Lock-free skip-list set (template specialization for RCU) More...

#include <cds/intrusive/skip_list_rcu.h>

Inheritance diagram for cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >:

Public Types
typedef cds::urcu::gc< RCU >	gc
	Garbage collector.

typedef T	value_type
	type of value stored in the skip-list

typedef Traits	traits
	Traits template parameter.

typedef traits::hook	hook
	hook type

typedef hook::node_type	node_type
	node type

typedef implementation_defined	key_comparator
	key comparison functor based on `Traits::compare` and `Traits::less`

typedef traits::disposer	disposer
	disposer

typedef get_node_traits< value_type, node_type, hook >::type	node_traits
	node traits

typedef traits::item_counter	item_counter
	Item counting policy used.

typedef traits::memory_model	memory_model
	Memory ordering, see `cds::opt::memory_model` option.

typedef traits::random_level_generator	random_level_generator
	random level generator

typedef traits::allocator	allocator_type
	allocator for maintaining array of next pointers of the node

typedef traits::back_off	back_off
	Back-off strategy.

typedef traits::stat	stat
	internal statistics type

typedef traits::rcu_check_deadlock	rcu_check_deadlock
	Deadlock checking policy.

typedef gc::scoped_lock	rcu_lock
	RCU scoped lock.

using	exempt_ptr = cds::urcu::exempt_ptr< gc, value_type, value_type, node_disposer, void >
	pointer to extracted node

typedef cds::urcu::raw_ptr< gc, value_type, raw_ptr_disposer >	raw_ptr
	Result of `get()`, `get_with()` functions - pointer to the node found.

Public Member Functions
	SkipListSet ()
	Default constructor.

	~SkipListSet ()
	Clears and destructs the skip-list.

bool	insert (value_type &val)
	Inserts new node. More...

template<typename Func >
bool	insert (value_type &val, Func f)
	Inserts new node. More...

template<typename Func >
std::pair< bool, bool >	update (value_type &val, Func func, bool bInsert=true)
	Updates the node. More...

bool	unlink (value_type &val)
	Unlinks the item `val` from the set. More...

template<typename Q >
exempt_ptr	extract (Q const &key)
	Extracts the item from the set with specified `key`. More...

template<typename Q , typename Less >
exempt_ptr	extract_with (Q const &key, Less pred)
	Extracts the item from the set with comparing functor `pred`. More...

exempt_ptr	extract_min ()
	Extracts an item with minimal key from the list. More...

exempt_ptr	extract_max ()
	Extracts an item with maximal key from the list. More...

template<typename Q >
bool	erase (const Q &key)
	Deletes the item from the set. More...

template<typename Q , typename Less >
bool	erase_with (const Q &key, Less pred)
	Delete the item from the set with comparing functor `pred`. More...

template<typename Q , typename Func >
bool	erase (Q const &key, Func f)
	Deletes the item from the set. More...

template<typename Q , typename Less , typename Func >
bool	erase_with (Q const &key, Less pred, Func f)
	Delete the item from the set with comparing functor `pred`. More...

template<typename Q , typename Func >
bool	find (Q &key, Func f)
	Finds `key`. More...

template<typename Q , typename Less , typename Func >
bool	find_with (Q &key, Less pred, Func f)
	Finds the key `key` with comparing functor `pred`. More...

template<typename Q >
bool	contains (Q const &key)
	Checks whether the set contains `key`. More...

template<typename Q , typename Less >
bool	contains (Q const &key, Less pred)
	Checks whether the set contains `key` using `pred` predicate for searching. More...

template<typename Q >
raw_ptr	get (Q const &key)
	Finds `key` and return the item found. More...

template<typename Q , typename Less >
raw_ptr	get_with (Q const &key, Less pred)
	Finds `key` and return the item found. More...

size_t	size () const
	Returns item count in the set. More...

bool	empty () const
	Checks if the set is empty.

void	clear ()
	Clears the set (not atomic) More...

stat const &	statistics () const
	Returns const reference to internal statistics.

