248 lines
8.6 KiB
C++
248 lines
8.6 KiB
C++
/*
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* Copyright (C) 2011 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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#include <ctime>
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#include "object.h"
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#include "art_field.h"
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#include "art_field-inl.h"
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#include "array-inl.h"
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#include "class.h"
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#include "class-inl.h"
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#include "class_linker-inl.h"
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#include "field_helper.h"
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#include "gc/accounting/card_table-inl.h"
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#include "gc/heap.h"
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#include "iftable-inl.h"
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#include "monitor.h"
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#include "object-inl.h"
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#include "object_array-inl.h"
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#include "runtime.h"
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#include "handle_scope-inl.h"
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#include "throwable.h"
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#include "well_known_classes.h"
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namespace art {
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namespace mirror {
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Atomic<uint32_t> Object::hash_code_seed(987654321U + std::time(nullptr));
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class CopyReferenceFieldsWithReadBarrierVisitor {
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public:
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explicit CopyReferenceFieldsWithReadBarrierVisitor(Object* dest_obj)
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: dest_obj_(dest_obj) {}
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void operator()(Object* obj, MemberOffset offset, bool /* is_static */) const
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ALWAYS_INLINE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
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// GetFieldObject() contains a RB.
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Object* ref = obj->GetFieldObject<Object>(offset);
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// No WB here as a large object space does not have a card table
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// coverage. Instead, cards will be marked separately.
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dest_obj_->SetFieldObjectWithoutWriteBarrier<false, false>(offset, ref);
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}
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void operator()(mirror::Class* klass, mirror::Reference* ref) const
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ALWAYS_INLINE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
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// Copy java.lang.ref.Reference.referent which isn't visited in
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// Object::VisitReferences().
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DCHECK(klass->IsTypeOfReferenceClass());
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this->operator()(ref, mirror::Reference::ReferentOffset(), false);
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}
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private:
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Object* const dest_obj_;
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};
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Object* Object::CopyObject(Thread* self, mirror::Object* dest, mirror::Object* src,
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size_t num_bytes) {
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// Copy instance data. We assume memcpy copies by words.
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// TODO: expose and use move32.
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byte* src_bytes = reinterpret_cast<byte*>(src);
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byte* dst_bytes = reinterpret_cast<byte*>(dest);
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size_t offset = sizeof(Object);
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memcpy(dst_bytes + offset, src_bytes + offset, num_bytes - offset);
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if (kUseBakerOrBrooksReadBarrier) {
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// We need a RB here. After the memcpy that covers the whole
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// object above, copy references fields one by one again with a
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// RB. TODO: Optimize this later?
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CopyReferenceFieldsWithReadBarrierVisitor visitor(dest);
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src->VisitReferences<true>(visitor, visitor);
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}
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gc::Heap* heap = Runtime::Current()->GetHeap();
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// Perform write barriers on copied object references.
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Class* c = src->GetClass();
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if (c->IsArrayClass()) {
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if (!c->GetComponentType()->IsPrimitive()) {
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ObjectArray<Object>* array = dest->AsObjectArray<Object>();
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heap->WriteBarrierArray(dest, 0, array->GetLength());
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}
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} else {
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heap->WriteBarrierEveryFieldOf(dest);
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}
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if (c->IsFinalizable()) {
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heap->AddFinalizerReference(self, &dest);
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}
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return dest;
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}
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// An allocation pre-fence visitor that copies the object.
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class CopyObjectVisitor {
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public:
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explicit CopyObjectVisitor(Thread* self, Handle<Object>* orig, size_t num_bytes)
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: self_(self), orig_(orig), num_bytes_(num_bytes) {
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}
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void operator()(Object* obj, size_t usable_size) const
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SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
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UNUSED(usable_size);
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Object::CopyObject(self_, obj, orig_->Get(), num_bytes_);
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}
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private:
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Thread* const self_;
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Handle<Object>* const orig_;
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const size_t num_bytes_;
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DISALLOW_COPY_AND_ASSIGN(CopyObjectVisitor);
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};
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Object* Object::Clone(Thread* self) {
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CHECK(!IsClass()) << "Can't clone classes.";
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// Object::SizeOf gets the right size even if we're an array. Using c->AllocObject() here would
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// be wrong.
