libtbb-dev 4.4~20151115-0ubuntu3 / usr / include / tbb / enumerable_thread_specific.h

/*
    Copyright 2005-2015 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_enumerable_thread_specific_H
#define __TBB_enumerable_thread_specific_H

#include "atomic.h"
#include "concurrent_vector.h"
#include "tbb_thread.h"
#include "tbb_allocator.h"
#include "cache_aligned_allocator.h"
#include "aligned_space.h"
#include "internal/_template_helpers.h"
#include "internal/_tbb_hash_compare_impl.h"
#include "tbb_profiling.h"
#include <string.h>  // for memcpy

#if _WIN32||_WIN64
#include "machine/windows_api.h"
#else
#include <pthread.h>
#endif

#define __TBB_ETS_USE_CPP11 \
    (__TBB_CPP11_RVALUE_REF_PRESENT && __TBB_CPP11_VARIADIC_TEMPLATES_PRESENT \
     && __TBB_CPP11_DECLTYPE_PRESENT && __TBB_CPP11_LAMBDAS_PRESENT)

namespace tbb {

//! enum for selecting between single key and key-per-instance versions
enum ets_key_usage_type { ets_key_per_instance, ets_no_key };

namespace interface6 {

    // Forward declaration to use in internal classes
    template <typename T, typename Allocator, ets_key_usage_type ETS_key_type>
    class enumerable_thread_specific;

    //! @cond
    namespace internal {

        using namespace tbb::internal;

        template<ets_key_usage_type ETS_key_type>
        class ets_base: tbb::internal::no_copy {
        protected:
            typedef tbb_thread::id key_type;
#if __TBB_PROTECTED_NESTED_CLASS_BROKEN
        public:
#endif
            struct slot;

            struct array {
                array* next;
                size_t lg_size;
                slot& at( size_t k ) {
                    return ((slot*)(void*)(this+1))[k];
                }
                size_t size() const {return (size_t)1<<lg_size;}
                size_t mask() const {return size()-1;}
                size_t start( size_t h ) const {
                    return h>>(8*sizeof(size_t)-lg_size);
                }
            };
            struct slot {
                key_type key;
                void* ptr;
                bool empty() const {return key == key_type();}
                bool match( key_type k ) const {return key == k;}
                bool claim( key_type k ) {
                    // TODO: maybe claim ptr, because key_type is not guaranteed to fit into word size
                    return atomic_compare_and_swap(key, k, key_type()) == key_type();
                }
            };
#if __TBB_PROTECTED_NESTED_CLASS_BROKEN
        protected:
#endif

            //! Root of linked list of arrays of decreasing size.
            /** NULL if and only if my_count==0.
                Each array in the list is half the size of its predecessor. */
            atomic<array*> my_root;
            atomic<size_t> my_count;
            virtual void* create_local() = 0;
            virtual void* create_array(size_t _size) = 0;  // _size in bytes
            virtual void free_array(void* ptr, size_t _size) = 0; // _size in bytes
            array* allocate( size_t lg_size ) {
                size_t n = 1<<lg_size;
                array* a = static_cast<array*>(create_array( sizeof(array)+n*sizeof(slot) ));
                a->lg_size = lg_size;
                std::memset( a+1, 0, n*sizeof(slot) );
                return a;
            }
            void free(array* a) {
                size_t n = 1<<(a->lg_size);
                free_array( (void *)a, size_t(sizeof(array)+n*sizeof(slot)) );
            }

            ets_base() {my_root=NULL; my_count=0;}
            virtual ~ets_base();  // g++ complains if this is not virtual
            void* table_lookup( bool& exists );
            void table_clear();
            // The following functions are not used in concurrent context,
            // so we don't need synchronization and ITT annotations there.
            void table_elementwise_copy( const ets_base& other,
                                         void*(*add_element)(ets_base&, void*) ) {
                __TBB_ASSERT(!my_root,NULL);
                __TBB_ASSERT(!my_count,NULL);
                if( !other.my_root ) return;
                array* root = my_root = allocate(other.my_root->lg_size);
                root->next = NULL;
                my_count = other.my_count;
                size_t mask = root->mask();
                for( array* r=other.my_root; r; r=r->next ) {
                    for( size_t i=0; i<r->size(); ++i ) {
                        slot& s1 = r->at(i);
                        if( !s1.empty() ) {
                            for( size_t j = root->start(tbb::tbb_hash<key_type>()(s1.key)); ; j=(j+1)&mask ) {
                                slot& s2 = root->at(j);
                                if( s2.empty() ) {
                                    s2.ptr = add_element(*this, s1.ptr);
                                    s2.key = s1.key;
                                    break;
                                }
                                else if( s2.match(s1.key) )
                                    break;
                            }
                        }
                    }
                }
            }
            void table_swap( ets_base& other ) {
               __TBB_ASSERT(this!=&other, "Don't swap an instance with itself");
               tbb::internal::swap<relaxed>(my_root, other.my_root);
               tbb::internal::swap<relaxed>(my_count, other.my_count);
            }
        };

