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android13/art/runtime/gc/accounting/mod_union_table.cc

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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 <memory>
#include "base/logging.h" // For VLOG
#include "base/stl_util.h"
#include "bitmap-inl.h"
#include "card_table-inl.h"
#include "gc/accounting/space_bitmap-inl.h"
#include "gc/heap.h"
#include "gc/space/image_space.h"
#include "gc/space/space.h"
#include "mirror/object-inl.h"
#include "mirror/object-refvisitor-inl.h"
#include "object_callbacks.h"
#include "space_bitmap-inl.h"
#include "thread-current-inl.h"
namespace art {
namespace gc {
namespace accounting {
class ModUnionAddToCardSetVisitor {
public:
explicit ModUnionAddToCardSetVisitor(ModUnionTable::CardSet* const cleared_cards)
: cleared_cards_(cleared_cards) {}
inline void operator()(uint8_t* card,
uint8_t expected_value,
uint8_t new_value ATTRIBUTE_UNUSED) const {
if (expected_value == CardTable::kCardDirty) {
cleared_cards_->insert(card);
}
}
private:
ModUnionTable::CardSet* const cleared_cards_;
};
class ModUnionAddToCardBitmapVisitor {
public:
ModUnionAddToCardBitmapVisitor(ModUnionTable::CardBitmap* bitmap, CardTable* card_table)
: bitmap_(bitmap), card_table_(card_table) {}
inline void operator()(uint8_t* card,
uint8_t expected_value,
uint8_t new_value ATTRIBUTE_UNUSED) const {
if (expected_value == CardTable::kCardDirty) {
// We want the address the card represents, not the address of the card.
bitmap_->Set(reinterpret_cast<uintptr_t>(card_table_->AddrFromCard(card)));
}
}
private:
ModUnionTable::CardBitmap* const bitmap_;
CardTable* const card_table_;
};
class ModUnionAddToCardVectorVisitor {
public:
explicit ModUnionAddToCardVectorVisitor(std::vector<uint8_t*>* cleared_cards)
: cleared_cards_(cleared_cards) {
}
void operator()(uint8_t* card, uint8_t expected_card, uint8_t new_card ATTRIBUTE_UNUSED) const {
if (expected_card == CardTable::kCardDirty) {
cleared_cards_->push_back(card);
}
}
private:
std::vector<uint8_t*>* const cleared_cards_;
};
class ModUnionUpdateObjectReferencesVisitor {
public:
ModUnionUpdateObjectReferencesVisitor(MarkObjectVisitor* visitor,
space::ContinuousSpace* from_space,
space::ContinuousSpace* immune_space,
bool* contains_reference_to_other_space)
: visitor_(visitor),
from_space_(from_space),
immune_space_(immune_space),
contains_reference_to_other_space_(contains_reference_to_other_space) {}
// Extra parameters are required since we use this same visitor signature for checking objects.
void operator()(mirror::Object* obj, MemberOffset offset, bool is_static ATTRIBUTE_UNUSED) const
REQUIRES_SHARED(Locks::mutator_lock_) {
MarkReference(obj->GetFieldObjectReferenceAddr(offset));
}
void VisitRootIfNonNull(mirror::CompressedReference<mirror::Object>* root) const
REQUIRES_SHARED(Locks::mutator_lock_) {
VisitRoot(root);
}
void VisitRoot(mirror::CompressedReference<mirror::Object>* root) const
REQUIRES_SHARED(Locks::mutator_lock_) {
MarkReference(root);
}
private:
template<typename CompressedReferenceType>
void MarkReference(CompressedReferenceType* obj_ptr) const
REQUIRES_SHARED(Locks::mutator_lock_) {
// Only add the reference if it is non null and fits our criteria.
mirror::Object* ref = obj_ptr->AsMirrorPtr();
if (ref != nullptr && !from_space_->HasAddress(ref) && !immune_space_->HasAddress(ref)) {
*contains_reference_to_other_space_ = true;
mirror::Object* new_object = visitor_->MarkObject(ref);
if (ref != new_object) {
obj_ptr->Assign(new_object);
}
}
}
MarkObjectVisitor* const visitor_;
// Space which we are scanning
space::ContinuousSpace* const from_space_;
space::ContinuousSpace* const immune_space_;
// Set if we have any references to another space.
bool* const contains_reference_to_other_space_;
};
class ModUnionScanImageRootVisitor {
public:
// Immune space is any other space which we don't care about references to. Currently this is
// the image space in the case of the zygote mod union table.