Static Public Member Functions
static constexpr unsigned int	max_height () noexcept
	Returns maximum height of skip-list. The max height is a constant for each object and does not exceed 32.

Static Public Attributes
static constexpr const bool	c_bExtractLockExternal = false
	Group of `extract_xxx` functions does not require external locking.

static unsigned int const	c_nMaxHeight
	Max node height. The actual node height should be in range `[0 .. c_nMaxHeight)` More...

Protected Types
typedef node_type::atomic_marked_ptr	atomic_node_ptr
	Atomic marked node pointer.

typedef node_type::marked_ptr	marked_node_ptr
	Node marked pointer.

Protected Attributes
skip_list::details::head_node< node_type >	m_Head
	head tower (max height)

random_level_generator	m_RandomLevelGen
	random level generator instance

atomics::atomic< unsigned int >	m_nHeight
	estimated high level

atomics::atomic< node_type * >	m_pDeferredDelChain
	Deferred deleted node chain.

item_counter	m_ItemCounter
	item counter

stat	m_Stat
	internal statistics

Forward iterators (thread-safe under RCU lock)
typedef skip_list::details::iterator< gc, node_traits, back_off, false >	iterator
	Forward iterator. More...

typedef skip_list::details::iterator< gc, node_traits, back_off, true >	const_iterator
	Const iterator type.

iterator	begin ()
	Returns a forward iterator addressing the first element in a set.

const_iterator	begin () const
	Returns a forward const iterator addressing the first element in a set.

const_iterator	cbegin () const
	Returns a forward const iterator addressing the first element in a set.

iterator	end ()
	Returns a forward iterator that addresses the location succeeding the last element in a set.

const_iterator	end () const
	Returns a forward const iterator that addresses the location succeeding the last element in a set.

const_iterator	cend () const
	Returns a forward const iterator that addresses the location succeeding the last element in a set.

Detailed Description

template<class RCU, typename T, typename Traits = skip_list::traits>
class cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >

Lock-free skip-list set (template specialization for RCU)

The implementation of well-known probabilistic data structure called skip-list invented by W.Pugh in his papers:

[1989] W.Pugh Skip Lists: A Probabilistic Alternative to Balanced Trees
[1990] W.Pugh A Skip List Cookbook

A skip-list is a probabilistic data structure that provides expected logarithmic time search without the need of rebalance. The skip-list is a collection of sorted linked list. Nodes are ordered by key. Each node is linked into a subset of the lists. Each list has a level, ranging from 0 to 32. The bottom-level list contains all the nodes, and each higher-level list is a sublist of the lower-level lists. Each node is created with a random top level (with a random height), and belongs to all lists up to that level. The probability that a node has the height 1 is 1/2. The probability that a node has the height N is 1/2 ** N (more precisely, the distribution depends on an random generator provided, but our generators have this property).

The lock-free variant of skip-list is implemented according to book

[2008] M.Herlihy, N.Shavit "The Art of Multiprocessor Programming", chapter 14.4 "A Lock-Free Concurrent Skiplist".

Template arguments:

RCU - one of RCU type
T - type to be stored in the list. The type must be based on skip_list::node (for skip_list::base_hook) or it must have a member of type skip_list::node (for skip_list::member_hook).
Traits - set traits, default is skip_list::traits It is possible to declare option-based list with cds::intrusive::skip_list::make_traits metafunction instead of Traits template argument.

Note: Before including <cds/intrusive/skip_list_rcu.h> you should include appropriate RCU header file, see RCU type for list of existing RCU class and corresponding header files.

Iterators

The class supports a forward iterator (iterator and const_iterator). The iteration is ordered.

You may iterate over skip-list set items only under RCU lock. Only in this case the iterator is thread-safe since while RCU is locked any set's item cannot be reclaimed.

