767 lines
22 KiB
C++
767 lines
22 KiB
C++
// MT-optimized allocator -*- C++ -*-
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// Copyright (C) 2003-2014 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file ext/mt_allocator.h
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* This file is a GNU extension to the Standard C++ Library.
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*/
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#ifndef _MT_ALLOCATOR_H
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#define _MT_ALLOCATOR_H 1
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#include <new>
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#include <cstdlib>
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#include <bits/functexcept.h>
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#include <ext/atomicity.h>
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#include <bits/move.h>
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#if __cplusplus >= 201103L
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#include <type_traits>
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#endif
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namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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using std::size_t;
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using std::ptrdiff_t;
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typedef void (*__destroy_handler)(void*);
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/// Base class for pool object.
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struct __pool_base
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{
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// Using short int as type for the binmap implies we are never
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// caching blocks larger than 32768 with this allocator.
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typedef unsigned short int _Binmap_type;
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// Variables used to configure the behavior of the allocator,
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// assigned and explained in detail below.
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struct _Tune
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{
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// Compile time constants for the default _Tune values.
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enum { _S_align = 8 };
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enum { _S_max_bytes = 128 };
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enum { _S_min_bin = 8 };
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enum { _S_chunk_size = 4096 - 4 * sizeof(void*) };
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enum { _S_max_threads = 4096 };
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enum { _S_freelist_headroom = 10 };
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// Alignment needed.
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// NB: In any case must be >= sizeof(_Block_record), that
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// is 4 on 32 bit machines and 8 on 64 bit machines.
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size_t _M_align;
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// Allocation requests (after round-up to power of 2) below
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// this value will be handled by the allocator. A raw new/
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// call will be used for requests larger than this value.
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// NB: Must be much smaller than _M_chunk_size and in any
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// case <= 32768.
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size_t _M_max_bytes;
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// Size in bytes of the smallest bin.
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// NB: Must be a power of 2 and >= _M_align (and of course
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// much smaller than _M_max_bytes).
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size_t _M_min_bin;
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// In order to avoid fragmenting and minimize the number of
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// new() calls we always request new memory using this
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// value. Based on previous discussions on the libstdc++
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// mailing list we have chosen the value below.
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// See http://gcc.gnu.org/ml/libstdc++/2001-07/msg00077.html
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// NB: At least one order of magnitude > _M_max_bytes.
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size_t _M_chunk_size;
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// The maximum number of supported threads. For
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// single-threaded operation, use one. Maximum values will
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// vary depending on details of the underlying system. (For
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// instance, Linux 2.4.18 reports 4070 in
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// /proc/sys/kernel/threads-max, while Linux 2.6.6 reports
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// 65534)
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size_t _M_max_threads;
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// Each time a deallocation occurs in a threaded application
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// we make sure that there are no more than
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// _M_freelist_headroom % of used memory on the freelist. If
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// the number of additional records is more than
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// _M_freelist_headroom % of the freelist, we move these
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// records back to the global pool.
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size_t _M_freelist_headroom;
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// Set to true forces all allocations to use new().
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bool _M_force_new;
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explicit
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_Tune()
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: _M_align(_S_align), _M_max_bytes(_S_max_bytes), _M_min_bin(_S_min_bin),
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_M_chunk_size(_S_chunk_size), _M_max_threads(_S_max_threads),
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_M_freelist_headroom(_S_freelist_headroom),
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_M_force_new(std::getenv("GLIBCXX_FORCE_NEW") ? true : false)
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{ }
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explicit
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_Tune(size_t __align, size_t __maxb, size_t __minbin, size_t __chunk,
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size_t __maxthreads, size_t __headroom, bool __force)
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: _M_align(__align), _M_max_bytes(__maxb), _M_min_bin(__minbin),
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_M_chunk_size(__chunk), _M_max_threads(__maxthreads),
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_M_freelist_headroom(__headroom), _M_force_new(__force)
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{ }
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};
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struct _Block_address
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{
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void* _M_initial;
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_Block_address* _M_next;
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};
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const _Tune&
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_M_get_options() const
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{ return _M_options; }
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void
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_M_set_options(_Tune __t)
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{
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if (!_M_init)
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_M_options = __t;
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}
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bool
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_M_check_threshold(size_t __bytes)
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{ return __bytes > _M_options._M_max_bytes || _M_options._M_force_new; }
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size_t
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_M_get_binmap(size_t __bytes)
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{ return _M_binmap[__bytes]; }
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size_t
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_M_get_align()
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{ return _M_options._M_align; }
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explicit
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__pool_base()
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: _M_options(_Tune()), _M_binmap(0), _M_init(false) { }
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explicit
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__pool_base(const _Tune& __options)
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: _M_options(__options), _M_binmap(0), _M_init(false) { }
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private:
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explicit
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__pool_base(const __pool_base&);
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__pool_base&
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operator=(const __pool_base&);
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protected:
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// Configuration options.