        template<ets_key_usage_type ETS_key_type>
        ets_base<ETS_key_type>::~ets_base() {
            __TBB_ASSERT(!my_root, NULL);
        }

        template<ets_key_usage_type ETS_key_type>
        void ets_base<ETS_key_type>::table_clear() {
            while( array* r = my_root ) {
                my_root = r->next;
                free(r);
            }
            my_count = 0;
        }

        template<ets_key_usage_type ETS_key_type>
        void* ets_base<ETS_key_type>::table_lookup( bool& exists ) {
            const key_type k = tbb::this_tbb_thread::get_id();

            __TBB_ASSERT(k != key_type(),NULL);
            void* found;
            size_t h = tbb::tbb_hash<key_type>()(k);
            for( array* r=my_root; r; r=r->next ) {
                call_itt_notify(acquired,r);
                size_t mask=r->mask();
                for(size_t i = r->start(h); ;i=(i+1)&mask) {
                    slot& s = r->at(i);
                    if( s.empty() ) break;
                    if( s.match(k) ) {
                        if( r==my_root ) {
                            // Success at top level
                            exists = true;
                            return s.ptr;
                        } else {
                            // Success at some other level.  Need to insert at top level.
                            exists = true;
                            found = s.ptr;
                            goto insert;
                        }
                    }
                }
            }
            // Key does not yet exist.  The density of slots in the table does not exceed 0.5,
            // for if this will occur a new table is allocated with double the current table
            // size, which is swapped in as the new root table.  So an empty slot is guaranteed.
            exists = false;
            found = create_local();
            {
                size_t c = ++my_count;
                array* r = my_root;
                call_itt_notify(acquired,r);
                if( !r || c>r->size()/2 ) {
                    size_t s = r ? r->lg_size : 2;
                    while( c>size_t(1)<<(s-1) ) ++s;
                    array* a = allocate(s);
                    for(;;) {
                        a->next = r;
                        call_itt_notify(releasing,a);
                        array* new_r = my_root.compare_and_swap(a,r);
                        if( new_r==r ) break;
                        call_itt_notify(acquired, new_r);
                        if( new_r->lg_size>=s ) {
                            // Another thread inserted an equal or  bigger array, so our array is superfluous.
                            free(a);
                            break;
                        }
                        r = new_r;
                    }
                }
            }
        insert:
        // Whether a slot has been found in an older table, or if it has been inserted at this level,
        // it has already been accounted for in the total.  Guaranteed to be room for it, and it is
        // not present, so search for empty slot and use it.
            array* ir = my_root;
            call_itt_notify(acquired, ir);
            size_t mask = ir->mask();
            for(size_t i = ir->start(h);;i=(i+1)&mask) {
                slot& s = ir->at(i);
                if( s.empty() ) {
                    if( s.claim(k) ) {
                        s.ptr = found;
                        return found;
                    }
                }
            }
        }

        //! Specialization that exploits native TLS
        template <>
        class ets_base<ets_key_per_instance>: protected ets_base<ets_no_key> {
            typedef ets_base<ets_no_key> super;
#if _WIN32||_WIN64
#if __TBB_WIN8UI_SUPPORT
            typedef DWORD tls_key_t;
            void create_key() { my_key = FlsAlloc(NULL); }
            void destroy_key() { FlsFree(my_key); }
            void set_tls(void * value) { FlsSetValue(my_key, (LPVOID)value); }
            void* get_tls() { return (void *)FlsGetValue(my_key); }
#else
            typedef DWORD tls_key_t;
            void create_key() { my_key = TlsAlloc(); }
            void destroy_key() { TlsFree(my_key); }
            void set_tls(void * value) { TlsSetValue(my_key, (LPVOID)value); }
            void* get_tls() { return (void *)TlsGetValue(my_key); }
#endif
#else
            typedef pthread_key_t tls_key_t;
            void create_key() { pthread_key_create(&my_key, NULL); }
            void destroy_key() { pthread_key_delete(my_key); }
            void set_tls( void * value ) const { pthread_setspecific(my_key, value); }
            void* get_tls() const { return pthread_getspecific(my_key); }
#endif
            tls_key_t my_key;
            virtual void* create_local() = 0;
            virtual void* create_array(size_t _size) = 0;  // _size in bytes
            virtual void free_array(void* ptr, size_t _size) = 0; // size in bytes
        protected:
            ets_base() {create_key();}
            ~ets_base() {destroy_key();}
            void* table_lookup( bool& exists ) {
                void* found = get_tls();
                if( found ) {
                    exists=true;
                } else {
                    found = super::table_lookup(exists);
                    set_tls(found);
                }
                return found;
            }
            void table_clear() {
                destroy_key();
                create_key();
                super::table_clear();
            }
            void table_swap( ets_base& other ) {
               using std::swap;
               __TBB_ASSERT(this!=&other, "Don't swap an instance with itself");
               swap(my_key, other.my_key);
               super::table_swap(other);
            }
        };

