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/
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10 modification, are permitted provided that the following conditions are met:
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13 list of conditions and the following disclaimer.
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16 this list of conditions and the following disclaimer in the documentation
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31 #ifndef CDSLIB_INTRUSIVE_DETAILS_SKIP_LIST_BASE_H
32 #define CDSLIB_INTRUSIVE_DETAILS_SKIP_LIST_BASE_H
34 #include <cds/intrusive/details/base.h>
35 #include <cds/details/marked_ptr.h>
36 #include <cds/algo/bitop.h>
37 #include <cds/os/timer.h>
38 #include <cds/urcu/options.h>
40 namespace cds { namespace intrusive {
41 /// SkipListSet related definitions
42 /** @ingroup cds_intrusive_helper
45 /// The maximum possible height of any skip-list
46 static unsigned int const c_nHeightLimit = 32;
51 - \p GC - garbage collector
52 - \p Tag - a \ref cds_intrusive_hook_tag "tag"
54 template <class GC, typename Tag = opt::none>
58 typedef GC gc; ///< Garbage collector
59 typedef Tag tag; ///< tag
61 typedef cds::details::marked_ptr<node, 1> marked_ptr; ///< marked pointer
62 typedef typename gc::template atomic_marked_ptr< marked_ptr> atomic_marked_ptr; ///< atomic marked pointer specific for GC
64 typedef atomic_marked_ptr tower_item_type;
68 atomic_marked_ptr m_pNext; ///< Next item in bottom-list (list at level 0)
69 unsigned int m_nHeight; ///< Node height (size of m_arrNext array). For node at level 0 the height is 1.
70 atomic_marked_ptr * m_arrNext; ///< Array of next items for levels 1 .. m_nHeight - 1. For node at level 0 \p m_arrNext is \p nullptr
73 /// Constructs a node of height 1 (a bottom-list node)
77 , m_arrNext( nullptr )
80 /// Constructs a node of height \p nHeight
81 void make_tower( unsigned int nHeight, atomic_marked_ptr * nextTower )
83 assert( nHeight > 0 );
84 assert( (nHeight == 1 && nextTower == nullptr) // bottom-list node
85 || (nHeight > 1 && nextTower != nullptr) // node at level of more than 0
88 m_arrNext = nextTower;
93 atomic_marked_ptr * release_tower()
95 atomic_marked_ptr * pTower = m_arrNext;
101 atomic_marked_ptr * get_tower() const
107 /// Access to element of next pointer array
108 atomic_marked_ptr& next( unsigned int nLevel )
110 assert( nLevel < height() );
111 assert( nLevel == 0 || (nLevel > 0 && m_arrNext != nullptr) );
113 # ifdef CDS_THREAD_SANITIZER_ENABLED
114 // TSan false positive: m_arrNext is read-only array
115 CDS_TSAN_ANNOTATE_IGNORE_READS_BEGIN;
116 atomic_marked_ptr& r = nLevel ? m_arrNext[ nLevel - 1] : m_pNext;
117 CDS_TSAN_ANNOTATE_IGNORE_READS_END;
120 return nLevel ? m_arrNext[ nLevel - 1] : m_pNext;
124 /// Access to element of next pointer array (const version)
125 atomic_marked_ptr const& next( unsigned int nLevel ) const
127 assert( nLevel < height() );
128 assert( nLevel == 0 || nLevel > 0 && m_arrNext != nullptr );
130 # ifdef CDS_THREAD_SANITIZER_ENABLED
131 // TSan false positive: m_arrNext is read-only array
132 CDS_TSAN_ANNOTATE_IGNORE_READS_BEGIN;
133 atomic_marked_ptr const& r = nLevel ? m_arrNext[ nLevel - 1] : m_pNext;
134 CDS_TSAN_ANNOTATE_IGNORE_READS_END;
137 return nLevel ? m_arrNext[ nLevel - 1] : m_pNext;
141 /// Access to element of next pointer array (same as \ref next function)
142 atomic_marked_ptr& operator[]( unsigned int nLevel )
144 return next( nLevel );
147 /// Access to element of next pointer array (same as \ref next function)
148 atomic_marked_ptr const& operator[]( unsigned int nLevel ) const
150 return next( nLevel );
153 /// Height of the node
154 unsigned int height() const
159 /// Clears internal links
162 assert( m_arrNext == nullptr );
163 m_pNext.store( marked_ptr(), atomics::memory_order_release );
167 bool is_cleared() const
169 return m_pNext == atomic_marked_ptr()
170 && m_arrNext == nullptr
178 struct default_hook {
179 typedef undefined_gc gc;
180 typedef opt::none tag;
185 template < typename HookType, typename... Options>
188 typedef typename opt::make_options< default_hook, Options...>::type options;
189 typedef typename options::gc gc;
190 typedef typename options::tag tag;
191 typedef node<gc, tag> node_type;
192 typedef HookType hook_type;
199 - \p opt::gc - garbage collector
200 - \p opt::tag - a \ref cds_intrusive_hook_tag "tag"
202 template < typename... Options >
203 struct base_hook: public hook< opt::base_hook_tag, Options... >
208 \p MemberOffset defines offset in bytes of \ref node member into your structure.