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_Tune _M_options;
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_Binmap_type* _M_binmap;
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// Configuration of the pool object via _M_options can happen
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// after construction but before initialization. After
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// initialization is complete, this variable is set to true.
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bool _M_init;
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};
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/**
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* @brief Data describing the underlying memory pool, parameterized on
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* threading support.
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*/
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template<bool _Thread>
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class __pool;
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/// Specialization for single thread.
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template<>
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class __pool<false> : public __pool_base
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{
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public:
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union _Block_record
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{
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// Points to the block_record of the next free block.
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_Block_record* _M_next;
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};
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struct _Bin_record
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{
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// An "array" of pointers to the first free block.
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_Block_record** _M_first;
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// A list of the initial addresses of all allocated blocks.
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_Block_address* _M_address;
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};
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void
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_M_initialize_once()
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{
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if (__builtin_expect(_M_init == false, false))
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_M_initialize();
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}
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void
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_M_destroy() throw();
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char*
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_M_reserve_block(size_t __bytes, const size_t __thread_id);
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void
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_M_reclaim_block(char* __p, size_t __bytes) throw ();
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size_t
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_M_get_thread_id() { return 0; }
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const _Bin_record&
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_M_get_bin(size_t __which)
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{ return _M_bin[__which]; }
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void
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_M_adjust_freelist(const _Bin_record&, _Block_record*, size_t)
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{ }
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explicit __pool()
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: _M_bin(0), _M_bin_size(1) { }
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explicit __pool(const __pool_base::_Tune& __tune)
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: __pool_base(__tune), _M_bin(0), _M_bin_size(1) { }
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private:
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// An "array" of bin_records each of which represents a specific
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// power of 2 size. Memory to this "array" is allocated in
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// _M_initialize().
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_Bin_record* _M_bin;
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// Actual value calculated in _M_initialize().
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size_t _M_bin_size;
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void
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_M_initialize();
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};
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#ifdef __GTHREADS
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/// Specialization for thread enabled, via gthreads.h.
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template<>
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class __pool<true> : public __pool_base
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{
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public:
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// Each requesting thread is assigned an id ranging from 1 to
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// _S_max_threads. Thread id 0 is used as a global memory pool.
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// In order to get constant performance on the thread assignment
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// routine, we keep a list of free ids. When a thread first
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// requests memory we remove the first record in this list and
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// stores the address in a __gthread_key. When initializing the
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// __gthread_key we specify a destructor. When this destructor
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// (i.e. the thread dies) is called, we return the thread id to
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// the front of this list.
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struct _Thread_record
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{
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// Points to next free thread id record. NULL if last record in list.
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_Thread_record* _M_next;
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// Thread id ranging from 1 to _S_max_threads.
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size_t _M_id;
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};
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union _Block_record
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{
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// Points to the block_record of the next free block.
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_Block_record* _M_next;
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// The thread id of the thread which has requested this block.
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size_t _M_thread_id;
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};
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struct _Bin_record
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{
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// An "array" of pointers to the first free block for each
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// thread id. Memory to this "array" is allocated in
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// _S_initialize() for _S_max_threads + global pool 0.
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_Block_record** _M_first;
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// A list of the initial addresses of all allocated blocks.