        //! Random access iterator for traversing the thread local copies.
        template< typename Container, typename Value >
        class enumerable_thread_specific_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) */
        {
            //! current position in the concurrent_vector

            Container *my_container;
            typename Container::size_type my_index;
            mutable Value *my_value;

            template<typename C, typename T>
            friend enumerable_thread_specific_iterator<C,T>
            operator+( ptrdiff_t offset, const enumerable_thread_specific_iterator<C,T>& v );

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

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

            template<typename C, typename T, typename U>
            friend ptrdiff_t operator-( const enumerable_thread_specific_iterator<C,T>& i,
                                        const enumerable_thread_specific_iterator<C,U>& j );

            template<typename C, typename U>
            friend class enumerable_thread_specific_iterator;

            public:

            enumerable_thread_specific_iterator( const Container &container, typename Container::size_type index ) :
                my_container(&const_cast<Container &>(container)), my_index(index), my_value(NULL) {}

            //! Default constructor
            enumerable_thread_specific_iterator() : my_container(NULL), my_index(0), my_value(NULL) {}

            template<typename U>
            enumerable_thread_specific_iterator( const enumerable_thread_specific_iterator<Container, U>& other ) :
                    my_container( other.my_container ), my_index( other.my_index), my_value( const_cast<Value *>(other.my_value) ) {}

            enumerable_thread_specific_iterator operator+( ptrdiff_t offset ) const {
                return enumerable_thread_specific_iterator(*my_container, my_index + offset);
            }

            enumerable_thread_specific_iterator &operator+=( ptrdiff_t offset ) {
                my_index += offset;
                my_value = NULL;
                return *this;
            }

            enumerable_thread_specific_iterator operator-( ptrdiff_t offset ) const {
                return enumerable_thread_specific_iterator( *my_container, my_index-offset );
            }

            enumerable_thread_specific_iterator &operator-=( ptrdiff_t offset ) {
                my_index -= offset;
                my_value = NULL;
                return *this;
            }

            Value& operator*() const {
                Value* value = my_value;
                if( !value ) {
                    value = my_value = (*my_container)[my_index].value();
                }
                __TBB_ASSERT( value==(*my_container)[my_index].value(), "corrupt cache" );
                return *value;
            }

            Value& operator[]( ptrdiff_t k ) const {
               return (*my_container)[my_index + k].value;
            }

            Value* operator->() const {return &operator*();}

            enumerable_thread_specific_iterator& operator++() {
                ++my_index;
                my_value = NULL;
                return *this;
            }

            enumerable_thread_specific_iterator& operator--() {
                --my_index;
                my_value = NULL;
                return *this;
            }

            //! Post increment
            enumerable_thread_specific_iterator operator++(int) {
                enumerable_thread_specific_iterator result = *this;
                ++my_index;
                my_value = NULL;
                return result;
            }

            //! Post decrement
            enumerable_thread_specific_iterator operator--(int) {
                enumerable_thread_specific_iterator result = *this;
                --my_index;
                my_value = NULL;
                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>
        enumerable_thread_specific_iterator<Container,T>
        operator+( ptrdiff_t offset, const enumerable_thread_specific_iterator<Container,T>& v ) {
            return enumerable_thread_specific_iterator<Container,T>( v.my_container, v.my_index + offset );
        }

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

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

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

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

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

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

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

    template<typename SegmentedContainer, typename Value >
        class segmented_iterator
#if defined(_WIN64) && defined(_MSC_VER)
        : public std::iterator<std::input_iterator_tag, Value>
#endif
        {
            template<typename C, typename T, typename U>
            friend bool operator==(const segmented_iterator<C,T>& i, const segmented_iterator<C,U>& j);

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

            template<typename C, typename U>
            friend class segmented_iterator;

            public:

                segmented_iterator() {my_segcont = NULL;}

                segmented_iterator( const SegmentedContainer& _segmented_container ) :
                    my_segcont(const_cast<SegmentedContainer*>(&_segmented_container)),
                    outer_iter(my_segcont->end()) { }

                ~segmented_iterator() {}

                typedef typename SegmentedContainer::iterator outer_iterator;
                typedef typename SegmentedContainer::value_type InnerContainer;
                typedef typename InnerContainer::iterator inner_iterator;

