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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "memory/arena.h"
#ifndef OS_WIN
#include <sys/mman.h>
#endif
#include <algorithm>
#include "logging/logging.h"
#include "port/malloc.h"
#include "port/port.h"
#include "rocksdb/env.h"
#include "test_util/sync_point.h"
#include "util/string_util.h"
namespace ROCKSDB_NAMESPACE {
// MSVC complains that it is already defined since it is static in the header.
#ifndef _MSC_VER
const size_t Arena::kInlineSize;
#endif
const size_t Arena::kMinBlockSize = 4096;
const size_t Arena::kMaxBlockSize = 2u << 30;
static const int kAlignUnit = alignof(max_align_t);
size_t OptimizeBlockSize(size_t block_size) {
// Make sure block_size is in optimal range
block_size = std::max(Arena::kMinBlockSize, block_size);
block_size = std::min(Arena::kMaxBlockSize, block_size);
// make sure block_size is the multiple of kAlignUnit
if (block_size % kAlignUnit != 0) {
block_size = (1 + block_size / kAlignUnit) * kAlignUnit;
}
return block_size;
}
Arena::Arena(size_t block_size, AllocTracker* tracker, size_t huge_page_size)
: kBlockSize(OptimizeBlockSize(block_size)), tracker_(tracker) {
assert(kBlockSize >= kMinBlockSize && kBlockSize <= kMaxBlockSize &&
kBlockSize % kAlignUnit == 0);
TEST_SYNC_POINT_CALLBACK("Arena::Arena:0", const_cast<size_t*>(&kBlockSize));
alloc_bytes_remaining_ = sizeof(inline_block_);
blocks_memory_ += alloc_bytes_remaining_;
aligned_alloc_ptr_ = inline_block_;
unaligned_alloc_ptr_ = inline_block_ + alloc_bytes_remaining_;
#ifdef MAP_HUGETLB
hugetlb_size_ = huge_page_size;
if (hugetlb_size_ && kBlockSize > hugetlb_size_) {
hugetlb_size_ = ((kBlockSize - 1U) / hugetlb_size_ + 1U) * hugetlb_size_;
}
#else
(void)huge_page_size;
#endif
if (tracker_ != nullptr) {
tracker_->Allocate(kInlineSize);
}
}
Arena::~Arena() {
if (tracker_ != nullptr) {
assert(tracker_->is_freed());
tracker_->FreeMem();
}
for (const auto& block : blocks_) {
delete[] block;
}
#ifdef MAP_HUGETLB
for (const auto& mmap_info : huge_blocks_) {
if (mmap_info.addr_ == nullptr) {
continue;
}
auto ret = munmap(mmap_info.addr_, mmap_info.length_);
if (ret != 0) {
// TODO(sdong): Better handling
}
}
#endif
}
char* Arena::AllocateFallback(size_t bytes, bool aligned) {
if (bytes > kBlockSize / 4) {
++irregular_block_num;
// Object is more than a quarter of our block size. Allocate it separately
// to avoid wasting too much space in leftover bytes.
return AllocateNewBlock(bytes);
}
// We waste the remaining space in the current block.
size_t size = 0;
char* block_head = nullptr;
#ifdef MAP_HUGETLB
if (hugetlb_size_) {
size = hugetlb_size_;
block_head = AllocateFromHugePage(size);
}
#endif
if (!block_head) {
size = kBlockSize;
block_head = AllocateNewBlock(size);
}
alloc_bytes_remaining_ = size - bytes;
if (aligned) {
aligned_alloc_ptr_ = block_head + bytes;
unaligned_alloc_ptr_ = block_head + size;
return block_head;
} else {
aligned_alloc_ptr_ = block_head;
unaligned_alloc_ptr_ = block_head + size - bytes;
return unaligned_alloc_ptr_;
}
}
char* Arena::AllocateFromHugePage(size_t bytes) {
#ifdef MAP_HUGETLB
if (hugetlb_size_ == 0) {
return nullptr;
}
// Reserve space in `huge_blocks_` before calling `mmap`.
