2 This file is a part of libcds - Concurrent Data Structures library
4 (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2016
6 Source code repo: http://github.com/khizmax/libcds/
7 Download: http://sourceforge.net/projects/libcds/files/
9 Redistribution and use in source and binary forms, with or without
10 modification, are permitted provided that the following conditions are met:
12 * Redistributions of source code must retain the above copyright notice, this
13 list of conditions and the following disclaimer.
15 * Redistributions in binary form must reproduce the above copyright notice,
16 this list of conditions and the following disclaimer in the documentation
17 and/or other materials provided with the distribution.
19 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
20 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
22 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
23 FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
25 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
26 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
27 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H
32 #define CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H
35 #include <cds/container/details/michael_list_base.h>
36 #include <cds/intrusive/michael_list_rcu.h>
37 #include <cds/container/details/make_michael_list.h>
38 #include <cds/details/binary_functor_wrapper.h>
40 namespace cds { namespace container {
42 /// Michael's ordered list (template specialization for \ref cds_urcu_desc "RCU")
43 /** @ingroup cds_nonintrusive_list
44 \anchor cds_nonintrusive_MichaelList_rcu
46 Usually, ordered single-linked list is used as a building block for the hash table implementation.
47 The complexity of searching is <tt>O(N)</tt>.
50 - [2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"
52 This class is non-intrusive version of \ref cds_intrusive_MichaelList_rcu "cds::intrusive::MichaelList" RCU specialization.
55 - \p RCU - one of \ref cds_urcu_gc "RCU type"
56 - \p T - type stored in the list. The type must be default- and copy-constructible.
57 - \p Traits - type traits, default is michael_list::traits
59 The implementation does not divide type \p T into key and value part and
60 may be used as a main building block for hash set containers.
61 The key is a function (or a part) of type \p T, and this function is specified by <tt>Traits::compare</tt> functor
62 or <tt>Traits::less</tt> predicate.
64 \ref cds_nonintrusive_MichaelKVList_rcu "MichaelKVList" is a key-value version of Michael's
65 non-intrusive list that is closer to the C++ std library approach.
67 @note Before including <tt><cds/container/michael_list_rcu.h></tt> you should include appropriate RCU header file,
68 see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
70 It is possible to declare option-based list with cds::container::michael_list::make_traits metafunction istead of \p Traits template
71 argument. For example, the following traits-based declaration of Michael's list
74 #include <cds/urcu/general_buffered.h>
75 #include <cds/container/michael_list_rcu.h>
76 // Declare comparator for the item
78 int operator ()( int i1, int i2 )
85 struct my_traits: public cds::container::michael_list::traits
87 typedef my_compare compare;
90 // Declare traits-based list
91 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, int, my_traits > traits_based_list;
94 is equivalent for the following option-based list
96 #include <cds/urcu/general_buffered.h>
97 #include <cds/container/michael_list_rcu.h>
99 // my_compare is the same
101 // Declare option-based list
102 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, int,
103 typename cds::container::michael_list::make_traits<
104 cds::container::opt::compare< my_compare > // item comparator option
109 Template argument list \p Options of cds::container::michael_list::make_traits metafunction are:
110 - opt::compare - key comparison functor. No default functor is provided.
111 If the option is not specified, the opt::less is used.
112 - opt::less - specifies binary predicate used for key comparison. Default is \p std::less<T>.
113 - opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::empty is used.
114 - opt::item_counter - the type of item counting feature. Default is \ref atomicity::empty_item_counter that is no item counting.
115 - opt::allocator - the allocator used for creating and freeing list's item. Default is \ref CDS_DEFAULT_ALLOCATOR macro.
116 - opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default)
117 or opt::v::sequential_consistent (sequentially consisnent memory model).
