3 #ifndef CDSLIB_INTRUSIVE_SPLIT_LIST_H
4 #define CDSLIB_INTRUSIVE_SPLIT_LIST_H
7 #include <cds/intrusive/details/split_list_base.h>
9 namespace cds { namespace intrusive {
11 /// Split-ordered list
12 /** @ingroup cds_intrusive_map
13 \anchor cds_intrusive_SplitListSet_hp
15 Hash table implementation based on split-ordered list algorithm discovered by Ori Shalev and Nir Shavit, see
16 - [2003] Ori Shalev, Nir Shavit "Split-Ordered Lists - Lock-free Resizable Hash Tables"
17 - [2008] Nir Shavit "The Art of Multiprocessor Programming"
19 The split-ordered list is a lock-free implementation of an extensible unbounded hash table. It uses original
20 recursive split-ordering algorithm discovered by Ori Shalev and Nir Shavit that allows to split buckets
21 without item moving on resizing.
23 \anchor cds_SplitList_algo_desc
24 <b>Short description</b>
25 [from [2003] Ori Shalev, Nir Shavit "Split-Ordered Lists - Lock-free Resizable Hash Tables"]
27 The algorithm keeps all the items in one lock-free linked list, and gradually assigns the bucket pointers to
28 the places in the list where a sublist of
\93correct
\94 items can be found. A bucket is initialized upon first
29 access by assigning it to a new
\93dummy
\94 node (dashed contour) in the list, preceding all items that should be
30 in that bucket. A newly created bucket splits an older bucket
\92s chain, reducing the access cost to its items. The
31 table uses a modulo 2**i hash (there are known techniques for
\93pre-hashing
\94 before a modulo 2**i hash
32 to overcome possible binary correlations among values). The table starts at size 2 and repeatedly doubles in size.
34 Unlike moving an item, the operation of directing a bucket pointer can be done
35 in a single CAS operation, and since items are not moved, they are never
\93lost
\94.
36 However, to make this approach work, one must be able to keep the items in the
37 list sorted in such a way that any bucket
\92s sublist can be
\93split
\94 by directing a new
38 bucket pointer within it. This operation must be recursively repeatable, as every
39 split bucket may be split again and again as the hash table grows. To achieve this
40 goal the authors introduced recursive split-ordering, a new ordering on keys that keeps items
41 in a given bucket adjacent in the list throughout the repeated splitting process.
43 Magically, yet perhaps not surprisingly, recursive split-ordering is achieved by
44 simple binary reversal: reversing the bits of the hash key so that the new key
\92s
45 most significant bits (MSB) are those that were originally its least significant.
46 The split-order keys of regular nodes are exactly the bit-reverse image of the original
47 keys after turning on their MSB. For example, items 9 and 13 are in the <tt>1 mod
48 4</tt> bucket, which can be recursively split in two by inserting a new node between
51 To insert (respectively delete or search for) an item in the hash table, hash its
52 key to the appropriate bucket using recursive split-ordering, follow the pointer to
53 the appropriate location in the sorted items list, and traverse the list until the key
\92s
54 proper location in the split-ordering (respectively until the key or a key indicating
55 the item is not in the list is found). Because of the combinatorial structure induced
56 by the split-ordering, this will require traversal of no more than an expected constant number of items.
58 The design is modular: to implement the ordered items list, you can use one of several
59 non-blocking list-based set algorithms: MichaelList, LazyList.
63 Template parameters are:
64 - \p GC - Garbage collector. Note the \p GC must be the same as the \p GC used for \p OrderedList
65 - \p OrderedList - ordered list implementation used as a bucket for hash set, for example, \p MichaelList, \p LazyList.
66 The intrusive ordered list implementation specifies the type \p T stored in the hash-set, the reclamation
67 schema \p GC used by hash-set, the comparison functor for the type \p T and other features specific for
69 - \p Traits - split-list traits, default is \p split_list::traits.
70 Instead of defining \p Traits struct you may use option-based syntax with \p split_list::make_traits metafunction.
72 There are several specialization of the split-list class for different \p GC:
73 - for \ref cds_urcu_gc "RCU type" include <tt><cds/intrusive/split_list_rcu.h></tt> - see
74 \ref cds_intrusive_SplitListSet_rcu "RCU-based split-list"
75 - for cds::gc::nogc include <tt><cds/intrusive/split_list_nogc.h></tt> - see
76 \ref cds_intrusive_SplitListSet_nogc "persistent SplitListSet".
78 \anchor cds_SplitList_hash_functor
81 Some member functions of split-ordered list accept the key parameter of type \p Q which differs from \p value_type.
82 It is expected that type \p Q contains full key of \p value_type, and for equal keys of type \p Q and \p value_type
83 the hash values of these keys must be equal too.