                // STL support
                typedef ptrdiff_t difference_type;
                typedef Value value_type;
                typedef typename SegmentedContainer::size_type size_type;
                typedef Value* pointer;
                typedef Value& reference;
                typedef std::input_iterator_tag iterator_category;

                // Copy Constructor
                template<typename U>
                segmented_iterator(const segmented_iterator<SegmentedContainer, U>& other) :
                    my_segcont(other.my_segcont),
                    outer_iter(other.outer_iter),
                    // can we assign a default-constructed iterator to inner if we're at the end?
                    inner_iter(other.inner_iter)
                {}

                // assignment
                template<typename U>
                segmented_iterator& operator=( const segmented_iterator<SegmentedContainer, U>& other) {
                    if(this != &other) {
                        my_segcont = other.my_segcont;
                        outer_iter = other.outer_iter;
                        if(outer_iter != my_segcont->end()) inner_iter = other.inner_iter;
                    }
                    return *this;
                }

                // allow assignment of outer iterator to segmented iterator.  Once it is
                // assigned, move forward until a non-empty inner container is found or
                // the end of the outer container is reached.
                segmented_iterator& operator=(const outer_iterator& new_outer_iter) {
                    __TBB_ASSERT(my_segcont != NULL, NULL);
                    // check that this iterator points to something inside the segmented container
                    for(outer_iter = new_outer_iter ;outer_iter!=my_segcont->end(); ++outer_iter) {
                        if( !outer_iter->empty() ) {
                            inner_iter = outer_iter->begin();
                            break;
                        }
                    }
                    return *this;
                }

                // pre-increment
                segmented_iterator& operator++() {
                    advance_me();
                    return *this;
                }

                // post-increment
                segmented_iterator operator++(int) {
                    segmented_iterator tmp = *this;
                    operator++();
                    return tmp;
                }

                bool operator==(const outer_iterator& other_outer) const {
                    __TBB_ASSERT(my_segcont != NULL, NULL);
                    return (outer_iter == other_outer &&
                            (outer_iter == my_segcont->end() || inner_iter == outer_iter->begin()));
                }

                bool operator!=(const outer_iterator& other_outer) const {
                    return !operator==(other_outer);

                }

                // (i)* RHS
                reference operator*() const {
                    __TBB_ASSERT(my_segcont != NULL, NULL);
                    __TBB_ASSERT(outer_iter != my_segcont->end(), "Dereferencing a pointer at end of container");
                    __TBB_ASSERT(inner_iter != outer_iter->end(), NULL); // should never happen
                    return *inner_iter;
                }

                // i->
                pointer operator->() const { return &operator*();}

            private:
                SegmentedContainer*             my_segcont;
                outer_iterator outer_iter;
                inner_iterator inner_iter;

                void advance_me() {
                    __TBB_ASSERT(my_segcont != NULL, NULL);
                    __TBB_ASSERT(outer_iter != my_segcont->end(), NULL); // not true if there are no inner containers
                    __TBB_ASSERT(inner_iter != outer_iter->end(), NULL); // not true if the inner containers are all empty.
                    ++inner_iter;
                    while(inner_iter == outer_iter->end() && ++outer_iter != my_segcont->end()) {
                        inner_iter = outer_iter->begin();
                    }
                }
        };    // segmented_iterator

        template<typename SegmentedContainer, typename T, typename U>
        bool operator==( const segmented_iterator<SegmentedContainer,T>& i,
                         const segmented_iterator<SegmentedContainer,U>& j ) {
            if(i.my_segcont != j.my_segcont) return false;
            if(i.my_segcont == NULL) return true;
            if(i.outer_iter != j.outer_iter) return false;
            if(i.outer_iter == i.my_segcont->end()) return true;
            return i.inner_iter == j.inner_iter;
        }

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

        template<typename T>
        struct construct_by_default: tbb::internal::no_assign {
            void construct(void*where) {new(where) T();} // C++ note: the () in T() ensure zero initialization.
            construct_by_default( int ) {}
        };

        template<typename T>
        struct construct_by_exemplar: tbb::internal::no_assign {
            const T exemplar;
            void construct(void*where) {new(where) T(exemplar);}
            construct_by_exemplar( const T& t ) : exemplar(t) {}
#if __TBB_ETS_USE_CPP11
            construct_by_exemplar( T&& t ) : exemplar(std::move(t)) {}
#endif
        };

        template<typename T, typename Finit>
        struct construct_by_finit: tbb::internal::no_assign {
            Finit f;
            void construct(void* where) {new(where) T(f());}
            construct_by_finit( const Finit& f_ ) : f(f_) {}
#if __TBB_ETS_USE_CPP11
            construct_by_finit( Finit&& f_ ) : f(std::move(f_)) {}
#endif
        };

