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concurrent_vector.h

/*
    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.
*/

#ifndef __TBB_concurrent_vector_H
#define __TBB_concurrent_vector_H

#include "tbb_stddef.h"
#include <iterator>
#include <new>
#include "atomic.h"
#include "cache_aligned_allocator.h"
#include "blocked_range.h"

#include "tbb_machine.h"

namespace tbb {

template<typename T>
class concurrent_vector;

//! @cond INTERNAL
namespace internal {

    //! Base class of concurrent vector implementation.
    /** @ingroup containers */
    class concurrent_vector_base {
    protected:
        typedef unsigned long segment_index_t;

        //! Log2 of "min_segment_size".  
        static const int lg_min_segment_size = 4;

        //! Minimum size (in physical items) of a segment.
        static const int min_segment_size = segment_index_t(1)<<lg_min_segment_size;
      
        static segment_index_t segment_index_of( size_t index ) { 
            uintptr i = index|1<<(lg_min_segment_size-1);
            uintptr j = __TBB_Log2(i); 
            return segment_index_t(j-(lg_min_segment_size-1)); 
        }

        static segment_index_t segment_base( segment_index_t k ) { 
            return min_segment_size>>1<<k & -min_segment_size;
        }

        static segment_index_t segment_size( segment_index_t k ) {
            segment_index_t result = k==0 ? min_segment_size : min_segment_size/2<<k;
            __TBB_ASSERT( result==segment_base(k+1)-segment_base(k), NULL );
            return result;
        }

        typedef size_t size_type;

        void internal_reserve( size_type n, size_type element_size, size_type max_size );

        size_type internal_capacity() const;

        //! Requested size of vector
        atomic<size_type> my_early_size;

        /** Can be zero-initialized. */
        struct segment_t {
            /** Declared volatile because in weak memory model, must have ld.acq/st.rel  */
            void* volatile array;
#if TBB_DO_ASSERT
            ~segment_t() {
                __TBB_ASSERT( !array, "should have been set to NULL by clear" );
            }
#endif /* TBB_DO_ASSERT */
        };
 
        atomic<segment_t*> my_segment;

        segment_t my_storage[2];

        concurrent_vector_base() {
            my_early_size = 0;
            my_storage[0].array = NULL;
            my_storage[1].array = NULL;
            my_segment = my_storage;
        }

        //! An operation on an n-lement array starting at begin.
        typedef void(*internal_array_op1)(void* begin, size_type n );

        //! An operation on n-element destination array and n-element source array.
        typedef void(*internal_array_op2)(void* dst, const void* src, size_type n );

        void internal_grow_to_at_least( size_type new_size, size_type element_size, internal_array_op1 init );
        void internal_grow( size_type start, size_type finish, size_type element_size, internal_array_op1 init );
        size_type internal_grow_by( size_type delta, size_type element_size, internal_array_op1 init );
        void* internal_push_back( size_type element_size, size_type& index ); 
        void internal_clear( internal_array_op1 destroy, bool reclaim_storage );
        void internal_copy( const concurrent_vector_base& src, size_type element_size, internal_array_op2 copy );
        void internal_assign( const concurrent_vector_base& src, size_type element_size, 
                              internal_array_op1 destroy, internal_array_op2 assign, internal_array_op2 copy );
private:
        //! Private functionality that does not cross DLL boundary.
        class helper;

        friend class helper;
    };

    //! Meets requirements of a forward iterator for STL and a Value for a blocked_range.*/
    /** Value is either the T or const T type of the container.
        @ingroup containers */
    template<typename Container, typename Value>
    class vector_iterator 
#if defined(_WIN64) && defined(_MSC_VER) 
        // Ensure that Microsoft's internal template function _Val_type works correctly.
        : public std::iterator<std::random_access_iterator_tag,Value>
#endif /* defined(_WIN64) && defined(_MSC_VER) */
    {
        //! concurrent_vector over which we are iterating.
        Container* my_vector;

        //! Index into the vector 
        size_t my_index;

