gloo/common/aligned_allocator.h

0001 /**
0002  * Copyright (c) 2017-present, Facebook, Inc.
0003  * All rights reserved.
0004  *
0005  * This source code is licensed under the BSD-style license found in the
0006  * LICENSE file in the root directory of this source tree.
0007  */
0008
0009 #pragma once
0010
0011 #include <cstdlib>
0012 #include <memory>
0013
0014 namespace gloo {
0015
0016 // Align buffers to 32 bytes to support vectorized code
0017 const size_t kBufferAlignment = 32;
0018
0019 template <typename T, int ALIGNMENT = kBufferAlignment>
0020 class aligned_allocator {
0021   static_assert(
0022       !(ALIGNMENT & (ALIGNMENT - 1)),
0023       "alignment must be a power of 2");
0024
0025  public:
0026   using value_type = T;
0027   using pointer = value_type*;
0028   using const_pointer = const value_type*;
0029   using reference = value_type&;
0030   using const_reference = const value_type&;
0031   using size_type = std::size_t;
0032   using difference_type = std::ptrdiff_t;
0033
0034   template <typename U>
0035   struct rebind {
0036     using other = aligned_allocator<U, ALIGNMENT>;
0037   };
0038
0039   inline explicit aligned_allocator() = default;
0040   inline ~aligned_allocator() = default;
0041   inline explicit aligned_allocator(const aligned_allocator& a) = default;
0042
0043   inline pointer address(reference r) {
0044     return &r;
0045   }
0046
0047   inline const_pointer address(const_reference r) {
0048     return &r;
0049   }
0050
0051   inline pointer allocate(size_type sz) {
0052     pointer p;
0053     if (posix_memalign(
0054             reinterpret_cast<void**>(&p), ALIGNMENT, sizeof(T) * sz)) {
0055       abort();
0056     }
0057     return p;
0058   }
0059
0060   void deallocate(pointer p, size_type /*sz*/) {
0061     free(p);
0062   }
0063 };
0064
0065 } // namespace gloo