#if __TBB_ETS_USE_CPP11
        template<typename T, typename... P>
        struct construct_by_args: tbb::internal::no_assign {
            internal::stored_pack<P...> pack;
            void construct(void* where) {
                internal::call( [where](const typename strip<P>::type&... args ){
                   new(where) T(args...);
                }, pack );
            }
            construct_by_args( P&& ... args ) : pack(std::forward<P>(args)...) {}
        };
#endif 

        // storage for initialization function pointer
        // TODO: consider removing the template parameter T here and in callback_leaf
        template<typename T>
        class callback_base {
        public:
            // Clone *this
            virtual callback_base* clone() const = 0;
            // Destruct and free *this
            virtual void destroy() = 0;
            // Need virtual destructor to satisfy GCC compiler warning
            virtual ~callback_base() { }
            // Construct T at where
            virtual void construct(void* where) = 0;
        };

        template <typename T, typename Constructor>
        class callback_leaf: public callback_base<T>, Constructor {
#if __TBB_ETS_USE_CPP11
            template<typename... P> callback_leaf( P&& ... params ) : Constructor(std::forward<P>(params)...) {}
#else
            template<typename X> callback_leaf( const X& x ) : Constructor(x) {}
#endif
            // TODO: make the construction/destruction consistent (use allocator.construct/destroy)
            typedef typename tbb::tbb_allocator<callback_leaf> my_allocator_type;

            /*override*/ callback_base<T>* clone() const {
                return make(*this);
            }

            /*override*/ void destroy() {
                my_allocator_type().destroy(this);
                my_allocator_type().deallocate(this,1);
            }

            /*override*/ void construct(void* where) {
                Constructor::construct(where);
            }
        public:
#if __TBB_ETS_USE_CPP11
            template<typename... P>
            static callback_base<T>* make( P&& ... params ) {
                void* where = my_allocator_type().allocate(1);
                return new(where) callback_leaf( std::forward<P>(params)... );
            }
#else
            template<typename X>
            static callback_base<T>* make( const X& x ) {
                void* where = my_allocator_type().allocate(1);
                return new(where) callback_leaf(x);
            }
#endif
        };

        //! Template for recording construction of objects in table
        /** All maintenance of the space will be done explicitly on push_back,
            and all thread local copies must be destroyed before the concurrent
            vector is deleted.

            The flag is_built is initialized to false.  When the local is
            successfully-constructed, set the flag to true or call value_committed().
            If the constructor throws, the flag will be false.
        */
        // TODO: make a constructor for ets_element that takes a callback_base.  make is_built private
        template<typename U>
        struct ets_element {
            tbb::aligned_space<U> my_space;
            bool is_built;
            ets_element() { is_built = false; }  // not currently-built
            U* value() { return my_space.begin(); }
            U* value_committed() { is_built = true; return my_space.begin(); }
            ~ets_element() { 
                if(is_built) {
                    my_space.begin()->~U();
                    is_built = false;
                }
            }
        };

        // A predicate that can be used for a compile-time compatibility check of ETS instances
        // Ideally, it should have been declared inside the ETS class, but unfortunately
        // in that case VS2013 does not enable the variadic constructor.
        template<typename T, typename ETS> struct is_compatible_ets { static const bool value = false; };
        template<typename T, typename U, typename A, ets_key_usage_type C>
        struct is_compatible_ets< T, enumerable_thread_specific<U,A,C> > { static const bool value = internal::is_same_type<T,U>::value; };

#if __TBB_ETS_USE_CPP11
        // A predicate that checks whether, for a variable 'foo' of type T, foo() is a valid expression
        template <typename T>
        class is_callable_no_args {
        private:
            typedef char yes[1];
            typedef char no [2];

            template<typename U> static yes& decide( decltype(declval<U>()())* );
            template<typename U> static no&  decide(...);
        public:
            static const bool value = (sizeof(decide<T>(NULL)) == sizeof(yes));
        };
#endif

    } // namespace internal
    //! @endcond

    //! The enumerable_thread_specific container
    /** enumerable_thread_specific has the following properties:
        - thread-local copies are lazily created, with default, exemplar or function initialization.
        - thread-local copies do not move (during lifetime, and excepting clear()) so the address of a copy is invariant.
        - the contained objects need not have operator=() defined if combine is not used.
        - enumerable_thread_specific containers may be copy-constructed or assigned.
        - thread-local copies can be managed by hash-table, or can be accessed via TLS storage for speed.
        - outside of parallel contexts, the contents of all thread-local copies are accessible by iterator or using combine or combine_each methods

    @par Segmented iterator
        When the thread-local objects are containers with input_iterators defined, a segmented iterator may
        be used to iterate over all the elements of all thread-local copies.