ModUnionScanImageRootVisitor(MarkObjectVisitor* visitor,
space::ContinuousSpace* from_space,
space::ContinuousSpace* immune_space,
bool* contains_reference_to_other_space)
: visitor_(visitor),
from_space_(from_space),
immune_space_(immune_space),
contains_reference_to_other_space_(contains_reference_to_other_space) {}
void operator()(mirror::Object* root) const
REQUIRES(Locks::heap_bitmap_lock_)
REQUIRES_SHARED(Locks::mutator_lock_) {
DCHECK(root != nullptr);
ModUnionUpdateObjectReferencesVisitor ref_visitor(visitor_,
from_space_,
immune_space_,
contains_reference_to_other_space_);
root->VisitReferences(ref_visitor, VoidFunctor());
}
private:
MarkObjectVisitor* const visitor_;
// Space which we are scanning
space::ContinuousSpace* const from_space_;
space::ContinuousSpace* const immune_space_;
// Set if we have any references to another space.
bool* const contains_reference_to_other_space_;
};
void ModUnionTableReferenceCache::ProcessCards() {
CardTable* card_table = GetHeap()->GetCardTable();
ModUnionAddToCardSetVisitor 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);
}
void ModUnionTableReferenceCache::ClearTable() {
cleared_cards_.clear();
references_.clear();
}
class AddToReferenceArrayVisitor {
public:
AddToReferenceArrayVisitor(ModUnionTableReferenceCache* mod_union_table,
MarkObjectVisitor* visitor,
std::vector<mirror::HeapReference<mirror::Object>*>* references,
bool* has_target_reference)
: mod_union_table_(mod_union_table),
visitor_(visitor),
references_(references),
has_target_reference_(has_target_reference) {}
// Extra parameters are required since we use this same visitor signature for checking objects.
void operator()(mirror::Object* obj, MemberOffset offset, bool is_static ATTRIBUTE_UNUSED) const
REQUIRES_SHARED(Locks::mutator_lock_) {
mirror::HeapReference<mirror::Object>* ref_ptr = obj->GetFieldObjectReferenceAddr(offset);
mirror::Object* ref = ref_ptr->AsMirrorPtr();
// Only add the reference if it is non null and fits our criteria.
if (ref != nullptr && mod_union_table_->ShouldAddReference(ref)) {
// Push the adddress of the reference.
references_->push_back(ref_ptr);
}
}
void VisitRootIfNonNull(mirror::CompressedReference<mirror::Object>* root) const
REQUIRES_SHARED(Locks::mutator_lock_) {
if (!root->IsNull()) {
VisitRoot(root);
}
}
void VisitRoot(mirror::CompressedReference<mirror::Object>* root) const
REQUIRES_SHARED(Locks::mutator_lock_) {
if (mod_union_table_->ShouldAddReference(root->AsMirrorPtr())) {
*has_target_reference_ = true;
// TODO: Add MarkCompressedReference callback here.
mirror::Object* old_ref = root->AsMirrorPtr();
mirror::Object* new_ref = visitor_->MarkObject(old_ref);
if (old_ref != new_ref) {
root->Assign(new_ref);
}
}
}
private:
ModUnionTableReferenceCache* const mod_union_table_;
MarkObjectVisitor* const visitor_;
std::vector<mirror::HeapReference<mirror::Object>*>* const references_;
bool* const has_target_reference_;
};
class ModUnionReferenceVisitor {
public:
ModUnionReferenceVisitor(ModUnionTableReferenceCache* const mod_union_table,
MarkObjectVisitor* visitor,
std::vector<mirror::HeapReference<mirror::Object>*>* references,
bool* has_target_reference)
: mod_union_table_(mod_union_table),
visitor_(visitor),
references_(references),
has_target_reference_(has_target_reference) {}
void operator()(mirror::Object* obj) const
REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_) {
// 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_,
visitor_,
references_,
has_target_reference_);
obj->VisitReferences(visitor, VoidFunctor());
}
private:
ModUnionTableReferenceCache* const mod_union_table_;
MarkObjectVisitor* const visitor_;
std::vector<mirror::HeapReference<mirror::Object>*>* const references_;
bool* const has_target_reference_;
};
class CheckReferenceVisitor {
public:
CheckReferenceVisitor(ModUnionTableReferenceCache* mod_union_table,
