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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 "large_object_space.h"
#include <memory>
#include "gc/accounting/space_bitmap-inl.h"
#include "base/logging.h"
#include "base/mutex-inl.h"
#include "base/stl_util.h"
#include "image.h"
#include "os.h"
#include "space-inl.h"
#include "thread-inl.h"
#include "utils.h"
namespace art {
namespace gc {
namespace space {
class ValgrindLargeObjectMapSpace FINAL : public LargeObjectMapSpace {
public:
explicit ValgrindLargeObjectMapSpace(const std::string& name) : LargeObjectMapSpace(name) {
}
virtual mirror::Object* Alloc(Thread* self, size_t num_bytes, size_t* bytes_allocated,
size_t* usable_size) OVERRIDE {
mirror::Object* obj =
LargeObjectMapSpace::Alloc(self, num_bytes + kValgrindRedZoneBytes * 2, bytes_allocated,
usable_size);
mirror::Object* object_without_rdz = reinterpret_cast<mirror::Object*>(
reinterpret_cast<uintptr_t>(obj) + kValgrindRedZoneBytes);
VALGRIND_MAKE_MEM_NOACCESS(reinterpret_cast<void*>(obj), kValgrindRedZoneBytes);
VALGRIND_MAKE_MEM_NOACCESS(reinterpret_cast<uint8_t*>(object_without_rdz) + num_bytes,
kValgrindRedZoneBytes);
if (usable_size != nullptr) {
*usable_size = num_bytes; // Since we have redzones, shrink the usable size.
}
return object_without_rdz;
}
virtual size_t AllocationSize(mirror::Object* obj, size_t* usable_size) OVERRIDE {
mirror::Object* object_with_rdz = reinterpret_cast<mirror::Object*>(
reinterpret_cast<uintptr_t>(obj) - kValgrindRedZoneBytes);
return LargeObjectMapSpace::AllocationSize(object_with_rdz, usable_size);
}
virtual size_t Free(Thread* self, mirror::Object* obj) OVERRIDE {
mirror::Object* object_with_rdz = reinterpret_cast<mirror::Object*>(
reinterpret_cast<uintptr_t>(obj) - kValgrindRedZoneBytes);
VALGRIND_MAKE_MEM_UNDEFINED(object_with_rdz, AllocationSize(obj, nullptr));
return LargeObjectMapSpace::Free(self, object_with_rdz);
}
bool Contains(const mirror::Object* obj) const OVERRIDE {
mirror::Object* object_with_rdz = reinterpret_cast<mirror::Object*>(
reinterpret_cast<uintptr_t>(obj) - kValgrindRedZoneBytes);
return LargeObjectMapSpace::Contains(object_with_rdz);
}
private:
static constexpr size_t kValgrindRedZoneBytes = kPageSize;
};
void LargeObjectSpace::SwapBitmaps() {
live_bitmap_.swap(mark_bitmap_);
// Swap names to get more descriptive diagnostics.
std::string temp_name = live_bitmap_->GetName();
live_bitmap_->SetName(mark_bitmap_->GetName());
mark_bitmap_->SetName(temp_name);
}
LargeObjectSpace::LargeObjectSpace(const std::string& name, uint8_t* begin, uint8_t* end)
: DiscontinuousSpace(name, kGcRetentionPolicyAlwaysCollect),
num_bytes_allocated_(0), num_objects_allocated_(0), total_bytes_allocated_(0),
total_objects_allocated_(0), begin_(begin), end_(end) {
}
void LargeObjectSpace::CopyLiveToMarked() {
mark_bitmap_->CopyFrom(live_bitmap_.get());
}
LargeObjectMapSpace::LargeObjectMapSpace(const std::string& name)
: LargeObjectSpace(name, nullptr, nullptr),
lock_("large object map space lock", kAllocSpaceLock) {}
LargeObjectMapSpace* LargeObjectMapSpace::Create(const std::string& name) {
if (Runtime::Current()->RunningOnValgrind()) {
return new ValgrindLargeObjectMapSpace(name);
} else {
return new LargeObjectMapSpace(name);
}
}
mirror::Object* LargeObjectMapSpace::Alloc(Thread* self, size_t num_bytes,
size_t* bytes_allocated, size_t* usable_size) {
std::string error_msg;
MemMap* mem_map = MemMap::MapAnonymous("large object space allocation", NULL, num_bytes,
PROT_READ | PROT_WRITE, true, &error_msg);
if (UNLIKELY(mem_map == NULL)) {
LOG(WARNING) << "Large object allocation failed: " << error_msg;
return NULL;
}
MutexLock mu(self, lock_);
