src/mod_union_table.cc - platform/art - Git at Google

 /*
  * 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 "heap.h"
 #include "heap_bitmap.h"
 #include "mark_sweep.h"
 #include "mod_union_table.h"
 #include "space.h"
 #include "stl_util.h"
 #include "UniquePtr.h"

 namespace art {

 class MarkIfReachesAllocspaceVisitor {
  public:
   explicit MarkIfReachesAllocspaceVisitor(MarkSweep* const mark_sweep, SpaceBitmap* bitmap)
     : mark_sweep_(mark_sweep),
       bitmap_(bitmap) {
   }

   // Extra parameters are required since we use this same visitor signature for checking objects.
   void operator ()(const Object* obj, const Object* ref, const MemberOffset& /* offset */, bool /* is_static */) const {
     // TODO: Optimize?
     // TODO: C++0x auto
     const Spaces& spaces = mark_sweep_->heap_->GetSpaces();
     for (Spaces::const_iterator cur = spaces.begin(); cur != spaces.end(); ++cur) {
       if ((*cur)->IsAllocSpace() && (*cur)->Contains(ref)) {
         bitmap_->Set(obj);
       }
     }
   }

  private:
   MarkSweep* const mark_sweep_;
   SpaceBitmap* bitmap_;
 };

 class ModUnionVisitor {
  public:
   explicit ModUnionVisitor(MarkSweep* const mark_sweep, SpaceBitmap* bitmap)
     : mark_sweep_(mark_sweep),
       bitmap_(bitmap) {
   }

   void operator ()(Object* obj) const {
     DCHECK(obj != NULL);
     // We don't have an early exit since we use the visitor pattern, an early
     // exit should significantly speed this up.
     MarkIfReachesAllocspaceVisitor visitor(mark_sweep_, bitmap_);
     mark_sweep_->VisitObjectReferences(obj, visitor);
   }
  private:
   MarkSweep* const mark_sweep_;
   SpaceBitmap* bitmap_;
 };

 class ModUnionClearCardVisitor {
  public:
   explicit ModUnionClearCardVisitor(std::vector<byte*>* cleared_cards)
     : cleared_cards_(cleared_cards) {
   }

   void operator ()(byte* card) const {
     cleared_cards_->push_back(card);
   }
  private:
   std::vector<byte*>* cleared_cards_;
 };

 ModUnionTableBitmap::ModUnionTableBitmap(Heap* heap) : heap_(heap) {
   // Prevent fragmentation of the heap which is caused by resizing of the vector.
   // TODO: Make a new vector which uses madvise (basically same as a mark stack).
   cleared_cards_.reserve(32);
 }

 ModUnionTableBitmap::~ModUnionTableBitmap() {
   STLDeleteValues(&bitmaps_);
 }

 void ModUnionTableBitmap::Init() {
   const Spaces& spaces = heap_->GetSpaces();

   // Create one heap bitmap per image space.
   for (size_t i = 0; i < spaces.size(); ++i) {
     if (spaces[i]->IsImageSpace()) {
       // Allocate the mod-union table
       // The mod-union table is only needed when we have an image space since it's purpose is to cache image roots.
       UniquePtr<SpaceBitmap> bitmap(SpaceBitmap::Create("mod-union table bitmap", spaces[i]->Begin(), spaces[i]->Capacity()));
       if (bitmap.get() == NULL) {
         LOG(FATAL) << "Failed to create mod-union bitmap";
       }

       bitmaps_.Put(spaces[i], bitmap.release());
     }
   }
 }

 void ModUnionTableBitmap::ClearCards() {
   CardTable* card_table = heap_->GetCardTable();
   for (BitmapMap::iterator it = bitmaps_.begin(); it != bitmaps_.end(); ++it) {
     const Space* space = it->first;
     ModUnionClearCardVisitor visitor(&cleared_cards_);
     // Clear dirty cards in the this image space and update the corresponding mod-union bits.
     card_table->VisitClear(space->Begin(), space->End(), visitor);
   }
 }

 void ModUnionTableBitmap::Update(MarkSweep* mark_sweep) {
   CardTable* card_table = heap_->GetCardTable();
   while (!cleared_cards_.empty()) {
     byte* card = cleared_cards_.back();
     cleared_cards_.pop_back();

