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// Copyright 2015 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.
#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_GC_INFO_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_HEAP_GC_INFO_H_
#include <atomic>
#include "base/gtest_prod_util.h"
#include "third_party/blink/renderer/platform/heap/finalizer_traits.h"
#include "third_party/blink/renderer/platform/heap/name_traits.h"
#include "third_party/blink/renderer/platform/heap/visitor.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/assertions.h"
#include "third_party/blink/renderer/platform/wtf/deque.h"
#include "third_party/blink/renderer/platform/wtf/hash_counted_set.h"
#include "third_party/blink/renderer/platform/wtf/hash_map.h"
#include "third_party/blink/renderer/platform/wtf/hash_set.h"
#include "third_party/blink/renderer/platform/wtf/hash_table.h"
#include "third_party/blink/renderer/platform/wtf/linked_hash_set.h"
#include "third_party/blink/renderer/platform/wtf/list_hash_set.h"
#include "third_party/blink/renderer/platform/wtf/type_traits.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"
namespace blink {
// GCInfo contains metadata for objects that are instantiated from classes that
// inherit from GarbageCollected.
struct GCInfo {
const TraceCallback trace;
const FinalizationCallback finalize;
const NameCallback name;
const bool has_v_table;
};
#if DCHECK_IS_ON()
PLATFORM_EXPORT void AssertObjectHasGCInfo(const void*, uint32_t gc_info_index);
#endif
class PLATFORM_EXPORT GCInfoTable {
public:
// At maximum |kMaxIndex - 1| indices are supported.
//
// We assume that 14 bits is enough to represent all possible types: during
// telemetry runs, we see about 1,000 different types; looking at the output
// of the Oilpan GC Clang plugin, there appear to be at most about 6,000
// types. Thus 14 bits should be more than twice as many bits as we will ever
// need.
static constexpr uint32_t kMaxIndex = 1 << 14;
// Sets up a singleton table that can be acquired using Get().
static void CreateGlobalTable();
static GCInfoTable& Get() { return *global_table_; }
inline const GCInfo* GCInfoFromIndex(uint32_t index) {
DCHECK_GE(index, 1u);
DCHECK_LT(index, kMaxIndex);
DCHECK(table_);
const GCInfo* info = table_[index];
DCHECK(info);
return info;
}
uint32_t EnsureGCInfoIndex(const GCInfo*, std::atomic<std::uint32_t>*);
uint32_t GcInfoIndex() const { return current_index_; }
private:
FRIEND_TEST_ALL_PREFIXES(GCInfoTest, InitialEmpty);
FRIEND_TEST_ALL_PREFIXES(GCInfoTest, ResizeToMaxIndex);
// Singleton for each process. Retrieved through Get().
static GCInfoTable* global_table_;
// Use GCInfoTable::Get() for retrieving the global table outside of testing
// code.
GCInfoTable();
void Resize();
// Holds the per-class GCInfo descriptors; each HeapObjectHeader keeps an
// index into this table.
const GCInfo** table_ = nullptr;
// GCInfo indices start from 1 for heap objects, with 0 being treated
// specially as the index for freelist entries and large heap objects.
uint32_t current_index_ = 0;
// The limit (exclusive) of the currently allocated table.
uint32_t limit_ = 0;
Mutex table_mutex_;
};
template <typename T>
struct GCInfoTrait {
STATIC_ONLY(GCInfoTrait);
static uint32_t Index() {
static_assert(sizeof(T), "T must be fully defined");
static const GCInfo kGcInfo = {
TraceTrait<T>::Trace,
FinalizerTrait<T>::kNonTrivialFinalizer ? FinalizerTrait<T>::Finalize
: nullptr,
NameTrait<T>::GetName, std::is_polymorphic<T>::value};
// This is more complicated than using threadsafe initialization, but this
// is instantiated many times (once for every GC type).
static std::atomic<std::uint32_t> gc_info_index{0};
uint32_t index = gc_info_index.load(std::memory_order_acquire);
if (!index)
index = GCInfoTable::Get().EnsureGCInfoIndex(&kGcInfo, &gc_info_index);
DCHECK_GE(index, 1u);
DCHECK_LT(index, GCInfoTable::kMaxIndex);
return index;
}
};
template <typename U>
class GCInfoTrait<const U> : public GCInfoTrait<U> {};
template <typename T, typename U, typename V, typename W, typename X>
class HeapHashMap;
template <typename T, typename U, typename V>
class HeapHashSet;
template <typename T, typename U, typename V>
class HeapLinkedHashSet;
template <typename T, wtf_size_t inlineCapacity, typename U>
class HeapListHashSet;
template <typename ValueArg, wtf_size_t inlineCapacity>
class HeapListHashSetAllocator;
template <typename T, wtf_size_t inlineCapacity>
class HeapVector;
template <typename T, wtf_size_t inlineCapacity>
class HeapDeque;
template <typename T, typename U, typename V>
class HeapHashCountedSet;
template <typename T, typename U, typename V, typename W, typename X>
struct GCInfoTrait<HeapHashMap<T, U, V, W, X>>
: public GCInfoTrait<HashMap<T, U, V, W, X, HeapAllocator>> {};
template <typename T, typename U, typename V>
struct GCInfoTrait<HeapHashSet<T, U, V>>
: public GCInfoTrait<HashSet<T, U, V, HeapAllocator>> {};
template <typename T, typename U, typename V>
struct GCInfoTrait<HeapLinkedHashSet<T, U, V>>
: public GCInfoTrait<LinkedHashSet<T, U, V, HeapAllocator>> {};
template <typename T, wtf_size_t inlineCapacity, typename U>
struct GCInfoTrait<HeapListHashSet<T, inlineCapacity, U>>
: public GCInfoTrait<
ListHashSet<T,
inlineCapacity,
U,
HeapListHashSetAllocator<T, inlineCapacity>>> {};
template <typename T, wtf_size_t inlineCapacity>
struct GCInfoTrait<HeapVector<T, inlineCapacity>>
: public GCInfoTrait<Vector<T, inlineCapacity, HeapAllocator>> {};
template <typename T, wtf_size_t inlineCapacity>
struct GCInfoTrait<HeapDeque<T, inlineCapacity>>
: public GCInfoTrait<Deque<T, inlineCapacity, HeapAllocator>> {};
template <typename T, typename U, typename V>
struct GCInfoTrait<HeapHashCountedSet<T, U, V>>
: public GCInfoTrait<HashCountedSet<T, U, V, HeapAllocator>> {};
} // namespace blink
#endif
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