mirror::Object* obj = reinterpret_cast<mirror::Object*>(mem_map->Begin());
large_objects_.push_back(obj);
mem_maps_.Put(obj, mem_map);
const size_t allocation_size = mem_map->BaseSize();
DCHECK(bytes_allocated != nullptr);
begin_ = std::min(begin_, reinterpret_cast<uint8_t*>(obj));
uint8_t* obj_end = reinterpret_cast<uint8_t*>(obj) + allocation_size;
if (end_ == nullptr || obj_end > end_) {
end_ = obj_end;
}
*bytes_allocated = allocation_size;
if (usable_size != nullptr) {
*usable_size = allocation_size;
}
num_bytes_allocated_ += allocation_size;
total_bytes_allocated_ += allocation_size;
++num_objects_allocated_;
++total_objects_allocated_;
return obj;
}
size_t LargeObjectMapSpace::Free(Thread* self, mirror::Object* ptr) {
MutexLock mu(self, lock_);
MemMaps::iterator found = mem_maps_.find(ptr);
if (UNLIKELY(found == mem_maps_.end())) {
Runtime::Current()->GetHeap()->DumpSpaces(LOG(ERROR));
LOG(FATAL) << "Attempted to free large object " << ptr << " which was not live";
}
const size_t map_size = found->second->BaseSize();
DCHECK_GE(num_bytes_allocated_, map_size);
size_t allocation_size = map_size;
num_bytes_allocated_ -= allocation_size;
--num_objects_allocated_;
delete found->second;
mem_maps_.erase(found);
return allocation_size;
}
size_t LargeObjectMapSpace::AllocationSize(mirror::Object* obj, size_t* usable_size) {
MutexLock mu(Thread::Current(), lock_);
auto found = mem_maps_.find(obj);
CHECK(found != mem_maps_.end()) << "Attempted to get size of a large object which is not live";
return found->second->BaseSize();
}
size_t LargeObjectSpace::FreeList(Thread* self, size_t num_ptrs, mirror::Object** ptrs) {
size_t total = 0;
for (size_t i = 0; i < num_ptrs; ++i) {
if (kDebugSpaces) {
CHECK(Contains(ptrs[i]));
}
total += Free(self, ptrs[i]);
}
return total;
}
void LargeObjectMapSpace::Walk(DlMallocSpace::WalkCallback callback, void* arg) {
MutexLock mu(Thread::Current(), lock_);
for (auto it = mem_maps_.begin(); it != mem_maps_.end(); ++it) {
MemMap* mem_map = it->second;
callback(mem_map->Begin(), mem_map->End(), mem_map->Size(), arg);
callback(NULL, NULL, 0, arg);
}
}
bool LargeObjectMapSpace::Contains(const mirror::Object* obj) const {
Thread* self = Thread::Current();
if (lock_.IsExclusiveHeld(self)) {
// We hold lock_ so do the check.
return mem_maps_.find(const_cast<mirror::Object*>(obj)) != mem_maps_.end();
} else {
MutexLock mu(self, lock_);
return mem_maps_.find(const_cast<mirror::Object*>(obj)) != mem_maps_.end();
}
}
// Keeps track of allocation sizes + whether or not the previous allocation is free.
// Used to coalesce free blocks and find the best fit block for an allocation.
class AllocationInfo {
public:
AllocationInfo() : prev_free_(0), alloc_size_(0) {
}
// Return the number of pages that the allocation info covers.
size_t AlignSize() const {
return alloc_size_ & ~kFlagFree;
}
// Returns the allocation size in bytes.
size_t ByteSize() const {
return AlignSize() * FreeListSpace::kAlignment;
}
// Updates the allocation size and whether or not it is free.
void SetByteSize(size_t size, bool free) {
DCHECK_ALIGNED(size, FreeListSpace::kAlignment);
alloc_size_ = (size / FreeListSpace::kAlignment) | (free ? kFlagFree : 0U);
}
bool IsFree() const {
return (alloc_size_ & kFlagFree) != 0;
}
// Finds and returns the next non free allocation info after ourself.
AllocationInfo* GetNextInfo() {
return this + AlignSize();
}
const AllocationInfo* GetNextInfo() const {
return this + AlignSize();
}
// Returns the previous free allocation info by using the prev_free_ member to figure out
// where it is. This is only used for coalescing so we only need to be able to do it if the
// previous allocation info is free.