Note: The requirement of RCU lock during iterating means that any type of modification of the skip list (i.e. inserting, erasing and so on) is not possible.

Warning: The iterator object cannot be passed between threads.

Example how to use skip-list set iterators:

// First, you should include the header for RCU type you have chosen
#include <cds/urcu/general_buffered.h>
#include <cds/intrusive/skip_list_rcu.h>
typedef cds::urcu::gc< cds::urcu::general_buffered<> > rcu_type;
struct Foo {
    // ...
};
// Traits for your skip-list.
// At least, you should define cds::opt::less or cds::opt::compare for Foo struct
struct my_traits: public cds::intrusive::skip_list::traits
{
    // ...
};
typedef cds::intrusive::SkipListSet< rcu_type, Foo, my_traits > my_skiplist_set;
my_skiplist_set theSet;
// ...
// Begin iteration
{
    // Apply RCU locking manually
    typename rcu_type::scoped_lock sl;
    for ( auto it = theList.begin(); it != theList.end(); ++it ) {
        // ...
    }
    // rcu_type::scoped_lock destructor releases RCU lock implicitly
}

The iterator class supports the following minimalistic interface:

struct iterator {
    // Default ctor
    iterator();
    // Copy ctor
    iterator( iterator const& s);
    value_type * operator ->() const;
    value_type& operator *() const;
    // Pre-increment
    iterator& operator ++();
    // Copy assignment
    iterator& operator = (const iterator& src);
    bool operator ==(iterator const& i ) const;
    bool operator !=(iterator const& i ) const;
};

Note, the iterator object returned by end, cend member functions points to nullptr and should not be dereferenced.

How to use

You should incorporate skip_list::node into your struct T and provide appropriate skip_list::traits::hook in your Traits template parameters. Usually, for Traits you define a struct based on skip_list::traits.

Example for cds::urcu::general_buffered<> RCU and base hook:

// First, you should include the header for RCU type you have chosen
#include <cds/urcu/general_buffered.h>
// Include RCU skip-list specialization
#include <cds/intrusive/skip_list_rcu.h>
// RCU type typedef
typedef cds::urcu::gc< cds::urcu::general_buffered<> > rcu_type;
// Data stored in skip list
struct my_data: public cds::intrusive::skip_list::node< rcu_type >
{
    // key field
    std::string     strKey;
    // other data
    // ...
};
// my_data compare functor
struct my_data_cmp {
    int operator()( const my_data& d1, const my_data& d2 )
    {
        return d1.strKey.compare( d2.strKey );
    }
    int operator()( const my_data& d, const std::string& s )
    {
        return d.strKey.compare(s);
    }
    int operator()( const std::string& s, const my_data& d )
    {
        return s.compare( d.strKey );
    }
};
// Declare traits
struct my_traits: public cds::intrusive::skip_list::traits
{
    typedef cds::intrusive::skip_list::base_hook< cds::opt::gc< rcu_type > >   hook;
    typedef my_data_cmp compare;
};
// Declare skip-list set type
typedef cds::intrusive::SkipListSet< rcu_type, my_data, my_traits >     traits_based_set;

Equivalent option-based code:

#include <cds/urcu/general_buffered.h>
#include <cds/intrusive/skip_list_rcu.h>
typedef cds::urcu::gc< cds::urcu::general_buffered<> > rcu_type;
struct my_data {
    // see above
};
struct compare {
    // see above
};
// Declare option-based skip-list set
typedef cds::intrusive::SkipListSet< rcu_type
    ,my_data
    , typename cds::intrusive::skip_list::make_traits<
        cds::intrusive::opt::hook< cds::intrusive::skip_list::base_hook< cds::opt::gc< rcu_type > > >
        ,cds::intrusive::opt::compare< my_data_cmp >
    >::type
> option_based_set;

Member Typedef Documentation

◆ iterator

template<class RCU , typename T , typename Traits = skip_list::traits>

typedef skip_list::details::iterator< gc, node_traits, back_off, false > cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::iterator

Forward iterator.