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_Block_address* _M_address;
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// An "array" of counters used to keep track of the amount of
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// blocks that are on the freelist/used for each thread id.
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// - Note that the second part of the allocated _M_used "array"
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// actually hosts (atomic) counters of reclaimed blocks: in
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// _M_reserve_block and in _M_reclaim_block those numbers are
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// subtracted from the first ones to obtain the actual size
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// of the "working set" of the given thread.
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// - Memory to these "arrays" is allocated in _S_initialize()
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// for _S_max_threads + global pool 0.
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size_t* _M_free;
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size_t* _M_used;
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// Each bin has its own mutex which is used to ensure data
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// integrity while changing "ownership" on a block. The mutex
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// is initialized in _S_initialize().
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__gthread_mutex_t* _M_mutex;
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};
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// XXX GLIBCXX_ABI Deprecated
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void
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_M_initialize(__destroy_handler);
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void
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_M_initialize_once()
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{
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if (__builtin_expect(_M_init == false, false))
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_M_initialize();
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}
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void
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_M_destroy() throw();
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char*
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_M_reserve_block(size_t __bytes, const size_t __thread_id);
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void
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_M_reclaim_block(char* __p, size_t __bytes) throw ();
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const _Bin_record&
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_M_get_bin(size_t __which)
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{ return _M_bin[__which]; }
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void
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_M_adjust_freelist(const _Bin_record& __bin, _Block_record* __block,
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size_t __thread_id)
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{
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if (__gthread_active_p())
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{
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__block->_M_thread_id = __thread_id;
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--__bin._M_free[__thread_id];
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++__bin._M_used[__thread_id];
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}
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}
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// XXX GLIBCXX_ABI Deprecated
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_GLIBCXX_CONST void
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_M_destroy_thread_key(void*) throw ();
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size_t
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_M_get_thread_id();
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explicit __pool()
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: _M_bin(0), _M_bin_size(1), _M_thread_freelist(0)
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{ }
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explicit __pool(const __pool_base::_Tune& __tune)
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: __pool_base(__tune), _M_bin(0), _M_bin_size(1),
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_M_thread_freelist(0)
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{ }
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private:
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// An "array" of bin_records each of which represents a specific
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// power of 2 size. Memory to this "array" is allocated in
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// _M_initialize().
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_Bin_record* _M_bin;
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// Actual value calculated in _M_initialize().
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size_t _M_bin_size;
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_Thread_record* _M_thread_freelist;
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void* _M_thread_freelist_initial;
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void
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_M_initialize();
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};
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#endif
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template<template <bool> class _PoolTp, bool _Thread>
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struct __common_pool
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{
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typedef _PoolTp<_Thread> pool_type;
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static pool_type&
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_S_get_pool()
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{
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static pool_type _S_pool;
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return _S_pool;
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}
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};
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template<template <bool> class _PoolTp, bool _Thread>
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struct __common_pool_base;
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template<template <bool> class _PoolTp>
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struct __common_pool_base<_PoolTp, false>
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: public __common_pool<_PoolTp, false>
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{
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using __common_pool<_PoolTp, false>::_S_get_pool;
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static void
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_S_initialize_once()
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{
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static bool __init;
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if (__builtin_expect(__init == false, false))
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{
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_S_get_pool()._M_initialize_once();
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__init = true;
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}
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}
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};
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#ifdef __GTHREADS
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template<template <bool> class _PoolTp>
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struct __common_pool_base<_PoolTp, true>
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: public __common_pool<_PoolTp, true>
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{
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using __common_pool<_PoolTp, true>::_S_get_pool;
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static void
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_S_initialize()
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{ _S_get_pool()._M_initialize_once(); }
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static void
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_S_initialize_once()
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{
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static bool __init;
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if (__builtin_expect(__init == false, false))
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{
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if (__gthread_active_p())
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{
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// On some platforms, __gthread_once_t is an aggregate.
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static __gthread_once_t __once = __GTHREAD_ONCE_INIT;
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__gthread_once(&__once, _S_initialize);
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}
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// Double check initialization. May be necessary on some
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// systems for proper construction when not compiling with
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// thread flags.