    @par combine and combine_each
        - Both methods are defined for enumerable_thread_specific.
        - combine() requires the type T have operator=() defined.
        - neither method modifies the contents of the object (though there is no guarantee that the applied methods do not modify the object.)
        - Both are evaluated in serial context (the methods are assumed to be non-benign.)

    @ingroup containers */
    template <typename T,
              typename Allocator=cache_aligned_allocator<T>,
              ets_key_usage_type ETS_key_type=ets_no_key >
    class enumerable_thread_specific: internal::ets_base<ETS_key_type> {

        template<typename U, typename A, ets_key_usage_type C> friend class enumerable_thread_specific;

        typedef internal::padded< internal::ets_element<T> > padded_element;

        //! A generic range, used to create range objects from the iterators
        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_ = 1) : blocked_range<I>(begin_,end_,grainsize_) {}
            template<typename U>
            generic_range_type( const generic_range_type<U>& r) : blocked_range<I>(r.begin(),r.end(),r.grainsize()) {}
            generic_range_type( generic_range_type& r, split ) : blocked_range<I>(r,split()) {}
        };

        typedef typename Allocator::template rebind< padded_element >::other padded_allocator_type;
        typedef tbb::concurrent_vector< padded_element, padded_allocator_type > internal_collection_type;

        internal::callback_base<T> *my_construct_callback;

        internal_collection_type my_locals;

        // TODO: consider unifying the callback mechanism for all create_local* methods below
        //   (likely non-compatible and requires interface version increase)
        /*override*/ void* create_local() {
            padded_element& lref = *my_locals.grow_by(1);
            my_construct_callback->construct(lref.value());
            return lref.value_committed();
        }

        static void* create_local_by_copy( internal::ets_base<ets_no_key>& base, void* p ) {
            enumerable_thread_specific& ets = static_cast<enumerable_thread_specific&>(base);
            padded_element& lref = *ets.my_locals.grow_by(1);
            new(lref.value()) T(*static_cast<T*>(p));
            return lref.value_committed();
        }

#if __TBB_ETS_USE_CPP11
        static void* create_local_by_move( internal::ets_base<ets_no_key>& base, void* p ) {
            enumerable_thread_specific& ets = static_cast<enumerable_thread_specific&>(base);
            padded_element& lref = *ets.my_locals.grow_by(1);
            new(lref.value()) T(std::move(*static_cast<T*>(p)));
            return lref.value_committed();
        }
#endif

        typedef typename Allocator::template rebind< uintptr_t >::other array_allocator_type;

        // _size is in bytes
        /*override*/ void* create_array(size_t _size) {
            size_t nelements = (_size + sizeof(uintptr_t) -1) / sizeof(uintptr_t);
            return array_allocator_type().allocate(nelements);
        }

        /*override*/ void free_array( void* _ptr, size_t _size) {
            size_t nelements = (_size + sizeof(uintptr_t) -1) / sizeof(uintptr_t);
            array_allocator_type().deallocate( reinterpret_cast<uintptr_t *>(_ptr),nelements);
        }

    public:

        //! Basic types
        typedef Allocator allocator_type;
        typedef T value_type;
        typedef T& reference;
        typedef const T& const_reference;
        typedef T* pointer;
        typedef const T* const_pointer;
        typedef typename internal_collection_type::size_type size_type;
        typedef typename internal_collection_type::difference_type difference_type;

        // Iterator types
        typedef typename internal::enumerable_thread_specific_iterator< internal_collection_type, value_type > iterator;
        typedef typename internal::enumerable_thread_specific_iterator< internal_collection_type, const value_type > const_iterator;

        // Parallel range types
        typedef generic_range_type< iterator > range_type;
        typedef generic_range_type< const_iterator > const_range_type;

        //! Default constructor.  Each local instance of T is default constructed.
        enumerable_thread_specific() : my_construct_callback(
            internal::callback_leaf<T,internal::construct_by_default<T> >::make(/*dummy argument*/0)
        ){}

        //! Constructor with initializer functor.  Each local instance of T is constructed by T(finit()).
        template <typename Finit
#if __TBB_ETS_USE_CPP11
                  , typename = typename internal::enable_if<internal::is_callable_no_args<typename internal::strip<Finit>::type>::value>::type
#endif
        >
        enumerable_thread_specific( Finit finit ) : my_construct_callback(
            internal::callback_leaf<T,internal::construct_by_finit<T,Finit> >::make( tbb::internal::move(finit) )
        ){}

        //! Constructor with exemplar. Each local instance of T is copy-constructed from the exemplar.
        enumerable_thread_specific( const T& exemplar ) : my_construct_callback(
            internal::callback_leaf<T,internal::construct_by_exemplar<T> >::make( exemplar )
        ){}