84 The hash functor \p Traits::hash should accept parameters of both type:
88 std::string key_ ; // key field
94 size_t operator()( const std::string& s ) const
96 return std::hash( s );
99 size_t operator()( const Foo& f ) const
101 return (*this)( f.key_ );
108 First, you should choose ordered list type to use in your split-list set:
110 // For gc::HP-based MichaelList implementation
111 #include <cds/intrusive/michael_list_hp.h>
113 // cds::intrusive::SplitListSet declaration
114 #include <cds/intrusive/split_list.h>
117 // Note you should declare your struct based on cds::intrusive::split_list::node
118 // which is a wrapper for ordered-list node struct.
119 // In our case, the node type for HP-based MichaelList is cds::intrusive::michael_list::node< cds::gc::HP >
120 struct Foo: public cds::intrusive::split_list::node< cds::intrusive::michael_list::node< cds::gc::HP > >
122 std::string key_ ; // key field
123 unsigned val_ ; // value field
124 // ... other value fields
127 // Declare comparator for the item
130 int operator()( const Foo& f1, const Foo& f2 ) const
132 return f1.key_.compare( f2.key_ );
136 // Declare base ordered-list type for split-list
137 typedef cds::intrusive::MichaelList< cds::gc::HP, Foo,
138 typename cds::intrusive::michael_list::make_traits<
140 cds::intrusive::opt::hook< cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::HP > > >
141 // item comparator option
142 ,cds::opt::compare< FooCmp >
147 Second, you should declare split-list set container:
150 // Declare hash functor
151 // Note, the hash functor accepts parameter type Foo and std::string
153 size_t operator()( const Foo& f ) const
155 return cds::opt::v::hash<std::string>()( f.key_ );
157 size_t operator()( const std::string& s ) const
159 return cds::opt::v::hash<std::string>()( s );
163 // Split-list set typedef
164 typedef cds::intrusive::SplitListSet<
167 ,typename cds::intrusive::split_list::make_traits<
168 cds::opt::hash< FooHash >
173 Now, you can use \p Foo_set in your application.
179 fooSet.insert( *foo );
187 # ifdef CDS_DOXYGEN_INVOKED
188 class Traits = split_list::traits
196 typedef GC gc; ///< Garbage collector
197 typedef Traits traits; ///< Set traits
200 typedef cds::intrusive::split_list::implementation_tag implementation_tag;
205 typedef split_list::details::rebind_list_traits<OrderedList, traits> wrapped_ordered_list;
209 # ifdef CDS_DOXYGEN_INVOKED
210 typedef OrderedList ordered_list; ///< type of ordered list used as a base for split-list
212 typedef typename wrapped_ordered_list::result ordered_list;
214 typedef typename ordered_list::value_type value_type; ///< type of value stored in the split-list
215 typedef typename ordered_list::key_comparator key_comparator; ///< key comparison functor
216 typedef typename ordered_list::disposer disposer; ///< Node disposer functor
218 /// Hash functor for \p %value_type and all its derivatives that you use
219 typedef typename cds::opt::v::hash_selector< typename traits::hash >::type hash;
221 typedef typename traits::item_counter item_counter; ///< Item counter type
222 typedef typename traits::back_off back_off; ///< back-off strategy for spinning
223 typedef typename traits::memory_model memory_model; ///< Memory ordering. See cds::opt::memory_model option
224 typedef typename traits::stat stat; ///< Internal statistics, see \p spit_list::stat
225 typedef typename ordered_list::guarded_ptr guarded_ptr; ///< Guarded pointer
228 typedef typename ordered_list::node_type list_node_type; ///< Node type as declared in ordered list
229 typedef split_list::node<list_node_type> node_type; ///< split-list node type
230 typedef node_type dummy_node_type; ///< dummy node type
232 /// Split-list node traits
234 This traits is intended for converting between underlying ordered list node type \p list_node_type
235 and split-list node type \p node_type
237 typedef split_list::node_traits<typename ordered_list::node_traits> node_traits;
240 /// Bucket table implementation
241 typedef typename split_list::details::bucket_table_selector<
242 traits::dynamic_bucket_table
245 , opt::allocator< typename traits::allocator >
246 , opt::memory_model< memory_model >
247 >::type bucket_table;
252 /// Ordered list wrapper to access protected members
253 class ordered_list_wrapper: public ordered_list
255 typedef ordered_list base_class;
256 typedef typename base_class::auxiliary_head bucket_head_type;
259 bool insert_at( dummy_node_type * pHead, value_type& val )
261 assert( pHead != nullptr );
262 bucket_head_type h(pHead);
263 return base_class::insert_at( h, val );