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_S_get_pool()._M_initialize_once();
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__init = true;
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}
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}
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};
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#endif
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/// Policy for shared __pool objects.
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template<template <bool> class _PoolTp, bool _Thread>
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struct __common_pool_policy : public __common_pool_base<_PoolTp, _Thread>
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{
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template<typename _Tp1, template <bool> class _PoolTp1 = _PoolTp,
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bool _Thread1 = _Thread>
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struct _M_rebind
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{ typedef __common_pool_policy<_PoolTp1, _Thread1> other; };
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using __common_pool_base<_PoolTp, _Thread>::_S_get_pool;
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using __common_pool_base<_PoolTp, _Thread>::_S_initialize_once;
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};
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template<typename _Tp, template <bool> class _PoolTp, bool _Thread>
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struct __per_type_pool
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{
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typedef _Tp value_type;
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typedef _PoolTp<_Thread> pool_type;
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static pool_type&
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_S_get_pool()
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{
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// Sane defaults for the _PoolTp.
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typedef typename pool_type::_Block_record _Block_record;
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const static size_t __a = (__alignof__(_Tp) >= sizeof(_Block_record)
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? __alignof__(_Tp) : sizeof(_Block_record));
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typedef typename __pool_base::_Tune _Tune;
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static _Tune _S_tune(__a, sizeof(_Tp) * 64,
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sizeof(_Tp) * 2 >= __a ? sizeof(_Tp) * 2 : __a,
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sizeof(_Tp) * size_t(_Tune::_S_chunk_size),
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_Tune::_S_max_threads,
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_Tune::_S_freelist_headroom,
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std::getenv("GLIBCXX_FORCE_NEW") ? true : false);
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static pool_type _S_pool(_S_tune);
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return _S_pool;
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}
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};
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template<typename _Tp, template <bool> class _PoolTp, bool _Thread>
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struct __per_type_pool_base;
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template<typename _Tp, template <bool> class _PoolTp>
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struct __per_type_pool_base<_Tp, _PoolTp, false>
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: public __per_type_pool<_Tp, _PoolTp, false>
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{
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using __per_type_pool<_Tp, _PoolTp, false>::_S_get_pool;
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static void
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_S_initialize_once()
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{
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static bool __init;
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if (__builtin_expect(__init == false, false))
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{
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_S_get_pool()._M_initialize_once();
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__init = true;
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}
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}
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};
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#ifdef __GTHREADS
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template<typename _Tp, template <bool> class _PoolTp>
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struct __per_type_pool_base<_Tp, _PoolTp, true>
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: public __per_type_pool<_Tp, _PoolTp, true>
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{
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using __per_type_pool<_Tp, _PoolTp, true>::_S_get_pool;
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static void
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_S_initialize()
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{ _S_get_pool()._M_initialize_once(); }
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static void
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_S_initialize_once()
|
|
{
|
|
static bool __init;
|
|
if (__builtin_expect(__init == false, false))
|
|
{
|
|
if (__gthread_active_p())
|
|
{
|
|
// On some platforms, __gthread_once_t is an aggregate.
|
|
static __gthread_once_t __once = __GTHREAD_ONCE_INIT;
|
|
__gthread_once(&__once, _S_initialize);
|
|
}
|
|
|
|
// Double check initialization. May be necessary on some
|
|
// systems for proper construction when not compiling with
|
|
// thread flags.
|
|
_S_get_pool()._M_initialize_once();
|
|
__init = true;
|
|
}
|
|
}
|
|
};
|
|
#endif
|
|
|
|
/// Policy for individual __pool objects.
|
|
template<typename _Tp, template <bool> class _PoolTp, bool _Thread>
|
|
struct __per_type_pool_policy
|
|
: public __per_type_pool_base<_Tp, _PoolTp, _Thread>
|
|
{
|
|
template<typename _Tp1, template <bool> class _PoolTp1 = _PoolTp,
|
|
bool _Thread1 = _Thread>
|
|
struct _M_rebind
|
|
{ typedef __per_type_pool_policy<_Tp1, _PoolTp1, _Thread1> other; };
|
|
|
|
using __per_type_pool_base<_Tp, _PoolTp, _Thread>::_S_get_pool;
|
|
using __per_type_pool_base<_Tp, _PoolTp, _Thread>::_S_initialize_once;
|
|
};
|
|
|
|
|
|
/// Base class for _Tp dependent member functions.