     // Find out which bitmap the card maps to.
     SpaceBitmap* bitmap = 0;
     const Space* space = 0;
     for (BitmapMap::iterator cur = bitmaps_.begin(); cur != bitmaps_.end(); ++cur) {
       space = cur->first;
       if (space->Contains(reinterpret_cast<Object*>(card_table->AddrFromCard(card)))) {
         bitmap = cur->second;
         break;
       }
     }
     DCHECK(bitmap != NULL);

     uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card));
     uintptr_t end = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card + 1));

     // Clear the mod-union bitmap range corresponding to this card so that we
     // don't have any objects marked which do not reach the alloc space.
     bitmap->VisitRange(start, end, SpaceBitmap::ClearVisitor(bitmap));

     // At this point we need to update the mod-union bitmap to contain all the
     // objects which reach the alloc space.
     ModUnionVisitor visitor(mark_sweep, bitmap);
     space->GetLiveBitmap()->VisitMarkedRange(start, end, visitor);
   }
 }

 void ModUnionTableBitmap::MarkReferences(MarkSweep* mark_sweep) {
   // Some tests have no image space, and therefore no mod-union bitmap.
   for (BitmapMap::iterator cur = bitmaps_.begin(); cur != bitmaps_.end(); ++cur) {
     const Space* space = cur->first;
     uintptr_t begin = reinterpret_cast<uintptr_t>(space->Begin());
     uintptr_t end = reinterpret_cast<uintptr_t>(space->End());
     cur->second->VisitRange(begin, end, MarkSweep::ScanImageRootVisitor, mark_sweep);
   }
 }


 ModUnionTableReferenceCache::ModUnionTableReferenceCache(Heap* heap) : heap_(heap) {
   cleared_cards_.reserve(32);
 }

 ModUnionTableReferenceCache::~ModUnionTableReferenceCache() {

 }

 void ModUnionTableReferenceCache::Init() {

 }

 void ModUnionTableReferenceCache::ClearCards() {
   const Spaces& spaces = heap_->GetSpaces();
   CardTable* card_table = heap_->GetCardTable();

   // Create one heap bitmap per image space.
   for (size_t i = 0; i < spaces.size(); ++i) {
     if (spaces[i]->IsImageSpace()) {
       ModUnionClearCardVisitor visitor(&cleared_cards_);
       // Clear dirty cards in the this image space and update the corresponding mod-union bits.
       card_table->VisitClear(spaces[i]->Begin(), spaces[i]->End(), visitor);
     }
   }
 }

 class AddIfReachesAllocSpaceVisitor {
  public:
   explicit AddIfReachesAllocSpaceVisitor(
         MarkSweep* const mark_sweep,
         ModUnionTableReferenceCache::ReferenceArray* references)
     : mark_sweep_(mark_sweep),
       references_(references) {
   }

   // Extra parameters are required since we use this same visitor signature for checking objects.
   void operator ()(const Object* /* obj */, const Object* ref, const MemberOffset& /* offset */, bool /* is_static */) const {
     if (mark_sweep_->heap_->GetAllocSpace()->Contains(ref)) {
       references_->push_back(ref);
     }
   }

  private:
   MarkSweep* const mark_sweep_;
   ModUnionTableReferenceCache::ReferenceArray* references_;
 };

 class ModUnionReferenceVisitor {
  public:
   explicit ModUnionReferenceVisitor(
         MarkSweep* const mark_sweep,
         ModUnionTableReferenceCache::ReferenceArray* references)
     : mark_sweep_(mark_sweep),
       references_(references) {
   }

