/*
    Copyright 2005-2009 Intel Corporation.  All Rights Reserved.

    This file is part of Threading Building Blocks.

    Threading Building Blocks is free software; you can redistribute it
    and/or modify it under the terms of the GNU General Public License
    version 2 as published by the Free Software Foundation.

    Threading Building Blocks is distributed in the hope that it will be
    useful, but WITHOUT ANY WARRANTY; without even the implied warranty
    of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Threading Building Blocks; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    As a special exception, you may use this file as part of a free software
    library without restriction.  Specifically, if other files instantiate
    templates or use macros or inline functions from this file, or you compile
    this file and link it with other files to produce an executable, this
    file does not by itself cause the resulting executable to be covered by
    the GNU General Public License.  This exception does not however
    invalidate any other reasons why the executable file might be covered by
    the GNU General Public License.
*/

#include "tbb/concurrent_hash_map.h"

namespace tbb {

namespace internal {
#if !TBB_NO_LEGACY
struct hash_map_segment_base {
    typedef spin_rw_mutex segment_mutex_t;
    //! Type of a hash code.
    typedef size_t hashcode_t;
    //! Log2 of n_segment
    static const size_t n_segment_bits = 6;
    //! Maximum size of array of chains
    static const size_t max_physical_size = size_t(1)<<(8*sizeof(hashcode_t)-n_segment_bits);
    //! Mutex that protects this segment
    segment_mutex_t my_mutex;
    // Number of nodes
    atomic<size_t> my_logical_size;
    // Size of chains
    /** Always zero or a power of two */
    size_t my_physical_size;
    //! True if my_logical_size>=my_physical_size.
    /** Used to support Intel(R) Thread Checker. */
    bool __TBB_EXPORTED_METHOD internal_grow_predicate() const;
};

bool hash_map_segment_base::internal_grow_predicate() const {
    // Intel(R) Thread Checker considers the following reads to be races, so we hide them in the 
    // library so that Intel(R) Thread Checker will ignore them.  The reads are used in a double-check
    // context, so the program is nonetheless correct despite the race.
    return my_logical_size >= my_physical_size && my_physical_size < max_physical_size;
}
#endif//!TBB_NO_LEGACY

} // namespace internal

} // namespace tbb

