boost/asio/detail/thread_info_base.hpp
//
// detail/thread_info_base.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2017 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// 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)
//
#ifndef BOOST_ASIO_DETAIL_THREAD_INFO_BASE_HPP
#define BOOST_ASIO_DETAIL_THREAD_INFO_BASE_HPP
#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
#include <climits>
#include <cstddef>
#include <boost/asio/detail/noncopyable.hpp>
#include <boost/asio/detail/push_options.hpp>
namespace boost {
namespace asio {
namespace detail {
class thread_info_base
: private noncopyable
{
public:
thread_info_base()
: reusable_memory_(0)
{
}
~thread_info_base()
{
if (reusable_memory_)
::operator delete(reusable_memory_);
}
static void* allocate(thread_info_base* this_thread, std::size_t size)
{
std::size_t chunks = (size + chunk_size - 1) / chunk_size;
if (this_thread && this_thread->reusable_memory_)
{
void* const pointer = this_thread->reusable_memory_;
this_thread->reusable_memory_ = 0;
unsigned char* const mem = static_cast<unsigned char*>(pointer);
if (static_cast<std::size_t>(mem[0]) >= chunks)
{
mem[size] = mem[0];
return pointer;
}
::operator delete(pointer);
}
void* const pointer = ::operator new(chunks * chunk_size + 1);
unsigned char* const mem = static_cast<unsigned char*>(pointer);
mem[size] = (chunks <= UCHAR_MAX) ? static_cast<unsigned char>(chunks) : 0;
return pointer;
}
static void deallocate(thread_info_base* this_thread,
void* pointer, std::size_t size)
{
if (size <= chunk_size * UCHAR_MAX)
{
if (this_thread && this_thread->reusable_memory_ == 0)
{
unsigned char* const mem = static_cast<unsigned char*>(pointer);
mem[0] = mem[size];
this_thread->reusable_memory_ = pointer;
return;
}
}
::operator delete(pointer);
}
private:
enum { chunk_size = 4 };
void* reusable_memory_;
};
} // namespace detail
} // namespace asio
} // namespace boost
#include <boost/asio/detail/pop_options.hpp>
#endif // BOOST_ASIO_DETAIL_THREAD_INFO_BASE_HPP