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/*
* Copyright (C) 2012 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 "mod_union_table.h"
#include "base/stl_util.h"
#include "card_table-inl.h"
#include "heap_bitmap.h"
#include "gc/collector/mark_sweep.h"
#include "gc/collector/mark_sweep-inl.h"
#include "gc/heap.h"
#include "gc/space/space.h"
#include "mirror/art_field-inl.h"
#include "mirror/object-inl.h"
#include "mirror/class-inl.h"
#include "mirror/object_array-inl.h"
#include "space_bitmap-inl.h"
#include "thread.h"
#include "UniquePtr.h"
using ::art::mirror::Object;
namespace art {
namespace gc {
namespace accounting {
class ModUnionClearCardSetVisitor {
public:
explicit ModUnionClearCardSetVisitor(ModUnionTable::CardSet* const cleared_cards)
: cleared_cards_(cleared_cards) {
}
inline void operator()(byte* card, byte expected_value, byte new_value) const {
if (expected_value == CardTable::kCardDirty) {
cleared_cards_->insert(card);
}
}
private:
ModUnionTable::CardSet* const cleared_cards_;
};
class ModUnionClearCardVisitor {
public:
explicit ModUnionClearCardVisitor(std::vector<byte*>* cleared_cards)
: cleared_cards_(cleared_cards) {
}
void operator()(byte* card, byte expected_card, byte new_card) const {
if (expected_card == CardTable::kCardDirty) {
cleared_cards_->push_back(card);
}
}
private:
std::vector<byte*>* const cleared_cards_;
};
class ModUnionUpdateObjectReferencesVisitor {
public:
ModUnionUpdateObjectReferencesVisitor(RootVisitor visitor, void* arg)
: visitor_(visitor),
arg_(arg) {
}
// Extra parameters are required since we use this same visitor signature for checking objects.
void operator()(Object* obj, Object* ref, const MemberOffset& offset,
bool /* is_static */) const SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
// Only add the reference if it is non null and fits our criteria.
if (ref != nullptr) {
Object* new_ref = visitor_(ref, arg_);
if (new_ref != ref) {
// Use SetFieldPtr to avoid card mark as an optimization which reduces dirtied pages and
// improves performance.
obj->SetFieldPtr(offset, new_ref, true);
}
}
}
private:
RootVisitor* visitor_;
void* arg_;
};
class ModUnionScanImageRootVisitor {
public:
ModUnionScanImageRootVisitor(RootVisitor visitor, void* arg)
: visitor_(visitor), arg_(arg) {}
void operator()(Object* root) const
EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
DCHECK(root != NULL);
ModUnionUpdateObjectReferencesVisitor ref_visitor(visitor_, arg_);
collector::MarkSweep::VisitObjectReferences(root, ref_visitor, true);
}
private:
RootVisitor* visitor_;
void* arg_;
};
void ModUnionTableReferenceCache::ClearCards() {
CardTable* card_table = GetHeap()->GetCardTable();
ModUnionClearCardSetVisitor visitor(&cleared_cards_);
// Clear dirty cards in the this space and update the corresponding mod-union bits.
card_table->ModifyCardsAtomic(space_->Begin(), space_->End(), AgeCardVisitor(), visitor);
}
class AddToReferenceArrayVisitor {
public:
explicit AddToReferenceArrayVisitor(ModUnionTableReferenceCache* mod_union_table,
std::vector<Object**>* references)
: mod_union_table_(mod_union_table),
references_(references) {
}
// Extra parameters are required since we use this same visitor signature for checking objects.
void operator()(Object* obj, Object* ref, const MemberOffset& offset,
bool /* is_static */) const {
// Only add the reference if it is non null and fits our criteria.
if (ref != nullptr && mod_union_table_->AddReference(obj, ref)) {
// Push the adddress of the reference.
references_->push_back(obj->GetFieldObjectAddr(offset));
}
}
private:
ModUnionTableReferenceCache* const mod_union_table_;
std::vector<Object**>* const references_;
};
class ModUnionReferenceVisitor {
public:
explicit ModUnionReferenceVisitor(ModUnionTableReferenceCache* const mod_union_table,
std::vector<Object**>* references)
: mod_union_table_(mod_union_table),
references_(references) {
}
void operator()(Object* obj) const
SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_) {
DCHECK(obj != NULL);
// We don't have an early exit since we use the visitor pattern, an early
// exit should significantly speed this up.
