1 // Copyright (c) 2011 The LevelDB Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. See the AUTHORS file for names of contributors.
5 #ifndef STORAGE_LEVELDB_UTIL_ARENA_H_
6 #define STORAGE_LEVELDB_UTIL_ARENA_H_
20 // Return a pointer to a newly allocated memory block of "bytes" bytes.
21 char* Allocate(size_t bytes);
23 // Allocate memory with the normal alignment guarantees provided by malloc
24 char* AllocateAligned(size_t bytes);
26 // Returns an estimate of the total memory usage of data allocated
27 // by the arena (including space allocated but not yet used for user
29 size_t MemoryUsage() const {
30 return blocks_memory_ + blocks_.capacity() * sizeof(char*);
34 char* AllocateFallback(size_t bytes);
35 char* AllocateNewBlock(size_t block_bytes);
39 size_t alloc_bytes_remaining_;
41 // Array of new[] allocated memory blocks
42 std::vector<char*> blocks_;
44 // Bytes of memory in blocks allocated so far
45 size_t blocks_memory_;
49 void operator=(const Arena&);
52 inline char* Arena::Allocate(size_t bytes) {
53 // The semantics of what to return are a bit messy if we allow
54 // 0-byte allocations, so we disallow them here (we don't need
55 // them for our internal use).
57 if (bytes <= alloc_bytes_remaining_) {
58 char* result = alloc_ptr_;
60 alloc_bytes_remaining_ -= bytes;
63 return AllocateFallback(bytes);
66 } // namespace leveldb
68 #endif // STORAGE_LEVELDB_UTIL_ARENA_H_