118 - opt::rcu_check_deadlock - a deadlock checking policy. Default is opt::v::rcu_throw_deadlock
123 #ifdef CDS_DOXYGEN_INVOKED
124 typename Traits = michael_list::traits
129 class MichaelList< cds::urcu::gc<RCU>, T, Traits > :
130 #ifdef CDS_DOXYGEN_INVOKED
131 protected intrusive::MichaelList< cds::urcu::gc<RCU>, T, Traits >
133 protected details::make_michael_list< cds::urcu::gc<RCU>, T, Traits >::type
137 typedef details::make_michael_list< cds::urcu::gc<RCU>, T, Traits > maker;
138 typedef typename maker::type base_class;
142 typedef cds::urcu::gc<RCU> gc; ///< RCU
143 typedef T value_type; ///< Type of value stored in the list
144 typedef Traits traits; ///< List traits
146 typedef typename base_class::back_off back_off; ///< Back-off strategy used
147 typedef typename maker::allocator_type allocator_type; ///< Allocator type used for allocate/deallocate the nodes
148 typedef typename base_class::item_counter item_counter; ///< Item counting policy used
149 typedef typename maker::key_comparator key_comparator; ///< key comparison functor
150 typedef typename base_class::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
151 typedef typename base_class::rcu_check_deadlock rcu_check_deadlock ; ///< RCU deadlock checking policy
153 typedef typename gc::scoped_lock rcu_lock ; ///< RCU scoped lock
154 static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal; ///< Group of \p extract_xxx functions do not require external locking
158 typedef typename base_class::value_type node_type;
159 typedef typename maker::cxx_allocator cxx_allocator;
160 typedef typename maker::node_deallocator node_deallocator;
161 typedef typename maker::intrusive_traits::compare intrusive_key_comparator;
163 typedef typename base_class::atomic_node_ptr head_type;
167 using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer >; ///< pointer to extracted node
171 struct raw_ptr_converter
173 value_type * operator()( node_type * p ) const
175 return p ? &p->m_Value : nullptr;
178 value_type& operator()( node_type& n ) const
183 value_type const& operator()( node_type const& n ) const
191 /// Result of \p get(), \p get_with() functions - pointer to the node found
192 typedef cds::urcu::raw_ptr_adaptor< value_type, typename base_class::raw_ptr, raw_ptr_converter > raw_ptr;
196 static value_type& node_to_value( node_type& n )
200 static value_type const& node_to_value( node_type const& n )
208 template <typename Q>
209 static node_type * alloc_node( Q const& v )
211 return cxx_allocator().New( v );
214 template <typename... Args>
215 static node_type * alloc_node( Args&&... args )
217 return cxx_allocator().MoveNew( std::forward<Args>(args)... );
220 static void free_node( node_type * pNode )
222 cxx_allocator().Delete( pNode );
225 struct node_disposer {
226 void operator()( node_type * pNode )
231 typedef std::unique_ptr< node_type, node_disposer > scoped_node_ptr;
235 return base_class::m_pHead;
238 head_type& head() const
240 return const_cast<head_type&>( base_class::m_pHead );
246 template <bool IsConst>
247 class iterator_type: protected base_class::template iterator_type<IsConst>
249 typedef typename base_class::template iterator_type<IsConst> iterator_base;
251 iterator_type( head_type const& pNode )
252 : iterator_base( pNode )
255 friend class MichaelList;
258 typedef typename cds::details::make_const_type<value_type, IsConst>::pointer value_ptr;
259 typedef typename cds::details::make_const_type<value_type, IsConst>::reference value_ref;
264 iterator_type( iterator_type const& src )
265 : iterator_base( src )
268 value_ptr operator ->() const
270 typename iterator_base::value_ptr p = iterator_base::operator ->();
271 return p ? &(p->m_Value) : nullptr;
274 value_ref operator *() const
276 return (iterator_base::operator *()).m_Value;
280 iterator_type& operator ++()
282 iterator_base::operator ++();
287 bool operator ==(iterator_type<C> const& i ) const
289 return iterator_base::operator ==(i);
292 bool operator !=(iterator_type<C> const& i ) const
294 return iterator_base::operator !=(i);
301 typedef iterator_type<false> iterator;
303 /// Const forward iterator
304 typedef iterator_type<true> const_iterator;
306 ///@name Forward iterators (only for debugging purpose)
308 /// Returns a forward iterator addressing the first element in a list
310 For empty list \code begin() == end() \endcode
314 return iterator( head() );
317 /// Returns an iterator that addresses the location succeeding the last element in a list
319 Do not use the value returned by <tt>end</tt> function to access any item.
320 Internally, <tt>end</tt> returning value equals to \p nullptr.
322 The returned value can be used only to control reaching the end of the list.
323 For empty list \code begin() == end() \endcode
330 /// Returns a forward const iterator addressing the first element in a list
331 const_iterator begin() const
333 return const_iterator( head() );
336 /// Returns a forward const iterator addressing the first element in a list
337 const_iterator cbegin() const
339 return const_iterator( head() );
342 /// Returns an const iterator that addresses the location succeeding the last element in a list
343 const_iterator end() const
345 return const_iterator();
348 /// Returns an const iterator that addresses the location succeeding the last element in a list
349 const_iterator cend() const
351 return const_iterator();
356 /// Default constructor
358 Initialize empty list
374 The function creates a node with copy of \p val value
375 and then inserts the node created into the list.