209 Use \p offsetof macro to define \p MemberOffset
212 - \p opt::gc - garbage collector
213 - \p opt::tag - a \ref cds_intrusive_hook_tag "tag"
215 template < size_t MemberOffset, typename... Options >
216 struct member_hook: public hook< opt::member_hook_tag, Options... >
219 static const size_t c_nMemberOffset = MemberOffset;
225 \p NodeTraits defines type traits for node.
226 See \ref node_traits for \p NodeTraits interface description
229 - \p opt::gc - garbage collector
230 - \p opt::tag - a \ref cds_intrusive_hook_tag "tag"
232 template <typename NodeTraits, typename... Options >
233 struct traits_hook: public hook< opt::traits_hook_tag, Options... >
236 typedef NodeTraits node_traits;
240 /// Option specifying random level generator
242 The random level generator is an important part of skip-list algorithm.
243 The node height in the skip-list have a probabilistic distribution
244 where half of the nodes that have level \p i pointers also have level <tt>i+1</tt> pointers
246 The random level generator should provide such distribution.
248 The \p Type functor interface is:
250 struct random_generator {
251 static unsigned int const c_nUpperBound = 32;
253 unsigned int operator()();
258 - \p c_nUpperBound - constant that specifies the upper bound of random number generated.
259 The generator produces a number from range <tt>[0 .. c_nUpperBound)</tt> (upper bound excluded).
260 \p c_nUpperBound must be no more than 32.
261 - <tt>random_generator()</tt> - the constructor of generator object initialises the generator instance (its internal state).
262 - <tt>unsigned int operator()()</tt> - the main generating function. Returns random level from range 0..31.
264 Stateful generators are supported.
266 Available \p Type implementations:
267 - \p skip_list::xorshift
268 - \p skip_list::turbo_pascal
270 template <typename Type>
271 struct random_level_generator {
273 template <typename Base>
274 struct pack: public Base
276 typedef Type random_level_generator;
281 /// Xor-shift random level generator
283 The simplest of the generators described in George
284 Marsaglia's "Xorshift RNGs" paper. This is not a high-quality
285 generator but is acceptable for skip-list.
287 The random generator should return numbers from range [0..31].
289 From Doug Lea's ConcurrentSkipListMap.java.
293 atomics::atomic<unsigned int> m_nSeed;
296 /// The upper bound of generator's return value. The generator produces random number in range <tt>[0..c_nUpperBound)</tt>
297 static unsigned int const c_nUpperBound = c_nHeightLimit;
299 /// Initializes the generator instance
302 m_nSeed.store( (unsigned int) cds::OS::Timer::random_seed(), atomics::memory_order_relaxed );
305 /// Main generator function
306 unsigned int operator()()
308 /* ConcurrentSkipListMap.java
309 private int randomLevel() {
313 randomSeed = x ^= x << 5;
314 if ((x & 0x80000001) != 0) // test highest and lowest bits
317 while (((x >>>= 1) & 1) != 0) ++level;
321 unsigned int x = m_nSeed.load( atomics::memory_order_relaxed );
325 m_nSeed.store( x, atomics::memory_order_relaxed );
326 unsigned int nLevel = ((x & 0x00000001) != 0) ? 0 : cds::bitop::LSB( (~(x >> 1)) & 0x7FFFFFFF );
327 assert( nLevel < c_nUpperBound );