AllocationInfo* GetPrevFreeInfo() {
DCHECK_NE(prev_free_, 0U);
return this - prev_free_;
}
// Returns the address of the object associated with this allocation info.
mirror::Object* GetObjectAddress() {
return reinterpret_cast<mirror::Object*>(reinterpret_cast<uintptr_t>(this) + sizeof(*this));
}
// Return how many kAlignment units there are before the free block.
size_t GetPrevFree() const {
return prev_free_;
}
// Returns how many free bytes there is before the block.
size_t GetPrevFreeBytes() const {
return GetPrevFree() * FreeListSpace::kAlignment;
}
// Update the size of the free block prior to the allocation.
void SetPrevFreeBytes(size_t bytes) {
DCHECK_ALIGNED(bytes, FreeListSpace::kAlignment);
prev_free_ = bytes / FreeListSpace::kAlignment;
}
private:
// Used to implement best fit object allocation. Each allocation has an AllocationInfo which
// contains the size of the previous free block preceding it. Implemented in such a way that we
// can also find the iterator for any allocation info pointer.
static constexpr uint32_t kFlagFree = 0x8000000;
// Contains the size of the previous free block with kAlignment as the unit. If 0 then the
// allocation before us is not free.
// These variables are undefined in the middle of allocations / free blocks.
uint32_t prev_free_;
// Allocation size of this object in kAlignment as the unit.
uint32_t alloc_size_;
};
size_t FreeListSpace::GetSlotIndexForAllocationInfo(const AllocationInfo* info) const {
DCHECK_GE(info, allocation_info_);
DCHECK_LT(info, reinterpret_cast<AllocationInfo*>(allocation_info_map_->End()));
return info - allocation_info_;
}
AllocationInfo* FreeListSpace::GetAllocationInfoForAddress(uintptr_t address) {
return &allocation_info_[GetSlotIndexForAddress(address)];
}
const AllocationInfo* FreeListSpace::GetAllocationInfoForAddress(uintptr_t address) const {
return &allocation_info_[GetSlotIndexForAddress(address)];
}
inline bool FreeListSpace::SortByPrevFree::operator()(const AllocationInfo* a,
const AllocationInfo* b) const {
if (a->GetPrevFree() < b->GetPrevFree()) return true;
if (a->GetPrevFree() > b->GetPrevFree()) return false;
if (a->AlignSize() < b->AlignSize()) return true;
if (a->AlignSize() > b->AlignSize()) return false;
return reinterpret_cast<uintptr_t>(a) < reinterpret_cast<uintptr_t>(b);
}
FreeListSpace* FreeListSpace::Create(const std::string& name, uint8_t* requested_begin, size_t size) {
CHECK_EQ(size % kAlignment, 0U);
std::string error_msg;
MemMap* mem_map = MemMap::MapAnonymous(name.c_str(), requested_begin, size,
PROT_READ | PROT_WRITE, true, &error_msg);
CHECK(mem_map != NULL) << "Failed to allocate large object space mem map: " << error_msg;
return new FreeListSpace(name, mem_map, mem_map->Begin(), mem_map->End());
}
FreeListSpace::FreeListSpace(const std::string& name, MemMap* mem_map, uint8_t* begin, uint8_t* end)
: LargeObjectSpace(name, begin, end),
mem_map_(mem_map),
lock_("free list space lock", kAllocSpaceLock) {
const size_t space_capacity = end - begin;
free_end_ = space_capacity;
CHECK_ALIGNED(space_capacity, kAlignment);
const size_t alloc_info_size = sizeof(AllocationInfo) * (space_capacity / kAlignment);
std::string error_msg;
allocation_info_map_.reset(MemMap::MapAnonymous("large object free list space allocation info map",
nullptr, alloc_info_size, PROT_READ | PROT_WRITE,
false, &error_msg));
CHECK(allocation_info_map_.get() != nullptr) << "Failed to allocate allocation info map"
<< error_msg;
allocation_info_ = reinterpret_cast<AllocationInfo*>(allocation_info_map_->Begin());
}
FreeListSpace::~FreeListSpace() {}
void FreeListSpace::Walk(DlMallocSpace::WalkCallback callback, void* arg) {
MutexLock mu(Thread::Current(), lock_);
const uintptr_t free_end_start = reinterpret_cast<uintptr_t>(end_) - free_end_;
AllocationInfo* cur_info = &allocation_info_[0];
const AllocationInfo* end_info = GetAllocationInfoForAddress(free_end_start);
while (cur_info < end_info) {
if (!cur_info->IsFree()) {
size_t alloc_size = cur_info->ByteSize();
uint8_t* byte_start = reinterpret_cast<uint8_t*>(GetAddressForAllocationInfo(cur_info));
uint8_t* byte_end = byte_start + alloc_size;
callback(byte_start, byte_end, alloc_size, arg);
callback(nullptr, nullptr, 0, arg);
}
cur_info = cur_info->GetNextInfo();
}
CHECK_EQ(cur_info, end_info);
}
void FreeListSpace::RemoveFreePrev(AllocationInfo* info) {
CHECK_GT(info->GetPrevFree(), 0U);
auto it = free_blocks_.lower_bound(info);
CHECK(it != free_blocks_.end());
CHECK_EQ(*it, info);
free_blocks_.erase(it);
}
size_t FreeListSpace::Free(Thread* self, mirror::Object* obj) {
MutexLock mu(self, lock_);
DCHECK(Contains(obj)) << reinterpret_cast<void*>(Begin()) << " " << obj << " "
<< reinterpret_cast<void*>(End());
DCHECK_ALIGNED(obj, kAlignment);
AllocationInfo* info = GetAllocationInfoForAddress(reinterpret_cast<uintptr_t>(obj));
DCHECK(!info->IsFree());
const size_t allocation_size = info->ByteSize();
DCHECK_GT(allocation_size, 0U);
DCHECK_ALIGNED(allocation_size, kAlignment);
info->SetByteSize(allocation_size, true); // Mark as free.