266 template <typename Func>
267 bool insert_at( dummy_node_type * pHead, value_type& val, Func f )
269 assert( pHead != nullptr );
270 bucket_head_type h(pHead);
271 return base_class::insert_at( h, val, f );
274 template <typename Func>
275 std::pair<bool, bool> ensure_at( dummy_node_type * pHead, value_type& val, Func func )
277 assert( pHead != nullptr );
278 bucket_head_type h(pHead);
279 return base_class::ensure_at( h, val, func );
282 bool unlink_at( dummy_node_type * pHead, value_type& val )
284 assert( pHead != nullptr );
285 bucket_head_type h(pHead);
286 return base_class::unlink_at( h, val );
289 template <typename Q, typename Compare, typename Func>
290 bool erase_at( dummy_node_type * pHead, split_list::details::search_value_type<Q> const& val, Compare cmp, Func f )
292 assert( pHead != nullptr );
293 bucket_head_type h(pHead);
294 return base_class::erase_at( h, val, cmp, f );
297 template <typename Q, typename Compare>
298 bool erase_at( dummy_node_type * pHead, split_list::details::search_value_type<Q> const& val, Compare cmp )
300 assert( pHead != nullptr );
301 bucket_head_type h(pHead);
302 return base_class::erase_at( h, val, cmp );
305 template <typename Q, typename Compare>
306 bool extract_at( dummy_node_type * pHead, typename guarded_ptr::native_guard& guard, split_list::details::search_value_type<Q> const& val, Compare cmp )
308 assert( pHead != nullptr );
309 bucket_head_type h(pHead);
310 return base_class::extract_at( h, guard, val, cmp );
313 template <typename Q, typename Compare, typename Func>
314 bool find_at( dummy_node_type * pHead, split_list::details::search_value_type<Q>& val, Compare cmp, Func f )
316 assert( pHead != nullptr );
317 bucket_head_type h(pHead);
318 return base_class::find_at( h, val, cmp, f );
321 template <typename Q, typename Compare>
322 bool find_at( dummy_node_type * pHead, split_list::details::search_value_type<Q> const& val, Compare cmp )
324 assert( pHead != nullptr );
325 bucket_head_type h(pHead);
326 return base_class::find_at( h, val, cmp );
329 template <typename Q, typename Compare>
330 bool get_at( dummy_node_type * pHead, typename guarded_ptr::native_guard& guard, split_list::details::search_value_type<Q> const& val, Compare cmp )
332 assert( pHead != nullptr );
333 bucket_head_type h(pHead);
334 return base_class::get_at( h, guard, val, cmp );
337 bool insert_aux_node( dummy_node_type * pNode )
339 return base_class::insert_aux_node( pNode );
341 bool insert_aux_node( dummy_node_type * pHead, dummy_node_type * pNode )
343 bucket_head_type h(pHead);
344 return base_class::insert_aux_node( h, pNode );
350 ordered_list_wrapper m_List; ///< Ordered list containing split-list items
351 bucket_table m_Buckets; ///< bucket table
352 atomics::atomic<size_t> m_nBucketCountLog2; ///< log2( current bucket count )
353 atomics::atomic<size_t> m_nMaxItemCount; ///< number of items container can hold, before we have to resize
354 item_counter m_ItemCounter; ///< Item counter
355 hash m_HashFunctor; ///< Hash functor
356 stat m_Stat; ///< Internal statistics
360 typedef cds::details::Allocator< dummy_node_type, typename traits::allocator > dummy_node_allocator;
362 dummy_node_type * alloc_dummy_node( size_t nHash )
364 m_Stat.onHeadNodeAllocated();
365 return dummy_node_allocator().New( nHash );
367 void free_dummy_node( dummy_node_type * p )
369 dummy_node_allocator().Delete( p );
370 m_Stat.onHeadNodeFreed();
373 /// Calculates hash value of \p key
374 template <typename Q>
375 size_t hash_value( Q const& key ) const
377 return m_HashFunctor( key );
380 size_t bucket_no( size_t nHash ) const
382 return nHash & ( (1 << m_nBucketCountLog2.load(memory_model::memory_order_relaxed)) - 1 );
385 static size_t parent_bucket( size_t nBucket )
387 assert( nBucket > 0 );
388 return nBucket & ~( 1 << bitop::MSBnz( nBucket ) );
391 dummy_node_type * init_bucket( size_t nBucket )
393 assert( nBucket > 0 );
394 size_t nParent = parent_bucket( nBucket );
396 dummy_node_type * pParentBucket = m_Buckets.bucket( nParent );
397 if ( pParentBucket == nullptr ) {
398 pParentBucket = init_bucket( nParent );
399 m_Stat.onRecursiveInitBucket();
402 assert( pParentBucket != nullptr );
404 // Allocate a dummy node for new bucket
406 dummy_node_type * pBucket = alloc_dummy_node( split_list::dummy_hash( nBucket ) );
407 if ( m_List.insert_aux_node( pParentBucket, pBucket ) ) {
408 m_Buckets.bucket( nBucket, pBucket );
409 m_Stat.onNewBucket();
412 free_dummy_node( pBucket );
415 // Another thread set the bucket. Wait while it done
417 // In this point, we must wait while nBucket is empty.
