/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_RUNTIME_CLASS_TABLE_H_
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#define ART_RUNTIME_CLASS_TABLE_H_
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#include <string>
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#include <utility>
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#include <vector>
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#include "base/allocator.h"
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#include "base/hash_set.h"
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#include "base/macros.h"
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#include "base/mutex.h"
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#include "gc_root.h"
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#include "obj_ptr.h"
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namespace art {
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class OatFile;
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namespace linker {
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class ImageWriter;
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} // namespace linker
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namespace linker {
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class OatWriter;
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} // namespace linker
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namespace mirror {
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class Class;
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class ClassLoader;
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class Object;
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} // namespace mirror
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// Each loader has a ClassTable
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class ClassTable {
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public:
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class TableSlot {
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public:
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TableSlot() : data_(0u) {}
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TableSlot(const TableSlot& copy) : data_(copy.data_.load(std::memory_order_relaxed)) {}
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explicit TableSlot(ObjPtr<mirror::Class> klass);
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TableSlot(ObjPtr<mirror::Class> klass, uint32_t descriptor_hash);
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TableSlot& operator=(const TableSlot& copy) {
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data_.store(copy.data_.load(std::memory_order_relaxed), std::memory_order_relaxed);
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return *this;
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}
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bool IsNull() const REQUIRES_SHARED(Locks::mutator_lock_) {
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return Read<kWithoutReadBarrier>() == nullptr;
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}
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uint32_t Hash() const {
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return MaskHash(data_.load(std::memory_order_relaxed));
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}
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static uint32_t MaskHash(uint32_t hash) {
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return hash & kHashMask;
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}
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bool MaskedHashEquals(uint32_t other) const {
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return MaskHash(other) == Hash();
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}
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static uint32_t HashDescriptor(ObjPtr<mirror::Class> klass)
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REQUIRES_SHARED(Locks::mutator_lock_);
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template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
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mirror::Class* Read() const REQUIRES_SHARED(Locks::mutator_lock_);
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// NO_THREAD_SAFETY_ANALYSIS since the visitor may require heap bitmap lock.
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template<typename Visitor>
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void VisitRoot(const Visitor& visitor) const NO_THREAD_SAFETY_ANALYSIS;
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private:
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// Extract a raw pointer from an address.
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static ObjPtr<mirror::Class> ExtractPtr(uint32_t data)
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REQUIRES_SHARED(Locks::mutator_lock_);
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static uint32_t Encode(ObjPtr<mirror::Class> klass, uint32_t hash_bits)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Data contains the class pointer GcRoot as well as the low bits of the descriptor hash.
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mutable Atomic<uint32_t> data_;
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static const uint32_t kHashMask = kObjectAlignment - 1;
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};
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using DescriptorHashPair = std::pair<const char*, uint32_t>;
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class ClassDescriptorHashEquals {
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public:
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// uint32_t for cross compilation.
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uint32_t operator()(const TableSlot& slot) const NO_THREAD_SAFETY_ANALYSIS;
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// Same class loader and descriptor.
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bool operator()(const TableSlot& a, const TableSlot& b) const
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NO_THREAD_SAFETY_ANALYSIS;
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// Same descriptor.
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bool operator()(const TableSlot& a, const DescriptorHashPair& b) const
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NO_THREAD_SAFETY_ANALYSIS;
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// uint32_t for cross compilation.
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uint32_t operator()(const DescriptorHashPair& pair) const NO_THREAD_SAFETY_ANALYSIS;
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};
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class TableSlotEmptyFn {
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public:
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void MakeEmpty(TableSlot& item) const NO_THREAD_SAFETY_ANALYSIS {
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item = TableSlot();
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DCHECK(IsEmpty(item));
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}
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bool IsEmpty(const TableSlot& item) const NO_THREAD_SAFETY_ANALYSIS {
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return item.IsNull();
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}
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};
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// Hash set that hashes class descriptor, and compares descriptors and class loaders. Results
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// should be compared for a matching class descriptor and class loader.
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typedef HashSet<TableSlot,
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TableSlotEmptyFn,
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ClassDescriptorHashEquals,
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ClassDescriptorHashEquals,
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TrackingAllocator<TableSlot, kAllocatorTagClassTable>> ClassSet;
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ClassTable();
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// Used by image writer for checking.
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bool Contains(ObjPtr<mirror::Class> klass)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Freeze the current class tables by allocating a new table and never updating or modifying the
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// existing table. This helps prevents dirty pages after caused by inserting after zygote fork.