        //! Caches my_vector-&gt;internal_subscript(my_index)
        /** NULL if cached value is not available */
        mutable Value* my_item;
    
        template<typename C, typename T, typename U>
        friend bool operator==( const vector_iterator<C,T>& i, const vector_iterator<C,U>& j );

        template<typename C, typename T, typename U>
        friend bool operator<( const vector_iterator<C,T>& i, const vector_iterator<C,U>& j );

        template<typename C, typename T, typename U>
        friend ptrdiff_t operator-( const vector_iterator<C,T>& i, const vector_iterator<C,U>& j );
    
        template<typename C, typename U>
        friend class internal::vector_iterator;

#if !defined(_MSC_VER) || defined(__INTEL_COMPILER)
        template<typename T>
        friend class tbb::concurrent_vector;
#else
public: // workaround for MSVC
#endif 

        vector_iterator( const Container& vector, size_t index ) : 
            my_vector(const_cast<Container*>(&vector)), 
            my_index(index), 
            my_item(NULL)
        {}

    public:
        //! Default constructor
        vector_iterator() : my_vector(NULL), my_index(~size_t(0)), my_item(NULL) {}

        vector_iterator( const vector_iterator<Container,typename Container::value_type>& other ) :
            my_vector(other.my_vector),
            my_index(other.my_index),
            my_item(other.my_item)
        {}

        vector_iterator operator+( ptrdiff_t offset ) const {
            return vector_iterator( *my_vector, my_index+offset );
        }
        friend vector_iterator operator+( ptrdiff_t offset, const vector_iterator& v ) {
            return vector_iterator( *v.my_vector, v.my_index+offset );
        }
        vector_iterator operator+=( ptrdiff_t offset ) {
            my_index+=offset;
            my_item = NULL;
            return *this;
        }
        vector_iterator operator-( ptrdiff_t offset ) const {
            return vector_iterator( *my_vector, my_index-offset );
        }
        vector_iterator operator-=( ptrdiff_t offset ) {
            my_index-=offset;
            my_item = NULL;
            return *this;
        }
        Value& operator*() const {
            Value* item = my_item;
            if( !item ) {
                item = my_item = &my_vector->internal_subscript(my_index);
            }
            __TBB_ASSERT( item==&my_vector->internal_subscript(my_index), "corrupt cache" );
            return *item;
        }
        Value& operator[]( ptrdiff_t k ) const {
            return my_vector->internal_subscript(my_index+k);
        }
        Value* operator->() const {return &operator*();}

        //! Pre increment
        vector_iterator& operator++() {
            size_t k = ++my_index;
            if( my_item ) {
                // Following test uses 2's-complement wizardry and fact that
                // min_segment_size is a power of 2.
                if( (k& k-concurrent_vector<Container>::min_segment_size)==0 ) {
                    // k is a power of two that is at least k-min_segment_size  
                    my_item= NULL;
                } else {
                    ++my_item;
                }
            }
            return *this;
        }

        //! Pre decrement
        vector_iterator& operator--() {
            __TBB_ASSERT( my_index>0, "operator--() applied to iterator already at beginning of concurrent_vector" ); 
            size_t k = my_index--;
            if( my_item ) {
                // Following test uses 2's-complement wizardry and fact that
                // min_segment_size is a power of 2.
                if( (k& k-concurrent_vector<Container>::min_segment_size)==0 ) {
                    // k is a power of two that is at least k-min_segment_size  
                    my_item= NULL;
                } else {
                    --my_item;
                }
            }
            return *this;
        }

        //! Post increment
        vector_iterator operator++(int) {
            vector_iterator result = *this;
            operator++();
            return result;
        }

        //! Post decrement
        vector_iterator operator--(int) {
            vector_iterator result = *this;
            operator--();
            return result;
        }

