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concurrent_vector.cpp

/*
    Copyright 2005-2007 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_vector.h"
#include "tbb_misc.h"
#include <stdexcept>
#include "itt_notify.h"
#include "tbb/task.h"


namespace tbb {

namespace internal {

void concurrent_vector_base::internal_grow_to_at_least( size_type new_size, size_type element_size, internal_array_op1 init ) {
    size_type e = my_early_size;
    while( e<new_size ) {
        size_type f = my_early_size.compare_and_swap(new_size,e);
        if( f==e ) {
            internal_grow( e, new_size, element_size, init );
            return;
        }
        e = f;
    }
}

class concurrent_vector_base::helper {
    static void extend_segment( concurrent_vector_base& v );
public:
    static segment_index_t find_segment_end( const concurrent_vector_base& v ) {
        const size_t pointers_per_long_segment = sizeof(void*)==4 ? 32 : 64;
        const size_t pointers_per_short_segment = 2;
        //unsigned u = v.my_segment==v.my_storage ? pointers_per_short_segment : pointers_per_long_segment;
        segment_index_t u = v.my_segment==(&(v.my_storage[0])) ? pointers_per_short_segment : pointers_per_long_segment;
        segment_index_t k = 0;
        while( k<u && v.my_segment[k].array )
            ++k;
        return k;
    }
    static void extend_segment_if_necessary( concurrent_vector_base& v, size_t k ) {
        const size_t pointers_per_short_segment = 2;
        if( k>=pointers_per_short_segment && v.my_segment==v.my_storage ) {
            extend_segment(v);
        }
    }
};

void concurrent_vector_base::helper::extend_segment( concurrent_vector_base& v ) {
    const size_t pointers_per_long_segment = sizeof(void*)==4 ? 32 : 64;
    segment_t* s = (segment_t*)NFS_Allocate( pointers_per_long_segment, sizeof(segment_t), NULL );
    memset( s, 0, pointers_per_long_segment*sizeof(segment_t) );
    // If other threads are trying to set pointers in the short segment, wait for them to finish their
    // assigments before we copy the short segment to the long segment.
    ExponentialBackoff backoff;
    while( !v.my_storage[0].array || !v.my_storage[1].array ) {
        backoff.pause();
    }
    s[0] = v.my_storage[0]; 
    s[1] = v.my_storage[1]; 
    if( v.my_segment.compare_and_swap( s, v.my_storage )!=v.my_storage ) 
        NFS_Free(s);
}

concurrent_vector_base::size_type concurrent_vector_base::internal_capacity() const {
    return segment_base( helper::find_segment_end(*this) );
}

void concurrent_vector_base::internal_reserve( size_type n, size_type element_size, size_type max_size ) {
    if( n>max_size ) {
        throw std::length_error("argument to ConcurrentVector::reserve exceeds ConcurrentVector::max_size()");
    }
    for( segment_index_t k = helper::find_segment_end(*this); segment_base(k)<n; ++k ) {
        helper::extend_segment_if_necessary(*this,k);
        size_t m = segment_size(k);
        __TBB_ASSERT( !my_segment[k].array, "concurrent operation during reserve(...)?" );
        my_segment[k].array = NFS_Allocate( m, element_size, NULL );
    }
}

void concurrent_vector_base::internal_copy( const concurrent_vector_base& src, size_type element_size, internal_array_op2 copy ) {
    size_type n = src.my_early_size;
    my_early_size = n;
    my_segment = my_storage;
    if( n ) {
        size_type b;
        for( segment_index_t k=0; (b=segment_base(k))<n; ++k ) {
            helper::extend_segment_if_necessary(*this,k);
            size_t m = segment_size(k);
            __TBB_ASSERT( !my_segment[k].array, "concurrent operation during copy construction?" );
            my_segment[k].array = NFS_Allocate( m, element_size, NULL );
            if( m>n-b ) m = n-b; 
            copy( my_segment[k].array, src.my_segment[k].array, m );
        }
    }
}

void concurrent_vector_base::internal_assign( const concurrent_vector_base& src, size_type element_size, internal_array_op1 destroy, internal_array_op2 assign, internal_array_op2 copy ) {
    size_type n = src.my_early_size;
    while( my_early_size>n ) { 
        segment_index_t k = segment_index_of( my_early_size-1 );
        size_type b=segment_base(k);
        size_type new_end = b>=n ? b : n;
        __TBB_ASSERT( my_early_size>new_end, NULL );
        destroy( (char*)my_segment[k].array+element_size*(new_end-b), my_early_size-new_end );
        my_early_size = new_end;
    }
    size_type dst_initialized_size = my_early_size;
    my_early_size = n;
    size_type b;
    for( segment_index_t k=0; (b=segment_base(k))<n; ++k ) {
        helper::extend_segment_if_necessary(*this,k);
        size_t m = segment_size(k);
        if( !my_segment[k].array )
            my_segment[k].array = NFS_Allocate( m, element_size, NULL );
        if( m>n-b ) m = n-b; 
        size_type a = 0;
        if( dst_initialized_size>b ) {
            a = dst_initialized_size-b;
            if( a>m ) a = m;
            assign( my_segment[k].array, src.my_segment[k].array, a );
            m -= a; 
            a *= element_size; 
        }
        if( m>0 ) 
            copy( (char*)my_segment[k].array+a, (char*)src.my_segment[k].array+a, m );
    }
    __TBB_ASSERT( src.my_early_size==n, "detected use of ConcurrentVector::operator= with right side that was concurrently modified" );
}