418 // The compiler can decide that waiting loop can be "optimized" (stripped)
419 // To prevent this situation, we use waiting on volatile bucket_head_ptr pointer.
420 m_Stat.onBucketInitContenton();
423 dummy_node_type volatile * p = m_Buckets.bucket( nBucket );
425 return const_cast<dummy_node_type *>( p );
427 m_Stat.onBusyWaitBucketInit();
431 dummy_node_type * get_bucket( size_t nHash )
433 size_t nBucket = bucket_no( nHash );
435 dummy_node_type * pHead = m_Buckets.bucket( nBucket );
436 if ( pHead == nullptr )
437 pHead = init_bucket( nBucket );
439 assert( pHead->is_dummy() );
446 // GC and OrderedList::gc must be the same
447 static_assert( std::is_same<gc, typename ordered_list::gc>::value, "GC and OrderedList::gc must be the same");
449 // atomicity::empty_item_counter is not allowed as a item counter
450 static_assert( !std::is_same<item_counter, cds::atomicity::empty_item_counter>::value,
451 "cds::atomicity::empty_item_counter is not allowed as a item counter");
453 // Initialize bucket 0
454 dummy_node_type * pNode = alloc_dummy_node( 0 /*split_list::dummy_hash(0)*/ );
456 // insert_aux_node cannot return false for empty list
457 CDS_VERIFY( m_List.insert_aux_node( pNode ));
459 m_Buckets.bucket( 0, pNode );
462 static size_t max_item_count( size_t nBucketCount, size_t nLoadFactor )
464 return nBucketCount * nLoadFactor;
467 void inc_item_count()
469 size_t nMaxCount = m_nMaxItemCount.load(memory_model::memory_order_relaxed);
470 if ( ++m_ItemCounter <= nMaxCount )
473 size_t sz = m_nBucketCountLog2.load(memory_model::memory_order_relaxed);
474 const size_t nBucketCount = static_cast<size_t>(1) << sz;
475 if ( nBucketCount < m_Buckets.capacity() ) {
476 // we may grow the bucket table
477 const size_t nLoadFactor = m_Buckets.load_factor();
478 if ( nMaxCount < max_item_count( nBucketCount, nLoadFactor ))
479 return; // someone already have updated m_nBucketCountLog2, so stop here
481 const size_t nNewMaxCount = (nBucketCount < m_Buckets.capacity()) ? max_item_count( nBucketCount << 1, nLoadFactor )
482 : std::numeric_limits<size_t>::max();
483 m_nMaxItemCount.compare_exchange_strong( nMaxCount, nNewMaxCount, memory_model::memory_order_relaxed, atomics::memory_order_relaxed );
484 m_nBucketCountLog2.compare_exchange_strong( sz, sz + 1, memory_model::memory_order_relaxed, atomics::memory_order_relaxed );
488 template <typename Q, typename Compare, typename Func>
489 bool find_( Q& val, Compare cmp, Func f )
491 size_t nHash = hash_value( val );
492 split_list::details::search_value_type<Q> sv( val, split_list::regular_hash( nHash ));
493 dummy_node_type * pHead = get_bucket( nHash );
494 assert( pHead != nullptr );
496 return m_Stat.onFind(
497 m_List.find_at( pHead, sv, cmp,
498 [&f](value_type& item, split_list::details::search_value_type<Q>& val){ f(item, val.val ); })
502 template <typename Q, typename Compare>
503 bool find_( Q const& val, Compare cmp )
505 size_t nHash = hash_value( val );
506 split_list::details::search_value_type<Q const> sv( val, split_list::regular_hash( nHash ));
507 dummy_node_type * pHead = get_bucket( nHash );
508 assert( pHead != nullptr );
510 return m_Stat.onFind( m_List.find_at( pHead, sv, cmp ));
513 template <typename Q, typename Compare>
514 bool get_( typename guarded_ptr::native_guard& guard, Q const& val, Compare cmp )
516 size_t nHash = hash_value( val );
517 split_list::details::search_value_type<Q const> sv( val, split_list::regular_hash( nHash ));
518 dummy_node_type * pHead = get_bucket( nHash );
519 assert( pHead != nullptr );
521 return m_Stat.onFind( m_List.get_at( pHead, guard, sv, cmp ));
524 template <typename Q>
