/usr/include/boost/smart_ptr/detail/quick_allocator.hpp is in libboost1.55-dev 1.55.0+dfsg-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 | #ifndef BOOST_SMART_PTR_DETAIL_QUICK_ALLOCATOR_HPP_INCLUDED
#define BOOST_SMART_PTR_DETAIL_QUICK_ALLOCATOR_HPP_INCLUDED
// MS compatible compilers support #pragma once
#if defined(_MSC_VER) && (_MSC_VER >= 1020)
# pragma once
#endif
//
// detail/quick_allocator.hpp
//
// Copyright (c) 2003 David Abrahams
// Copyright (c) 2003 Peter Dimov
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
#include <boost/config.hpp>
#include <boost/smart_ptr/detail/lightweight_mutex.hpp>
#include <boost/type_traits/type_with_alignment.hpp>
#include <boost/type_traits/alignment_of.hpp>
#include <new> // ::operator new, ::operator delete
#include <cstddef> // std::size_t
namespace boost
{
namespace detail
{
template<unsigned size, unsigned align_> union freeblock
{
typedef typename boost::type_with_alignment<align_>::type aligner_type;
aligner_type aligner;
char bytes[size];
freeblock * next;
};
template<unsigned size, unsigned align_> struct allocator_impl
{
typedef freeblock<size, align_> block;
// It may seem odd to use such small pages.
//
// However, on a typical Windows implementation that uses
// the OS allocator, "normal size" pages interact with the
// "ordinary" operator new, slowing it down dramatically.
//
// 512 byte pages are handled by the small object allocator,
// and don't interfere with ::new.
//
// The other alternative is to use much bigger pages (1M.)
//
// It is surprisingly easy to hit pathological behavior by
// varying the page size. g++ 2.96 on Red Hat Linux 7.2,
// for example, passionately dislikes 496. 512 seems OK.
#if defined(BOOST_QA_PAGE_SIZE)
enum { items_per_page = BOOST_QA_PAGE_SIZE / size };
#else
enum { items_per_page = 512 / size }; // 1048560 / size
#endif
#ifdef BOOST_HAS_THREADS
static lightweight_mutex & mutex()
{
static freeblock< sizeof( lightweight_mutex ), boost::alignment_of< lightweight_mutex >::value > fbm;
static lightweight_mutex * pm = new( &fbm ) lightweight_mutex;
return *pm;
}
static lightweight_mutex * mutex_init;
#endif
static block * free;
static block * page;
static unsigned last;
static inline void * alloc()
{
#ifdef BOOST_HAS_THREADS
lightweight_mutex::scoped_lock lock( mutex() );
#endif
if(block * x = free)
{
free = x->next;
return x;
}
else
{
if(last == items_per_page)
{
// "Listen to me carefully: there is no memory leak"
// -- Scott Meyers, Eff C++ 2nd Ed Item 10
page = ::new block[items_per_page];
last = 0;
}
return &page[last++];
}
}
static inline void * alloc(std::size_t n)
{
if(n != size) // class-specific new called for a derived object
{
return ::operator new(n);
}
else
{
#ifdef BOOST_HAS_THREADS
lightweight_mutex::scoped_lock lock( mutex() );
#endif
if(block * x = free)
{
free = x->next;
return x;
}
else
{
if(last == items_per_page)
{
page = ::new block[items_per_page];
last = 0;
}
return &page[last++];
}
}
}
static inline void dealloc(void * pv)
{
if(pv != 0) // 18.4.1.1/13
{
#ifdef BOOST_HAS_THREADS
lightweight_mutex::scoped_lock lock( mutex() );
#endif
block * pb = static_cast<block *>(pv);
pb->next = free;
free = pb;
}
}
static inline void dealloc(void * pv, std::size_t n)
{
if(n != size) // class-specific delete called for a derived object
{
::operator delete(pv);
}
else if(pv != 0) // 18.4.1.1/13
{
#ifdef BOOST_HAS_THREADS
lightweight_mutex::scoped_lock lock( mutex() );
#endif
block * pb = static_cast<block *>(pv);
pb->next = free;
free = pb;
}
}
};
#ifdef BOOST_HAS_THREADS
template<unsigned size, unsigned align_>
lightweight_mutex * allocator_impl<size, align_>::mutex_init = &allocator_impl<size, align_>::mutex();
#endif
template<unsigned size, unsigned align_>
freeblock<size, align_> * allocator_impl<size, align_>::free = 0;
template<unsigned size, unsigned align_>
freeblock<size, align_> * allocator_impl<size, align_>::page = 0;
template<unsigned size, unsigned align_>
unsigned allocator_impl<size, align_>::last = allocator_impl<size, align_>::items_per_page;
template<class T>
struct quick_allocator: public allocator_impl< sizeof(T), boost::alignment_of<T>::value >
{
};
} // namespace detail
} // namespace boost
#endif // #ifndef BOOST_SMART_PTR_DETAIL_QUICK_ALLOCATOR_HPP_INCLUDED
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