AddToReferenceArrayVisitor visitor(mod_union_table_, references_);
collector::MarkSweep::VisitObjectReferences(obj, visitor, true);
}
private:
ModUnionTableReferenceCache* const mod_union_table_;
std::vector<Object**>* const references_;
};
class CheckReferenceVisitor {
public:
explicit CheckReferenceVisitor(ModUnionTableReferenceCache* mod_union_table,
const std::set<const Object*>& references)
: mod_union_table_(mod_union_table),
references_(references) {
}
// Extra parameters are required since we use this same visitor signature for checking objects.
// TODO: Fixme when anotatalysis works with visitors.
void operator()(const Object* obj, const Object* ref,
const MemberOffset& /* offset */, bool /* is_static */) const
SHARED_LOCKS_REQUIRED(Locks::heap_bitmap_lock_, Locks::mutator_lock_) {
Heap* heap = mod_union_table_->GetHeap();
if (ref != NULL && mod_union_table_->AddReference(obj, ref) &&
references_.find(ref) == references_.end()) {
space::ContinuousSpace* from_space = heap->FindContinuousSpaceFromObject(obj, false);
space::ContinuousSpace* to_space = heap->FindContinuousSpaceFromObject(ref, false);
LOG(INFO) << "Object " << reinterpret_cast<const void*>(obj) << "(" << PrettyTypeOf(obj) << ")"
<< "References " << reinterpret_cast<const void*>(ref)
<< "(" << PrettyTypeOf(ref) << ") without being in mod-union table";
LOG(INFO) << "FromSpace " << from_space->GetName() << " type " << from_space->GetGcRetentionPolicy();
LOG(INFO) << "ToSpace " << to_space->GetName() << " type " << to_space->GetGcRetentionPolicy();
mod_union_table_->GetHeap()->DumpSpaces();
LOG(FATAL) << "FATAL ERROR";
}
}
private:
ModUnionTableReferenceCache* const mod_union_table_;
const std::set<const Object*>& references_;
};
class ModUnionCheckReferences {
public:
explicit ModUnionCheckReferences(ModUnionTableReferenceCache* mod_union_table,
const std::set<const Object*>& references)
EXCLUSIVE_LOCKS_REQUIRED(Locks::heap_bitmap_lock_)
: mod_union_table_(mod_union_table), references_(references) {
}
void operator()(Object* obj) const NO_THREAD_SAFETY_ANALYSIS {
Locks::heap_bitmap_lock_->AssertSharedHeld(Thread::Current());
DCHECK(obj != NULL);
CheckReferenceVisitor visitor(mod_union_table_, references_);
collector::MarkSweep::VisitObjectReferences(obj, visitor, true);
}
private:
ModUnionTableReferenceCache* const mod_union_table_;
const std::set<const Object*>& references_;
};
void ModUnionTableReferenceCache::Verify() {
// Start by checking that everything in the mod union table is marked.
for (const auto& ref_pair : references_) {
for (Object** ref : ref_pair.second) {
CHECK(heap_->IsLiveObjectLocked(*ref));
}
}
// Check the references of each clean card which is also in the mod union table.
