1 files changed, 132 insertions, 0 deletions
diff --git a/Userland/Libraries/LibJS/Heap/Heap.h b/Userland/Libraries/LibJS/Heap/Heap.h
new file mode 100644
index 0000000000..8d7d32298f
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+++ b/Userland/Libraries/LibJS/Heap/Heap.h
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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.
+ */
+
+#pragma once
+
+#include <AK/HashTable.h>
+#include <AK/Noncopyable.h>
+#include <AK/NonnullOwnPtr.h>
+#include <AK/Types.h>
+#include <AK/Vector.h>
+#include <LibCore/Forward.h>
+#include <LibJS/Forward.h>
+#include <LibJS/Heap/Allocator.h>
+#include <LibJS/Heap/Handle.h>
+#include <LibJS/Runtime/Cell.h>
+#include <LibJS/Runtime/Object.h>
+
+namespace JS {
+
+class Heap {
+    AK_MAKE_NONCOPYABLE(Heap);
+    AK_MAKE_NONMOVABLE(Heap);
+
+public:
+    explicit Heap(VM&);
+    ~Heap();
+
+    template<typename T, typename... Args>
+    T* allocate_without_global_object(Args&&... args)
+    {
+        auto* memory = allocate_cell(sizeof(T));
+        new (memory) T(forward<Args>(args)...);
+        return static_cast<T*>(memory);
+    }
+
+    template<typename T, typename... Args>
+    T* allocate(GlobalObject& global_object, Args&&... args)
+    {
+        auto* memory = allocate_cell(sizeof(T));
+        new (memory) T(forward<Args>(args)...);
+        auto* cell = static_cast<T*>(memory);
+        constexpr bool is_object = IsBaseOf<Object, T>::value;
+        if constexpr (is_object)
+            static_cast<Object*>(cell)->disable_transitions();
+        cell->initialize(global_object);
+        if constexpr (is_object)
+            static_cast<Object*>(cell)->enable_transitions();
+        return cell;
+    }
+
+    enum class CollectionType {
+        CollectGarbage,
+        CollectEverything,
+    };
+
+    void collect_garbage(CollectionType = CollectionType::CollectGarbage, bool print_report = false);
+
+    VM& vm() { return m_vm; }
+
+    bool should_collect_on_every_allocation() const { return m_should_collect_on_every_allocation; }
+    void set_should_collect_on_every_allocation(bool b) { m_should_collect_on_every_allocation = b; }
+
+    void did_create_handle(Badge<HandleImpl>, HandleImpl&);
+    void did_destroy_handle(Badge<HandleImpl>, HandleImpl&);
+
+    void did_create_marked_value_list(Badge<MarkedValueList>, MarkedValueList&);
+    void did_destroy_marked_value_list(Badge<MarkedValueList>, MarkedValueList&);
+
+    void defer_gc(Badge<DeferGC>);
+    void undefer_gc(Badge<DeferGC>);
+
+private:
+    Cell* allocate_cell(size_t);
+
+    void gather_roots(HashTable<Cell*>&);
+    void gather_conservative_roots(HashTable<Cell*>&);
+    void mark_live_cells(const HashTable<Cell*>& live_cells);
+    void sweep_dead_cells(bool print_report, const Core::ElapsedTimer&);
+
+    Allocator& allocator_for_size(size_t);
+
+    template<typename Callback>
+    void for_each_block(Callback callback)
+    {
+        for (auto& allocator : m_allocators) {
+            if (allocator->for_each_block(callback) == IterationDecision::Break)
+                return;
+        }
+    }
+
+    size_t m_max_allocations_between_gc { 10000 };
+    size_t m_allocations_since_last_gc { false };
+
+    bool m_should_collect_on_every_allocation { false };
+
+    VM& m_vm;
+
+    Vector<NonnullOwnPtr<Allocator>> m_allocators;
+    HashTable<HandleImpl*> m_handles;
+
+    HashTable<MarkedValueList*> m_marked_value_lists;
+
+    size_t m_gc_deferrals { 0 };
+    bool m_should_gc_when_deferral_ends { false };
+
+    bool m_collecting_garbage { false };
+};
+
+}