const std::set<mirror::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()(mirror::Object* obj, MemberOffset offset, bool is_static ATTRIBUTE_UNUSED) const
REQUIRES_SHARED(Locks::heap_bitmap_lock_, Locks::mutator_lock_) {
mirror::Object* ref = obj->GetFieldObject<mirror::Object>(offset);
if (ref != nullptr &&
mod_union_table_->ShouldAddReference(ref) &&
references_.find(ref) == references_.end()) {
Heap* heap = mod_union_table_->GetHeap();
space::ContinuousSpace* from_space = heap->FindContinuousSpaceFromObject(obj, false);
space::ContinuousSpace* to_space = heap->FindContinuousSpaceFromObject(ref, false);
LOG(INFO) << "Object " << reinterpret_cast<const void*>(obj) << "(" << obj->PrettyTypeOf()
<< ")" << "References "
<< reinterpret_cast<const void*>(ref) << "(" << mirror::Object::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();
heap->DumpSpaces(LOG_STREAM(INFO));
LOG(FATAL) << "FATAL ERROR";
}
}
void VisitRootIfNonNull(mirror::CompressedReference<mirror::Object>* root) const
REQUIRES_SHARED(Locks::mutator_lock_) {
if (kIsDebugBuild && !root->IsNull()) {
VisitRoot(root);
}
}
void VisitRoot(mirror::CompressedReference<mirror::Object>* root) const
REQUIRES_SHARED(Locks::mutator_lock_) {
DCHECK(!mod_union_table_->ShouldAddReference(root->AsMirrorPtr()));
}
private:
ModUnionTableReferenceCache* const mod_union_table_;
const std::set<mirror::Object*>& references_;
};
class ModUnionCheckReferences {
public:
ModUnionCheckReferences(ModUnionTableReferenceCache* mod_union_table,
const std::set<mirror::Object*>& references)
REQUIRES(Locks::heap_bitmap_lock_)
: mod_union_table_(mod_union_table), references_(references) {}
void operator()(mirror::Object* obj) const NO_THREAD_SAFETY_ANALYSIS {
Locks::heap_bitmap_lock_->AssertSharedHeld(Thread::Current());
CheckReferenceVisitor visitor(mod_union_table_, references_);
obj->VisitReferences(visitor, VoidFunctor());
}
private:
ModUnionTableReferenceCache* const mod_union_table_;
const std::set<mirror::Object*>& references_;
};
class EmptyMarkObjectVisitor : public MarkObjectVisitor {
public:
mirror::Object* MarkObject(mirror::Object* obj) override {return obj;}
void MarkHeapReference(mirror::HeapReference<mirror::Object>*, bool) override {}
};
void ModUnionTable::FilterCards() {
EmptyMarkObjectVisitor visitor;
// Use empty visitor since filtering is automatically done by UpdateAndMarkReferences.
UpdateAndMarkReferences(&visitor);
}
void ModUnionTableReferenceCache::Verify() {
// Start by checking that everything in the mod union table is marked.
for (const auto& ref_pair : references_) {
for (mirror::HeapReference<mirror::Object>* ref : ref_pair.second) {
CHECK(heap_->IsLiveObjectLocked(ref->AsMirrorPtr()));
}
}
// Check the references of each clean card which is also in the mod union table.
CardTable* card_table = heap_->GetCardTable();
ContinuousSpaceBitmap* live_bitmap = space_->GetLiveBitmap();
for (const auto& ref_pair : references_) {
const uint8_t* card = ref_pair.first;
if (*card == CardTable::kCardClean) {
std::set<mirror::Object*> reference_set;
for (mirror::HeapReference<mirror::Object>* obj_ptr : ref_pair.second) {
reference_set.insert(obj_ptr->AsMirrorPtr());
}
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 (uint8_t* 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 uint8_t* 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 (mirror::HeapReference<mirror::Object>* ref : ref_pair.second) {
os << reinterpret_cast<const void*>(ref->AsMirrorPtr()) << ",";
}
os << "},";
}
}
void ModUnionTableReferenceCache::VisitObjects(ObjectCallback callback, void* arg) {
CardTable* const card_table = heap_->GetCardTable();
ContinuousSpaceBitmap* live_bitmap = space_->GetLiveBitmap();
for (uint8_t* card : cleared_cards_) {
uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card));
uintptr_t end = start + CardTable::kCardSize;
live_bitmap->VisitMarkedRange(start,
end,
[callback, arg](mirror::Object* obj) {
callback(obj, arg);
});
}
// This may visit the same card twice, TODO avoid this.