525 bool get_( typename guarded_ptr::native_guard& guard, Q const& key )
527 return get_( guard, key, key_comparator());
530 template <typename Q, typename Less>
531 bool get_with_( typename guarded_ptr::native_guard& guard, Q const& key, Less )
533 return get_( guard, key, typename wrapped_ordered_list::template make_compare_from_less<Less>());
536 template <typename Q, typename Compare, typename Func>
537 bool erase_( Q const& val, Compare cmp, Func f )
539 size_t nHash = hash_value( val );
540 split_list::details::search_value_type<Q const> sv( val, split_list::regular_hash( nHash ));
541 dummy_node_type * pHead = get_bucket( nHash );
542 assert( pHead != nullptr );
544 if ( m_List.erase_at( pHead, sv, cmp, f )) {
546 m_Stat.onEraseSuccess();
549 m_Stat.onEraseFailed();
553 template <typename Q, typename Compare>
554 bool erase_( Q const& val, Compare cmp )
556 size_t nHash = hash_value( val );
557 split_list::details::search_value_type<Q const> sv( val, split_list::regular_hash( nHash ));
558 dummy_node_type * pHead = get_bucket( nHash );
559 assert( pHead != nullptr );
561 if ( m_List.erase_at( pHead, sv, cmp ) ) {
563 m_Stat.onEraseSuccess();
566 m_Stat.onEraseFailed();
570 template <typename Q, typename Compare>
571 bool extract_( typename guarded_ptr::native_guard& guard, Q const& val, Compare cmp )
573 size_t nHash = hash_value( val );
574 split_list::details::search_value_type<Q const> sv( val, split_list::regular_hash( nHash ));
575 dummy_node_type * pHead = get_bucket( nHash );
576 assert( pHead != nullptr );
578 if ( m_List.extract_at( pHead, guard, sv, cmp ) ) {
580 m_Stat.onExtractSuccess();
583 m_Stat.onExtractFailed();
587 template <typename Q>
588 bool extract_( typename guarded_ptr::native_guard& guard, Q const& key )
590 return extract_( guard, key, key_comparator());
593 template <typename Q, typename Less>
594 bool extract_with_( typename guarded_ptr::native_guard& guard, Q const& key, Less )
596 return extract_( guard, key, typename wrapped_ordered_list::template make_compare_from_less<Less>() );
601 /// Initialize split-ordered list of default capacity
603 The default capacity is defined in bucket table constructor.
604 See \p split_list::expandable_bucket_table, \p split_list::static_bucket_table
605 which selects by \p split_list::dynamic_bucket_table option.
608 : m_nBucketCountLog2(1)
609 , m_nMaxItemCount( max_item_count(2, m_Buckets.load_factor()) )
614 /// Initialize split-ordered list
616 size_t nItemCount ///< estimate average of item count
617 , size_t nLoadFactor = 1 ///< load factor - average item count per bucket. Small integer up to 8, default is 1.
619 : m_Buckets( nItemCount, nLoadFactor )
620 , m_nBucketCountLog2(1)
621 , m_nMaxItemCount( max_item_count(2, m_Buckets.load_factor()) )
629 The function inserts \p val in the set if it does not contain
630 an item with key equal to \p val.
632 Returns \p true if \p val is placed into the set, \p false otherwise.
634 bool insert( value_type& val )
636 size_t nHash = hash_value( val );
637 dummy_node_type * pHead = get_bucket( nHash );
638 assert( pHead != nullptr );
640 node_traits::to_node_ptr( val )->m_nHash = split_list::regular_hash( nHash );
642 if ( m_List.insert_at( pHead, val )) {
644 m_Stat.onInsertSuccess();
647 m_Stat.onInsertFailed();
653 This function is intended for derived non-intrusive containers.
655 The function allows to split creating of new item into two part:
656 - create item with key only
657 - insert new item into the set
658 - if inserting is success, calls \p f functor to initialize value-field of \p val.
660 The functor signature is:
662 void func( value_type& val );
664 where \p val is the item inserted.
