/*
* Copyright (C) 2013 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 "bump_pointer_space.h"
#include "bump_pointer_space-inl.h"
#include "mirror/object-inl.h"
#include "mirror/class-inl.h"
#include "thread_list.h"
namespace art {
namespace gc {
namespace space {
BumpPointerSpace* BumpPointerSpace::Create(const std::string& name, size_t capacity,
uint8_t* requested_begin) {
capacity = RoundUp(capacity, kPageSize);
std::string error_msg;
std::unique_ptr<MemMap> mem_map(MemMap::MapAnonymous(name.c_str(), requested_begin, capacity,
PROT_READ | PROT_WRITE, true, false,
&error_msg));
if (mem_map.get() == nullptr) {
LOG(ERROR) << "Failed to allocate pages for alloc space (" << name << ") of size "
<< PrettySize(capacity) << " with message " << error_msg;
return nullptr;
}
return new BumpPointerSpace(name, mem_map.release());
}
BumpPointerSpace* BumpPointerSpace::CreateFromMemMap(const std::string& name, MemMap* mem_map) {
return new BumpPointerSpace(name, mem_map);
}
BumpPointerSpace::BumpPointerSpace(const std::string& name, uint8_t* begin, uint8_t* limit)
: ContinuousMemMapAllocSpace(name, nullptr, begin, begin, limit,
kGcRetentionPolicyAlwaysCollect),
growth_end_(limit),
objects_allocated_(0), bytes_allocated_(0),
block_lock_("Block lock"),
main_block_size_(0),
num_blocks_(0) {
}
BumpPointerSpace::BumpPointerSpace(const std::string& name, MemMap* mem_map)
: ContinuousMemMapAllocSpace(name, mem_map, mem_map->Begin(), mem_map->Begin(), mem_map->End(),
kGcRetentionPolicyAlwaysCollect),
growth_end_(mem_map->End()),
objects_allocated_(0), bytes_allocated_(0),
block_lock_("Block lock", kBumpPointerSpaceBlockLock),
main_block_size_(0),
num_blocks_(0) {
}
void BumpPointerSpace::Clear() {
// Release the pages back to the operating system.
if (!kMadviseZeroes) {
memset(Begin(), 0, Limit() - Begin());
}
CHECK_NE(madvise(Begin(), Limit() - Begin(), MADV_DONTNEED), -1) << "madvise failed";
// Reset the end of the space back to the beginning, we move the end forward as we allocate
// objects.
SetEnd(Begin());
objects_allocated_.StoreRelaxed(0);
bytes_allocated_.StoreRelaxed(0);
growth_end_ = Limit();
{
MutexLock mu(Thread::Current(), block_lock_);
num_blocks_ = 0;
main_block_size_ = 0;
}
}
void BumpPointerSpace::Dump(std::ostream& os) const {
os << GetName() << " "
<< reinterpret_cast<void*>(Begin()) << "-" << reinterpret_cast<void*>(End()) << " - "
<< reinterpret_cast<void*>(Limit());
}
mirror::Object* BumpPointerSpace::GetNextObject(mirror::Object* obj) {
const uintptr_t position = reinterpret_cast<uintptr_t>(obj) + obj->SizeOf();
return reinterpret_cast<mirror::Object*>(RoundUp(position, kAlignment));
}
size_t BumpPointerSpace::RevokeThreadLocalBuffers(Thread* thread) {
MutexLock mu(Thread::Current(), block_lock_);
RevokeThreadLocalBuffersLocked(thread);
return 0U;
}
size_t BumpPointerSpace::RevokeAllThreadLocalBuffers() {
Thread* self = Thread::Current();
MutexLock mu(self, *Locks::runtime_shutdown_lock_);
MutexLock mu2(self, *Locks::thread_list_lock_);
// TODO: Not do a copy of the thread list?
std::list<Thread*> thread_list = Runtime::Current()->GetThreadList()->GetList();
for (Thread* thread : thread_list) {
RevokeThreadLocalBuffers(thread);
}
return 0U;
}
void BumpPointerSpace::AssertThreadLocalBuffersAreRevoked(Thread* thread) {
if (kIsDebugBuild) {
MutexLock mu(Thread::Current(), block_lock_);
DCHECK(!thread->HasTlab());
}
}
void BumpPointerSpace::AssertAllThreadLocalBuffersAreRevoked() {
if (kIsDebugBuild) {
Thread* self = Thread::Current();
MutexLock mu(self, *Locks::runtime_shutdown_lock_);
MutexLock mu2(self, *Locks::thread_list_lock_);
// TODO: Not do a copy of the thread list?
std::list<Thread*> thread_list = Runtime::Current()->GetThreadList()->GetList();
for (Thread* thread : thread_list) {
AssertThreadLocalBuffersAreRevoked(thread);
}
}
}
void BumpPointerSpace::UpdateMainBlock() {
DCHECK_EQ(num_blocks_, 0U);
main_block_size_ = Size();
}
// Returns the start of the storage.
uint8_t* BumpPointerSpace::AllocBlock(size_t bytes) {
bytes = RoundUp(bytes, kAlignment);
if (!num_blocks_) {
UpdateMainBlock();
}
uint8_t* storage = reinterpret_cast<uint8_t*>(
AllocNonvirtualWithoutAccounting(bytes + sizeof(BlockHeader)));
if (LIKELY(storage != nullptr)) {
BlockHeader* header = reinterpret_cast<BlockHeader*>(storage);
header->size_ = bytes; // Write out the block header.