CardTable* card_table = heap_->GetCardTable();
SpaceBitmap* live_bitmap = space_->GetLiveBitmap();
for (const auto& ref_pair : references_) {
const byte* card = ref_pair.first;
if (*card == CardTable::kCardClean) {
std::set<const Object*> reference_set;
for (Object** obj_ptr : ref_pair.second) {
reference_set.insert(*obj_ptr);
}
ModUnionCheckReferences visitor(this, reference_set);
uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card));
live_bitmap->VisitMarkedRange(start, start + CardTable::kCardSize, visitor);
}
}
}
void ModUnionTableReferenceCache::Dump(std::ostream& os) {
CardTable* card_table = heap_->GetCardTable();
os << "ModUnionTable cleared cards: [";
for (byte* card_addr : cleared_cards_) {
uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card_addr));
uintptr_t end = start + CardTable::kCardSize;
os << reinterpret_cast<void*>(start) << "-" << reinterpret_cast<void*>(end) << ",";
}
os << "]\nModUnionTable references: [";
for (const auto& ref_pair : references_) {
const byte* card_addr = ref_pair.first;
uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card_addr));
uintptr_t end = start + CardTable::kCardSize;
os << reinterpret_cast<void*>(start) << "-" << reinterpret_cast<void*>(end) << "->{";
for (Object** ref : ref_pair.second) {
os << reinterpret_cast<const void*>(*ref) << ",";
}
os << "},";
}
}
void ModUnionTableReferenceCache::UpdateAndMarkReferences(RootVisitor visitor, void* arg) {
Heap* heap = GetHeap();
CardTable* card_table = heap->GetCardTable();
std::vector<Object**> cards_references;
ModUnionReferenceVisitor add_visitor(this, &cards_references);
for (const auto& card : cleared_cards_) {
// Clear and re-compute alloc space references associated with this card.
cards_references.clear();
uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card));
uintptr_t end = start + CardTable::kCardSize;
auto* space = heap->FindContinuousSpaceFromObject(reinterpret_cast<Object*>(start), false);
DCHECK(space != nullptr);
SpaceBitmap* live_bitmap = space->GetLiveBitmap();
live_bitmap->VisitMarkedRange(start, end, add_visitor);
// Update the corresponding references for the card.
auto found = references_.find(card);
if (found == references_.end()) {
if (cards_references.empty()) {
// No reason to add empty array.
continue;
}
references_.Put(card, cards_references);
} else {
found->second = cards_references;
}
}
cleared_cards_.clear();
size_t count = 0;
for (const auto& ref : references_) {
for (const auto& obj_ptr : ref.second) {
Object* obj = *obj_ptr;
if (obj != nullptr) {
Object* new_obj = visitor(obj, arg);
// Avoid dirtying pages in the image unless necessary.
if (new_obj != obj) {
*obj_ptr = new_obj;
}
}
}
count += ref.second.size();
}
if (VLOG_IS_ON(heap)) {
VLOG(gc) << "Marked " << count << " references in mod union table";
}
}
void ModUnionTableCardCache::ClearCards() {
CardTable* card_table = GetHeap()->GetCardTable();
ModUnionClearCardSetVisitor visitor(&cleared_cards_);
// Clear dirty cards in the this space and update the corresponding mod-union bits.
card_table->ModifyCardsAtomic(space_->Begin(), space_->End(), AgeCardVisitor(), visitor);
}
// Mark all references to the alloc space(s).
void ModUnionTableCardCache::UpdateAndMarkReferences(RootVisitor visitor, void* arg) {
CardTable* card_table = heap_->GetCardTable();
ModUnionScanImageRootVisitor scan_visitor(visitor, arg);
SpaceBitmap* bitmap = space_->GetLiveBitmap();
for (const byte* card_addr : cleared_cards_) {
uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card_addr));
DCHECK(space_->HasAddress(reinterpret_cast<Object*>(start)));
bitmap->VisitMarkedRange(start, start + CardTable::kCardSize, scan_visitor);
}
}
void ModUnionTableCardCache::Dump(std::ostream& os) {
CardTable* card_table = heap_->GetCardTable();
os << "ModUnionTable dirty cards: [";
for (const byte* card_addr : cleared_cards_) {
auto start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card_addr));
auto end = start + CardTable::kCardSize;
os << reinterpret_cast<void*>(start) << "-" << reinterpret_cast<void*>(end) << "\n";
}
os << "]";
}
} // namespace accounting
} // namespace gc
} // namespace art