#if __TBB_ETS_USE_CPP11
        enumerable_thread_specific( T&& exemplar ) : my_construct_callback(
            internal::callback_leaf<T,internal::construct_by_exemplar<T> >::make( std::move(exemplar) )
        ){}

        //! Variadic constructor with initializer arguments.  Each local instance of T is constructed by T(args...)
        template <typename P1, typename... P,
                  typename = typename internal::enable_if<!internal::is_callable_no_args<typename internal::strip<P1>::type>::value
                                                          && !internal::is_compatible_ets<T, typename internal::strip<P1>::type>::value
                                                          && !internal::is_same_type<T, typename internal::strip<P1>::type>::value
                                                         >::type>
        enumerable_thread_specific( P1&& arg1, P&& ... args ) : my_construct_callback(
            internal::callback_leaf<T,internal::construct_by_args<T,P1,P...> >::make( std::forward<P1>(arg1), std::forward<P>(args)... )
        ){}
#endif

        //! Destructor
        ~enumerable_thread_specific() {
            if(my_construct_callback) my_construct_callback->destroy();
            // Deallocate the hash table before overridden free_array() becomes inaccessible
            this->internal::ets_base<ets_no_key>::table_clear();
        }

        //! returns reference to local, discarding exists
        reference local() {
            bool exists;
            return local(exists);
        }

        //! Returns reference to calling thread's local copy, creating one if necessary
        reference local(bool& exists)  {
            void* ptr = this->table_lookup(exists);
            return *(T*)ptr;
        }

        //! Get the number of local copies
        size_type size() const { return my_locals.size(); }

        //! true if there have been no local copies created
        bool empty() const { return my_locals.empty(); }

        //! begin iterator
        iterator begin() { return iterator( my_locals, 0 ); }
        //! end iterator
        iterator end() { return iterator(my_locals, my_locals.size() ); }

        //! begin const iterator
        const_iterator begin() const { return const_iterator(my_locals, 0); }

        //! end const iterator
        const_iterator end() const { return const_iterator(my_locals, my_locals.size()); }

        //! Get range for parallel algorithms
        range_type range( size_t grainsize=1 ) { return range_type( begin(), end(), grainsize ); }

        //! Get const range for parallel algorithms
        const_range_type range( size_t grainsize=1 ) const { return const_range_type( begin(), end(), grainsize ); }

        //! Destroys local copies
        void clear() {
            my_locals.clear();
            this->table_clear();
            // callback is not destroyed
        }

    private:

        template<typename A2, ets_key_usage_type C2>
        void internal_copy(const enumerable_thread_specific<T, A2, C2>& other) {
#if __TBB_ETS_USE_CPP11 && TBB_USE_ASSERT
            // this tests is_compatible_ets
            __TBB_STATIC_ASSERT( (internal::is_compatible_ets<T, typename internal::strip<decltype(other)>::type>::value), "is_compatible_ets fails" );
#endif
            // Initialize my_construct_callback first, so that it is valid even if rest of this routine throws an exception.
            my_construct_callback = other.my_construct_callback->clone();
            __TBB_ASSERT(my_locals.size()==0,NULL);
            my_locals.reserve(other.size());
            this->table_elementwise_copy( other, create_local_by_copy );
        }

        void internal_swap(enumerable_thread_specific& other) {
            using std::swap;
            __TBB_ASSERT( this!=&other, NULL );
            swap(my_construct_callback, other.my_construct_callback);
            // concurrent_vector::swap() preserves storage space,
            // so addresses to the vector kept in ETS hash table remain valid.
            swap(my_locals, other.my_locals);
            this->internal::ets_base<ETS_key_type>::table_swap(other);
        }

#if __TBB_ETS_USE_CPP11
        template<typename A2, ets_key_usage_type C2>
        void internal_move(enumerable_thread_specific<T, A2, C2>&& other) {
#if TBB_USE_ASSERT
            // this tests is_compatible_ets
            __TBB_STATIC_ASSERT( (internal::is_compatible_ets<T, typename internal::strip<decltype(other)>::type>::value), "is_compatible_ets fails" );
#endif
            my_construct_callback = other.my_construct_callback;
            other.my_construct_callback = NULL;
            __TBB_ASSERT(my_locals.size()==0,NULL);
            my_locals.reserve(other.size());
            this->table_elementwise_copy( other, create_local_by_move );
        }
#endif

    public:

        enumerable_thread_specific( const enumerable_thread_specific& other )
        : internal::ets_base<ETS_key_type>() /* prevents GCC warnings with -Wextra */
        {
            internal_copy(other);
        }

        template<typename Alloc, ets_key_usage_type Cachetype>
        enumerable_thread_specific( const enumerable_thread_specific<T, Alloc, Cachetype>& other )
        {
            internal_copy(other);
        }