|
|
template<typename _Tp>
|
|
class __mt_alloc_base
|
|
{
|
|
public:
|
|
typedef size_t size_type;
|
|
typedef ptrdiff_t difference_type;
|
|
typedef _Tp* pointer;
|
|
typedef const _Tp* const_pointer;
|
|
typedef _Tp& reference;
|
|
typedef const _Tp& const_reference;
|
|
typedef _Tp value_type;
|
|
|
|
#if __cplusplus >= 201103L
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 2103. propagate_on_container_move_assignment
|
|
typedef std::true_type propagate_on_container_move_assignment;
|
|
#endif
|
|
|
|
pointer
|
|
address(reference __x) const _GLIBCXX_NOEXCEPT
|
|
{ return std::__addressof(__x); }
|
|
|
|
const_pointer
|
|
address(const_reference __x) const _GLIBCXX_NOEXCEPT
|
|
{ return std::__addressof(__x); }
|
|
|
|
size_type
|
|
max_size() const _GLIBCXX_USE_NOEXCEPT
|
|
{ return size_t(-1) / sizeof(_Tp); }
|
|
|
|
#if __cplusplus >= 201103L
|
|
template<typename _Up, typename... _Args>
|
|
void
|
|
construct(_Up* __p, _Args&&... __args)
|
|
{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
|
|
|
|
template<typename _Up>
|
|
void
|
|
destroy(_Up* __p) { __p->~_Up(); }
|
|
#else
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 402. wrong new expression in [some_] allocator::construct
|
|
void
|
|
construct(pointer __p, const _Tp& __val)
|
|
{ ::new((void *)__p) _Tp(__val); }
|
|
|
|
void
|
|
destroy(pointer __p) { __p->~_Tp(); }
|
|
#endif
|
|
};
|
|
|
|
#ifdef __GTHREADS
|
|
#define __thread_default true
|
|
#else
|
|
#define __thread_default false
|
|
#endif
|
|
|
|
/**
|
|
* @brief This is a fixed size (power of 2) allocator which - when
|
|
* compiled with thread support - will maintain one freelist per
|
|
* size per thread plus a @a global one. Steps are taken to limit
|
|
* the per thread freelist sizes (by returning excess back to
|
|
* the @a global list).
|
|
* @ingroup allocators
|
|
*
|
|
* Further details:
|
|
* http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt12ch32.html
|
|
*/
|
|
template<typename _Tp,
|
|
typename _Poolp = __common_pool_policy<__pool, __thread_default> >
|
|
class __mt_alloc : public __mt_alloc_base<_Tp>
|
|
{
|
|
public:
|
|
typedef size_t size_type;
|
|
typedef ptrdiff_t difference_type;
|
|
typedef _Tp* pointer;
|
|
typedef const _Tp* const_pointer;
|
|
typedef _Tp& reference;
|
|
typedef const _Tp& const_reference;
|
|
typedef _Tp value_type;
|
|
typedef _Poolp __policy_type;
|
|
typedef typename _Poolp::pool_type __pool_type;
|
|
|
|
template<typename _Tp1, typename _Poolp1 = _Poolp>
|
|
struct rebind
|
|
{
|
|
typedef typename _Poolp1::template _M_rebind<_Tp1>::other pol_type;
|
|
typedef __mt_alloc<_Tp1, pol_type> other;
|
|
};
|
|
|
|
__mt_alloc() _GLIBCXX_USE_NOEXCEPT { }
|
|
|
|
__mt_alloc(const __mt_alloc&) _GLIBCXX_USE_NOEXCEPT { }
|
|
|
|
template<typename _Tp1, typename _Poolp1>
|
|
__mt_alloc(const __mt_alloc<_Tp1, _Poolp1>&) _GLIBCXX_USE_NOEXCEPT { }
|
|
|
|
~__mt_alloc() _GLIBCXX_USE_NOEXCEPT { }
|
|
|
|
pointer
|
|
allocate(size_type __n, const void* = 0);
|
|
|
|
void
|
|
deallocate(pointer __p, size_type __n);
|
|
|
|
const __pool_base::_Tune
|
|
_M_get_options()
|
|
{
|
|
// Return a copy, not a reference, for external consumption.
