_concurrent_unordered_impl.h

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/*
    Copyright (c) 2005-2020 Intel Corporation

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/

/* Container implementations in this header are based on PPL implementations
   provided by Microsoft. */

#ifndef __TBB__concurrent_unordered_impl_H
#define __TBB__concurrent_unordered_impl_H
#if !defined(__TBB_concurrent_unordered_map_H) && !defined(__TBB_concurrent_unordered_set_H) && !defined(__TBB_concurrent_hash_map_H)
#error Do not #include this internal file directly; use public TBB headers instead.
#endif

#include "../tbb_stddef.h"

#include <iterator>
#include <utility>      // Need std::pair
#include <functional>   // Need std::equal_to (in ../concurrent_unordered_*.h)
#include <string>       // For tbb_hasher
#include <cstring>      // Need std::memset
#include __TBB_STD_SWAP_HEADER

#include "../atomic.h"
#include "../tbb_exception.h"
#include "../tbb_allocator.h"

#if __TBB_INITIALIZER_LISTS_PRESENT
    #include <initializer_list>
#endif

#if __TBB_CPP11_RVALUE_REF_PRESENT && !__TBB_IMPLICIT_COPY_DELETION_BROKEN
    #define __TBB_UNORDERED_NODE_HANDLE_PRESENT 1
#endif

#include "_allocator_traits.h"
#include "_tbb_hash_compare_impl.h"
#include "_template_helpers.h"

#if __TBB_UNORDERED_NODE_HANDLE_PRESENT
#include "_node_handle_impl.h"
#endif // __TBB_UNORDERED_NODE_HANDLE_PRESENT

namespace tbb {
namespace interface5 {
namespace internal {

template <typename T, typename Allocator>
class split_ordered_list;
template <typename Traits>
class concurrent_unordered_base;

// Forward list iterators (without skipping dummy elements)
template<class Solist, typename Value>
class flist_iterator : public std::iterator<std::forward_iterator_tag, Value>
{
    template <typename T, typename Allocator>
    friend class split_ordered_list;
    template <typename Traits>
    friend class concurrent_unordered_base;
    template<class M, typename V>
    friend class flist_iterator;

    typedef typename Solist::nodeptr_t nodeptr_t;
public:
    typedef typename Solist::value_type value_type;
    typedef typename Solist::difference_type difference_type;
    typedef typename Solist::pointer pointer;
    typedef typename Solist::reference reference;

    flist_iterator() : my_node_ptr(0) {}
    flist_iterator( const flist_iterator<Solist, typename Solist::value_type> &other )
        : my_node_ptr(other.my_node_ptr) {}

    flist_iterator& operator=( const flist_iterator<Solist, typename Solist::value_type> &other ) {
        my_node_ptr = other.my_node_ptr;
        return *this;
    }

    reference operator*() const { return my_node_ptr->my_element; }
    pointer operator->() const { return &**this; }

    flist_iterator& operator++() {
        my_node_ptr = my_node_ptr->my_next;
        return *this;
    }

    flist_iterator operator++(int) {
        flist_iterator tmp = *this;
        ++*this;
        return tmp;
    }

protected:
    flist_iterator(nodeptr_t pnode) : my_node_ptr(pnode) {}
    nodeptr_t get_node_ptr() const { return my_node_ptr; }

    nodeptr_t my_node_ptr;

    template<typename M, typename T, typename U>
    friend bool operator==( const flist_iterator<M,T> &i, const flist_iterator<M,U> &j );
    template<typename M, typename T, typename U>
    friend bool operator!=( const flist_iterator<M,T>& i, const flist_iterator<M,U>& j );
};

template<typename Solist, typename T, typename U>
bool operator==( const flist_iterator<Solist,T> &i, const flist_iterator<Solist,U> &j ) {
    return i.my_node_ptr == j.my_node_ptr;
}
template<typename Solist, typename T, typename U>
bool operator!=( const flist_iterator<Solist,T>& i, const flist_iterator<Solist,U>& j ) {
    return i.my_node_ptr != j.my_node_ptr;
}

// Split-order list iterators, needed to skip dummy elements
template<class Solist, typename Value>
class solist_iterator : public flist_iterator<Solist, Value>
{
    typedef flist_iterator<Solist, Value> base_type;
    typedef typename Solist::nodeptr_t nodeptr_t;
    using base_type::get_node_ptr;
    template <typename T, typename Allocator>
    friend class split_ordered_list;
    template<class M, typename V>
    friend class solist_iterator;
    template <typename Traits>
    friend class concurrent_unordered_base;
    template<typename M, typename T, typename U>
    friend bool operator==( const solist_iterator<M,T> &i, const solist_iterator<M,U> &j );
    template<typename M, typename T, typename U>
    friend bool operator!=( const solist_iterator<M,T>& i, const solist_iterator<M,U>& j );

    const Solist *my_list_ptr;
    solist_iterator(nodeptr_t pnode, const Solist *plist) : base_type(pnode), my_list_ptr(plist) {}

public:
    typedef typename Solist::value_type value_type;
    typedef typename Solist::difference_type difference_type;
    typedef typename Solist::pointer pointer;
    typedef typename Solist::reference reference;

    solist_iterator() {}
    solist_iterator( const solist_iterator<Solist, typename Solist::value_type> &other )
        : base_type(other), my_list_ptr(other.my_list_ptr) {}

    solist_iterator& operator=( const solist_iterator<Solist, typename Solist::value_type> &other ) {
        base_type::my_node_ptr = other.get_node_ptr();
        my_list_ptr = other.my_list_ptr;
        return *this;
    }

    reference operator*() const {
        return this->base_type::operator*();
    }

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

    solist_iterator& operator++() {
        do ++(*(base_type *)this);
        while (get_node_ptr() != NULL && get_node_ptr()->is_dummy());

        return (*this);
    }

    solist_iterator operator++(int) {
        solist_iterator tmp = *this;
        do ++*this;
        while (get_node_ptr() != NULL && get_node_ptr()->is_dummy());

        return (tmp);
    }
};

template<typename Solist, typename T, typename U>
bool operator==( const solist_iterator<Solist,T> &i, const solist_iterator<Solist,U> &j ) {
    return i.my_node_ptr == j.my_node_ptr && i.my_list_ptr == j.my_list_ptr;
}
template<typename Solist, typename T, typename U>
bool operator!=( const solist_iterator<Solist,T>& i, const solist_iterator<Solist,U>& j ) {
    return i.my_node_ptr != j.my_node_ptr || i.my_list_ptr != j.my_list_ptr;
}

// Forward type and class definitions
typedef size_t sokey_t;