#if __TBB_ETS_USE_CPP11
        enumerable_thread_specific( enumerable_thread_specific&& other ) : my_construct_callback()
        {
            internal_swap(other);
        }

        template<typename Alloc, ets_key_usage_type Cachetype>
        enumerable_thread_specific( enumerable_thread_specific<T, Alloc, Cachetype>&& other ) : my_construct_callback()
        {
            internal_move(std::move(other));
        }
#endif

        enumerable_thread_specific& operator=( const enumerable_thread_specific& other )
        {
            if( this != &other ) {
                this->clear();
                my_construct_callback->destroy();
                internal_copy( other );
            }
            return *this;
        }

        template<typename Alloc, ets_key_usage_type Cachetype>
        enumerable_thread_specific& operator=( const enumerable_thread_specific<T, Alloc, Cachetype>& other )
        {
            __TBB_ASSERT( static_cast<void*>(this)!=static_cast<const void*>(&other), NULL ); // Objects of different types
            this->clear();
            my_construct_callback->destroy();
            internal_copy(other);
            return *this;
        }

#if __TBB_ETS_USE_CPP11
        enumerable_thread_specific& operator=( enumerable_thread_specific&& other )
        {
            if( this != &other )
                internal_swap(other);
            return *this;
        }

        template<typename Alloc, ets_key_usage_type Cachetype>
        enumerable_thread_specific& operator=( enumerable_thread_specific<T, Alloc, Cachetype>&& other )
        {
            __TBB_ASSERT( static_cast<void*>(this)!=static_cast<const void*>(&other), NULL ); // Objects of different types
            this->clear();
            my_construct_callback->destroy();
            internal_move(std::move(other));
            return *this;
        }
#endif

        // combine_func_t has signature T(T,T) or T(const T&, const T&)
        template <typename combine_func_t>
        T combine(combine_func_t f_combine) {
            if(begin() == end()) {
                internal::ets_element<T> location;
                my_construct_callback->construct(location.value());
                return *location.value_committed();
            }
            const_iterator ci = begin();
            T my_result = *ci;
            while(++ci != end())
                my_result = f_combine( my_result, *ci );
            return my_result;
        }

        // combine_func_t takes T by value or by [const] reference, and returns nothing
        template <typename combine_func_t>
        void combine_each(combine_func_t f_combine) {
            for(iterator ci = begin(); ci != end(); ++ci) {
                f_combine( *ci );
            }
        }

    }; // enumerable_thread_specific

    template< typename Container >
    class flattened2d {

        // This intermediate typedef is to address issues with VC7.1 compilers
        typedef typename Container::value_type conval_type;

    public:

        //! Basic types
        typedef typename conval_type::size_type size_type;
        typedef typename conval_type::difference_type difference_type;
        typedef typename conval_type::allocator_type allocator_type;
        typedef typename conval_type::value_type value_type;
        typedef typename conval_type::reference reference;
        typedef typename conval_type::const_reference const_reference;
        typedef typename conval_type::pointer pointer;
        typedef typename conval_type::const_pointer const_pointer;

        typedef typename internal::segmented_iterator<Container, value_type> iterator;
        typedef typename internal::segmented_iterator<Container, const value_type> const_iterator;

        flattened2d( const Container &c, typename Container::const_iterator b, typename Container::const_iterator e ) :
            my_container(const_cast<Container*>(&c)), my_begin(b), my_end(e) { }

        flattened2d( const Container &c ) :
            my_container(const_cast<Container*>(&c)), my_begin(c.begin()), my_end(c.end()) { }

        iterator begin() { return iterator(*my_container) = my_begin; }
        iterator end() { return iterator(*my_container) = my_end; }
        const_iterator begin() const { return const_iterator(*my_container) = my_begin; }
        const_iterator end() const { return const_iterator(*my_container) = my_end; }

        size_type size() const {
            size_type tot_size = 0;
            for(typename Container::const_iterator i = my_begin; i != my_end; ++i) {
                tot_size += i->size();
            }
            return tot_size;
        }

    private:

        Container *my_container;
        typename Container::const_iterator my_begin;
        typename Container::const_iterator my_end;

    };

    template <typename Container>
    flattened2d<Container> flatten2d(const Container &c, const typename Container::const_iterator b, const typename Container::const_iterator e) {
        return flattened2d<Container>(c, b, e);
    }

    template <typename Container>
    flattened2d<Container> flatten2d(const Container &c) {
        return flattened2d<Container>(c);
    }

} // interface6

namespace internal {
using interface6::internal::segmented_iterator;
}

using interface6::enumerable_thread_specific;
using interface6::flattened2d;
using interface6::flatten2d;

} // namespace tbb

#endif