for (const auto& pair : references_) {
const uint8_t* card = pair.first;
uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card));
uintptr_t end = start + CardTable::kCardSize;
live_bitmap->VisitMarkedRange(start,
end,
[callback, arg](mirror::Object* obj) {
callback(obj, arg);
});
}
}
void ModUnionTableReferenceCache::UpdateAndMarkReferences(MarkObjectVisitor* visitor) {
CardTable* const card_table = heap_->GetCardTable();
std::vector<mirror::HeapReference<mirror::Object>*> cards_references;
// If has_target_reference is true then there was a GcRoot compressed reference which wasn't
// added. In this case we need to keep the card dirty.
// We don't know if the GcRoot addresses will remain constant, for example, classloaders have a
// hash set of GcRoot which may be resized or modified.
bool has_target_reference;
ModUnionReferenceVisitor add_visitor(this, visitor, &cards_references, &has_target_reference);
CardSet new_cleared_cards;
for (uint8_t* card : cleared_cards_) {
// Clear and re-compute alloc space references associated with this card.
cards_references.clear();
has_target_reference = false;
uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card));
uintptr_t end = start + CardTable::kCardSize;
space::ContinuousSpace* space =
heap_->FindContinuousSpaceFromObject(reinterpret_cast<mirror::Object*>(start), false);
DCHECK(space != nullptr);
ContinuousSpaceBitmap* 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()) {
// Don't add card for an empty reference array.
if (!cards_references.empty()) {
references_.Put(card, cards_references);
}
} else {
if (cards_references.empty()) {
references_.erase(found);
} else {
found->second = cards_references;
}
}
if (has_target_reference) {
// Keep this card for next time since it contains a GcRoot which matches the
// ShouldAddReference criteria. This usually occurs for class loaders.
new_cleared_cards.insert(card);
}
}
cleared_cards_ = std::move(new_cleared_cards);
size_t count = 0;
for (auto it = references_.begin(); it != references_.end();) {
std::vector<mirror::HeapReference<mirror::Object>*>& references = it->second;
// Since there is no card mark for setting a reference to null, we check each reference.
// If all of the references of a card are null then we can remove that card. This is racy
// with the mutators, but handled by rescanning dirty cards.
bool all_null = true;
for (mirror::HeapReference<mirror::Object>* obj_ptr : references) {
if (obj_ptr->AsMirrorPtr() != nullptr) {
all_null = false;
visitor->MarkHeapReference(obj_ptr, /*do_atomic_update=*/ false);
}
}
count += references.size();
if (!all_null) {
++it;
} else {
// All null references, erase the array from the set.
it = references_.erase(it);
}
}
if (VLOG_IS_ON(heap)) {
VLOG(gc) << "Marked " << count << " references in mod union table";
}
}
ModUnionTableCardCache::ModUnionTableCardCache(const std::string& name,
Heap* heap,
space::ContinuousSpace* space)
: ModUnionTable(name, heap, space) {
// Normally here we could use End() instead of Limit(), but for testing we may want to have a
// mod-union table for a space which can still grow.
if (!space->IsImageSpace()) {
CHECK_ALIGNED(reinterpret_cast<uintptr_t>(space->Limit()), CardTable::kCardSize);
}
card_bitmap_.reset(CardBitmap::Create(
"mod union bitmap", reinterpret_cast<uintptr_t>(space->Begin()),
RoundUp(reinterpret_cast<uintptr_t>(space->Limit()), CardTable::kCardSize)));
}
class CardBitVisitor {
public:
CardBitVisitor(MarkObjectVisitor* visitor,
space::ContinuousSpace* space,
space::ContinuousSpace* immune_space,
ModUnionTable::CardBitmap* card_bitmap)
: visitor_(visitor),
space_(space),
immune_space_(immune_space),
bitmap_(space->GetLiveBitmap()),
card_bitmap_(card_bitmap) {
DCHECK(immune_space_ != nullptr);
}
void operator()(size_t bit_index) const {
const uintptr_t start = card_bitmap_->AddrFromBitIndex(bit_index);
DCHECK(space_->HasAddress(reinterpret_cast<mirror::Object*>(start)))
<< start << " " << *space_;
bool reference_to_other_space = false;
ModUnionScanImageRootVisitor scan_visitor(visitor_, space_, immune_space_,
&reference_to_other_space);
bitmap_->VisitMarkedRange(start, start + CardTable::kCardSize, scan_visitor);
if (!reference_to_other_space) {
// No non null reference to another space, clear the bit.