        // STL support

        typedef ptrdiff_t difference_type;
        typedef Value value_type;
        typedef Value* pointer;
        typedef Value& reference;
        typedef std::random_access_iterator_tag iterator_category;
    };

    template<typename Container, typename T, typename U>
    bool operator==( const vector_iterator<Container,T>& i, const vector_iterator<Container,U>& j ) {
        return i.my_index==j.my_index;
    }

    template<typename Container, typename T, typename U>
    bool operator!=( const vector_iterator<Container,T>& i, const vector_iterator<Container,U>& j ) {
        return !(i==j);
    }

    template<typename Container, typename T, typename U>
    bool operator<( const vector_iterator<Container,T>& i, const vector_iterator<Container,U>& j ) {
        return i.my_index<j.my_index;
    }

    template<typename Container, typename T, typename U>
    bool operator>( const vector_iterator<Container,T>& i, const vector_iterator<Container,U>& j ) {
        return j<i;
    }

    template<typename Container, typename T, typename U>
    bool operator>=( const vector_iterator<Container,T>& i, const vector_iterator<Container,U>& j ) {
        return !(i<j);
    }

    template<typename Container, typename T, typename U>
    bool operator<=( const vector_iterator<Container,T>& i, const vector_iterator<Container,U>& j ) {
        return !(j<i);
    }

    template<typename Container, typename T, typename U>
    ptrdiff_t operator-( const vector_iterator<Container,T>& i, const vector_iterator<Container,U>& j ) {
        return ptrdiff_t(i.my_index)-ptrdiff_t(j.my_index);
    }

} // namespace internal
//! @endcond

//! Concurrent vector
/** @ingroup containers */
template<typename T>
00313 class concurrent_vector: private internal::concurrent_vector_base {
public:
    using internal::concurrent_vector_base::size_type;
private:
    template<typename I>
    class generic_range_type: public blocked_range<I> {
    public:
        typedef T value_type;
        typedef T& reference;
        typedef const T& const_reference;
        typedef I iterator;
        typedef ptrdiff_t difference_type;
        generic_range_type( I begin_, I end_, size_t grainsize ) : blocked_range<I>(begin_,end_,grainsize) {} 
        generic_range_type( generic_range_type& r, split ) : blocked_range<I>(r,split()) {}
    };

    template<typename C, typename U>
    friend class internal::vector_iterator;
public:
    typedef T& reference;
    typedef const T& const_reference;

    //! Construct empty vector.
00336     concurrent_vector() {}

    //! Copy a vector.
00339     concurrent_vector( const concurrent_vector& vector ) {internal_copy(vector,sizeof(T),&copy_array);}

    //! Assignment 
00342     concurrent_vector& operator=( const concurrent_vector& vector ) {
        if( this!=&vector )
            internal_assign(vector,sizeof(T),&destroy_array,&assign_array,&copy_array);
        return *this;
    }

    //! Clear and destroy vector.
00349     ~concurrent_vector() {internal_clear(&destroy_array,/*reclaim_storage=*/true);}

    //------------------------------------------------------------------------
    // Concurrent operations
    //------------------------------------------------------------------------
    //! Grow by "delta" elements.
    /** Returns old size. */
00356     size_type grow_by( size_type delta ) {
        return delta ? internal_grow_by( delta, sizeof(T), &initialize_array ) : my_early_size;
    }

    //! Grow array until it has at least n elements.
00361     void grow_to_at_least( size_type n ) {
        if( my_early_size<n )
            internal_grow_to_at_least( n, sizeof(T), &initialize_array );
    };

    //! Push item 
00367     size_type push_back( const_reference item ) {
        size_type k;
        new( internal_push_back(sizeof(T),k) ) T(item);
        return k;
    }

    //! Get reference to element at given index.
    /** This method is thread-safe for concurrent reads, and also while growing the vector,
        as long as the calling thread has checked that index&lt;size(). */
00376     reference operator[]( size_type index ) {
        return internal_subscript(index);
    }

    //! Get const reference to element at given index.
00381     const_reference operator[]( size_type index ) const {
        return internal_subscript(index);
    }

    //------------------------------------------------------------------------
    // Parallel algorithm support
    //------------------------------------------------------------------------
    typedef internal::vector_iterator<concurrent_vector,T> iterator;
    typedef internal::vector_iterator<concurrent_vector,const T> const_iterator;