|
|
return __policy_type::_S_get_pool()._M_get_options();
|
|
}
|
|
|
|
void
|
|
_M_set_options(__pool_base::_Tune __t)
|
|
{ __policy_type::_S_get_pool()._M_set_options(__t); }
|
|
};
|
|
|
|
template<typename _Tp, typename _Poolp>
|
|
typename __mt_alloc<_Tp, _Poolp>::pointer
|
|
__mt_alloc<_Tp, _Poolp>::
|
|
allocate(size_type __n, const void*)
|
|
{
|
|
if (__n > this->max_size())
|
|
std::__throw_bad_alloc();
|
|
|
|
__policy_type::_S_initialize_once();
|
|
|
|
// Requests larger than _M_max_bytes are handled by operator
|
|
// new/delete directly.
|
|
__pool_type& __pool = __policy_type::_S_get_pool();
|
|
const size_t __bytes = __n * sizeof(_Tp);
|
|
if (__pool._M_check_threshold(__bytes))
|
|
{
|
|
void* __ret = ::operator new(__bytes);
|
|
return static_cast<_Tp*>(__ret);
|
|
}
|
|
|
|
// Round up to power of 2 and figure out which bin to use.
|
|
const size_t __which = __pool._M_get_binmap(__bytes);
|
|
const size_t __thread_id = __pool._M_get_thread_id();
|
|
|
|
// Find out if we have blocks on our freelist. If so, go ahead
|
|
// and use them directly without having to lock anything.
|
|
char* __c;
|
|
typedef typename __pool_type::_Bin_record _Bin_record;
|
|
const _Bin_record& __bin = __pool._M_get_bin(__which);
|
|
if (__bin._M_first[__thread_id])
|
|
{
|
|
// Already reserved.
|
|
typedef typename __pool_type::_Block_record _Block_record;
|
|
_Block_record* __block = __bin._M_first[__thread_id];
|
|
__bin._M_first[__thread_id] = __block->_M_next;
|
|
|
|
__pool._M_adjust_freelist(__bin, __block, __thread_id);
|
|
__c = reinterpret_cast<char*>(__block) + __pool._M_get_align();
|
|
}
|
|
else
|
|
{
|
|
// Null, reserve.
|
|
__c = __pool._M_reserve_block(__bytes, __thread_id);
|
|
}
|
|
return static_cast<_Tp*>(static_cast<void*>(__c));
|
|
}
|
|
|
|
template<typename _Tp, typename _Poolp>
|
|
void
|
|
__mt_alloc<_Tp, _Poolp>::
|
|
deallocate(pointer __p, size_type __n)
|
|
{
|
|
if (__builtin_expect(__p != 0, true))
|
|
{
|
|
// Requests larger than _M_max_bytes are handled by
|
|
// operators new/delete directly.
|
|
__pool_type& __pool = __policy_type::_S_get_pool();
|
|
const size_t __bytes = __n * sizeof(_Tp);
|
|
if (__pool._M_check_threshold(__bytes))
|
|
::operator delete(__p);
|
|
else
|
|
__pool._M_reclaim_block(reinterpret_cast<char*>(__p), __bytes);
|
|
}
|
|
}
|
|
|
|
template<typename _Tp, typename _Poolp>
|
|
inline bool
|
|
operator==(const __mt_alloc<_Tp, _Poolp>&, const __mt_alloc<_Tp, _Poolp>&)
|
|
{ return true; }
|
|
|
|
template<typename _Tp, typename _Poolp>
|
|
inline bool
|
|
operator!=(const __mt_alloc<_Tp, _Poolp>&, const __mt_alloc<_Tp, _Poolp>&)
|
|
{ return false; }
|
|
|
|
#undef __thread_default
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace
|
|
|
|
#endif
|