// Look at the next chunk.
AllocationInfo* next_info = info->GetNextInfo();
// Calculate the start of the end free block.
uintptr_t free_end_start = reinterpret_cast<uintptr_t>(end_) - free_end_;
size_t prev_free_bytes = info->GetPrevFreeBytes();
size_t new_free_size = allocation_size;
if (prev_free_bytes != 0) {
// Coalesce with previous free chunk.
new_free_size += prev_free_bytes;
RemoveFreePrev(info);
info = info->GetPrevFreeInfo();
// The previous allocation info must not be free since we are supposed to always coalesce.
DCHECK_EQ(info->GetPrevFreeBytes(), 0U) << "Previous allocation was free";
}
uintptr_t next_addr = GetAddressForAllocationInfo(next_info);
if (next_addr >= free_end_start) {
// Easy case, the next chunk is the end free region.
CHECK_EQ(next_addr, free_end_start);
free_end_ += new_free_size;
} else {
AllocationInfo* new_free_info;
if (next_info->IsFree()) {
AllocationInfo* next_next_info = next_info->GetNextInfo();
// Next next info can't be free since we always coalesce.
DCHECK(!next_next_info->IsFree());
DCHECK(IsAligned<kAlignment>(next_next_info->ByteSize()));
new_free_info = next_next_info;
new_free_size += next_next_info->GetPrevFreeBytes();
RemoveFreePrev(next_next_info);
} else {
new_free_info = next_info;
}
new_free_info->SetPrevFreeBytes(new_free_size);
free_blocks_.insert(new_free_info);
info->SetByteSize(new_free_size, true);
DCHECK_EQ(info->GetNextInfo(), new_free_info);
}
--num_objects_allocated_;
DCHECK_LE(allocation_size, num_bytes_allocated_);
num_bytes_allocated_ -= allocation_size;
madvise(obj, allocation_size, MADV_DONTNEED);
if (kIsDebugBuild) {
// Can't disallow reads since we use them to find next chunks during coalescing.
mprotect(obj, allocation_size, PROT_READ);
}
return allocation_size;
}
size_t FreeListSpace::AllocationSize(mirror::Object* obj, size_t* usable_size) {
DCHECK(Contains(obj));
AllocationInfo* info = GetAllocationInfoForAddress(reinterpret_cast<uintptr_t>(obj));
DCHECK(!info->IsFree());
size_t alloc_size = info->ByteSize();
if (usable_size != nullptr) {
*usable_size = alloc_size;
}
return alloc_size;
}
mirror::Object* FreeListSpace::Alloc(Thread* self, size_t num_bytes, size_t* bytes_allocated,
size_t* usable_size) {
MutexLock mu(self, lock_);
const size_t allocation_size = RoundUp(num_bytes, kAlignment);
AllocationInfo temp_info;
temp_info.SetPrevFreeBytes(allocation_size);
temp_info.SetByteSize(0, false);
AllocationInfo* new_info;
// Find the smallest chunk at least num_bytes in size.
auto it = free_blocks_.lower_bound(&temp_info);
if (it != free_blocks_.end()) {
AllocationInfo* info = *it;
free_blocks_.erase(it);
// Fit our object in the previous allocation info free space.
new_info = info->GetPrevFreeInfo();
// Remove the newly allocated block from the info and update the prev_free_.
