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59 lines
2.6 KiB
C++
59 lines
2.6 KiB
C++
/*
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Copyright 2005-2014 Intel Corporation. All Rights Reserved.
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This file is part of Threading Building Blocks. Threading Building Blocks is free software;
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you can redistribute it and/or modify it under the terms of the GNU General Public License
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version 2 as published by the Free Software Foundation. Threading Building Blocks is
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distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the
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implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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See the GNU General Public License for more details. You should have received a copy of
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the GNU General Public License along with Threading Building Blocks; if not, write to the
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Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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As a special exception, you may use this file as part of a free software library without
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restriction. Specifically, if other files instantiate templates or use macros or inline
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functions from this file, or you compile this file and link it with other files to produce
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an executable, this file does not by itself cause the resulting executable to be covered
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by the GNU General Public License. This exception does not however invalidate any other
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reasons why the executable file might be covered by the GNU General Public License.
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*/
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#include "tbb/concurrent_hash_map.h"
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namespace tbb {
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namespace internal {
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#if !TBB_NO_LEGACY
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struct hash_map_segment_base {
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typedef spin_rw_mutex segment_mutex_t;
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//! Type of a hash code.
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typedef size_t hashcode_t;
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//! Log2 of n_segment
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static const size_t n_segment_bits = 6;
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//! Maximum size of array of chains
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static const size_t max_physical_size = size_t(1)<<(8*sizeof(hashcode_t)-n_segment_bits);
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//! Mutex that protects this segment
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segment_mutex_t my_mutex;
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// Number of nodes
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atomic<size_t> my_logical_size;
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// Size of chains
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/** Always zero or a power of two */
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size_t my_physical_size;
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//! True if my_logical_size>=my_physical_size.
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/** Used to support Intel(R) Thread Checker. */
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bool __TBB_EXPORTED_METHOD internal_grow_predicate() const;
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};
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bool hash_map_segment_base::internal_grow_predicate() const {
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// Intel(R) Thread Checker considers the following reads to be races, so we hide them in the
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// library so that Intel(R) Thread Checker will ignore them. The reads are used in a double-check
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// context, so the program is nonetheless correct despite the race.
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return my_logical_size >= my_physical_size && my_physical_size < max_physical_size;
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}
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#endif//!TBB_NO_LEGACY
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} // namespace internal
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} // namespace tbb
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