storage += sizeof(BlockHeader);
++num_blocks_;
}
return storage;
}
void BumpPointerSpace::Walk(ObjectCallback* callback, void* arg) {
uint8_t* pos = Begin();
uint8_t* end = End();
uint8_t* main_end = pos;
{
MutexLock mu(Thread::Current(), block_lock_);
// If we have 0 blocks then we need to update the main header since we have bump pointer style
// allocation into an unbounded region (actually bounded by Capacity()).
if (num_blocks_ == 0) {
UpdateMainBlock();
}
main_end = Begin() + main_block_size_;
if (num_blocks_ == 0) {
// We don't have any other blocks, this means someone else may be allocating into the main
// block. In this case, we don't want to try and visit the other blocks after the main block
// since these could actually be part of the main block.
end = main_end;
}
}
// Walk all of the objects in the main block first.
while (pos < main_end) {
mirror::Object* obj = reinterpret_cast<mirror::Object*>(pos);
// No read barrier because obj may not be a valid object.
if (obj->GetClass<kDefaultVerifyFlags, kWithoutReadBarrier>() == nullptr) {
// There is a race condition where a thread has just allocated an object but not set the
// class. We can't know the size of this object, so we don't visit it and exit the function
// since there is guaranteed to be not other blocks.
return;
} else {
callback(obj, arg);
pos = reinterpret_cast<uint8_t*>(GetNextObject(obj));
}
}
// Walk the other blocks (currently only TLABs).
while (pos < end) {
BlockHeader* header = reinterpret_cast<BlockHeader*>(pos);
size_t block_size = header->size_;
pos += sizeof(BlockHeader); // Skip the header so that we know where the objects
mirror::Object* obj = reinterpret_cast<mirror::Object*>(pos);
const mirror::Object* end_obj = reinterpret_cast<const mirror::Object*>(pos + block_size);
CHECK_LE(reinterpret_cast<const uint8_t*>(end_obj), End());
// We don't know how many objects are allocated in the current block. When we hit a null class
// assume its the end. TODO: Have a thread update the header when it flushes the block?
// No read barrier because obj may not be a valid object.
while (obj < end_obj && obj->GetClass<kDefaultVerifyFlags, kWithoutReadBarrier>() != nullptr) {
callback(obj, arg);
obj = GetNextObject(obj);
}
pos += block_size;
}
}
accounting::ContinuousSpaceBitmap::SweepCallback* BumpPointerSpace::GetSweepCallback() {
UNIMPLEMENTED(FATAL);
UNREACHABLE();
}
uint64_t BumpPointerSpace::GetBytesAllocated() {
// Start out pre-determined amount (blocks which are not being allocated into).
uint64_t total = static_cast<uint64_t>(bytes_allocated_.LoadRelaxed());
Thread* self = Thread::Current();
MutexLock mu(self, *Locks::runtime_shutdown_lock_);
MutexLock mu2(self, *Locks::thread_list_lock_);
std::list<Thread*> thread_list = Runtime::Current()->GetThreadList()->GetList();
MutexLock mu3(Thread::Current(), block_lock_);
// If we don't have any blocks, we don't have any thread local buffers. This check is required
// since there can exist multiple bump pointer spaces which exist at the same time.
if (num_blocks_ > 0) {
for (Thread* thread : thread_list) {
total += thread->GetThreadLocalBytesAllocated();
}
}
return total;
}
uint64_t BumpPointerSpace::GetObjectsAllocated() {
// Start out pre-determined amount (blocks which are not being allocated into).
uint64_t total = static_cast<uint64_t>(objects_allocated_.LoadRelaxed());
Thread* self = Thread::Current();
MutexLock mu(self, *Locks::runtime_shutdown_lock_);
MutexLock mu2(self, *Locks::thread_list_lock_);
std::list<Thread*> thread_list = Runtime::Current()->GetThreadList()->GetList();
MutexLock mu3(Thread::Current(), block_lock_);
// If we don't have any blocks, we don't have any thread local buffers. This check is required
// since there can exist multiple bump pointer spaces which exist at the same time.
if (num_blocks_ > 0) {
for (Thread* thread : thread_list) {
total += thread->GetThreadLocalObjectsAllocated();
}
}
return total;
}
void BumpPointerSpace::RevokeThreadLocalBuffersLocked(Thread* thread) {
objects_allocated_.FetchAndAddSequentiallyConsistent(thread->GetThreadLocalObjectsAllocated());
bytes_allocated_.FetchAndAddSequentiallyConsistent(thread->GetThreadLocalBytesAllocated());
thread->SetTlab(nullptr, nullptr, nullptr);
}
bool BumpPointerSpace::AllocNewTlab(Thread* self, size_t bytes) {
MutexLock mu(Thread::Current(), block_lock_);
RevokeThreadLocalBuffersLocked(self);
uint8_t* start = AllocBlock(bytes);
if (start == nullptr) {
return false;
}
self->SetTlab(start, start + bytes, start + bytes);
return true;
}
void BumpPointerSpace::LogFragmentationAllocFailure(std::ostream& os,
size_t /* failed_alloc_bytes */) {
size_t max_contiguous_allocation = Limit() - End();
os << "; failed due to fragmentation (largest possible contiguous allocation "
<< max_contiguous_allocation << " bytes)";
// Caller's job to print failed_alloc_bytes.
}
} // namespace space
} // namespace gc
} // namespace art