377 The type \p Q should contain as minimum the complete key of the node.
378 The object of \ref value_type should be constructible from \p val of type \p Q.
379 In trivial case, \p Q is equal to \ref value_type.
381 The function makes RCU lock internally.
383 Returns \p true if inserting successful, \p false otherwise.
385 template <typename Q>
386 bool insert( Q const& val )
388 return insert_at( head(), val );
393 This function inserts new node with default-constructed value and then it calls
394 \p func functor with signature
395 \code void func( value_type& itemValue ) ;\endcode
397 The argument \p itemValue of user-defined functor \p func is the reference
398 to the list's item inserted. User-defined functor \p func should guarantee that during changing
399 item's value no any other changes could be made on this list's item by concurrent threads.
401 The type \p Q should contain the complete key of the node.
402 The object of \ref value_type should be constructible from \p key of type \p Q.
404 The function allows to split creating of new item into two part:
405 - create item from \p key with initializing key-fields only;
406 - insert new item into the list;
407 - if inserting is successful, initialize non-key fields of item by calling \p f functor
409 This can be useful if complete initialization of object of \p value_type is heavyweight and
410 it is preferable that the initialization should be completed only if inserting is successful.
412 The function makes RCU lock internally.
414 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
416 template <typename Q, typename Func>
417 bool insert( Q const& key, Func func )
419 return insert_at( head(), key, func );
422 /// Updates data by \p key
424 The operation performs inserting or replacing the element with lock-free manner.
426 If the \p key not found in the list, then the new item created from \p key
427 will be inserted iff \p bAllowInsert is \p true.
428 Otherwise, if \p key is found, the functor \p func is called with item found.
430 The functor \p Func signature is:
433 void operator()( bool bNew, value_type& item, Q const& val );
438 - \p bNew - \p true if the item has been inserted, \p false otherwise
439 - \p item - item of the list
440 - \p val - argument \p key passed into the \p %update() function
442 The functor may change non-key fields of the \p item; however, \p func must guarantee
443 that during changing no any other modifications could be made on this item by concurrent threads.
445 The function applies RCU lock internally.
447 Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successfull,
448 \p second is true if new item has been added or \p false if the item with \p key
451 @warning See \ref cds_intrusive_item_creating "insert item troubleshooting"
453 template <typename Q, typename Func>
454 std::pair<bool, bool> update( Q const& key, Func func, bool bAllowInsert = true )
456 return update_at( head(), key, func, bAllowInsert );
459 template <typename Q, typename Func>
460 CDS_DEPRECATED("ensure() is deprecated, use update()")
461 std::pair<bool, bool> ensure( Q const& key, Func f )
463 return update( key, f, true );
467 /// Inserts data of type \ref value_type constructed from \p args
469 Returns \p true if inserting successful, \p false otherwise.
471 The function makes RCU lock internally.
473 template <typename... Args>
474 bool emplace( Args&&... args )
476 return emplace_at( head(), std::forward<Args>(args)... );
479 /// Deletes \p key from the list
480 /** \anchor cds_nonintrusive_MichealList_rcu_erase_val
481 Since the key of MichaelList's item type \p value_type is not explicitly specified,
482 template parameter \p Q defines the key type searching in the list.
483 The list item comparator should be able to compare values of the type \p value_type
484 and \p Q in any order.
486 RCU \p synchronize method can be called. RCU should not be locked.
488 Return \p true if key is found and deleted, \p false otherwise
490 template <typename Q>
491 bool erase( Q const& key )
493 return erase_at( head(), key, intrusive_key_comparator(), [](value_type const&){} );
496 /// Deletes the item from the list using \p pred predicate for searching
498 The function is an analog of \ref cds_nonintrusive_MichealList_rcu_erase_val "erase(Q const&)"
499 but \p pred is used for key comparing.
500 \p Less functor has the interface like \p std::less.
501 \p pred must imply the same element order as the comparator used for building the list.
503 template <typename Q, typename Less>
504 bool erase_with( Q const& key, Less pred )
507 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), [](value_type const&){} );
510 /// Deletes \p key from the list
511 /** \anchor cds_nonintrusive_MichaelList_rcu_erase_func
512 The function searches an item with key \p key, calls \p f functor with item found
513 and deletes it. If \p key is not found, the functor is not called.
515 The functor \p Func interface:
518 void operator()(const value_type& val) { ... }
522 Since the key of MichaelList's item type \p value_type is not explicitly specified,
523 template parameter \p Q defines the key type searching in the list.
524 The list item comparator should be able to compare the values of type \p value_type
525 and \p Q in any order.