665 The user-defined functor is called only if the inserting is success.
667 @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
668 \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level
671 template <typename Func>
672 bool insert( value_type& val, Func f )
674 size_t nHash = hash_value( val );
675 dummy_node_type * pHead = get_bucket( nHash );
676 assert( pHead != nullptr );
678 node_traits::to_node_ptr( val )->m_nHash = split_list::regular_hash( nHash );
680 if ( m_List.insert_at( pHead, val, f )) {
682 m_Stat.onInsertSuccess();
685 m_Stat.onInsertFailed();
689 /// Ensures that the \p val exists in the set
691 The operation performs inserting or changing data with lock-free manner.
693 If the item \p val is not found in the set, then \p val is inserted into the set.
694 Otherwise, the functor \p func is called with item found.
695 The functor signature is:
697 void func( bool bNew, value_type& item, value_type& val );
700 - \p bNew - \p true if the item has been inserted, \p false otherwise
701 - \p item - item of the set
702 - \p val - argument \p val passed into the \p ensure function
703 If new item has been inserted (i.e. \p bNew is \p true) then \p item and \p val arguments
704 refers to the same thing.
706 The functor can change non-key fields of the \p item.
708 Returns std::pair<bool, bool> where \p first is \p true if operation is successfull,
709 \p second is \p true if new item has been added or \p false if the item with \p key
710 already is in the set.
712 @warning For \ref cds_intrusive_MichaelList_hp "MichaelList" as the bucket see \ref cds_intrusive_item_creating "insert item troubleshooting".
713 \ref cds_intrusive_LazyList_hp "LazyList" provides exclusive access to inserted item and does not require any node-level
716 template <typename Func>
717 std::pair<bool, bool> ensure( value_type& val, Func func )
719 size_t nHash = hash_value( val );
720 dummy_node_type * pHead = get_bucket( nHash );
721 assert( pHead != nullptr );
723 node_traits::to_node_ptr( val )->m_nHash = split_list::regular_hash( nHash );
725 std::pair<bool, bool> bRet = m_List.ensure_at( pHead, val, func );
726 if ( bRet.first && bRet.second ) {
728 m_Stat.onEnsureNew();
731 m_Stat.onEnsureExist();
735 /// Unlinks the item \p val from the set
737 The function searches the item \p val in the set and unlinks it from the set
738 if it is found and is equal to \p val.
740 Difference between \ref erase and \p unlink functions: \p erase finds <i>a key</i>
741 and deletes the item found. \p unlink finds an item by key and deletes it
742 only if \p val is an item of that set, i.e. the pointer to item found
743 is equal to <tt> &val </tt>.
745 The function returns \p true if success and \p false otherwise.
747 bool unlink( value_type& val )
749 size_t nHash = hash_value( val );
750 dummy_node_type * pHead = get_bucket( nHash );
751 assert( pHead != nullptr );
753 if ( m_List.unlink_at( pHead, val ) ) {
755 m_Stat.onEraseSuccess();
758 m_Stat.onEraseFailed();
762 /// Deletes the item from the set
763 /** \anchor cds_intrusive_SplitListSet_hp_erase
764 The function searches an item with key equal to \p key in the set,
765 unlinks it from the set, and returns \p true.
766 If the item with key equal to \p key is not found the function return \p false.
768 Difference between \ref erase and \p unlink functions: \p erase finds <i>a key</i>
769 and deletes the item found. \p unlink finds an item by key and deletes it
770 only if \p key is an item of that set, i.e. the pointer to item found
771 is equal to <tt> &key </tt>.
773 Note the hash functor should accept a parameter of type \p Q that can be not the same as \p value_type.
775 template <typename Q>
776 bool erase( Q const& key )
778 return erase_( key, key_comparator() );
781 /// Deletes the item from the set with comparing functor \p pred
784 The function is an analog of \ref cds_intrusive_SplitListSet_hp_erase "erase(Q const&)"
785 but \p pred predicate is used for key comparing.
786 \p Less has the interface like \p std::less.
787 \p pred must imply the same element order as the comparator used for building the set.
789 template <typename Q, typename Less>
790 bool erase_with( const Q& key, Less pred )
793 return erase_( key, typename wrapped_ordered_list::template make_compare_from_less<Less>() );
796 /// Deletes the item from the set
797 /** \anchor cds_intrusive_SplitListSet_hp_erase_func
798 The function searches an item with key equal to \p key in the set,
799 call \p f functor with item found, unlinks it from the set, and returns \p true.
800 The \ref disposer specified by \p OrderedList class template parameter is called
801 by garbage collector \p GC asynchronously.
803 The \p Func interface is
806 void operator()( value_type const& item );
810 If the item with key equal to \p key is not found the function return \p false.
812 Note the hash functor should accept a parameter of type \p Q that can be not the same as \p value_type.
814 template <typename Q, typename Func>
815 bool erase( Q const& key, Func f )
817 return erase_( key, key_comparator(), f );
820 /// Deletes the item from the set with comparing functor \p pred
822 The function is an analog of \ref cds_intrusive_SplitListSet_hp_erase_func "erase(Q const&, Func)"
823 but \p pred predicate is used for key comparing.
