tomFlowee
c63519fa47
The leveldb and univalue 3rd party libraries are not installed and not needed by anyone outside of the Hub. So move them there, making it easier for 3rd party usage.
69 lines
1.9 KiB
C++
69 lines
1.9 KiB
C++
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "util/arena.h"
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#include <assert.h>
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namespace leveldb {
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static const int kBlockSize = 4096;
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Arena::Arena() {
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blocks_memory_ = 0;
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alloc_ptr_ = NULL; // First allocation will allocate a block
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alloc_bytes_remaining_ = 0;
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}
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Arena::~Arena() {
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for (size_t i = 0; i < blocks_.size(); i++) {
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delete[] blocks_[i];
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}
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}
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char* Arena::AllocateFallback(size_t bytes) {
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if (bytes > kBlockSize / 4) {
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// Object is more than a quarter of our block size. Allocate it separately
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// to avoid wasting too much space in leftover bytes.
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char* result = AllocateNewBlock(bytes);
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return result;
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}
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// We waste the remaining space in the current block.
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alloc_ptr_ = AllocateNewBlock(kBlockSize);
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alloc_bytes_remaining_ = kBlockSize;
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char* result = alloc_ptr_;
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alloc_ptr_ += bytes;
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alloc_bytes_remaining_ -= bytes;
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return result;
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}
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char* Arena::AllocateAligned(size_t bytes) {
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const int align = (sizeof(void*) > 8) ? sizeof(void*) : 8;
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assert((align & (align-1)) == 0); // Pointer size should be a power of 2
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size_t current_mod = reinterpret_cast<uintptr_t>(alloc_ptr_) & (align-1);
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size_t slop = (current_mod == 0 ? 0 : align - current_mod);
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size_t needed = bytes + slop;
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char* result;
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if (needed <= alloc_bytes_remaining_) {
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result = alloc_ptr_ + slop;
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alloc_ptr_ += needed;
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alloc_bytes_remaining_ -= needed;
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} else {
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// AllocateFallback always returned aligned memory
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result = AllocateFallback(bytes);
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}
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assert((reinterpret_cast<uintptr_t>(result) & (align-1)) == 0);
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return result;
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}
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char* Arena::AllocateNewBlock(size_t block_bytes) {
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char* result = new char[block_bytes];
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blocks_memory_ += block_bytes;
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blocks_.push_back(result);
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return result;
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}
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} // namespace leveldb
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