The forward iterator has some features:

it has no post-increment operator
it depends on iterator of underlying OrderedList

You may safely use iterators in multi-threaded environment only under RCU lock. Otherwise, a crash is possible if another thread deletes the element the iterator points to.

Member Function Documentation

◆ clear()

template<class RCU , typename T , typename Traits = skip_list::traits>

void cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::clear ( )

inline

Clears the set (not atomic)

The function unlink all items from the set. The function is not atomic, thus, in multi-threaded environment with parallel insertions this sequence

set.clear();

assert( set.empty());

the assertion could be raised.

For each item the disposer will be called automatically after unlinking.

◆ contains() [1/2]

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q >

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::contains ( Q const & key )

inline

Checks whether the set contains key.

The function searches the item with key equal to key and returns true if it is found, and false otherwise.

The function applies RCU lock internally.

◆ contains() [2/2]

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q , typename Less >

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::contains	(	Q const &	key,
		Less	pred
	)

inline

Checks whether the set contains key using pred predicate for searching.

The function is similar to contains( key ) but pred is used for key comparing. Less functor has the interface like std::less. Less must imply the same element order as the comparator used for building the set.

◆ erase() [1/2]

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q >

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::erase ( const Q & key )

inline

Deletes the item from the set.

The function searches an item with key equal to key in the set, unlinks it from the set, and returns true. If the item with key equal to key is not found the function return false.

Note the hash functor should accept a parameter of type Q that can be not the same as value_type.

RCU synchronize method can be called. RCU should not be locked.

◆ erase() [2/2]

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q , typename Func >

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::erase	(	Q const &	key,
		Func	f
	)

inline

Deletes the item from the set.

The function searches an item with key equal to key in the set, call f functor with item found, unlinks it from the set, and returns true. The disposer specified in Traits class template parameter is called by garbage collector GC asynchronously.

The Func interface is

struct functor {
    void operator()( value_type const& item );
};

If the item with key equal to key is not found the function return false.

Note the hash functor should accept a parameter of type Q that can be not the same as value_type.

RCU synchronize method can be called. RCU should not be locked.

◆ erase_with() [1/2]

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q , typename Less >

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::erase_with	(	const Q &	key,
		Less	pred
	)

inline

Delete the item from the set with comparing functor pred.

The function is an analog of erase(Q const&) but pred predicate is used for key comparing. Less has the interface like std::less. pred must imply the same element order as the comparator used for building the set.

◆ erase_with() [2/2]

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q , typename Less , typename Func >

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::erase_with	(	Q const &	key,
		Less	pred,
		Func	f
	)

inline

Delete the item from the set with comparing functor pred.

The function is an analog of erase(Q const&, Func) but pred predicate is used for key comparing. Less has the interface like std::less. pred must imply the same element order as the comparator used for building the set.

◆ extract()

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q >

exempt_ptr cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::extract ( Q const & key )

inline

Extracts the item from the set with specified key.

The function searches an item with key equal to key in the set, unlinks it from the set, and returns exempt_ptr pointer to the item found. If the item with key equal to key is not found the function returns an empty exempt_ptr.

Note the compare functor should accept a parameter of type Q that can be not the same as value_type.

RCU synchronize method can be called. RCU should NOT be locked. The function does not call the disposer for the item found. The disposer will be implicitly invoked when the returned object is destroyed or when its release() member function is called. Example:

typedef cds::intrusive::SkipListSet< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > skip_list;
skip_list theList;
// ...
typename skip_list::exempt_ptr ep( theList.extract( 5 ));
if ( ep ) {
    // Deal with ep
    //...
    // Dispose returned item.
    ep.release();
}

◆ extract_max()

template<class RCU , typename T , typename Traits = skip_list::traits>

exempt_ptr cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::extract_max ( )

inline

Extracts an item with maximal key from the list.