// Forward list in which elements are sorted in a split-order
template <typename T, typename Allocator>
class split_ordered_list
{
public:
    typedef split_ordered_list<T, Allocator> self_type;

    typedef typename tbb::internal::allocator_rebind<Allocator, T>::type allocator_type;

    struct node;
    typedef node *nodeptr_t;

    typedef typename tbb::internal::allocator_traits<allocator_type>::value_type value_type;
    typedef typename tbb::internal::allocator_traits<allocator_type>::size_type size_type;
    typedef typename tbb::internal::allocator_traits<allocator_type>::difference_type difference_type;
    typedef typename tbb::internal::allocator_traits<allocator_type>::pointer pointer;
    typedef typename tbb::internal::allocator_traits<allocator_type>::const_pointer const_pointer;
    // No support for reference/const_reference in allocator traits
    typedef value_type& reference;
    typedef const value_type& const_reference;

    typedef solist_iterator<self_type, const value_type> const_iterator;
    typedef solist_iterator<self_type, value_type> iterator;
    typedef flist_iterator<self_type, const value_type> raw_const_iterator;
    typedef flist_iterator<self_type, value_type> raw_iterator;

    // Node that holds the element in a split-ordered list
    struct node : tbb::internal::no_assign
    {
    private:
        // for compilers that try to generate default constructors though they are not needed.
        node();  // VS 2008, 2010, 2012
    public:
        // Initialize the node with the given order key
        void init(sokey_t order_key) {
            my_order_key = order_key;
            my_next = NULL;
        }

        // Return the order key (needed for hashing)
        sokey_t get_order_key() const { // TODO: remove
            return my_order_key;
        }

        // get() and value() is a common interface for getting access to node`s element (required by node_handle)
        value_type* storage() {
            return reinterpret_cast<value_type*>(&my_element);
        }

        value_type& value() {
        return *storage();
        }

        // Inserts the new element in the list in an atomic fashion
        nodeptr_t atomic_set_next(nodeptr_t new_node, nodeptr_t current_node)
        {
            // Try to change the next pointer on the current element to a new element, only if it still points to the cached next
            nodeptr_t exchange_node = tbb::internal::as_atomic(my_next).compare_and_swap(new_node, current_node);

            if (exchange_node == current_node) // TODO: why this branch?
            {
                // Operation succeeded, return the new node
                return new_node;
            }
            else
            {
                // Operation failed, return the "interfering" node
                return exchange_node;
            }
        }

        // Checks if this element in the list is a dummy, order enforcing node. Dummy nodes are used by buckets
        // in the hash table to quickly index into the right subsection of the split-ordered list.
        bool is_dummy() const {
            return (my_order_key & 0x1) == 0;
        }


        nodeptr_t  my_next;      // Next element in the list
        value_type my_element;   // Element storage
        sokey_t    my_order_key; // Order key for this element
    };

    // Allocate a new node with the given order key; used to allocate dummy nodes
    nodeptr_t create_node(sokey_t order_key) {
        nodeptr_t pnode = my_node_allocator.allocate(1);
        pnode->init(order_key);
        return (pnode);
    }

    // Allocate a new node with the given order key and value
    template<typename Arg>
    nodeptr_t create_node(sokey_t order_key, __TBB_FORWARDING_REF(Arg) t,
                          /*AllowCreate=*/tbb::internal::true_type=tbb::internal::true_type()){
        nodeptr_t pnode = my_node_allocator.allocate(1);

        //TODO: use RAII scoped guard instead of explicit catch
        __TBB_TRY {
            new(static_cast<void*>(&pnode->my_element)) T(tbb::internal::forward<Arg>(t));
            pnode->init(order_key);
        } __TBB_CATCH(...) {
            my_node_allocator.deallocate(pnode, 1);
            __TBB_RETHROW();
        }

        return (pnode);
    }

    // A helper to avoid excessive requiremens in internal_insert
    template<typename Arg>
    nodeptr_t create_node(sokey_t, __TBB_FORWARDING_REF(Arg),
                          /*AllowCreate=*/tbb::internal::false_type){
        __TBB_ASSERT(false, "This compile-time helper should never get called");
        return nodeptr_t();
    }

    // Allocate a new node with the given parameters for constructing value
    template<typename __TBB_PARAMETER_PACK Args>
    nodeptr_t create_node_v( __TBB_FORWARDING_REF(Args) __TBB_PARAMETER_PACK args){
        nodeptr_t pnode = my_node_allocator.allocate(1);

        //TODO: use RAII scoped guard instead of explicit catch
        __TBB_TRY {
            new(static_cast<void*>(&pnode->my_element)) T(__TBB_PACK_EXPANSION(tbb::internal::forward<Args>(args)));
        } __TBB_CATCH(...) {
            my_node_allocator.deallocate(pnode, 1);
            __TBB_RETHROW();
        }

        return (pnode);
    }

   split_ordered_list(allocator_type a = allocator_type())
       : my_node_allocator(a), my_element_count(0)
    {
        // Immediately allocate a dummy node with order key of 0. This node
        // will always be the head of the list.
        my_head = create_node(sokey_t(0));
    }

    ~split_ordered_list()
    {
        // Clear the list
        clear();

        // Remove the head element which is not cleared by clear()
        nodeptr_t pnode = my_head;
        my_head = NULL;

        __TBB_ASSERT(pnode != NULL && pnode->my_next == NULL, "Invalid head list node");

        destroy_node(pnode);
    }

    // Common forward list functions

    allocator_type get_allocator() const {
        return (my_node_allocator);
    }

    void clear() {
        nodeptr_t pnext;
        nodeptr_t pnode = my_head;

        __TBB_ASSERT(my_head != NULL, "Invalid head list node");
        pnext = pnode->my_next;
        pnode->my_next = NULL;
        pnode = pnext;

        while (pnode != NULL)
        {
            pnext = pnode->my_next;
            destroy_node(pnode);
            pnode = pnext;
        }

        my_element_count = 0;
    }

    // Returns a first non-dummy element in the SOL
    iterator begin() {
        return first_real_iterator(raw_begin());
    }

    // Returns a first non-dummy element in the SOL
    const_iterator begin() const {
        return first_real_iterator(raw_begin());
    }

    iterator end() {
        return (iterator(0, this));
    }

    const_iterator end() const {
        return (const_iterator(0, this));
    }

    const_iterator cbegin() const {
        return (((const self_type *)this)->begin());
    }

    const_iterator cend() const {
        return (((const self_type *)this)->end());
    }

    // Checks if the number of elements (non-dummy) is 0
    bool empty() const {
        return (my_element_count == 0);
    }

    // Returns the number of non-dummy elements in the list
    size_type size() const {
        return my_element_count;
    }

    // Returns the maximum size of the list, determined by the allocator
    size_type max_size() const {
        return my_node_allocator.max_size();
    }

    // Swaps 'this' list with the passed in one
    void swap(self_type& other)
    {
        if (this == &other)
        {
            // Nothing to do
            return;
        }

            std::swap(my_element_count, other.my_element_count);
            std::swap(my_head, other.my_head);
    }

    // Split-order list functions

    // Returns a first element in the SOL, which is always a dummy
    raw_iterator raw_begin() {
        return raw_iterator(my_head);
    }

    // Returns a first element in the SOL, which is always a dummy
    raw_const_iterator raw_begin() const {
        return raw_const_iterator(my_head);
    }

    raw_iterator raw_end() {
        return raw_iterator(0);
    }

    raw_const_iterator raw_end() const {
        return raw_const_iterator(0);
    }

    static sokey_t get_order_key(const raw_const_iterator& it) {
        return it.get_node_ptr()->get_order_key();
    }

    static sokey_t get_safe_order_key(const raw_const_iterator& it) {
        if( !it.get_node_ptr() )  return ~sokey_t(0);
        return it.get_node_ptr()->get_order_key();
    }

