heap()
{
}
Cell* Heap::allocate_cell(size_t size)
{
for (auto& block : m_blocks) {
if (size > block->cell_size())
continue;
if (auto* cell = block->allocate())
return cell;
}
auto block = HeapBlock::create_with_cell_size(*this, size);
auto* cell = block->allocate();
m_blocks.append(move(block));
return cell;
}
void Heap::collect_garbage()
{
HashTable<Cell*> roots;
collect_roots(roots);
mark_live_cells(roots);
sweep_dead_cells();
}
void Heap::collect_roots(HashTable<Cell*>& roots)
{
m_interpreter.collect_roots({}, roots);
#ifdef HEAP_DEBUG
dbg() << "collect_roots:";
for (auto* root : roots) {
dbg() << " + " << root;
}
#endif
}
class MarkingVisitor final : public Cell::Visitor {
public:
MarkingVisitor() {}
virtual void visit(Cell* cell)
{
if (cell->is_marked())
return;
#ifdef HEAP_DEBUG
dbg() << " ! " << cell;
#endif
cell->set_marked(true);
cell->visit_children(*this);
}
};
void Heap::mark_live_cells(const HashTable<Cell*>& roots)
{
#ifdef HEAP_DEBUG
dbg() << "mark_live_cells:";
#endif
MarkingVisitor visitor;
for (auto* root : roots)
visitor.visit(root);
}
void Heap::sweep_dead_cells()
{
#ifdef HEAP_DEBUG
dbg() << "sweep_dead_cells:";
#endif
for (auto& block : m_blocks) {
block->for_each_cell([&](Cell* cell) {
if (cell->is_live()) {
if (!cell->is_marked()) {
#ifdef HEAP_DEBUG
dbg() << " ~ " << cell;
#endif
block->deallocate(cell);
} else {
cell->set_marked(false);
}
}
});
}
}
}
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