527 RCU \p synchronize method can be called. RCU should not be locked.
529 Return \p true if key is found and deleted, \p false otherwise
531 template <typename Q, typename Func>
532 bool erase( Q const& key, Func f )
534 return erase_at( head(), key, intrusive_key_comparator(), f );
537 /// Deletes the item from the list using \p pred predicate for searching
539 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_erase_func "erase(Q const&, Func)"
540 but \p pred is used for key comparing.
541 \p Less functor has the interface like \p std::less.
542 \p pred must imply the same element order as the comparator used for building the list.
544 template <typename Q, typename Less, typename Func>
545 bool erase_with( Q const& key, Less pred, Func f )
548 return erase_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
551 /// Extracts an item from the list
553 @anchor cds_nonintrusive_MichaelList_rcu_extract
554 The function searches an item with key equal to \p key in the list,
555 unlinks it from the list, and returns \ref cds::urcu::exempt_ptr "exempt_ptr" pointer to the item found.
556 If the item with the key equal to \p key is not found the function returns an empty \p exempt_ptr.
558 @note The function does NOT dispose the item found. It just excludes the item from the list
559 and returns a pointer to the item.
560 You shouldn't lock RCU for current thread before calling this function.
563 #include <cds/urcu/general_buffered.h>
564 #include <cds/container/michael_list_rcu.h>
566 typedef cds::urcu::gc< general_buffered<> > rcu;
567 typedef cds::container::MichaelList< rcu, Foo > rcu_michael_list;
569 rcu_michael_list theList;
572 rcu_michael_list::exempt_ptr p;
574 // The RCU should NOT be locked when extract() is called!
575 assert( !rcu::is_locked() );
578 p = theList.extract( 10 )
580 // do something with p
584 // we may safely release extracted pointer here.
585 // release() passes the pointer to RCU reclamation cycle.
589 template <typename Q>
590 exempt_ptr extract( Q const& key )
592 return exempt_ptr( extract_at( head(), key, intrusive_key_comparator() ));
595 /// Extracts an item from the list using \p pred predicate for searching
597 This function is the analog for \p extract(Q const&).
599 The \p pred is a predicate used for key comparing.
600 \p Less has the interface like \p std::less.
601 \p pred must imply the same element order as \ref key_comparator.
603 template <typename Q, typename Less>
604 exempt_ptr extract_with( Q const& key, Less pred )
607 return exempt_ptr( extract_at( head(), key, typename maker::template less_wrapper<Less>::type() ));
610 /// Checks whether the list contains \p key
612 The function searches the item with key equal to \p key
613 and returns \p true if it is found, and \p false otherwise.
615 The function applies RCU lock internally.
617 template <typename Q>
618 bool contains( Q const& key )
620 return find_at( head(), key, intrusive_key_comparator() );
623 template <typename Q>
624 CDS_DEPRECATED("deprecated, use contains()")
625 bool find( Q const& key )
627 return contains( key );
631 /// Checks whether the list contains \p key using \p pred predicate for searching
633 The function is an analog of <tt>contains( key )</tt> but \p pred is used for key comparing.
634 \p Less functor has the interface like \p std::less.
635 \p pred must imply the same element order as the comparator used for building the list.
637 template <typename Q, typename Less>
638 bool contains( Q const& key, Less pred )
641 return find_at( head(), key, typename maker::template less_wrapper<Less>::type() );
644 // Deprecatd, use contains()
645 template <typename Q, typename Less>
646 bool find_with( Q const& key, Less pred )
649 return contains( key, pred );
653 /// Finds the key \p key and performs an action with it
654 /** \anchor cds_nonintrusive_MichaelList_rcu_find_func
655 The function searches an item with key equal to \p key and calls the functor \p f for the item found.
656 The interface of \p Func functor is:
659 void operator()( value_type& item, Q& key );
662 where \p item is the item found, \p key is the \p %find() function argument.
664 The functor may change non-key fields of \p item. Note that the function is only guarantee
665 that \p item cannot be deleted during functor is executing.
666 The function does not serialize simultaneous access to the list \p item. If such access is
667 possible you must provide your own synchronization schema to exclude unsafe item modifications.
669 The function makes RCU lock internally.
671 The function returns \p true if \p val is found, \p false otherwise.
673 template <typename Q, typename Func>
674 bool find( Q& key, Func f )
676 return find_at( head(), key, intrusive_key_comparator(), f );
679 template <typename Q, typename Func>
680 bool find( Q const& key, Func f )
682 return find_at( head(), key, intrusive_key_comparator(), f );
686 /// Finds the key \p key using \p pred predicate for searching
688 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_find_func "find(Q&, Func)"
689 but \p pred is used for key comparing.
690 \p Less functor has the interface like \p std::less.