   void operator ()(Object* obj) const {
     DCHECK(obj != NULL);
     // We don't have an early exit since we use the visitor pattern, an early
     // exit should significantly speed this up.
     AddIfReachesAllocSpaceVisitor visitor(mark_sweep_, references_);
     mark_sweep_->VisitObjectReferences(obj, visitor);
   }
  private:
   MarkSweep* const mark_sweep_;
   ModUnionTableReferenceCache::ReferenceArray* references_;
 };

 void ModUnionTableReferenceCache::Update(MarkSweep* mark_sweep) {
   CardTable* card_table = heap_->GetCardTable();
   while (!cleared_cards_.empty()) {
     byte* card = cleared_cards_.back();
     cleared_cards_.pop_back();

     // Update the corresponding references for the card
     // TODO: C++0x auto
     ReferenceMap::iterator found = references_.find(card);
     if (found == references_.end()) {
       references_.Put(card, ReferenceArray());
       found = references_.find(card);
     }

     // Clear and re-compute alloc space references associated with this card.
     ReferenceArray& cards_references = found->second;
     cards_references.clear();
     ModUnionReferenceVisitor visitor(mark_sweep, &cards_references);
     uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card));
     uintptr_t end = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card + 1));
     SpaceBitmap* live_bitmap =
         heap_->FindSpaceFromObject(reinterpret_cast<Object*>(start))->GetLiveBitmap();
     live_bitmap->VisitMarkedRange(start, end, visitor);
   }
 }

 void ModUnionTableReferenceCache::MarkReferences(MarkSweep* mark_sweep) {
   // TODO: C++0x auto
   size_t count = 0;
   for (ReferenceMap::const_iterator it = references_.begin(); it != references_.end(); ++it) {
     for (ReferenceArray::const_iterator it_ref = it->second.begin(); it_ref != it->second.end(); ++it_ref ) {
       mark_sweep->MarkObject(*it_ref);
       ++count;
     }
   }
   VLOG(heap) << "Marked " << count << " references in mod union table";
 }

 }  // namespace art
	/*
	* 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 "heap.h"
	#include "heap_bitmap.h"
	#include "mark_sweep.h"
	#include "mod_union_table.h"
	#include "space.h"
	#include "stl_util.h"
	#include "UniquePtr.h"

	namespace art {

	class MarkIfReachesAllocspaceVisitor {
	public:
	explicit MarkIfReachesAllocspaceVisitor(MarkSweep* const mark_sweep, SpaceBitmap* bitmap)
	: mark_sweep_(mark_sweep),
	bitmap_(bitmap) {
	}

	// Extra parameters are required since we use this same visitor signature for checking objects.
	void operator ()(const Object* obj, const Object* ref, const MemberOffset& /* offset /, bool / is_static */) const {
	// TODO: Optimize?
	// TODO: C++0x auto
	const Spaces& spaces = mark_sweep_->heap_->GetSpaces();
	for (Spaces::const_iterator cur = spaces.begin(); cur != spaces.end(); ++cur) {
	if ((cur)->IsAllocSpace() && (cur)->Contains(ref)) {
	bitmap_->Set(obj);
	}
	}
	}

	private:
	MarkSweep* const mark_sweep_;
	SpaceBitmap* bitmap_;
	};

	class ModUnionVisitor {
	public:
	explicit ModUnionVisitor(MarkSweep* const mark_sweep, SpaceBitmap* bitmap)
	: mark_sweep_(mark_sweep),
	bitmap_(bitmap) {
	}

	void operator ()(Object* obj) const {
	DCHECK(obj != NULL);
	// We don't have an early exit since we use the visitor pattern, an early
	// exit should significantly speed this up.
	MarkIfReachesAllocspaceVisitor visitor(mark_sweep_, bitmap_);
	mark_sweep_->VisitObjectReferences(obj, visitor);
	}
	private:
	MarkSweep* const mark_sweep_;
	SpaceBitmap* bitmap_;
	};

	class ModUnionClearCardVisitor {
	public:
	explicit ModUnionClearCardVisitor(std::vector<byte> cleared_cards)
	: cleared_cards_(cleared_cards) {
	}

	void operator ()(byte* card) const {
	cleared_cards_->push_back(card);
	}
	private:
	std::vector<byte> cleared_cards_;
	};