    // Returns a public iterator version of the internal iterator. Public iterator must not
    // be a dummy private iterator.
    iterator get_iterator(raw_iterator it) {
        __TBB_ASSERT(it.get_node_ptr() == NULL || !it.get_node_ptr()->is_dummy(), "Invalid user node (dummy)");
        return iterator(it.get_node_ptr(), this);
    }

    // Returns a public iterator version of the internal iterator. Public iterator must not
    // be a dummy private iterator.
    const_iterator get_iterator(raw_const_iterator it) const {
        __TBB_ASSERT(it.get_node_ptr() == NULL || !it.get_node_ptr()->is_dummy(), "Invalid user node (dummy)");
        return const_iterator(it.get_node_ptr(), this);
    }

    // Returns a non-const version of the raw_iterator
    raw_iterator get_iterator(raw_const_iterator it) {
        return raw_iterator(it.get_node_ptr());
    }

    // Returns a non-const version of the iterator
    static iterator get_iterator(const_iterator it) {
        return iterator(it.my_node_ptr, it.my_list_ptr);
    }

    // Returns a public iterator version of a first non-dummy internal iterator at or after
    // the passed in internal iterator.
    iterator first_real_iterator(raw_iterator it)
    {
        // Skip all dummy, internal only iterators
        while (it != raw_end() && it.get_node_ptr()->is_dummy())
            ++it;

        return iterator(it.get_node_ptr(), this);
    }

    // Returns a public iterator version of a first non-dummy internal iterator at or after
    // the passed in internal iterator.
    const_iterator first_real_iterator(raw_const_iterator it) const
    {
        // Skip all dummy, internal only iterators
        while (it != raw_end() && it.get_node_ptr()->is_dummy())
            ++it;

        return const_iterator(it.get_node_ptr(), this);
    }

    // Erase an element using the allocator
    void destroy_node(nodeptr_t pnode) {
        if (!pnode->is_dummy()) my_node_allocator.destroy(pnode);
        my_node_allocator.deallocate(pnode, 1);
    }

    // Try to insert a new element in the list.
    // If insert fails, return the node that was inserted instead.
    static nodeptr_t try_insert_atomic(nodeptr_t previous, nodeptr_t new_node, nodeptr_t current_node) {
        new_node->my_next = current_node;
        return previous->atomic_set_next(new_node, current_node);
    }

    // Insert a new element between passed in iterators
    std::pair<iterator, bool> try_insert(raw_iterator it, raw_iterator next, nodeptr_t pnode, size_type *new_count)
    {
        nodeptr_t inserted_node = try_insert_atomic(it.get_node_ptr(), pnode, next.get_node_ptr());

        if (inserted_node == pnode)
        {
            // If the insert succeeded, check that the order is correct and increment the element count
            check_range(it, next);
            *new_count = tbb::internal::as_atomic(my_element_count).fetch_and_increment();
            return std::pair<iterator, bool>(iterator(pnode, this), true);
        }
        else
        {
            return std::pair<iterator, bool>(end(), false);
        }
    }

    // Insert a new dummy element, starting search at a parent dummy element
    raw_iterator insert_dummy(raw_iterator it, sokey_t order_key)
    {
        raw_iterator last = raw_end();
        raw_iterator where = it;

        __TBB_ASSERT(where != last, "Invalid head node");

        ++where;

        // Create a dummy element up front, even though it may be discarded (due to concurrent insertion)
        nodeptr_t dummy_node = create_node(order_key);

        for (;;)
        {
            __TBB_ASSERT(it != last, "Invalid head list node");

            // If the head iterator is at the end of the list, or past the point where this dummy
            // node needs to be inserted, then try to insert it.
            if (where == last || get_order_key(where) > order_key)
            {
                __TBB_ASSERT(get_order_key(it) < order_key, "Invalid node order in the list");

                // Try to insert it in the right place
                nodeptr_t inserted_node = try_insert_atomic(it.get_node_ptr(), dummy_node, where.get_node_ptr());

                if (inserted_node == dummy_node)
                {
                    // Insertion succeeded, check the list for order violations
                    check_range(it, where);
                    return raw_iterator(dummy_node);
                }
                else
                {
                    // Insertion failed: either dummy node was inserted by another thread, or
                    // a real element was inserted at exactly the same place as dummy node.
                    // Proceed with the search from the previous location where order key was
                    // known to be larger (note: this is legal only because there is no safe
                    // concurrent erase operation supported).
                    where = it;
                    ++where;
                    continue;
                }
            }
            else if (get_order_key(where) == order_key)
            {
                // Another dummy node with the same value found, discard the new one.
                destroy_node(dummy_node);
                return where;
            }

            // Move the iterator forward
            it = where;
            ++where;
        }

    }

    nodeptr_t  erase_node_impl(raw_iterator previous, raw_const_iterator& where) {
        nodeptr_t pnode = (where++).get_node_ptr();
        nodeptr_t prevnode = previous.get_node_ptr();
        __TBB_ASSERT(prevnode->my_next == pnode, "Erase must take consecutive iterators");
        prevnode->my_next = pnode->my_next;
        return pnode;
    }

    // This erase function can handle both real and dummy nodes
    void erase_node(raw_iterator previous, raw_const_iterator& where,
                    /*allow_destroy*/tbb::internal::true_type)
    {
        nodeptr_t pnode = erase_node_impl(previous, where);
        destroy_node(pnode);
    }

    void erase_node(raw_iterator previous, raw_const_iterator& where,
                    /*allow_destroy*/tbb::internal::false_type)
    {
        erase_node_impl(previous, where);
    }

    void erase_node(raw_iterator previous, raw_const_iterator& where) {
        erase_node(previous, where, /*allow_destroy*/tbb::internal::true_type());
    }

    // Erase the element (previous node needs to be passed because this is a forward only list)
    template<typename AllowDestroy>
    iterator erase_node(raw_iterator previous, const_iterator where, AllowDestroy)
    {
        raw_const_iterator it = where;
        erase_node(previous, it, AllowDestroy());
        my_element_count--;

        return get_iterator(first_real_iterator(it));
    }

    iterator erase_node(raw_iterator previous, const_iterator& where) {
        return erase_node(previous, where, /*allow_destroy*/tbb::internal::true_type());
    }



    // Move all elements from the passed in split-ordered list to this one
    void move_all(self_type& source)
    {
        raw_const_iterator first = source.raw_begin();
        raw_const_iterator last = source.raw_end();

        if (first == last)
            return;

        nodeptr_t previous_node = my_head;
        raw_const_iterator begin_iterator = first++;

        // Move all elements one by one, including dummy ones
        for (raw_const_iterator it = first; it != last;)
        {
            nodeptr_t pnode = it.get_node_ptr();

            nodeptr_t dummy_node = pnode->is_dummy() ? create_node(pnode->get_order_key()) : create_node(pnode->get_order_key(), pnode->my_element);
            previous_node = try_insert_atomic(previous_node, dummy_node, NULL);
            __TBB_ASSERT(previous_node != NULL, "Insertion must succeed");
            raw_const_iterator where = it++;
            source.erase_node(get_iterator(begin_iterator), where);
        }
        check_range();
    }


private:
    //Need to setup private fields of split_ordered_list in move constructor and assignment of concurrent_unordered_base
    template <typename Traits>
    friend class concurrent_unordered_base;

