/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <ctime>
#include "object.h"
#include "art_field.h"
#include "art_field-inl.h"
#include "array-inl.h"
#include "class.h"
#include "class-inl.h"
#include "class_linker-inl.h"
#include "field_helper.h"
#include "gc/accounting/card_table-inl.h"
#include "gc/heap.h"
#include "iftable-inl.h"
#include "monitor.h"
#include "object-inl.h"
#include "object_array-inl.h"
#include "runtime.h"
#include "handle_scope-inl.h"
#include "throwable.h"
#include "well_known_classes.h"
namespace art {
namespace mirror {
class CopyReferenceFieldsWithReadBarrierVisitor {
public:
explicit CopyReferenceFieldsWithReadBarrierVisitor(Object* dest_obj)
: dest_obj_(dest_obj) {}
void operator()(Object* obj, MemberOffset offset, bool /* is_static */) const
ALWAYS_INLINE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
// GetFieldObject() contains a RB.
Object* ref = obj->GetFieldObject<Object>(offset);
// No WB here as a large object space does not have a card table
// coverage. Instead, cards will be marked separately.
dest_obj_->SetFieldObjectWithoutWriteBarrier<false, false>(offset, ref);
}
void operator()(mirror::Class* klass, mirror::Reference* ref) const
ALWAYS_INLINE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
// Copy java.lang.ref.Reference.referent which isn't visited in
// Object::VisitReferences().
DCHECK(klass->IsTypeOfReferenceClass());
this->operator()(ref, mirror::Reference::ReferentOffset(), false);
}
private:
Object* const dest_obj_;
};
Object* Object::CopyObject(Thread* self, mirror::Object* dest, mirror::Object* src,
size_t num_bytes) {
// Copy instance data. We assume memcpy copies by words.
// TODO: expose and use move32.
byte* src_bytes = reinterpret_cast<byte*>(src);
byte* dst_bytes = reinterpret_cast<byte*>(dest);
size_t offset = sizeof(Object);
memcpy(dst_bytes + offset, src_bytes + offset, num_bytes - offset);
if (kUseBakerOrBrooksReadBarrier) {
// We need a RB here. After the memcpy that covers the whole
// object above, copy references fields one by one again with a
// RB. TODO: Optimize this later?
CopyReferenceFieldsWithReadBarrierVisitor visitor(dest);
src->VisitReferences<true>(visitor, visitor);
}
gc::Heap* heap = Runtime::Current()->GetHeap();
// Perform write barriers on copied object references.
Class* c = src->GetClass();
if (c->IsArrayClass()) {
if (!c->GetComponentType()->IsPrimitive()) {
ObjectArray<Object>* array = dest->AsObjectArray<Object>();
heap->WriteBarrierArray(dest, 0, array->GetLength());
}
} else {
heap->WriteBarrierEveryFieldOf(dest);
}
if (c->IsFinalizable()) {
heap->AddFinalizerReference(self, &dest);
}
return dest;
}
// An allocation pre-fence visitor that copies the object.
class CopyObjectVisitor {
public:
explicit CopyObjectVisitor(Thread* self, Handle<Object>* orig, size_t num_bytes)
: self_(self), orig_(orig), num_bytes_(num_bytes) {
}
void operator()(Object* obj, size_t usable_size) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
UNUSED(usable_size);
Object::CopyObject(self_, obj, orig_->Get(), num_bytes_);
}
private:
Thread* const self_;
Handle<Object>* const orig_;
const size_t num_bytes_;
DISALLOW_COPY_AND_ASSIGN(CopyObjectVisitor);
};
Object* Object::Clone(Thread* self) {
CHECK(!IsClass()) << "Can't clone classes.";
// Object::SizeOf gets the right size even if we're an array. Using c->AllocObject() here would
// be wrong.