card_bitmap_->ClearBit(bit_index);
}
}
private:
MarkObjectVisitor* const visitor_;
space::ContinuousSpace* const space_;
space::ContinuousSpace* const immune_space_;
ContinuousSpaceBitmap* const bitmap_;
ModUnionTable::CardBitmap* const card_bitmap_;
};
void ModUnionTableCardCache::ProcessCards() {
CardTable* const card_table = GetHeap()->GetCardTable();
ModUnionAddToCardBitmapVisitor visitor(card_bitmap_.get(), card_table);
// Clear dirty cards in the this space and update the corresponding mod-union bits.
card_table->ModifyCardsAtomic(space_->Begin(), space_->End(), AgeCardVisitor(), visitor);
}
void ModUnionTableCardCache::ClearTable() {
card_bitmap_->Bitmap::Clear();
}
// Mark all references to the alloc space(s).
void ModUnionTableCardCache::UpdateAndMarkReferences(MarkObjectVisitor* visitor) {
// TODO: Needs better support for multi-images? b/26317072
space::ImageSpace* image_space =
heap_->GetBootImageSpaces().empty() ? nullptr : heap_->GetBootImageSpaces()[0];
// If we don't have an image space, just pass in space_ as the immune space. Pass in the same
// space_ instead of image_space to avoid a null check in ModUnionUpdateObjectReferencesVisitor.
CardBitVisitor bit_visitor(visitor, space_, image_space != nullptr ? image_space : space_,
card_bitmap_.get());
card_bitmap_->VisitSetBits(
0, RoundUp(space_->Size(), CardTable::kCardSize) / CardTable::kCardSize, bit_visitor);
}
void ModUnionTableCardCache::VisitObjects(ObjectCallback callback, void* arg) {
card_bitmap_->VisitSetBits(
0,
RoundUp(space_->Size(), CardTable::kCardSize) / CardTable::kCardSize,
[this, callback, arg](size_t bit_index) {
const uintptr_t start = card_bitmap_->AddrFromBitIndex(bit_index);
DCHECK(space_->HasAddress(reinterpret_cast<mirror::Object*>(start)))
<< start << " " << *space_;
space_->GetLiveBitmap()->VisitMarkedRange(start,
start + CardTable::kCardSize,
[callback, arg](mirror::Object* obj) {
callback(obj, arg);
});
});
}
void ModUnionTableCardCache::Dump(std::ostream& os) {
os << "ModUnionTable dirty cards: [";
// TODO: Find cleaner way of doing this.
for (uint8_t* addr = space_->Begin(); addr < AlignUp(space_->End(), CardTable::kCardSize);
addr += CardTable::kCardSize) {
if (card_bitmap_->Test(reinterpret_cast<uintptr_t>(addr))) {
os << reinterpret_cast<void*>(addr) << "-"
<< reinterpret_cast<void*>(addr + CardTable::kCardSize) << "\n";
}
}
os << "]";
}
void ModUnionTableCardCache::SetCards() {
// Only clean up to the end since there cannot be any objects past the End() of the space.
for (uint8_t* addr = space_->Begin(); addr < AlignUp(space_->End(), CardTable::kCardSize);
addr += CardTable::kCardSize) {
card_bitmap_->Set(reinterpret_cast<uintptr_t>(addr));
}
}
bool ModUnionTableCardCache::ContainsCardFor(uintptr_t addr) {
return card_bitmap_->Test(addr);
}
void ModUnionTableReferenceCache::SetCards() {
for (uint8_t* addr = space_->Begin(); addr < AlignUp(space_->End(), CardTable::kCardSize);
addr += CardTable::kCardSize) {
cleared_cards_.insert(heap_->GetCardTable()->CardFromAddr(reinterpret_cast<void*>(addr)));
}
}
bool ModUnionTableReferenceCache::ContainsCardFor(uintptr_t addr) {
auto* card_ptr = heap_->GetCardTable()->CardFromAddr(reinterpret_cast<void*>(addr));
return cleared_cards_.find(card_ptr) != cleared_cards_.end() ||
references_.find(card_ptr) != references_.end();
}
} // namespace accounting
} // namespace gc
} // namespace art
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