    // Check the list for order violations
    void check_range( raw_iterator first, raw_iterator last )
    {
#if TBB_USE_ASSERT
        for (raw_iterator it = first; it != last; ++it)
        {
            raw_iterator next = it;
            ++next;

            __TBB_ASSERT(next == raw_end() || get_order_key(next) >= get_order_key(it), "!!! List order inconsistency !!!");
        }
#else
        tbb::internal::suppress_unused_warning(first, last);
#endif
    }
    void check_range()
    {
#if TBB_USE_ASSERT
        check_range( raw_begin(), raw_end() );
#endif
    }

    typename tbb::internal::allocator_rebind<allocator_type, node>::type my_node_allocator; // allocator object for nodes
    size_type                                             my_element_count;   // Total item count, not counting dummy nodes
    nodeptr_t                                             my_head;            // pointer to head node
};

#if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
#pragma warning(push)
#pragma warning(disable: 4127) // warning C4127: conditional expression is constant
#endif

template <typename Traits>
class concurrent_unordered_base : public Traits
{
protected:
    // Type definitions
    typedef concurrent_unordered_base<Traits> self_type;
    typedef typename Traits::value_type value_type;
    typedef typename Traits::key_type key_type;
    typedef typename Traits::hash_compare hash_compare;
    typedef typename Traits::allocator_type allocator_type;
    typedef typename hash_compare::hasher hasher;
    typedef typename hash_compare::key_equal key_equal;

    typedef typename tbb::internal::allocator_traits<allocator_type>::size_type size_type;
    typedef typename tbb::internal::allocator_traits<allocator_type>::difference_type difference_type;
    typedef typename tbb::internal::allocator_traits<allocator_type>::pointer pointer;
    typedef typename tbb::internal::allocator_traits<allocator_type>::const_pointer const_pointer;
    // No support for reference/const_reference in allocator
    typedef typename allocator_type::value_type& reference;
    typedef const typename allocator_type::value_type& const_reference;

    typedef split_ordered_list<value_type, typename Traits::allocator_type> solist_t;
    typedef typename solist_t::nodeptr_t nodeptr_t;
    // Iterators that walk the entire split-order list, including dummy nodes
    typedef typename solist_t::raw_iterator raw_iterator;
    typedef typename solist_t::raw_const_iterator raw_const_iterator;
    typedef typename solist_t::iterator iterator; // TODO: restore const iterator for unordered_sets
    typedef typename solist_t::const_iterator const_iterator;
    typedef iterator local_iterator;
    typedef const_iterator const_local_iterator;
#if __TBB_UNORDERED_NODE_HANDLE_PRESENT
    typedef typename Traits::node_type node_type;
#endif // __TBB_UNORDERED_NODE_HANDLE_PRESENT
    using Traits::my_hash_compare;
    using Traits::get_key;
    using Traits::allow_multimapping;

    static const size_type initial_bucket_number = 8;                               // Initial number of buckets

private:
    template<typename OtherTraits>
    friend class concurrent_unordered_base;

    typedef std::pair<iterator, iterator> pairii_t;
    typedef std::pair<const_iterator, const_iterator> paircc_t;

    static size_type const pointers_per_table = sizeof(size_type) * 8;              // One bucket segment per bit
    static const size_type initial_bucket_load = 4;                                // Initial maximum number of elements per bucket

    struct call_internal_clear_on_exit{
        concurrent_unordered_base* my_instance;
        call_internal_clear_on_exit(concurrent_unordered_base* instance) : my_instance(instance) {}
        void dismiss(){ my_instance = NULL;}
        ~call_internal_clear_on_exit(){
            if (my_instance){
                my_instance->internal_clear();
            }
        }
    };
protected:
    // Constructors/Destructors
    concurrent_unordered_base(size_type n_of_buckets = initial_bucket_number,
        const hash_compare& hc = hash_compare(), const allocator_type& a = allocator_type())
        : Traits(hc), my_solist(a),
          my_allocator(a), my_maximum_bucket_size((float) initial_bucket_load)
    {
        if( n_of_buckets == 0) ++n_of_buckets;
        my_number_of_buckets = size_type(1)<<__TBB_Log2((uintptr_t)n_of_buckets*2-1); // round up to power of 2
        internal_init();
    }

    concurrent_unordered_base(const concurrent_unordered_base& right, const allocator_type& a)
        : Traits(right.my_hash_compare), my_solist(a), my_allocator(a)
    {
        internal_init();
        internal_copy(right);
    }

    concurrent_unordered_base(const concurrent_unordered_base& right)
        : Traits(right.my_hash_compare), my_solist(right.get_allocator()), my_allocator(right.get_allocator())
    {
        //FIXME:exception safety seems to be broken here
        internal_init();
        internal_copy(right);
    }

#if __TBB_CPP11_RVALUE_REF_PRESENT
    concurrent_unordered_base(concurrent_unordered_base&& right)
        : Traits(right.my_hash_compare), my_solist(right.get_allocator()), my_allocator(right.get_allocator()),
          my_maximum_bucket_size(float(initial_bucket_load))
    {
        my_number_of_buckets = initial_bucket_number;
        internal_init();
        swap(right);
    }

    concurrent_unordered_base(concurrent_unordered_base&& right, const allocator_type& a)
        : Traits(right.my_hash_compare), my_solist(a), my_allocator(a)
    {
        call_internal_clear_on_exit clear_buckets_on_exception(this);

        internal_init();
        if (a == right.get_allocator()){
            my_number_of_buckets = initial_bucket_number;
            my_maximum_bucket_size = float(initial_bucket_load);
            this->swap(right);
        }else{
            my_maximum_bucket_size = right.my_maximum_bucket_size;
            my_number_of_buckets = right.my_number_of_buckets;
            my_solist.my_element_count = right.my_solist.my_element_count;

            if (! right.my_solist.empty()){
                nodeptr_t previous_node = my_solist.my_head;

                // Move all elements one by one, including dummy ones
                for (raw_const_iterator it = ++(right.my_solist.raw_begin()), last = right.my_solist.raw_end(); it != last; ++it)
                {
                    const nodeptr_t pnode = it.get_node_ptr();
                    nodeptr_t node;
                    if (pnode->is_dummy()) {
                        node = my_solist.create_node(pnode->get_order_key());
                        size_type bucket = __TBB_ReverseBits(pnode->get_order_key()) % my_number_of_buckets;
                        set_bucket(bucket, node);
                    }else{
                        node = my_solist.create_node(pnode->get_order_key(), std::move(pnode->my_element));
                    }

                    previous_node = my_solist.try_insert_atomic(previous_node, node, NULL);
                    __TBB_ASSERT(previous_node != NULL, "Insertion of node failed. Concurrent inserts in constructor ?");
                }
                my_solist.check_range();
            }
        }

        clear_buckets_on_exception.dismiss();
    }

#endif // __TBB_CPP11_RVALUE_REF_PRESENT

    concurrent_unordered_base& operator=(const concurrent_unordered_base& right) {
        if (this != &right)
            internal_copy(right);
        return (*this);
    }