332 /// Turbo-pascal random level generator
334 This uses a cheap pseudo-random function that was used in Turbo Pascal.
336 The random generator should return numbers from range [0..31].
338 From Doug Lea's ConcurrentSkipListMap.java.
343 atomics::atomic<unsigned int> m_nSeed;
346 /// The upper bound of generator's return value. The generator produces random number in range <tt>[0..c_nUpperBound)</tt>
347 static unsigned int const c_nUpperBound = c_nHeightLimit;
349 /// Initializes the generator instance
352 m_nSeed.store( (unsigned int) cds::OS::Timer::random_seed(), atomics::memory_order_relaxed );
355 /// Main generator function
356 unsigned int operator()()
359 private int randomLevel() {
362 randomSeed = r * 134775813 + 1;
364 while ((r <<= 1) > 0)
371 The low bits are apparently not very random (the original used only
372 upper 16 bits) so we traverse from highest bit down (i.e., test
373 sign), thus hardly ever use lower bits.
375 unsigned int x = m_nSeed.load( atomics::memory_order_relaxed ) * 134775813 + 1;
376 m_nSeed.store( x, atomics::memory_order_relaxed );
377 unsigned int nLevel = ( x & 0x80000000 ) ? (31 - cds::bitop::MSBnz( (x & 0x7FFFFFFF) | 1 )) : 0;
378 assert( nLevel < c_nUpperBound );
383 /// \p SkipListSet internal statistics
384 template <typename EventCounter = cds::atomicity::event_counter>
386 typedef EventCounter event_counter ; ///< Event counter type
388 event_counter m_nNodeHeightAdd[c_nHeightLimit] ; ///< Count of added node of each height
389 event_counter m_nNodeHeightDel[c_nHeightLimit] ; ///< Count of deleted node of each height
390 event_counter m_nInsertSuccess ; ///< Count of success insertion
391 event_counter m_nInsertFailed ; ///< Count of failed insertion
392 event_counter m_nInsertRetries ; ///< Count of unsuccessful retries of insertion
393 event_counter m_nUpdateExist ; ///< Count of \p update() call for existed node
394 event_counter m_nUpdateNew ; ///< Count of \p update() call for new node
395 event_counter m_nUnlinkSuccess ; ///< Count of successful call of \p unlink
396 event_counter m_nUnlinkFailed ; ///< Count of failed call of \p unlink
397 event_counter m_nEraseSuccess ; ///< Count of successful call of \p erase
398 event_counter m_nEraseFailed ; ///< Count of failed call of \p erase
399 event_counter m_nEraseRetry ; ///< Count of retries while erasing node
400 event_counter m_nFindFastSuccess ; ///< Count of successful call of \p find and all derivatives (via fast-path)
401 event_counter m_nFindFastFailed ; ///< Count of failed call of \p find and all derivatives (via fast-path)
402 event_counter m_nFindSlowSuccess ; ///< Count of successful call of \p find and all derivatives (via slow-path)
403 event_counter m_nFindSlowFailed ; ///< Count of failed call of \p find and all derivatives (via slow-path)
404 event_counter m_nRenewInsertPosition ; ///< Count of renewing position events while inserting
405 event_counter m_nLogicDeleteWhileInsert ; ///< Count of events "The node has been logically deleted while inserting"
406 event_counter m_nNotFoundWhileInsert ; ///< Count of events "Inserting node is not found"
407 event_counter m_nFastErase ; ///< Fast erase event counter
408 event_counter m_nFastExtract ; ///< Fast extract event counter
409 event_counter m_nSlowErase ; ///< Slow erase event counter
410 event_counter m_nSlowExtract ; ///< Slow extract event counter