824 \p Less has the interface like \p std::less.
825 \p pred must imply the same element order as the comparator used for building the set.
827 template <typename Q, typename Less, typename Func>
828 bool erase_with( Q const& key, Less pred, Func f )
831 return erase_( key, typename wrapped_ordered_list::template make_compare_from_less<Less>(), f );
834 /// Extracts the item with specified \p key
835 /** \anchor cds_intrusive_SplitListSet_hp_extract
836 The function searches an item with key equal to \p key,
837 unlinks it from the set, and returns it as \p guarded_ptr.
838 If \p key is not found the function returns an empty guarded pointer.
840 Note the compare functor should accept a parameter of type \p Q that may be not the same as \p value_type.
842 The \p disposer specified in \p OrderedList class' template parameter is called automatically
843 by garbage collector \p GC when returned \p guarded_ptr object will be destroyed or released.
844 @note Each \p guarded_ptr object uses the GC's guard that can be limited resource.
848 typedef cds::intrusive::SplitListSet< your_template_args > splitlist_set;
849 splitlist_set theSet;
852 splitlist_set::guarded_ptr gp( theSet.extract( 5 ));
857 // Destructor of gp releases internal HP guard
861 template <typename Q>
862 guarded_ptr extract( Q const& key )
865 extract_( gp.guard(), key );
869 /// Extracts the item using compare functor \p pred
871 The function is an analog of \ref cds_intrusive_SplitListSet_hp_extract "extract(Q const&)"
872 but \p pred predicate is used for key comparing.
874 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
876 \p pred must imply the same element order as the comparator used for building the set.
878 template <typename Q, typename Less>
879 guarded_ptr extract_with( Q const& key, Less pred )
882 extract_with_( gp.guard(), key, pred );
886 /// Finds the key \p key
887 /** \anchor cds_intrusive_SplitListSet_hp_find_func
888 The function searches the item with key equal to \p key and calls the functor \p f for item found.
889 The interface of \p Func functor is:
892 void operator()( value_type& item, Q& key );
895 where \p item is the item found, \p key is the <tt>find</tt> function argument.
897 The functor can change non-key fields of \p item. Note that the functor is only guarantee
898 that \p item cannot be disposed during functor is executing.
899 The functor does not serialize simultaneous access to the set \p item. If such access is
900 possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.
902 Note the hash functor specified for class \p Traits template parameter
903 should accept a parameter of type \p Q that can be not the same as \p value_type.
905 The function returns \p true if \p key is found, \p false otherwise.
907 template <typename Q, typename Func>
908 bool find( Q& key, Func f )
910 return find_( key, key_comparator(), f );
913 template <typename Q, typename Func>
914 bool find( Q const& key, Func f )
916 return find_( key, key_comparator(), f );
920 /// Finds the key \p key with \p pred predicate for comparing
922 The function is an analog of \ref cds_intrusive_SplitListSet_hp_find_func "find(Q&, Func)"
923 but \p cmp is used for key compare.
924 \p Less has the interface like \p std::less.
925 \p cmp must imply the same element order as the comparator used for building the set.
927 template <typename Q, typename Less, typename Func>
928 bool find_with( Q& key, Less pred, Func f )
931 return find_( key, typename wrapped_ordered_list::template make_compare_from_less<Less>(), f );
934 template <typename Q, typename Less, typename Func>
935 bool find_with( Q const& key, Less pred, Func f )
938 return find_( key, typename wrapped_ordered_list::template make_compare_from_less<Less>(), f );
942 /// Finds the key \p key
943 /** \anchor cds_intrusive_SplitListSet_hp_find_val
944 The function searches the item with key equal to \p key
945 and returns \p true if it is found, and \p false otherwise.
947 Note the hash functor specified for class \p Traits template parameter
948 should accept a parameter of type \p Q that can be not the same as \p value_type.
949 Otherwise, you may use \p find_with functions with explicit predicate for key comparing.
951 template <typename Q>
952 bool find( Q const& key )
954 return find_( key, key_comparator() );
957 /// Finds the key \p key with \p pred predicate for comparing
959 The function is an analog of \ref cds_intrusive_SplitListSet_hp_find_val "find(Q const&)"
960 but \p cmp is used for key compare.
961 \p Less has the interface like \p std::less.
962 \p cmp must imply the same element order as the comparator used for building the set.