#if !defined(_MSC_VER) || _CPPLIB_VER>=300 
    // Assume ISO standard definition of std::reverse_iterator
    typedef std::reverse_iterator<iterator> reverse_iterator;
    typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
#else
    // Use non-standard std::reverse_iterator
    typedef std::reverse_iterator<iterator,T,T&,T*> reverse_iterator;
    typedef std::reverse_iterator<const_iterator,T,const T&,const T*> const_reverse_iterator;
#endif /* defined(_MSC_VER) && (_MSC_VER<1300) */

    typedef generic_range_type<iterator> range_type;
    typedef generic_range_type<const_iterator> const_range_type;

    range_type range( size_t grainsize = 1 ) {
        return range_type( begin(), end(), grainsize );
    }

    const_range_type range( size_t grainsize = 1 ) const {
        return const_range_type( begin(), end(), grainsize );
    }

    //------------------------------------------------------------------------
    // Capacity
    //------------------------------------------------------------------------
    //! Return size of vector.
00416     size_type size() const {return my_early_size;}

    //! Return size of vector.
00419     bool empty() const {return !my_early_size;}

    //! Maximum size to which array can grow without allocating more memory.
00422     size_type capacity() const {return internal_capacity();}

    //! Allocate enough space to grow to size n without having to allocate more memory later.
    /** Like most of the methods provided for STL compatibility, this method is *not* thread safe. 
        The capacity afterwards may be bigger than the requested reservation. */
00427     void reserve( size_type n ) {
        if( n )
            internal_reserve(n, sizeof(T), max_size());
    }

    //! Upper bound on argument to reserve.
00433     size_type max_size() const {return (~size_t(0))/sizeof(T);}

    //------------------------------------------------------------------------
    // STL support
    //------------------------------------------------------------------------

    typedef T value_type;
    typedef ptrdiff_t difference_type;

    iterator begin() {return iterator(*this,0);}
    iterator end() {return iterator(*this,size());}
    const_iterator begin() const {return const_iterator(*this,0);}
    const_iterator end() const {return const_iterator(*this,size());}

    reverse_iterator rbegin() {return reverse_iterator(end());}
    reverse_iterator rend() {return reverse_iterator(begin());}
    const_reverse_iterator rbegin() const {return const_reverse_iterator(end());}
    const_reverse_iterator rend() const {return const_reverse_iterator(begin());}

    //! Not thread safe
    /** Does not change capacity. */
00454     void clear() {internal_clear(&destroy_array,/*reclaim_storage=*/false);}       
private:
    //! Get reference to element at given index.
    T& internal_subscript( size_type index ) const;

    //! Construct n instances of T, starting at "begin".
    static void initialize_array( void* begin, size_type n );

    //! Construct n instances of T, starting at "begin".
    static void copy_array( void* dst, const void* src, size_type n );

    //! Assign n instances of T, starting at "begin".
    static void assign_array( void* dst, const void* src, size_type n );

    //! Destroy n instances of T, starting at "begin".
    static void destroy_array( void* begin, size_type n );
};

template<typename T>
00473 T& concurrent_vector<T>::internal_subscript( size_type index ) const {
    __TBB_ASSERT( index<size(), "index out of bounds" );
    segment_index_t k = segment_index_of( index );
    size_type j = index-segment_base(k);
    return static_cast<T*>(my_segment[k].array)[j];
}

template<typename T>
00481 void concurrent_vector<T>::initialize_array( void* begin, size_type n ) {
    T* array = static_cast<T*>(begin);
    for( size_type j=0; j<n; ++j )
        new( &array[j] ) T();
}

template<typename T>
00488 void concurrent_vector<T>::copy_array( void* dst, const void* src, size_type n ) {
    T* d = static_cast<T*>(dst);
    const T* s = static_cast<const T*>(src);
    for( size_type j=0; j<n; ++j )
        new( &d[j] ) T(s[j]);
}

template<typename T>
00496 void concurrent_vector<T>::assign_array( void* dst, const void* src, size_type n ) {
    T* d = static_cast<T*>(dst);
    const T* s = static_cast<const T*>(src);
    for( size_type j=0; j<n; ++j )
        d[j] = s[j];
}

template<typename T>
00504 void concurrent_vector<T>::destroy_array( void* begin, size_type n ) {
    T* array = static_cast<T*>(begin);
    for( size_type j=n; j>0; --j )
        array[j-1].~T();
}

} // namespace tbb

#endif /* __TBB_concurrent_vector_H */

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