gc::Heap* heap = Runtime::Current()->GetHeap();
size_t num_bytes = SizeOf();
StackHandleScope<1> hs(self);
Handle<Object> this_object(hs.NewHandle(this));
Object* copy;
CopyObjectVisitor visitor(self, &this_object, num_bytes);
if (heap->IsMovableObject(this)) {
copy = heap->AllocObject<true>(self, GetClass(), num_bytes, visitor);
} else {
copy = heap->AllocNonMovableObject<true>(self, GetClass(), num_bytes, visitor);
}
return copy;
}
int32_t Object::GenerateIdentityHashCode() {
static AtomicInteger seed(987654321 + std::time(nullptr));
int32_t expected_value, new_value;
do {
expected_value = static_cast<uint32_t>(seed.LoadRelaxed());
new_value = expected_value * 1103515245 + 12345;
} while ((expected_value & LockWord::kHashMask) == 0 ||
!seed.CompareExchangeWeakRelaxed(expected_value, new_value));
return expected_value & LockWord::kHashMask;
}
int32_t Object::IdentityHashCode() const {
mirror::Object* current_this = const_cast<mirror::Object*>(this);
while (true) {
LockWord lw = current_this->GetLockWord(false);
switch (lw.GetState()) {
case LockWord::kUnlocked: {
// Try to compare and swap in a new hash, if we succeed we will return the hash on the next
// loop iteration.
LockWord hash_word(LockWord::FromHashCode(GenerateIdentityHashCode()));
DCHECK_EQ(hash_word.GetState(), LockWord::kHashCode);
if (const_cast<Object*>(this)->CasLockWordWeakRelaxed(lw, hash_word)) {
return hash_word.GetHashCode();
}
break;
}
case LockWord::kThinLocked: {
// Inflate the thin lock to a monitor and stick the hash code inside of the monitor. May
// fail spuriously.
Thread* self = Thread::Current();
StackHandleScope<1> hs(self);
Handle<mirror::Object> h_this(hs.NewHandle(current_this));
Monitor::InflateThinLocked(self, h_this, lw, GenerateIdentityHashCode());
// A GC may have occurred when we switched to kBlocked.
current_this = h_this.Get();
break;
}
case LockWord::kFatLocked: {
// Already inflated, return the has stored in the monitor.
Monitor* monitor = lw.FatLockMonitor();
DCHECK(monitor != nullptr);
return monitor->GetHashCode();
}
case LockWord::kHashCode: {
return lw.GetHashCode();
}
default: {
LOG(FATAL) << "Invalid state during hashcode " << lw.GetState();
break;
}
}
}
LOG(FATAL) << "Unreachable";
return 0;
}
void Object::CheckFieldAssignmentImpl(MemberOffset field_offset, Object* new_value) {
Class* c = GetClass();
Runtime* runtime = Runtime::Current();
if (runtime->GetClassLinker() == nullptr || !runtime->IsStarted() ||
!runtime->GetHeap()->IsObjectValidationEnabled() || !c->IsResolved()) {
return;
}
for (Class* cur = c; cur != NULL; cur = cur->GetSuperClass()) {
ObjectArray<ArtField>* fields = cur->GetIFields();
if (fields != NULL) {
size_t num_ref_ifields = cur->NumReferenceInstanceFields();
for (size_t i = 0; i < num_ref_ifields; ++i) {
ArtField* field = fields->Get(i);
if (field->GetOffset().Int32Value() == field_offset.Int32Value()) {
StackHandleScope<1> hs(Thread::Current());
FieldHelper fh(hs.NewHandle(field));
CHECK(fh.GetType()->IsAssignableFrom(new_value->GetClass()));
return;
}
}
}
}
if (c->IsArrayClass()) {
// Bounds and assign-ability done in the array setter.
return;
}
if (IsClass()) {
ObjectArray<ArtField>* fields = AsClass()->GetSFields();
if (fields != NULL) {
size_t num_ref_sfields = AsClass()->NumReferenceStaticFields();
for (size_t i = 0; i < num_ref_sfields; ++i) {
ArtField* field = fields->Get(i);
if (field->GetOffset().Int32Value() == field_offset.Int32Value()) {
StackHandleScope<1> hs(Thread::Current());
FieldHelper fh(hs.NewHandle(field));
CHECK(fh.GetType()->IsAssignableFrom(new_value->GetClass()));
return;
}
}
}
}
LOG(FATAL) << "Failed to find field for assignment to " << reinterpret_cast<void*>(this)
<< " of type " << PrettyDescriptor(c) << " at offset " << field_offset;
}
} // namespace mirror
} // namespace art