964 template <typename Q, typename Less>
965 bool find_with( Q const& key, Less pred )
968 return find_( key, typename wrapped_ordered_list::template make_compare_from_less<Less>() );
971 /// Finds the key \p key and return the item found
972 /** \anchor cds_intrusive_SplitListSet_hp_get
973 The function searches the item with key equal to \p key
974 and returns the item found as \p guarded_ptr.
975 If \p key is not found the function returns an empty guarded pointer.
977 The \p disposer specified in \p OrderedList class' template parameter is called
978 by garbage collector \p GC automatically when returned \p guarded_ptr object
979 will be destroyed or released.
980 @note Each \p guarded_ptr object uses one GC's guard which can be limited resource.
984 typedef cds::intrusive::SplitListSet< your_template_params > splitlist_set;
985 splitlist_set theSet;
988 splitlist_set::guarded_ptr gp = theSet.get( 5 );
993 // Destructor of guarded_ptr releases internal HP guard
997 Note the compare functor specified for \p OrderedList template parameter
998 should accept a parameter of type \p Q that can be not the same as \p value_type.
1000 template <typename Q>
1001 guarded_ptr get( Q const& key )
1004 get_( gp.guard(), key );
1008 /// Finds the key \p key and return the item found
1010 The function is an analog of \ref cds_intrusive_SplitListSet_hp_get "get( Q const&)"
1011 but \p pred is used for comparing the keys.
1013 \p Less functor has the semantics like \p std::less but should take arguments of type \ref value_type and \p Q
1015 \p pred must imply the same element order as the comparator used for building the set.
1017 template <typename Q, typename Less>
1018 guarded_ptr get_with( Q const& key, Less pred )
1021 get_with_( gp.guard(), key, pred );
1025 /// Returns item count in the set
1028 return m_ItemCounter;
1031 /// Checks if the set is empty
1033 Emptiness is checked by item counting: if item count is zero then the set is empty.
1034 Thus, the correct item counting feature is an important part of split-list set implementation.
1041 /// Clears the set (non-atomic)
1043 The function unlink all items from the set.
1044 The function is not atomic. Therefore, \p clear may be used only for debugging purposes.
1046 For each item the \p disposer is called after unlinking.
1050 iterator it = begin();
1051 while ( it != end() ) {
1059 /// Returns internal statistics
1060 stat const& statistics() const
1067 template <bool IsConst>
1069 :public split_list::details::iterator_type<node_traits, ordered_list, IsConst>
1071 typedef split_list::details::iterator_type<node_traits, ordered_list, IsConst> iterator_base_class;
1072 typedef typename iterator_base_class::list_iterator list_iterator;
1075 : iterator_base_class()
1078 iterator_type( iterator_type const& src )
1079 : iterator_base_class( src )
1082 // This ctor should be protected...
1083 iterator_type( list_iterator itCur, list_iterator itEnd )
1084 : iterator_base_class( itCur, itEnd )
1089 /// Forward iterator
1091 The forward iterator for a split-list has some features:
1092 - it has no post-increment operator
1093 - it depends on iterator of underlying \p OrderedList
1094 - The iterator cannot be moved across thread boundary since it may contain GC's guard that is thread-private GC data.
1095 - Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent
1096 deleting operations it is no guarantee that you iterate all item in the split-list.
1098 Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container
1099 for debug purpose only.
1101 typedef iterator_type<false> iterator;
1102 /// Const forward iterator
1104 For iterator's features and requirements see \ref iterator
1106 typedef iterator_type<true> const_iterator;
1108 /// Returns a forward iterator addressing the first element in a split-list
1110 For empty list \code begin() == end() \endcode
1114 return iterator( m_List.begin(), m_List.end() );
1117 /// Returns an iterator that addresses the location succeeding the last element in a split-list
1119 Do not use the value returned by <tt>end</tt> function to access any item.
1121 The returned value can be used only to control reaching the end of the split-list.
1122 For empty list \code begin() == end() \endcode
1126 return iterator( m_List.end(), m_List.end() );
1129 /// Returns a forward const iterator addressing the first element in a split-list
1130 const_iterator begin() const
1134 /// Returns a forward const iterator addressing the first element in a split-list
1135 const_iterator cbegin() const
1137 return const_iterator( m_List.cbegin(), m_List.cend() );
1140 /// Returns an const iterator that addresses the location succeeding the last element in a split-list
1141 const_iterator end() const
1145 /// Returns an const iterator that addresses the location succeeding the last element in a split-list
1146 const_iterator cend() const
1148 return const_iterator( m_List.cend(), m_List.cend() );
1153 }} // namespace cds::intrusive
1155 #endif // #ifndef CDSLIB_INTRUSIVE_SPLIT_LIST_H