#if __TBB_CPP11_RVALUE_REF_PRESENT
    concurrent_unordered_base& operator=(concurrent_unordered_base&& other)
    {
        if(this != &other){
            typedef typename tbb::internal::allocator_traits<allocator_type>::propagate_on_container_move_assignment pocma_t;
            if(pocma_t::value || this->my_allocator == other.my_allocator) {
                concurrent_unordered_base trash (std::move(*this));
                swap(other);
                if (pocma_t::value) {
                    using std::swap;
                    //TODO: swapping allocators here may be a problem, replace with single direction moving
                    swap(this->my_solist.my_node_allocator, other.my_solist.my_node_allocator);
                    swap(this->my_allocator, other.my_allocator);
                }
            } else {
                concurrent_unordered_base moved_copy(std::move(other),this->my_allocator);
                this->swap(moved_copy);
            }
        }
        return *this;
    }

#endif // __TBB_CPP11_RVALUE_REF_PRESENT

#if __TBB_INITIALIZER_LISTS_PRESENT
    concurrent_unordered_base& operator=(std::initializer_list<value_type> il)
    {
        this->clear();
        this->insert(il.begin(),il.end());
        return (*this);
    }
#endif // __TBB_INITIALIZER_LISTS_PRESENT


    ~concurrent_unordered_base() {
        // Delete all node segments
        internal_clear();
    }

#if __TBB_UNORDERED_NODE_HANDLE_PRESENT
    template<typename SourceType>
    void internal_merge(SourceType& source) {
        typedef typename SourceType::iterator source_iterator;
        __TBB_STATIC_ASSERT((tbb::internal::is_same_type<node_type,
                            typename SourceType::node_type>::value),
                            "Incompatible containers cannot be merged");

        for(source_iterator it = source.begin(); it != source.end();) {
            source_iterator where = it++;
            if (allow_multimapping || find(get_key(*where)) == end()) {
                std::pair<node_type, raw_iterator> extract_result = source.internal_extract(where);

                // Remember the old order key
                sokey_t old_order_key = extract_result.first.my_node->get_order_key();

                // If the insertion fails, it returns ownership of the node to extract_result.first
                // extract_result.first remains valid node handle
                if (!insert(std::move(extract_result.first)).second) {
                    raw_iterator next = extract_result.second;
                    raw_iterator current = next++;

                    // Revert order key to old value
                    extract_result.first.my_node->init(old_order_key);

                    __TBB_ASSERT(extract_result.first.my_node->get_order_key() >= current.get_node_ptr()->get_order_key(),
                                "Wrong nodes order in source container");
                    __TBB_ASSERT(next==source.my_solist.raw_end() ||
                                 extract_result.first.my_node->get_order_key() <= next.get_node_ptr()->get_order_key(),
                                 "Wrong nodes order in source container");

                    size_t new_count = 0;// To use try_insert()
                    bool insert_result =
                        source.my_solist.try_insert(current, next, extract_result.first.my_node, &new_count).second;
                    __TBB_ASSERT_EX(insert_result, "Return to source must be successful. "
                                                   "Changing source container while merging is unsafe.");
                }
                extract_result.first.deactivate();
            }
        }
    }
#endif // __TBB_UNORDERED_NODE_HANDLE_PRESENT

public:
    allocator_type get_allocator() const {
        return my_solist.get_allocator();
    }

    // Size and capacity function
    bool empty() const {
        return my_solist.empty();
    }

    size_type size() const {
        return my_solist.size();
    }

    size_type max_size() const {
        return my_solist.max_size();
    }

    // Iterators
    iterator begin() {
        return my_solist.begin();
    }

    const_iterator begin() const {
        return my_solist.begin();
    }

    iterator end() {
        return my_solist.end();
    }

    const_iterator end() const {
        return my_solist.end();
    }

    const_iterator cbegin() const {
        return my_solist.cbegin();
    }

    const_iterator cend() const {
        return my_solist.cend();
    }

    // Parallel traversal support
    class const_range_type : tbb::internal::no_assign {
        const concurrent_unordered_base &my_table;
        raw_const_iterator my_begin_node;
        raw_const_iterator my_end_node;
        mutable raw_const_iterator my_midpoint_node;
    public:
        typedef typename concurrent_unordered_base::size_type size_type;
        typedef typename concurrent_unordered_base::value_type value_type;
        typedef typename concurrent_unordered_base::reference reference;
        typedef typename concurrent_unordered_base::difference_type difference_type;
        typedef typename concurrent_unordered_base::const_iterator iterator;

        bool empty() const {return my_begin_node == my_end_node;}

        bool is_divisible() const {
            return my_midpoint_node != my_end_node;
        }
        const_range_type( const_range_type &r, split ) :
            my_table(r.my_table), my_end_node(r.my_end_node)
        {
            r.my_end_node = my_begin_node = r.my_midpoint_node;
            __TBB_ASSERT( !empty(), "Splitting despite the range is not divisible" );
            __TBB_ASSERT( !r.empty(), "Splitting despite the range is not divisible" );
            set_midpoint();
            r.set_midpoint();
        }
        const_range_type( const concurrent_unordered_base &a_table ) :
            my_table(a_table), my_begin_node(a_table.my_solist.begin()),
            my_end_node(a_table.my_solist.end())
        {
            set_midpoint();
        }
        iterator begin() const { return my_table.my_solist.get_iterator(my_begin_node); }
        iterator end() const { return my_table.my_solist.get_iterator(my_end_node); }
        size_type grainsize() const { return 1; }

        void set_midpoint() const {
            if( my_begin_node == my_end_node ) // not divisible
                my_midpoint_node = my_end_node;
            else {
                sokey_t begin_key = solist_t::get_safe_order_key(my_begin_node);
                sokey_t end_key = solist_t::get_safe_order_key(my_end_node);
                size_t mid_bucket = __TBB_ReverseBits( begin_key + (end_key-begin_key)/2 ) % my_table.my_number_of_buckets;
                while ( !my_table.is_initialized(mid_bucket) ) mid_bucket = my_table.get_parent(mid_bucket);
                if(__TBB_ReverseBits(mid_bucket) > begin_key) {
                    // found a dummy_node between begin and end
                    my_midpoint_node = my_table.my_solist.first_real_iterator(my_table.get_bucket( mid_bucket ));
                }
                else {
                    // didn't find a dummy node between begin and end.
                    my_midpoint_node = my_end_node;
                }
#if TBB_USE_ASSERT
                {
                    sokey_t mid_key = solist_t::get_safe_order_key(my_midpoint_node);
                    __TBB_ASSERT( begin_key < mid_key, "my_begin_node is after my_midpoint_node" );
                    __TBB_ASSERT( mid_key <= end_key, "my_midpoint_node is after my_end_node" );
                }
#endif // TBB_USE_ASSERT
            }
        }
    };

    class range_type : public const_range_type {
    public:
        typedef typename concurrent_unordered_base::iterator iterator;
        range_type( range_type &r, split ) : const_range_type( r, split() ) {}
        range_type( const concurrent_unordered_base &a_table ) : const_range_type(a_table) {}

        iterator begin() const { return solist_t::get_iterator( const_range_type::begin() ); }
        iterator end() const { return solist_t::get_iterator( const_range_type::end() ); }
    };

    range_type range() {
        return range_type( *this );
    }

    const_range_type range() const {
        return const_range_type( *this );
    }

    // Modifiers
    std::pair<iterator, bool> insert(const value_type& value) {
        return internal_insert</*AllowCreate=*/tbb::internal::true_type,
                               /*AllowDestroy=*/tbb::internal::true_type>(value);
    }

    iterator insert(const_iterator, const value_type& value) {
        // Ignore hint
        return insert(value).first;
    }