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void FreezeSnapshot()
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Returns the number of classes in previous snapshots defined by `defining_loader`.
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size_t NumZygoteClasses(ObjPtr<mirror::ClassLoader> defining_loader) const
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Returns all off the classes in the lastest snapshot defined by `defining_loader`.
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size_t NumNonZygoteClasses(ObjPtr<mirror::ClassLoader> defining_loader) const
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Returns the number of classes in previous snapshots no matter the defining loader.
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size_t NumReferencedZygoteClasses() const
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Returns all off the classes in the lastest snapshot no matter the defining loader.
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size_t NumReferencedNonZygoteClasses() const
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Update a class in the table with the new class. Returns the existing class which was replaced.
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mirror::Class* UpdateClass(const char* descriptor, mirror::Class* new_klass, size_t hash)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// NO_THREAD_SAFETY_ANALYSIS for object marking requiring heap bitmap lock.
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template<class Visitor>
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void VisitRoots(Visitor& visitor)
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NO_THREAD_SAFETY_ANALYSIS
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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template<class Visitor>
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void VisitRoots(const Visitor& visitor)
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NO_THREAD_SAFETY_ANALYSIS
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Stops visit if the visitor returns false.
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template <typename Visitor, ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
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bool Visit(Visitor& visitor)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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template <typename Visitor, ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
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bool Visit(const Visitor& visitor)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Return the first class that matches the descriptor. Returns null if there are none.
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mirror::Class* Lookup(const char* descriptor, size_t hash)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Return the first class that matches the descriptor of klass. Returns null if there are none.
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mirror::Class* LookupByDescriptor(ObjPtr<mirror::Class> klass)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Try to insert a class and return the inserted class if successful. If another class
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// with the same descriptor is already in the table, return the existing entry.
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ObjPtr<mirror::Class> TryInsert(ObjPtr<mirror::Class> klass)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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void Insert(ObjPtr<mirror::Class> klass)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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void InsertWithHash(ObjPtr<mirror::Class> klass, size_t hash)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Returns true if the class was found and removed, false otherwise.
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bool Remove(const char* descriptor)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Return true if we inserted the strong root, false if it already exists.
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bool InsertStrongRoot(ObjPtr<mirror::Object> obj)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Return true if we inserted the oat file, false if it already exists.
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bool InsertOatFile(const OatFile* oat_file)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Combines all of the tables into one class set.
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size_t WriteToMemory(uint8_t* ptr) const
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Read a table from ptr and put it at the front of the class set.
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size_t ReadFromMemory(uint8_t* ptr)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Add a class set to the front of classes.
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void AddClassSet(ClassSet&& set)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Clear strong roots (other than classes themselves).
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void ClearStrongRoots()
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Filter strong roots (other than classes themselves).
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template <typename Filter>
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void RemoveStrongRoots(const Filter& filter)
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REQUIRES(!lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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ReaderWriterMutex& GetLock() {
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return lock_;
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}
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private:
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// Only copies classes.
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void CopyWithoutLocks(const ClassTable& source_table) NO_THREAD_SAFETY_ANALYSIS;
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void InsertWithoutLocks(ObjPtr<mirror::Class> klass) NO_THREAD_SAFETY_ANALYSIS;
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size_t CountDefiningLoaderClasses(ObjPtr<mirror::ClassLoader> defining_loader,
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const ClassSet& set) const
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REQUIRES(lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Return true if we inserted the oat file, false if it already exists.
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bool InsertOatFileLocked(const OatFile* oat_file)
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REQUIRES(lock_)
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REQUIRES_SHARED(Locks::mutator_lock_);
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// Lock to guard inserting and removing.
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mutable ReaderWriterMutex lock_;
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// We have a vector to help prevent dirty pages after the zygote forks by calling FreezeSnapshot.
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std::vector<ClassSet> classes_ GUARDED_BY(lock_);
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// Extra strong roots that can be either dex files or dex caches. Dex files used by the class
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// loader which may not be owned by the class loader must be held strongly live. Also dex caches
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// are held live to prevent them being unloading once they have classes in them.
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std::vector<GcRoot<mirror::Object>> strong_roots_ GUARDED_BY(lock_);
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// Keep track of oat files with GC roots associated with dex caches in `strong_roots_`.
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std::vector<const OatFile*> oat_files_ GUARDED_BY(lock_);
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friend class linker::ImageWriter; // for InsertWithoutLocks.
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};
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} // namespace art
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#endif // ART_RUNTIME_CLASS_TABLE_H_
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