info->SetPrevFreeBytes(info->GetPrevFreeBytes() - allocation_size);
if (info->GetPrevFreeBytes() > 0) {
AllocationInfo* new_free = info - info->GetPrevFree();
new_free->SetPrevFreeBytes(0);
new_free->SetByteSize(info->GetPrevFreeBytes(), true);
// If there is remaining space, insert back into the free set.
free_blocks_.insert(info);
}
} else {
// Try to steal some memory from the free space at the end of the space.
if (LIKELY(free_end_ >= allocation_size)) {
// Fit our object at the start of the end free block.
new_info = GetAllocationInfoForAddress(reinterpret_cast<uintptr_t>(End()) - free_end_);
free_end_ -= allocation_size;
} else {
return nullptr;
}
}
DCHECK(bytes_allocated != nullptr);
*bytes_allocated = allocation_size;
if (usable_size != nullptr) {
*usable_size = allocation_size;
}
// Need to do these inside of the lock.
++num_objects_allocated_;
++total_objects_allocated_;
num_bytes_allocated_ += allocation_size;
total_bytes_allocated_ += allocation_size;
mirror::Object* obj = reinterpret_cast<mirror::Object*>(GetAddressForAllocationInfo(new_info));
// We always put our object at the start of the free block, there can not be another free block
// before it.
if (kIsDebugBuild) {
mprotect(obj, allocation_size, PROT_READ | PROT_WRITE);
}
new_info->SetPrevFreeBytes(0);
new_info->SetByteSize(allocation_size, false);
return obj;
}
void FreeListSpace::Dump(std::ostream& os) const {
MutexLock mu(Thread::Current(), const_cast<Mutex&>(lock_));
os << GetName() << " -"
<< " begin: " << reinterpret_cast<void*>(Begin())
<< " end: " << reinterpret_cast<void*>(End()) << "\n";
uintptr_t free_end_start = reinterpret_cast<uintptr_t>(end_) - free_end_;
const AllocationInfo* cur_info =
GetAllocationInfoForAddress(reinterpret_cast<uintptr_t>(Begin()));
const AllocationInfo* end_info = GetAllocationInfoForAddress(free_end_start);
while (cur_info < end_info) {
size_t size = cur_info->ByteSize();
uintptr_t address = GetAddressForAllocationInfo(cur_info);
if (cur_info->IsFree()) {
os << "Free block at address: " << reinterpret_cast<const void*>(address)
<< " of length " << size << " bytes\n";
} else {
os << "Large object at address: " << reinterpret_cast<const void*>(address)
<< " of length " << size << " bytes\n";
}
cur_info = cur_info->GetNextInfo();
}
if (free_end_) {
os << "Free block at address: " << reinterpret_cast<const void*>(free_end_start)
<< " of length " << free_end_ << " bytes\n";
}
}
void LargeObjectSpace::SweepCallback(size_t num_ptrs, mirror::Object** ptrs, void* arg) {
SweepCallbackContext* context = static_cast<SweepCallbackContext*>(arg);
space::LargeObjectSpace* space = context->space->AsLargeObjectSpace();
Thread* self = context->self;
Locks::heap_bitmap_lock_->AssertExclusiveHeld(self);
// If the bitmaps aren't swapped we need to clear the bits since the GC isn't going to re-swap
// the bitmaps as an optimization.
if (!context->swap_bitmaps) {
accounting::LargeObjectBitmap* bitmap = space->GetLiveBitmap();
for (size_t i = 0; i < num_ptrs; ++i) {
bitmap->Clear(ptrs[i]);
}
}
context->freed.objects += num_ptrs;
context->freed.bytes += space->FreeList(self, num_ptrs, ptrs);
}
collector::ObjectBytePair LargeObjectSpace::Sweep(bool swap_bitmaps) {
if (Begin() >= End()) {
return collector::ObjectBytePair(0, 0);
}
accounting::LargeObjectBitmap* live_bitmap = GetLiveBitmap();
accounting::LargeObjectBitmap* mark_bitmap = GetMarkBitmap();
if (swap_bitmaps) {
std::swap(live_bitmap, mark_bitmap);
}
AllocSpace::SweepCallbackContext scc(swap_bitmaps, this);
accounting::LargeObjectBitmap::SweepWalk(*live_bitmap, *mark_bitmap,
reinterpret_cast<uintptr_t>(Begin()),
reinterpret_cast<uintptr_t>(End()), SweepCallback, &scc);
return scc.freed;
}
void LargeObjectSpace::LogFragmentationAllocFailure(std::ostream& /*os*/,
size_t /*failed_alloc_bytes*/) {
UNIMPLEMENTED(FATAL);
}
} // namespace space
} // namespace gc
} // namespace art