	ModUnionTableBitmap::ModUnionTableBitmap(Heap* heap) : heap_(heap) {
	// Prevent fragmentation of the heap which is caused by resizing of the vector.
	// TODO: Make a new vector which uses madvise (basically same as a mark stack).
	cleared_cards_.reserve(32);
	}

	ModUnionTableBitmap::~ModUnionTableBitmap() {
	STLDeleteValues(&bitmaps_);
	}

	void ModUnionTableBitmap::Init() {
	const Spaces& spaces = heap_->GetSpaces();

	// Create one heap bitmap per image space.
	for (size_t i = 0; i < spaces.size(); ++i) {
	if (spaces[i]->IsImageSpace()) {
	// Allocate the mod-union table
	// The mod-union table is only needed when we have an image space since it's purpose is to cache image roots.
	UniquePtr<SpaceBitmap> bitmap(SpaceBitmap::Create("mod-union table bitmap", spaces[i]->Begin(), spaces[i]->Capacity()));
	if (bitmap.get() == NULL) {
	LOG(FATAL) << "Failed to create mod-union bitmap";
	}

	bitmaps_.Put(spaces[i], bitmap.release());
	}
	}
	}

	void ModUnionTableBitmap::ClearCards() {
	CardTable* card_table = heap_->GetCardTable();
	for (BitmapMap::iterator it = bitmaps_.begin(); it != bitmaps_.end(); ++it) {
	const Space* space = it->first;
	ModUnionClearCardVisitor visitor(&cleared_cards_);
	// Clear dirty cards in the this image space and update the corresponding mod-union bits.
	card_table->VisitClear(space->Begin(), space->End(), visitor);
	}
	}

	void ModUnionTableBitmap::Update(MarkSweep* mark_sweep) {
	CardTable* card_table = heap_->GetCardTable();
	while (!cleared_cards_.empty()) {
	byte* card = cleared_cards_.back();
	cleared_cards_.pop_back();

	// Find out which bitmap the card maps to.
	SpaceBitmap* bitmap = 0;
	const Space* space = 0;
	for (BitmapMap::iterator cur = bitmaps_.begin(); cur != bitmaps_.end(); ++cur) {
	space = cur->first;
	if (space->Contains(reinterpret_cast<Object*>(card_table->AddrFromCard(card)))) {
	bitmap = cur->second;
	break;
	}
	}
	DCHECK(bitmap != NULL);

	uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card));
	uintptr_t end = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card + 1));

	// Clear the mod-union bitmap range corresponding to this card so that we
	// don't have any objects marked which do not reach the alloc space.
	bitmap->VisitRange(start, end, SpaceBitmap::ClearVisitor(bitmap));

	// At this point we need to update the mod-union bitmap to contain all the
	// objects which reach the alloc space.
	ModUnionVisitor visitor(mark_sweep, bitmap);
	space->GetLiveBitmap()->VisitMarkedRange(start, end, visitor);
	}
	}

	void ModUnionTableBitmap::MarkReferences(MarkSweep* mark_sweep) {
	// Some tests have no image space, and therefore no mod-union bitmap.
	for (BitmapMap::iterator cur = bitmaps_.begin(); cur != bitmaps_.end(); ++cur) {
	const Space* space = cur->first;
	uintptr_t begin = reinterpret_cast<uintptr_t>(space->Begin());
	uintptr_t end = reinterpret_cast<uintptr_t>(space->End());
	cur->second->VisitRange(begin, end, MarkSweep::ScanImageRootVisitor, mark_sweep);
	}
	}


	ModUnionTableReferenceCache::ModUnionTableReferenceCache(Heap* heap) : heap_(heap) {
	cleared_cards_.reserve(32);
	}