void* concurrent_vector_base::internal_push_back( size_type element_size, size_type& index ) {
    __TBB_ASSERT( sizeof(my_early_size)==sizeof(reference_count), NULL );
    //size_t tmp = __TBB_FetchAndIncrementWacquire(*(tbb::internal::reference_count*)&my_early_size);
    size_t tmp = __TBB_FetchAndIncrementWacquire((tbb::internal::reference_count*)&my_early_size);
    index = tmp;
    segment_index_t k_old = segment_index_of( tmp );
    size_type base = segment_base(k_old);
    helper::extend_segment_if_necessary(*this,k_old);
    segment_t& s = my_segment[k_old];
    void* array = s.array;
    if( !array ) {
        // FIXME - consider factoring this out and share with internal_grow_by
      if( base==tmp ) {
          __TBB_ASSERT( !s.array, NULL );
            size_t n = segment_size(k_old);
          array = NFS_Allocate( n, element_size, NULL );
          ITT_NOTIFY( sync_releasing, &s.array );
          s.array = array;
      } else {
          ITT_NOTIFY(sync_prepare, &s.array);
          internal::SpinwaitWhileEq( s.array, (void*)0 );
          ITT_NOTIFY(sync_acquired, &s.array);
          array = s.array;
      }
    }
    size_type j_begin = tmp-base;
    return (void*)((char*)array+element_size*j_begin);
}

concurrent_vector_base::size_type concurrent_vector_base::internal_grow_by( size_type delta, size_type element_size, internal_array_op1 init ) {
    size_type result = my_early_size.fetch_and_add(delta);
    internal_grow( result, result+delta, element_size, init );
    return result;
}

void concurrent_vector_base::internal_grow( const size_type start, size_type finish, size_type element_size, internal_array_op1 init ) {
    __TBB_ASSERT( start<finish, "start must be less than finish" );
    size_t tmp = start;
    do {
        segment_index_t k_old = segment_index_of( tmp );
        size_type base = segment_base(k_old);
        size_t n = segment_size(k_old);
        helper::extend_segment_if_necessary(*this,k_old);
        segment_t& s = my_segment[k_old];
        void* array = s.array;
        if( !array ) {
            if( base==tmp ) {
                __TBB_ASSERT( !s.array, NULL );
                array = NFS_Allocate( n, element_size, NULL );
                ITT_NOTIFY( sync_releasing, &s.array );
                s.array = array;
            } else {
                ITT_NOTIFY(sync_prepare, &s.array);
                internal::SpinwaitWhileEq( s.array, (void*)0 );
                ITT_NOTIFY(sync_acquired, &s.array);
                array = s.array;
            }
        }
        size_type j_begin = tmp-base;
        size_type j_end = n > finish-base ? finish-base : n;
        (*init)( (void*)((char*)array+element_size*j_begin), j_end-j_begin );
        tmp = base+j_end;
    } while( tmp<finish );
}

void concurrent_vector_base::internal_clear( internal_array_op1 destroy, bool reclaim_storage ) {
    // Set "my_early_size" early, so that subscripting errors can be caught.
    // FIXME - doing so may be hurting exception saftey
    __TBB_ASSERT( my_segment, NULL );
    size_type finish = my_early_size;
    my_early_size = 0;
    while( finish>0 ) {
        segment_index_t k_old = segment_index_of(finish-1);
        segment_t& s = my_segment[k_old];
        __TBB_ASSERT( s.array, NULL );
        size_type base = segment_base(k_old);
        size_type j_end = finish-base;
        __TBB_ASSERT( j_end, NULL );
        (*destroy)( s.array, j_end );
        finish = base;
    }

    // Free the arrays
    if( reclaim_storage ) {
        size_t k = helper::find_segment_end(*this);
        while( k>0 ) {
            --k;
            segment_t& s = my_segment[k];
            void* array = s.array;
            s.array = NULL;
            NFS_Free( array );
        }
        // Clear short segment.  
        my_storage[0].array = NULL;
        my_storage[1].array = NULL;
        segment_t* s = my_segment;
        if( s!=my_storage ) {
            my_segment = my_storage;
            NFS_Free( s );
        } 
    }
}

} // namespace internal

} // tbb

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