#if __TBB_CPP11_RVALUE_REF_PRESENT
    std::pair<iterator, bool> insert(value_type&& value) {
        return internal_insert</*AllowCreate=*/tbb::internal::true_type,
                               /*AllowDestroy=*/tbb::internal::true_type>(std::move(value));
    }

    iterator insert(const_iterator, value_type&& value) {
        // Ignore hint
        return insert(std::move(value)).first;
    }
#endif /*__TBB_CPP11_RVALUE_REF_PRESENT*/

#if __TBB_UNORDERED_NODE_HANDLE_PRESENT
    std::pair<iterator, bool> insert(node_type&& nh) {
        if (!nh.empty()) {
            nodeptr_t handled_node = nh.my_node;
            std::pair<iterator, bool> insert_result =
                                      internal_insert</*AllowCreate=*/tbb::internal::false_type,
                                                      /*AllowDestroy=*/tbb::internal::false_type>
                                                      (handled_node->my_element, handled_node);
            if (insert_result.second)
                nh.deactivate();
            return insert_result;
        }
        return std::pair<iterator, bool>(end(), false);
    }

    iterator insert(const_iterator, node_type&& nh) {
        return insert(std::move(nh)).first;
    }
#endif // __TBB_UNORDERED_NODE_HANDLE_PRESENT

#if __TBB_CPP11_VARIADIC_TEMPLATES_PRESENT && __TBB_CPP11_RVALUE_REF_PRESENT
    template<typename... Args>
    std::pair<iterator, bool> emplace(Args&&... args) {
        nodeptr_t pnode = my_solist.create_node_v(tbb::internal::forward<Args>(args)...);

        return internal_insert</*AllowCreate=*/tbb::internal::false_type,
                               /*AllowDestroy=*/tbb::internal::true_type>(pnode->my_element, pnode);
    }

    template<typename... Args>
    iterator emplace_hint(const_iterator, Args&&... args) {
        // Ignore hint
        return emplace(tbb::internal::forward<Args>(args)...).first;
    }
#endif // __TBB_CPP11_VARIADIC_TEMPLATES_PRESENT && __TBB_CPP11_RVALUE_REF_PRESENT


    template<class Iterator>
    void insert(Iterator first, Iterator last) {
        for (Iterator it = first; it != last; ++it)
            insert(*it);
    }

#if __TBB_INITIALIZER_LISTS_PRESENT
    void insert(std::initializer_list<value_type> il) {
        insert(il.begin(), il.end());
    }
#endif

    iterator unsafe_erase(const_iterator where) {
        return internal_erase(where);
    }

    iterator unsafe_erase(const_iterator first, const_iterator last) {
        while (first != last)
            unsafe_erase(first++);
        return my_solist.get_iterator(first);
    }

    size_type unsafe_erase(const key_type& key) {
        pairii_t where = equal_range(key);
        size_type item_count = internal_distance(where.first, where.second);
        unsafe_erase(where.first, where.second);
        return item_count;
    }

#if __TBB_UNORDERED_NODE_HANDLE_PRESENT
    node_type unsafe_extract(const_iterator where) {
        return internal_extract(where).first;
    }

    node_type unsafe_extract(const key_type& key) {
        pairii_t where = equal_range(key);
        if (where.first == end()) return node_type(); // element was not found
        return internal_extract(where.first).first;
    }
#endif // __TBB_UNORDERED_NODE_HANDLE_PRESENT

    void swap(concurrent_unordered_base& right) {
        if (this != &right) {
            std::swap(my_hash_compare, right.my_hash_compare);
            my_solist.swap(right.my_solist);
            internal_swap_buckets(right);
            std::swap(my_number_of_buckets, right.my_number_of_buckets);
            std::swap(my_maximum_bucket_size, right.my_maximum_bucket_size);
        }
    }

    // Observers
    hasher hash_function() const {
        return my_hash_compare.my_hash_object;
    }

    key_equal key_eq() const {
        return my_hash_compare.my_key_compare_object;
    }

    void clear() {
        // Clear list
        my_solist.clear();

        // Clear buckets
        internal_clear();

        // Initialize bucket 0
        __TBB_ASSERT(my_buckets[0] == NULL, NULL);
        raw_iterator dummy_node = my_solist.raw_begin();
        set_bucket(0, dummy_node);
    }

    // Lookup
    iterator find(const key_type& key) {
        return internal_find(key);
    }

    const_iterator find(const key_type& key) const {
        return const_cast<self_type*>(this)->internal_find(key);
    }

    size_type count(const key_type& key) const {
        if(allow_multimapping) {
            paircc_t answer = equal_range(key);
            size_type item_count = internal_distance(answer.first, answer.second);
            return item_count;
        } else {
            return const_cast<self_type*>(this)->internal_find(key) == end()?0:1;
        }
    }

    std::pair<iterator, iterator> equal_range(const key_type& key) {
        return internal_equal_range(key);
    }

    std::pair<const_iterator, const_iterator> equal_range(const key_type& key) const {
        return const_cast<self_type*>(this)->internal_equal_range(key);
    }

    // Bucket interface - for debugging
    size_type unsafe_bucket_count() const {
        return my_number_of_buckets;
    }

    size_type unsafe_max_bucket_count() const {
        return segment_size(pointers_per_table-1);
    }

    size_type unsafe_bucket_size(size_type bucket) {
        size_type item_count = 0;
        if (is_initialized(bucket)) {
            raw_iterator it = get_bucket(bucket);
            ++it;
            for (; it != my_solist.raw_end() && !it.get_node_ptr()->is_dummy(); ++it)
                ++item_count;
        }
        return item_count;
    }

    size_type unsafe_bucket(const key_type& key) const {
        sokey_t order_key = (sokey_t) my_hash_compare(key);
        size_type bucket = order_key % my_number_of_buckets;
        return bucket;
    }

    // If the bucket is initialized, return a first non-dummy element in it
    local_iterator unsafe_begin(size_type bucket) {
        if (!is_initialized(bucket))
            return end();

        raw_iterator it = get_bucket(bucket);
        return my_solist.first_real_iterator(it);
    }

    // If the bucket is initialized, return a first non-dummy element in it
    const_local_iterator unsafe_begin(size_type bucket) const
    {
        if (!is_initialized(bucket))
            return end();

        raw_const_iterator it = get_bucket(bucket);
        return my_solist.first_real_iterator(it);
    }