	ModUnionTableReferenceCache::~ModUnionTableReferenceCache() {

	}

	void ModUnionTableReferenceCache::Init() {

	}

	void ModUnionTableReferenceCache::ClearCards() {
	const Spaces& spaces = heap_->GetSpaces();
	CardTable* card_table = heap_->GetCardTable();

	// Create one heap bitmap per image space.
	for (size_t i = 0; i < spaces.size(); ++i) {
	if (spaces[i]->IsImageSpace()) {
	ModUnionClearCardVisitor visitor(&cleared_cards_);
	// Clear dirty cards in the this image space and update the corresponding mod-union bits.
	card_table->VisitClear(spaces[i]->Begin(), spaces[i]->End(), visitor);
	}
	}
	}

	class AddIfReachesAllocSpaceVisitor {
	public:
	explicit AddIfReachesAllocSpaceVisitor(
	MarkSweep* const mark_sweep,
	ModUnionTableReferenceCache::ReferenceArray* references)
	: mark_sweep_(mark_sweep),
	references_(references) {
	}

	// Extra parameters are required since we use this same visitor signature for checking objects.
	void operator ()(const Object* /* obj /, const Object ref, const MemberOffset& /* offset /, bool / is_static */) const {
	if (mark_sweep_->heap_->GetAllocSpace()->Contains(ref)) {
	references_->push_back(ref);
	}
	}

	private:
	MarkSweep* const mark_sweep_;
	ModUnionTableReferenceCache::ReferenceArray* references_;
	};

	class ModUnionReferenceVisitor {
	public:
	explicit ModUnionReferenceVisitor(
	MarkSweep* const mark_sweep,
	ModUnionTableReferenceCache::ReferenceArray* references)
	: mark_sweep_(mark_sweep),
	references_(references) {
	}

	void operator ()(Object* obj) const {
	DCHECK(obj != NULL);
	// We don't have an early exit since we use the visitor pattern, an early
	// exit should significantly speed this up.
	AddIfReachesAllocSpaceVisitor visitor(mark_sweep_, references_);
	mark_sweep_->VisitObjectReferences(obj, visitor);
	}
	private:
	MarkSweep* const mark_sweep_;
	ModUnionTableReferenceCache::ReferenceArray* references_;
	};

	void ModUnionTableReferenceCache::Update(MarkSweep* mark_sweep) {
	CardTable* card_table = heap_->GetCardTable();
	while (!cleared_cards_.empty()) {
	byte* card = cleared_cards_.back();
	cleared_cards_.pop_back();

	// Update the corresponding references for the card
	// TODO: C++0x auto
	ReferenceMap::iterator found = references_.find(card);
	if (found == references_.end()) {
	references_.Put(card, ReferenceArray());
	found = references_.find(card);
	}

	// Clear and re-compute alloc space references associated with this card.
	ReferenceArray& cards_references = found->second;
	cards_references.clear();
	ModUnionReferenceVisitor visitor(mark_sweep, &cards_references);
	uintptr_t start = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card));
	uintptr_t end = reinterpret_cast<uintptr_t>(card_table->AddrFromCard(card + 1));
	SpaceBitmap* live_bitmap =
	heap_->FindSpaceFromObject(reinterpret_cast<Object*>(start))->GetLiveBitmap();
	live_bitmap->VisitMarkedRange(start, end, visitor);
	}
	}

	void ModUnionTableReferenceCache::MarkReferences(MarkSweep* mark_sweep) {
	// TODO: C++0x auto
	size_t count = 0;
	for (ReferenceMap::const_iterator it = references_.begin(); it != references_.end(); ++it) {
	for (ReferenceArray::const_iterator it_ref = it->second.begin(); it_ref != it->second.end(); ++it_ref ) {
	mark_sweep->MarkObject(*it_ref);
	++count;
	}
	}
	VLOG(heap) << "Marked " << count << " references in mod union table";
	}

	} // namespace art