411 event_counter m_nExtractSuccess ; ///< Count of successful call of \p extract
412 event_counter m_nExtractFailed ; ///< Count of failed call of \p extract
413 event_counter m_nExtractRetries ; ///< Count of retries of \p extract call
414 event_counter m_nExtractMinSuccess ; ///< Count of successful call of \p extract_min
415 event_counter m_nExtractMinFailed ; ///< Count of failed call of \p extract_min
416 event_counter m_nExtractMinRetries ; ///< Count of retries of \p extract_min call
417 event_counter m_nExtractMaxSuccess ; ///< Count of successful call of \p extract_max
418 event_counter m_nExtractMaxFailed ; ///< Count of failed call of \p extract_max
419 event_counter m_nExtractMaxRetries ; ///< Count of retries of \p extract_max call
420 event_counter m_nEraseWhileFind ; ///< Count of erased item while searching
421 event_counter m_nExtractWhileFind ; ///< Count of extracted item while searching (RCU only)
424 void onAddNode( unsigned int nHeight )
426 assert( nHeight > 0 && nHeight <= sizeof(m_nNodeHeightAdd) / sizeof(m_nNodeHeightAdd[0]));
427 ++m_nNodeHeightAdd[nHeight - 1];
429 void onRemoveNode( unsigned int nHeight )
431 assert( nHeight > 0 && nHeight <= sizeof(m_nNodeHeightDel) / sizeof(m_nNodeHeightDel[0]));
432 ++m_nNodeHeightDel[nHeight - 1];
435 void onInsertSuccess() { ++m_nInsertSuccess ; }
436 void onInsertFailed() { ++m_nInsertFailed ; }
437 void onInsertRetry() { ++m_nInsertRetries ; }
438 void onUpdateExist() { ++m_nUpdateExist ; }
439 void onUpdateNew() { ++m_nUpdateNew ; }
440 void onUnlinkSuccess() { ++m_nUnlinkSuccess ; }
441 void onUnlinkFailed() { ++m_nUnlinkFailed ; }
442 void onEraseSuccess() { ++m_nEraseSuccess ; }
443 void onEraseFailed() { ++m_nEraseFailed ; }
444 void onEraseRetry() { ++m_nEraseRetry; }
445 void onFindFastSuccess() { ++m_nFindFastSuccess ; }
446 void onFindFastFailed() { ++m_nFindFastFailed ; }
447 void onFindSlowSuccess() { ++m_nFindSlowSuccess ; }
448 void onFindSlowFailed() { ++m_nFindSlowFailed ; }
449 void onEraseWhileFind() { ++m_nEraseWhileFind ; }
450 void onExtractWhileFind() { ++m_nExtractWhileFind ; }
451 void onRenewInsertPosition() { ++m_nRenewInsertPosition; }
452 void onLogicDeleteWhileInsert() { ++m_nLogicDeleteWhileInsert; }
453 void onNotFoundWhileInsert() { ++m_nNotFoundWhileInsert; }
454 void onFastErase() { ++m_nFastErase; }
455 void onFastExtract() { ++m_nFastExtract; }
456 void onSlowErase() { ++m_nSlowErase; }
457 void onSlowExtract() { ++m_nSlowExtract; }
458 void onExtractSuccess() { ++m_nExtractSuccess; }
459 void onExtractFailed() { ++m_nExtractFailed; }
460 void onExtractRetry() { ++m_nExtractRetries; }
461 void onExtractMinSuccess() { ++m_nExtractMinSuccess; }
462 void onExtractMinFailed() { ++m_nExtractMinFailed; }
463 void onExtractMinRetry() { ++m_nExtractMinRetries; }
464 void onExtractMaxSuccess() { ++m_nExtractMaxSuccess; }
465 void onExtractMaxFailed() { ++m_nExtractMaxFailed; }
466 void onExtractMaxRetry() { ++m_nExtractMaxRetries; }
471 /// \p SkipListSet empty internal statistics
474 void onAddNode( unsigned int /*nHeight*/ ) const {}
475 void onRemoveNode( unsigned int /*nHeight*/ ) const {}
476 void onInsertSuccess() const {}
477 void onInsertFailed() const {}
478 void onInsertRetry() const {}
479 void onUpdateExist() const {}
480 void onUpdateNew() const {}
481 void onUnlinkSuccess() const {}
482 void onUnlinkFailed() const {}
483 void onEraseSuccess() const {}
