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/*
* Copyright (C) 2018 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 "mem_map_arena_pool.h"
#include <sys/mman.h>
#include <algorithm>
#include <cstddef>
#include <iomanip>
#include <numeric>
#include <android-base/logging.h>
#include "base/arena_allocator-inl.h"
#include "base/mem_map.h"
#include "base/systrace.h"
namespace art {
class MemMapArena final : public Arena {
public:
MemMapArena(size_t size, bool low_4gb, const char* name);
virtual ~MemMapArena();
void Release() override;
private:
static MemMap Allocate(size_t size, bool low_4gb, const char* name);
MemMap map_;
};
MemMapArena::MemMapArena(size_t size, bool low_4gb, const char* name)
: map_(Allocate(size, low_4gb, name)) {
memory_ = map_.Begin();
static_assert(ArenaAllocator::kArenaAlignment <= kPageSize,
"Arena should not need stronger alignment than kPageSize.");
DCHECK_ALIGNED(memory_, ArenaAllocator::kArenaAlignment);
size_ = map_.Size();
}
MemMap MemMapArena::Allocate(size_t size, bool low_4gb, const char* name) {
// Round up to a full page as that's the smallest unit of allocation for mmap()
// and we want to be able to use all memory that we actually allocate.
size = RoundUp(size, kPageSize);
std::string error_msg;
MemMap map = MemMap::MapAnonymous(name,
size,
PROT_READ | PROT_WRITE,
low_4gb,
&error_msg);
CHECK(map.IsValid()) << error_msg;
return map;
}
MemMapArena::~MemMapArena() {
// Destroys MemMap via std::unique_ptr<>.
}
void MemMapArena::Release() {
if (bytes_allocated_ > 0) {
map_.MadviseDontNeedAndZero();
bytes_allocated_ = 0;
}
}
MemMapArenaPool::MemMapArenaPool(bool low_4gb, const char* name)
: low_4gb_(low_4gb),
name_(name),
free_arenas_(nullptr) {
MemMap::Init();
}
MemMapArenaPool::~MemMapArenaPool() {
ReclaimMemory();
}
void MemMapArenaPool::ReclaimMemory() {
while (free_arenas_ != nullptr) {
Arena* arena = free_arenas_;
free_arenas_ = free_arenas_->next_;
delete arena;
}
}
void MemMapArenaPool::LockReclaimMemory() {
std::lock_guard<std::mutex> lock(lock_);
ReclaimMemory();
}
Arena* MemMapArenaPool::AllocArena(size_t size) {
Arena* ret = nullptr;
{
std::lock_guard<std::mutex> lock(lock_);
if (free_arenas_ != nullptr && LIKELY(free_arenas_->Size() >= size)) {
ret = free_arenas_;
free_arenas_ = free_arenas_->next_;
}
}
if (ret == nullptr) {
ret = new MemMapArena(size, low_4gb_, name_);
}
ret->Reset();
return ret;
}
void MemMapArenaPool::TrimMaps() {
ScopedTrace trace(__PRETTY_FUNCTION__);
std::lock_guard<std::mutex> lock(lock_);
for (Arena* arena = free_arenas_; arena != nullptr; arena = arena->next_) {
arena->Release();
}
}
size_t MemMapArenaPool::GetBytesAllocated() const {
size_t total = 0;
std::lock_guard<std::mutex> lock(lock_);
for (Arena* arena = free_arenas_; arena != nullptr; arena = arena->next_) {
total += arena->GetBytesAllocated();
}
return total;
}
void MemMapArenaPool::FreeArenaChain(Arena* first) {
if (kRunningOnMemoryTool) {
for (Arena* arena = first; arena != nullptr; arena = arena->next_) {
MEMORY_TOOL_MAKE_UNDEFINED(arena->memory_, arena->bytes_allocated_);
}
}
if (arena_allocator::kArenaAllocatorPreciseTracking) {
// Do not reuse arenas when tracking.
while (first != nullptr) {
Arena* next = first->next_;
delete first;
first = next;
}
return;
}
if (first != nullptr) {
Arena* last = first;
while (last->next_ != nullptr) {
last = last->next_;
}
std::lock_guard<std::mutex> lock(lock_);
last->next_ = free_arenas_;
free_arenas_ = first;
}
}
} // namespace art
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