    // @REVIEW: Takes O(n)
    // Returns the iterator after the last non-dummy element in the bucket
    local_iterator unsafe_end(size_type bucket)
    {
        if (!is_initialized(bucket))
            return end();

        raw_iterator it = get_bucket(bucket);

        // Find the end of the bucket, denoted by the dummy element
        do ++it;
        while(it != my_solist.raw_end() && !it.get_node_ptr()->is_dummy());

        // Return the first real element past the end of the bucket
        return my_solist.first_real_iterator(it);
    }

    // @REVIEW: Takes O(n)
    // Returns the iterator after the last non-dummy element in the bucket
    const_local_iterator unsafe_end(size_type bucket) const
    {
        if (!is_initialized(bucket))
            return end();

        raw_const_iterator it = get_bucket(bucket);

        // Find the end of the bucket, denoted by the dummy element
        do ++it;
        while(it != my_solist.raw_end() && !it.get_node_ptr()->is_dummy());

        // Return the first real element past the end of the bucket
        return my_solist.first_real_iterator(it);
    }

    const_local_iterator unsafe_cbegin(size_type bucket) const {
        return ((const self_type *) this)->unsafe_begin(bucket);
    }

    const_local_iterator unsafe_cend(size_type bucket) const {
        return ((const self_type *) this)->unsafe_end(bucket);
    }

    // Hash policy
    float load_factor() const {
        return (float) size() / (float) unsafe_bucket_count();
    }

    float max_load_factor() const {
        return my_maximum_bucket_size;
    }

    void max_load_factor(float newmax) {
        if (newmax != newmax || newmax < 0)
            tbb::internal::throw_exception(tbb::internal::eid_invalid_load_factor);
        my_maximum_bucket_size = newmax;
    }

    // This function is a noop, because the underlying split-ordered list
    // is already sorted, so an increase in the bucket number will be
    // reflected next time this bucket is touched.
    void rehash(size_type buckets) {
        size_type current_buckets = my_number_of_buckets;
        if (current_buckets >= buckets)
            return;
        my_number_of_buckets = size_type(1)<<__TBB_Log2((uintptr_t)buckets*2-1); // round up to power of 2
    }

private:

    // Initialize the hash and keep the first bucket open
    void internal_init() {
        // Initialize the array of segment pointers
        memset(my_buckets, 0, sizeof(my_buckets));

        // Initialize bucket 0
        raw_iterator dummy_node = my_solist.raw_begin();
        set_bucket(0, dummy_node);
    }

    void internal_clear() {
        for (size_type index = 0; index < pointers_per_table; ++index) {
            if (my_buckets[index] != NULL) {
                size_type sz = segment_size(index);
                for (size_type index2 = 0; index2 < sz; ++index2)
                    my_allocator.destroy(&my_buckets[index][index2]);
                my_allocator.deallocate(my_buckets[index], sz);
                my_buckets[index] = 0;
            }
        }
    }

    void internal_copy(const self_type& right) {
        clear();

        my_maximum_bucket_size = right.my_maximum_bucket_size;
        my_number_of_buckets = right.my_number_of_buckets;

        __TBB_TRY {
            insert(right.begin(), right.end());
            my_hash_compare = right.my_hash_compare;
        } __TBB_CATCH(...) {
            my_solist.clear();
            __TBB_RETHROW();
        }
    }

    void internal_swap_buckets(concurrent_unordered_base& right)
    {
        // Swap all node segments
        for (size_type index = 0; index < pointers_per_table; ++index)
        {
            raw_iterator * iterator_pointer = my_buckets[index];
            my_buckets[index] = right.my_buckets[index];
            right.my_buckets[index] = iterator_pointer;
        }
    }

    //TODO: why not use std::distance?
    // Hash APIs
    static size_type internal_distance(const_iterator first, const_iterator last)
    {
        size_type num = 0;

        for (const_iterator it = first; it != last; ++it)
            ++num;

        return num;
    }

    // Insert an element in the hash given its value
    template<typename AllowCreate, typename AllowDestroy, typename ValueType>
    std::pair<iterator, bool> internal_insert(__TBB_FORWARDING_REF(ValueType) value, nodeptr_t pnode = NULL)
    {
        const key_type *pkey = &get_key(value);
        sokey_t hash_key = (sokey_t) my_hash_compare(*pkey);
        size_type new_count = 0;
        sokey_t order_key = split_order_key_regular(hash_key);
        raw_iterator previous = prepare_bucket(hash_key);
        raw_iterator last = my_solist.raw_end();
        __TBB_ASSERT(previous != last, "Invalid head node");

        if (pnode) {
            // Set new order_key to node
            pnode->init(order_key);
        }

        // First node is a dummy node
        for (raw_iterator where = previous;;)
        {
            ++where;
            if (where == last || solist_t::get_order_key(where) > order_key ||
                // if multimapped, stop at the first item equal to us.
                (allow_multimapping && solist_t::get_order_key(where) == order_key &&
                 !my_hash_compare(get_key(*where), *pkey))) // TODO: fix negation
            {
                if (!pnode) {
                    pnode = my_solist.create_node(order_key, tbb::internal::forward<ValueType>(value), AllowCreate());
                    // If the value was moved, the known reference to key might be invalid
                    pkey = &get_key(pnode->my_element);
                }

                // Try to insert 'pnode' between 'previous' and 'where'
                std::pair<iterator, bool> result = my_solist.try_insert(previous, where, pnode, &new_count);

                if (result.second)
                {
                    // Insertion succeeded, adjust the table size, if needed
                    adjust_table_size(new_count, my_number_of_buckets);
                    return result;
                }
                else
                {
                    // Insertion failed: either the same node was inserted by another thread, or
                    // another element was inserted at exactly the same place as this node.
                    // Proceed with the search from the previous location where order key was
                    // known to be larger (note: this is legal only because there is no safe
                    // concurrent erase operation supported).
                    where = previous;
                    continue;
                }
            }
            else if (!allow_multimapping && solist_t::get_order_key(where) == order_key &&
                     !my_hash_compare(get_key(*where), *pkey)) // TODO: fix negation
            { // Element already in the list, return it
                 if (pnode && AllowDestroy::value)
                     my_solist.destroy_node(pnode);
                return std::pair<iterator, bool>(my_solist.get_iterator(where), false);
            }
            // Move the iterator forward
            previous = where;
        }
    }

    // Find the element in the split-ordered list
    iterator internal_find(const key_type& key)
    {
        sokey_t hash_key = (sokey_t) my_hash_compare(key);
        sokey_t order_key = split_order_key_regular(hash_key);
        raw_iterator last = my_solist.raw_end();

        for (raw_iterator it = prepare_bucket(hash_key); it != last; ++it)
        {
            if (solist_t::get_order_key(it) > order_key)
            {
                // If the order key is smaller than the current order key, the element
                // is not in the hash.
                return end();
            }
            else if (solist_t::get_order_key(it) == order_key)
            {
                // The fact that order keys match does not mean that the element is found.
                // Key function comparison has to be performed to check whether this is the
                // right element. If not, keep searching while order key is the same.
                if (!my_hash_compare(get_key(*it), key)) // TODO: fix negation
                    return my_solist.get_iterator(it);
            }
        }

        return end();
    }

    // Erase an element from the list. This is not a concurrency safe function.
    iterator internal_erase(const_iterator it)
    {
        sokey_t hash_key = (sokey_t) my_hash_compare(get_key(*it));
        raw_iterator previous = prepare_bucket(hash_key);
        raw_iterator last = my_solist.raw_end();
        __TBB_ASSERT(previous != last, "Invalid head node");