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gc::Heap* heap = Runtime::Current()->GetHeap();
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size_t num_bytes = SizeOf();
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StackHandleScope<1> hs(self);
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Handle<Object> this_object(hs.NewHandle(this));
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Object* copy;
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CopyObjectVisitor visitor(self, &this_object, num_bytes);
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if (heap->IsMovableObject(this)) {
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copy = heap->AllocObject<true>(self, GetClass(), num_bytes, visitor);
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} else {
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copy = heap->AllocNonMovableObject<true>(self, GetClass(), num_bytes, visitor);
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}
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return copy;
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}
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uint32_t Object::GenerateIdentityHashCode() {
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uint32_t expected_value, new_value;
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do {
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expected_value = hash_code_seed.LoadRelaxed();
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new_value = expected_value * 1103515245 + 12345;
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} while (!hash_code_seed.CompareExchangeWeakRelaxed(expected_value, new_value) ||
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(expected_value & LockWord::kHashMask) == 0);
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return expected_value & LockWord::kHashMask;
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}
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void Object::SetHashCodeSeed(uint32_t new_seed) {
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hash_code_seed.StoreRelaxed(new_seed);
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}
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int32_t Object::IdentityHashCode() const {
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mirror::Object* current_this = const_cast<mirror::Object*>(this);
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while (true) {
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LockWord lw = current_this->GetLockWord(false);
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switch (lw.GetState()) {
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case LockWord::kUnlocked: {
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// Try to compare and swap in a new hash, if we succeed we will return the hash on the next
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// loop iteration.
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LockWord hash_word(LockWord::FromHashCode(GenerateIdentityHashCode()));
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DCHECK_EQ(hash_word.GetState(), LockWord::kHashCode);
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if (const_cast<Object*>(this)->CasLockWordWeakRelaxed(lw, hash_word)) {
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return hash_word.GetHashCode();
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}
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break;
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}
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case LockWord::kThinLocked: {
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// Inflate the thin lock to a monitor and stick the hash code inside of the monitor. May
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// fail spuriously.
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Thread* self = Thread::Current();
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StackHandleScope<1> hs(self);
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Handle<mirror::Object> h_this(hs.NewHandle(current_this));
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Monitor::InflateThinLocked(self, h_this, lw, GenerateIdentityHashCode());
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// A GC may have occurred when we switched to kBlocked.
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current_this = h_this.Get();
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break;
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}
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case LockWord::kFatLocked: {
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// Already inflated, return the has stored in the monitor.
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Monitor* monitor = lw.FatLockMonitor();
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DCHECK(monitor != nullptr);
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return monitor->GetHashCode();
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}
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case LockWord::kHashCode: {
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return lw.GetHashCode();
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}
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default: {
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LOG(FATAL) << "Invalid state during hashcode " << lw.GetState();
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break;
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}
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}
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}
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LOG(FATAL) << "Unreachable";
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return 0;
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}
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void Object::CheckFieldAssignmentImpl(MemberOffset field_offset, Object* new_value) {
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Class* c = GetClass();
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Runtime* runtime = Runtime::Current();
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if (runtime->GetClassLinker() == nullptr || !runtime->IsStarted() ||
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!runtime->GetHeap()->IsObjectValidationEnabled() || !c->IsResolved()) {
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return;
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}
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for (Class* cur = c; cur != NULL; cur = cur->GetSuperClass()) {
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ObjectArray<ArtField>* fields = cur->GetIFields();
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if (fields != NULL) {
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size_t num_ifields = fields->GetLength();
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for (size_t i = 0; i < num_ifields; ++i) {
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ArtField* field = fields->Get(i);
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if (field->GetOffset().Int32Value() == field_offset.Int32Value()) {
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CHECK_NE(field->GetTypeAsPrimitiveType(), Primitive::kPrimNot);
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StackHandleScope<1> hs(Thread::Current());
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FieldHelper fh(hs.NewHandle(field));
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CHECK(fh.GetType()->IsAssignableFrom(new_value->GetClass()));
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return;
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}
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}
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}
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}
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if (c->IsArrayClass()) {
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// Bounds and assign-ability done in the array setter.
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return;
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}
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if (IsClass()) {
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ObjectArray<ArtField>* fields = AsClass()->GetSFields();
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if (fields != NULL) {
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size_t num_sfields = fields->GetLength();
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for (size_t i = 0; i < num_sfields; ++i) {
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ArtField* field = fields->Get(i);
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if (field->GetOffset().Int32Value() == field_offset.Int32Value()) {
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CHECK_NE(field->GetTypeAsPrimitiveType(), Primitive::kPrimNot);
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StackHandleScope<1> hs(Thread::Current());
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FieldHelper fh(hs.NewHandle(field));
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CHECK(fh.GetType()->IsAssignableFrom(new_value->GetClass()));
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return;
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}
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}
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}
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}
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LOG(FATAL) << "Failed to find field for assignment to " << reinterpret_cast<void*>(this)
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<< " of type " << PrettyDescriptor(c) << " at offset " << field_offset;
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}
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} // namespace mirror
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} // namespace art
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