691 \p pred must imply the same element order as the comparator used for building the list.
693 template <typename Q, typename Less, typename Func>
694 bool find_with( Q& key, Less pred, Func f )
697 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
700 template <typename Q, typename Less, typename Func>
701 bool find_with( Q const& key, Less pred, Func f )
704 return find_at( head(), key, typename maker::template less_wrapper<Less>::type(), f );
708 /// Finds the key \p key and return the item found
709 /** \anchor cds_nonintrusive_MichaelList_rcu_get
710 The function searches the item with key equal to \p key and returns the pointer to item found.
711 If \p key is not found it returns an empty \p raw_ptr.
713 Note the compare functor should accept a parameter of type \p Q that can be not the same as \p value_type.
715 RCU should be locked before call of this function.
716 Returned item is valid only while RCU is locked:
718 typedef cds::container::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > ord_list;
721 typename ord_list::raw_ptr rp;
724 ord_list::rcu_lock lock;
726 rp = theList.get( 5 );
731 // Unlock RCU by rcu_lock destructor
732 // A value owned by rp can be freed at any time after RCU has been unlocked
734 // You can manually release rp after RCU-locked section
738 template <typename Q>
739 raw_ptr get( Q const& key )
741 return get_at( head(), key, intrusive_key_comparator());
744 /// Finds \p key and return the item found
746 The function is an analog of \ref cds_nonintrusive_MichaelList_rcu_get "get(Q const&)"
747 but \p pred is used for comparing the keys.
749 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
751 \p pred must imply the same element order as the comparator used for building the list.
753 template <typename Q, typename Less>
754 raw_ptr get_with( Q const& key, Less pred )
757 return get_at( head(), key, typename maker::template less_wrapper<Less>::type());
760 /// Checks if the list is empty
763 return base_class::empty();
766 /// Returns list's item count
768 The value returned depends on item counter provided by \p Traits. For \p atomicity::empty_item_counter,
769 this function always returns 0.
771 @note Even if you use real item counter and it returns 0, this fact does not mean that the list
772 is empty. To check list emptyness use \p empty() method.
776 return base_class::size();
787 bool insert_node_at( head_type& refHead, node_type * pNode )
790 scoped_node_ptr p(pNode);
791 if ( base_class::insert_at( refHead, *pNode )) {
799 template <typename Q>
800 bool insert_at( head_type& refHead, Q const& val )
802 return insert_node_at( refHead, alloc_node( val ));
805 template <typename Q, typename Func>
806 bool insert_at( head_type& refHead, Q const& key, Func f )
808 scoped_node_ptr pNode( alloc_node( key ));
810 if ( base_class::insert_at( refHead, *pNode, [&f]( node_type& node ) { f( node_to_value(node) ); } )) {
817 template <typename... Args>
818 bool emplace_at( head_type& refHead, Args&&... args )
820 return insert_node_at( refHead, alloc_node( std::forward<Args>(args) ... ));
823 template <typename Q, typename Compare, typename Func>
824 bool erase_at( head_type& refHead, Q const& key, Compare cmp, Func f )
826 return base_class::erase_at( refHead, key, cmp, [&f](node_type const& node){ f( node_to_value(node) ); } );
829 template <typename Q, typename Func>
830 std::pair<bool, bool> update_at( head_type& refHead, Q const& key, Func f, bool bAllowInsert )
832 scoped_node_ptr pNode( alloc_node( key ));
834 std::pair<bool, bool> ret = base_class::update_at( refHead, *pNode,
835 [&f, &key](bool bNew, node_type& node, node_type&){ f( bNew, node_to_value(node), key );},
837 if ( ret.first && ret.second )
843 template <typename Q, typename Compare>
844 node_type * extract_at( head_type& refHead, Q const& key, Compare cmp )
846 return base_class::extract_at( refHead, key, cmp );
849 template <typename Q, typename Compare>
850 bool find_at( head_type& refHead, Q const& key, Compare cmp )
852 return base_class::find_at( refHead, key, cmp, [](node_type&, Q const &) {} );
855 template <typename Q, typename Compare, typename Func>
856 bool find_at( head_type& refHead, Q& val, Compare cmp, Func f )
858 return base_class::find_at( refHead, val, cmp, [&f](node_type& node, Q& v){ f( node_to_value(node), v ); });
861 template <typename Q, typename Compare>
862 raw_ptr get_at( head_type& refHead, Q const& val, Compare cmp )
864 return raw_ptr( base_class::get_at( refHead, val, cmp ));
870 }} // namespace cds::container
872 #endif // #ifndef CDSLIB_CONTAINER_MICHAEL_LIST_RCU_H