        // First node is a dummy node
        for (raw_iterator where = previous; where != last; previous = where) {
            ++where;
            if (my_solist.get_iterator(where) == it)
                return my_solist.erase_node(previous, it);
        }
        return end();
    }

#if __TBB_UNORDERED_NODE_HANDLE_PRESENT
    std::pair<node_type, raw_iterator> internal_extract(const_iterator it) {
        sokey_t hash_key = sokey_t(my_hash_compare(get_key(*it)));
        raw_iterator previous = prepare_bucket(hash_key);
        raw_iterator last = my_solist.raw_end();
        __TBB_ASSERT(previous != last, "Invalid head node");

        for(raw_iterator where = previous; where != last; previous = where) {
            ++where;
            if (my_solist.get_iterator(where) == it) {
                const_iterator result = it;
                my_solist.erase_node(previous, it, /*allow_destroy*/tbb::internal::false_type());
                return std::pair<node_type, raw_iterator>( node_type(result.get_node_ptr()),
                                                           previous);
            }
        }
        return std::pair<node_type, iterator>(node_type(), end());
    }
#endif // __TBB_UNORDERED_NODE_HANDLE_PRESENT

    // Return the [begin, end) pair of iterators with the same key values.
    // This operation makes sense only if mapping is many-to-one.
    pairii_t internal_equal_range(const key_type& key)
    {
        sokey_t hash_key = (sokey_t) my_hash_compare(key);
        sokey_t order_key = split_order_key_regular(hash_key);
        raw_iterator end_it = my_solist.raw_end();

        for (raw_iterator it = prepare_bucket(hash_key); it != end_it; ++it)
        {
            if (solist_t::get_order_key(it) > order_key)
            {
                // There is no element with the given key
                return pairii_t(end(), end());
            }
            else if (solist_t::get_order_key(it) == order_key &&
                     !my_hash_compare(get_key(*it), key)) // TODO: fix negation; also below
            {
                iterator first = my_solist.get_iterator(it);
                iterator last = first;
                do ++last; while( allow_multimapping && last != end() && !my_hash_compare(get_key(*last), key) );
                return pairii_t(first, last);
            }
        }

        return pairii_t(end(), end());
    }

    // Bucket APIs
    void init_bucket(size_type bucket)
    {
        // Bucket 0 has no parent.
        __TBB_ASSERT( bucket != 0, "The first bucket must always be initialized");

        size_type parent_bucket = get_parent(bucket);

        // All parent_bucket buckets have to be initialized before this bucket is
        if (!is_initialized(parent_bucket))
            init_bucket(parent_bucket);

        raw_iterator parent = get_bucket(parent_bucket);

        // Create a dummy first node in this bucket
        raw_iterator dummy_node = my_solist.insert_dummy(parent, split_order_key_dummy(bucket));
        set_bucket(bucket, dummy_node);
    }

    void adjust_table_size(size_type total_elements, size_type current_size)
    {
        // Grow the table by a factor of 2 if possible and needed
        if ( ((float) total_elements / (float) current_size) > my_maximum_bucket_size )
        {
            // Double the size of the hash only if size has not changed in between loads
            my_number_of_buckets.compare_and_swap(2u*current_size, current_size);
            //Simple "my_number_of_buckets.compare_and_swap( current_size<<1, current_size );" does not work for VC8
            //due to overzealous compiler warnings in /Wp64 mode
        }
    }

    size_type get_parent(size_type bucket) const
    {
        // Unsets bucket's most significant turned-on bit
        size_type msb = __TBB_Log2((uintptr_t)bucket);
        return bucket & ~(size_type(1) << msb);
    }


    // Dynamic sized array (segments)
    static size_type segment_index_of( size_type index ) {
        return size_type( __TBB_Log2( uintptr_t(index|1) ) );
    }

    static size_type segment_base( size_type k ) {
        return (size_type(1)<<k & ~size_type(1));
    }

    static size_type segment_size( size_type k ) {
        return k? size_type(1)<<k : 2;
    }

    raw_iterator get_bucket(size_type bucket) const {
        size_type segment = segment_index_of(bucket);
        bucket -= segment_base(segment);
        __TBB_ASSERT( my_buckets[segment], "bucket must be in an allocated segment" );
        return my_buckets[segment][bucket];
    }

    raw_iterator prepare_bucket(sokey_t hash_key) {
        size_type bucket = hash_key % my_number_of_buckets;
        size_type segment = segment_index_of(bucket);
        size_type index = bucket - segment_base(segment);
        if (my_buckets[segment] == NULL || my_buckets[segment][index].get_node_ptr() == NULL)
            init_bucket(bucket);
        return my_buckets[segment][index];
    }

    void set_bucket(size_type bucket, raw_iterator dummy_head) {
        size_type segment = segment_index_of(bucket);
        bucket -= segment_base(segment);

        if (my_buckets[segment] == NULL) {
            size_type sz = segment_size(segment);
            raw_iterator * new_segment = my_allocator.allocate(sz);
            std::memset(static_cast<void*>(new_segment), 0, sz*sizeof(raw_iterator));

            if (my_buckets[segment].compare_and_swap( new_segment, NULL) != NULL)
                my_allocator.deallocate(new_segment, sz);
        }

        my_buckets[segment][bucket] = dummy_head;
    }

    bool is_initialized(size_type bucket) const {
        size_type segment = segment_index_of(bucket);
        bucket -= segment_base(segment);

        if (my_buckets[segment] == NULL)
            return false;

        raw_iterator it = my_buckets[segment][bucket];
        return (it.get_node_ptr() != NULL);
    }

    // Utilities for keys

    // A regular order key has its original hash value reversed and the last bit set
    sokey_t split_order_key_regular(sokey_t order_key) const {
        return __TBB_ReverseBits(order_key) | 0x1;
    }

    // A dummy order key has its original hash value reversed and the last bit unset
    sokey_t split_order_key_dummy(sokey_t order_key) const {
        return __TBB_ReverseBits(order_key) & ~sokey_t(0x1);
    }

    // Shared variables
    atomic<size_type>                                             my_number_of_buckets;       // Current table size
    solist_t                                                      my_solist;                  // List where all the elements are kept
    typename tbb::internal::allocator_rebind<allocator_type, raw_iterator>::type my_allocator; // Allocator object for segments
    float                                                         my_maximum_bucket_size;     // Maximum size of the bucket
    atomic<raw_iterator*>                                         my_buckets[pointers_per_table]; // The segment table
};
#if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
#pragma warning(pop) // warning 4127 is back
#endif

} // namespace internal
} // namespace interface5
} // namespace tbb
#endif // __TBB__concurrent_unordered_impl_H