484 void onEraseFailed() const {}
485 void onEraseRetry() const {}
486 void onFindFastSuccess() const {}
487 void onFindFastFailed() const {}
488 void onFindSlowSuccess() const {}
489 void onFindSlowFailed() const {}
490 void onEraseWhileFind() const {}
491 void onExtractWhileFind() const {}
492 void onRenewInsertPosition() const {}
493 void onLogicDeleteWhileInsert() const {}
494 void onNotFoundWhileInsert() const {}
495 void onFastErase() const {}
496 void onFastExtract() const {}
497 void onSlowErase() const {}
498 void onSlowExtract() const {}
499 void onExtractSuccess() const {}
500 void onExtractFailed() const {}
501 void onExtractRetry() const {}
502 void onExtractMinSuccess() const {}
503 void onExtractMinFailed() const {}
504 void onExtractMinRetry() const {}
505 void onExtractMaxSuccess() const {}
506 void onExtractMaxFailed() const {}
507 void onExtractMaxRetry() const {}
513 // For internal use only!!!
514 template <typename Type>
515 struct internal_node_builder {
516 template <typename Base>
517 struct pack: public Base
519 typedef Type internal_node_builder;
524 /// \p SkipListSet traits
529 Possible values are: \p skip_list::base_hook, \p skip_list::member_hook, \p skip_list::traits_hook.
531 typedef base_hook<> hook;
533 /// Key comparison functor
535 No default functor is provided. If the option is not specified, the \p less is used.
537 typedef opt::none compare;
539 /// specifies binary predicate used for key compare.
541 Default is \p std::less<T>.
543 typedef opt::none less;
547 The functor used for dispose removed items. Default is \p opt::v::empty_disposer.
549 typedef opt::v::empty_disposer disposer;
553 The type for item counting feature.
554 By default, item counting is disabled (\p atomicity::empty_item_counter)
555 \p atomicity::item_counter enables it.
557 typedef atomicity::empty_item_counter item_counter;
559 /// C++ memory ordering model
561 List of available memory ordering see \p opt::memory_model
563 typedef opt::v::relaxed_ordering memory_model;
565 /// Random level generator
567 The random level generator is an important part of skip-list algorithm.
568 The node height in the skip-list have a probabilistic distribution
569 where half of the nodes that have level \p i pointers also have level <tt>i+1</tt> pointers
570 (i = 0..30). So, the height of a node is in range [0..31].
572 See \p skip_list::random_level_generator option setter.
574 typedef turbo_pascal random_level_generator;
578 Although the skip-list is an intrusive container,
579 an allocator should be provided to maintain variable randomly-calculated height of the node
580 since the node can contain up to 32 next pointers.
581 The allocator specified is used to allocate an array of next pointers
582 for nodes which height is more than 1.
584 typedef CDS_DEFAULT_ALLOCATOR allocator;
586 /// back-off strategy
588 If the option is not specified, the \p cds::backoff::Default is used.
590 typedef cds::backoff::Default back_off;
592 /// Internal statistics
594 By default, internal statistics is disabled (\p skip_list::empty_stat).
595 Use \p skip_list::stat to enable it.
597 typedef empty_stat stat;
599 /// RCU deadlock checking policy (only for \ref cds_intrusive_SkipListSet_rcu "RCU-based SkipListSet")
601 List of available options see \p opt::rcu_check_deadlock
603 typedef opt::v::rcu_throw_deadlock rcu_check_deadlock;
606 // For internal use only!!!