// Use `emplace_back()` instead of `reserve()` to let std::vector manage its
// own memory and do fewer reallocations.
//
// - If `emplace_back` throws, no memory leaks because we haven't called
// `mmap` yet.
// - If `mmap` throws, no memory leaks because the vector will be cleaned up
// via RAII.
huge_blocks_.emplace_back(nullptr /* addr */, 0 /* length */);
void* addr = mmap(nullptr, bytes, (PROT_READ | PROT_WRITE),
(MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB), -1, 0);
if (addr == MAP_FAILED) {
return nullptr;
}
huge_blocks_.back() = MmapInfo(addr, bytes);
blocks_memory_ += bytes;
if (tracker_ != nullptr) {
tracker_->Allocate(bytes);
}
return reinterpret_cast<char*>(addr);
#else
(void)bytes;
return nullptr;
#endif
}
char* Arena::AllocateAligned(size_t bytes, size_t huge_page_size,
Logger* logger) {
assert((kAlignUnit & (kAlignUnit - 1)) ==
0); // Pointer size should be a power of 2
#ifdef MAP_HUGETLB
if (huge_page_size > 0 && bytes > 0) {
// Allocate from a huge page TLB table.
size_t reserved_size =
((bytes - 1U) / huge_page_size + 1U) * huge_page_size;
assert(reserved_size >= bytes);
char* addr = AllocateFromHugePage(reserved_size);
if (addr == nullptr) {
ROCKS_LOG_WARN(logger,
"AllocateAligned fail to allocate huge TLB pages: %s",
errnoStr(errno).c_str());
// fail back to malloc
} else {
return addr;
}
}
#else
(void)huge_page_size;
(void)logger;
#endif
size_t current_mod =
reinterpret_cast<uintptr_t>(aligned_alloc_ptr_) & (kAlignUnit - 1);
size_t slop = (current_mod == 0 ? 0 : kAlignUnit - current_mod);
size_t needed = bytes + slop;
char* result;
if (needed <= alloc_bytes_remaining_) {
result = aligned_alloc_ptr_ + slop;
aligned_alloc_ptr_ += needed;
alloc_bytes_remaining_ -= needed;
} else {
// AllocateFallback always returns aligned memory
result = AllocateFallback(bytes, true /* aligned */);
}
assert((reinterpret_cast<uintptr_t>(result) & (kAlignUnit - 1)) == 0);
return result;
}
char* Arena::AllocateNewBlock(size_t block_bytes) {
// Reserve space in `blocks_` before allocating memory via new.
// Use `emplace_back()` instead of `reserve()` to let std::vector manage its
// own memory and do fewer reallocations.
//
// - If `emplace_back` throws, no memory leaks because we haven't called `new`
// yet.
// - If `new` throws, no memory leaks because the vector will be cleaned up
// via RAII.
blocks_.emplace_back(nullptr);
char* block = new char[block_bytes];
size_t allocated_size;
#ifdef ROCKSDB_MALLOC_USABLE_SIZE
allocated_size = malloc_usable_size(block);
#ifndef NDEBUG
// It's hard to predict what malloc_usable_size() returns.
// A callback can allow users to change the costed size.
std::pair<size_t*, size_t*> pair(&allocated_size, &block_bytes);
TEST_SYNC_POINT_CALLBACK("Arena::AllocateNewBlock:0", &pair);
#endif // NDEBUG
#else
allocated_size = block_bytes;
#endif // ROCKSDB_MALLOC_USABLE_SIZE
blocks_memory_ += allocated_size;
if (tracker_ != nullptr) {
tracker_->Allocate(allocated_size);
}
blocks_.back() = block;
return block;
}
} // namespace ROCKSDB_NAMESPACE
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