The function searches an item with maximal key, unlinks it, and returns exempt_ptr pointer to the item. If the skip-list is empty the function returns an empty exempt_ptr.

RCU synchronize method can be called. RCU should NOT be locked. The function does not call the disposer for the item found. The disposer will be implicitly invoked when the returned object is destroyed or when its release() member function is manually called. Example:

typedef cds::intrusive::SkipListSet< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > skip_list;
skip_list theList;
// ...
typename skip_list::exempt_ptr ep( theList.extract_max());
if ( ep ) {
    // Deal with ep
    //...
    // Dispose returned item.
    ep.release();
}

Note: Due the concurrent nature of the list, the function extracts nearly maximal key. It means that the function gets rightmost item and tries to unlink it. During unlinking, a concurrent thread can insert an item with key greater than rightmost item's key. So, the function returns the item with maximum key at the moment of list traversing.

◆ extract_min()

template<class RCU , typename T , typename Traits = skip_list::traits>

exempt_ptr cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::extract_min ( )

inline

Extracts an item with minimal key from the list.

The function searches an item with minimal key, unlinks it, and returns exempt_ptr pointer to the item. If the skip-list is empty the function returns an empty exempt_ptr.

RCU synchronize method can be called. RCU should NOT be locked. The function does not call the disposer for the item found. The disposer will be implicitly invoked when the returned object is destroyed or when its release() member function is manually called. Example:

typedef cds::intrusive::SkipListSet< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > skip_list;
skip_list theList;
// ...
typename skip_list::exempt_ptr ep(theList.extract_min());
if ( ep ) {
    // Deal with ep
    //...
    // Dispose returned item.
    ep.release();
}

Note: Due the concurrent nature of the list, the function extracts nearly minimum key. It means that the function gets leftmost item and tries to unlink it. During unlinking, a concurrent thread may insert an item with key less than leftmost item's key. So, the function returns the item with minimum key at the moment of list traversing.

◆ extract_with()

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q , typename Less >

exempt_ptr cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::extract_with	(	Q const &	key,
		Less	pred
	)

inline

Extracts the item from the set with comparing functor pred.

The function is an analog of extract(Q const&) but pred predicate is used for key comparing. Less has the interface like std::less. pred must imply the same element order as the comparator used for building the set.

◆ find()

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q , typename Func >

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::find	(	Q &	key,
		Func	f
	)

inline

Finds key.

The function searches the item with key equal to key and calls the functor f for item found. The interface of Func functor is:

struct functor {
    void operator()( value_type& item, Q& key );
};

where item is the item found, key is the find function argument.

The functor can change non-key fields of item. Note that the functor is only guarantee that item cannot be disposed during functor is executing. The functor does not serialize simultaneous access to the set item. If such access is possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.

The key argument is non-const since it can be used as f functor destination i.e., the functor can modify both arguments.

The function applies RCU lock internally.

The function returns true if key is found, false otherwise.

◆ find_with()

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q , typename Less , typename Func >

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::find_with	(	Q &	key,
		Less	pred,
		Func	f
	)

inline

Finds the key key with comparing functor pred.

The function is an analog of find(Q&, Func) but cmp is used for key comparison. Less functor has the interface like std::less. cmp must imply the same element order as the comparator used for building the set.

◆ get()

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q >

raw_ptr cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::get ( Q const & key )

inline

Finds key and return the item found.

The function searches the item with key equal to key and returns a raw_ptr object pointed to item found. If key is not found it returns empty raw_ptr.

Note the compare functor should accept a parameter of type Q that can be not the same as value_type.

