runtime/mirror/object.cc - platform/art - Gitiles

 /*
  * 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 "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 "object_utils.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->IsReferenceClass());
     this->operator()(ref, mirror::Reference::ReferentOffset(), false);
   }

  private:
   Object* const dest_obj_;
 };

 static Object* CopyObject(Thread* self, mirror::Object* dest, mirror::Object* src, size_t num_bytes)
     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
   // 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);
     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)->CasLockWord(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.
         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()) {
           FieldHelper fh(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()) {
           FieldHelper fh(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
	/*
	* 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 "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 "object_utils.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->IsReferenceClass());
	this->operator()(ref, mirror::Reference::ReferentOffset(), false);
	}

	private:
	Object* const dest_obj_;
	};

	static Object* CopyObject(Thread* self, mirror::Object* dest, mirror::Object* src, size_t num_bytes)
	SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
	// 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);
	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)->CasLockWord(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.
	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()) {
	FieldHelper fh(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()) {
	FieldHelper fh(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