607 typedef opt::none internal_node_builder;
611 /// Metafunction converting option list to \p SkipListSet traits
614 - \p opt::hook - hook used. Possible values are: \p skip_list::base_hook, \p skip_list::member_hook, \p skip_list::traits_hook.
615 If the option is not specified, <tt>skip_list::base_hook<></tt> and \p gc::HP is used.
616 - \p opt::compare - key comparison functor. No default functor is provided.
617 If the option is not specified, the \p opt::less is used.
618 - \p opt::less - specifies binary predicate used for key comparison. Default is \p std::less<T>.
619 - \p opt::disposer - the functor used for dispose removed items. Default is \p opt::v::empty_disposer. Due the nature
620 of GC schema the disposer may be called asynchronously.
621 - \p opt::item_counter - the type of item counting feature. Default is disabled, i.e. \p atomicity::empty_item_counter.
622 To enable it use \p atomicity::item_counter
623 - \p opt::memory_model - C++ memory ordering model. Can be \p opt::v::relaxed_ordering (relaxed memory model, the default)
624 or \p opt::v::sequential_consistent (sequentially consisnent memory model).
625 - \p skip_list::random_level_generator - random level generator. Can be \p skip_list::xorshift,
626 \p skip_list::turbo_pascal (the default) or
627 user-provided one. See \p skip_list::random_level_generator option description for explanation.
628 - \p opt::allocator - although the skip-list is an intrusive container,
629 an allocator should be provided to maintain variable randomly-calculated height of the node
630 since the node can contain up to 32 next pointers. The allocator option is used to allocate an array of next pointers
631 for nodes which height is more than 1. Default is \ref CDS_DEFAULT_ALLOCATOR.
632 - \p opt::back_off - back-off strategy, default is \p cds::backoff::Default.
633 - \p opt::stat - internal statistics. By default, it is disabled (\p skip_list::empty_stat).
634 To enable it use \p skip_list::stat
636 template <typename... Options>
638 # ifdef CDS_DOXYGEN_INVOKED
639 typedef implementation_defined type ; ///< Metafunction result
641 typedef typename cds::opt::make_options<
642 typename cds::opt::find_type_traits< traits, Options... >::type
650 template <typename Node>
651 class head_node: public Node
653 typedef Node node_type;
654 typename node_type::atomic_marked_ptr m_Tower[skip_list::c_nHeightLimit];
657 head_node( unsigned int nHeight )
659 for ( size_t i = 0; i < sizeof(m_Tower) / sizeof(m_Tower[0]); ++i )
660 m_Tower[i].store( typename node_type::marked_ptr(), atomics::memory_order_relaxed );
662 node_type::make_tower( nHeight, m_Tower );
665 node_type * head() const
667 return const_cast<node_type *>( static_cast<node_type const *>(this));
671 template <typename NodeType, typename AtomicNodePtr, typename Alloc>
672 struct intrusive_node_builder
674 typedef NodeType node_type;
675 typedef AtomicNodePtr atomic_node_ptr;
676 typedef Alloc allocator_type;
678 typedef cds::details::Allocator< atomic_node_ptr, allocator_type > tower_allocator;
680 template <typename RandomGen>
681 static node_type * make_tower( node_type * pNode, RandomGen& gen )
683 return make_tower( pNode, gen() + 1 );
686 static node_type * make_tower( node_type * pNode, unsigned int nHeight )
689 pNode->make_tower( nHeight, tower_allocator().NewArray( nHeight - 1, nullptr ) );
693 static void dispose_tower( node_type * pNode )
695 unsigned int nHeight = pNode->height();
697 tower_allocator().Delete( pNode->release_tower(), nHeight );
700 struct node_disposer {
701 void operator()( node_type * pNode )
703 dispose_tower( pNode );
708 // Forward declaration
709 template <class GC, typename NodeTraits, typename BackOff, bool IsConst>
712 } // namespace details
715 } // namespace skip_list
717 // Forward declaration
718 template <class GC, typename T, typename Traits = skip_list::traits >
721 }} // namespace cds::intrusive
723 #endif // #ifndef CDSLIB_INTRUSIVE_DETAILS_SKIP_LIST_BASE_H