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author | Ilya Zhuravlev <zhuravlevilya@ya.ru> | 2012-10-23 01:18:44 +0400 |
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committer | Sfan5 <sfan5@live.de> | 2013-09-09 22:50:50 +0200 |
commit | 58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9 (patch) | |
tree | 6012bbb1905231025dff89aa73782a7c38666839 /src/leveldb/util/arena.h | |
parent | 71a8769bb5ded4acb3f9e5a8502bb8af277f824d (diff) | |
download | minetest-58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9.tar.gz minetest-58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9.tar.bz2 minetest-58841ef12f6cba1bb622353c1fcaa0e3c6fb46c9.zip |
Add dummy and LevelDB database backends
Diffstat (limited to 'src/leveldb/util/arena.h')
-rw-r--r-- | src/leveldb/util/arena.h | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/src/leveldb/util/arena.h b/src/leveldb/util/arena.h new file mode 100644 index 000000000..8f7dde226 --- /dev/null +++ b/src/leveldb/util/arena.h @@ -0,0 +1,68 @@ +// 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. + +#ifndef STORAGE_LEVELDB_UTIL_ARENA_H_ +#define STORAGE_LEVELDB_UTIL_ARENA_H_ + +#include <cstddef> +#include <vector> +#include <assert.h> +#include <stdint.h> + +namespace leveldb { + +class Arena { + public: + Arena(); + ~Arena(); + + // Return a pointer to a newly allocated memory block of "bytes" bytes. + char* Allocate(size_t bytes); + + // Allocate memory with the normal alignment guarantees provided by malloc + char* AllocateAligned(size_t bytes); + + // Returns an estimate of the total memory usage of data allocated + // by the arena (including space allocated but not yet used for user + // allocations). + size_t MemoryUsage() const { + return blocks_memory_ + blocks_.capacity() * sizeof(char*); + } + + private: + char* AllocateFallback(size_t bytes); + char* AllocateNewBlock(size_t block_bytes); + + // Allocation state + char* alloc_ptr_; + size_t alloc_bytes_remaining_; + + // Array of new[] allocated memory blocks + std::vector<char*> blocks_; + + // Bytes of memory in blocks allocated so far + size_t blocks_memory_; + + // No copying allowed + Arena(const Arena&); + void operator=(const Arena&); +}; + +inline char* Arena::Allocate(size_t bytes) { + // The semantics of what to return are a bit messy if we allow + // 0-byte allocations, so we disallow them here (we don't need + // them for our internal use). + assert(bytes > 0); + if (bytes <= alloc_bytes_remaining_) { + char* result = alloc_ptr_; + alloc_ptr_ += bytes; + alloc_bytes_remaining_ -= bytes; + return result; + } + return AllocateFallback(bytes); +} + +} // namespace leveldb + +#endif // STORAGE_LEVELDB_UTIL_ARENA_H_ |