RCU should be locked before call of this function. Returned item is valid only while RCU is locked:

typedef cds::intrusive::SkipListSet< cds::urcu::gc< cds::urcu::general_buffered<> >, foo, my_traits > skip_list;
skip_list theList;
// ...
typename skip_list::raw_ptr pVal;
{
    // Lock RCU
    skip_list::rcu_lock lock;
    pVal = theList.get( 5 );
    if ( pVal ) {
        // Deal with pVal
        //...
    }
}
// You can manually release pVal after RCU-locked section
pVal.release();

◆ get_with()

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Q , typename Less >

raw_ptr cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::get_with	(	Q const &	key,
		Less	pred
	)

inline

Finds key and return the item found.

The function is an analog of get(Q const&) but pred is used for comparing the keys.

Less functor has the semantics like std::less but should take arguments of type value_type and Q in any order. pred must imply the same element order as the comparator used for building the set.

◆ insert() [1/2]

template<class RCU , typename T , typename Traits = skip_list::traits>

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::insert ( value_type & val )

inline

Inserts new node.

The function inserts val in the set if it does not contain an item with key equal to val.

The function applies RCU lock internally.

Returns true if val is placed into the set, false otherwise.

◆ insert() [2/2]

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Func >

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::insert	(	value_type &	val,
		Func	f
	)

inline

Inserts new node.

This function is intended for derived non-intrusive containers.

The function allows to split creating of new item into two part:

create item with key only
insert new item into the set
if inserting is success, calls f functor to initialize value-field of val.

The functor signature is:

void func( value_type& val );

where val is the item inserted. User-defined functor f should guarantee that during changing val no any other changes could be made on this set's item by concurrent threads. The user-defined functor is called only if the inserting is success.

RCU synchronize method can be called. RCU should not be locked.

◆ size()

template<class RCU , typename T , typename Traits = skip_list::traits>

size_t cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::size ( ) const

inline

Returns item count in the set.

The value returned depends on item counter type provided by Traits template parameter. For atomicity::empty_item_counter the function always returns 0. Therefore, the function is not suitable for checking the set emptiness, use empty() member function for this purpose.

◆ unlink()

template<class RCU , typename T , typename Traits = skip_list::traits>

bool cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::unlink ( value_type & val )

inline

Unlinks the item val from the set.

The function searches the item val in the set and unlink it from the set if it is found and is equal to val.

Difference between erase() and unlink() functions: erase() finds a key and deletes the item found. unlink() searches an item by key and deletes it only if val is an item of that set, i.e. the pointer to item found is equal to &val .

RCU synchronize method can be called. RCU should not be locked.

The disposer specified in Traits class template parameter is called by garbage collector GC asynchronously.

The function returns true if success and false otherwise.

◆ update()

template<class RCU , typename T , typename Traits = skip_list::traits>

template<typename Func >

std::pair<bool, bool> cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::update	(	value_type &	val,
		Func	func,
		bool	bInsert = `true`
	)

inline

Updates the node.

The operation performs inserting or changing data with lock-free manner.

If the item val is not found in the set, then val is inserted into the set iff bInsert is true. Otherwise, the functor func is called with item found. The functor signature is:

void func( bool bNew, value_type& item, value_type& val );

with arguments:

bNew - true if the item has been inserted, false otherwise
item - item of the set
val - argument val passed into the update() function If new item has been inserted (i.e. bNew is true) then item and val arguments refer to the same thing.

The functor can change non-key fields of the item; however, func must guarantee that during changing no any other modifications could be made on this item by concurrent threads.

RCU synchronize method can be called. RCU should not be locked.

Returns std::pair<bool, bool> where first is true if operation is successful, i.e. the node has been inserted or updated, second is true if new item has been added or false if the item with key already exists.

Warning: See insert item troubleshooting

Field Documentation

◆ c_nMaxHeight

template<class RCU , typename T , typename Traits = skip_list::traits>

unsigned int const cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::c_nMaxHeight

static

Initial value:

= std::conditional<
            (random_level_generator::c_nUpperBound <= skip_list::c_nHeightLimit),
            std::integral_constant< unsigned int, random_level_generator::c_nUpperBound >,
            std::integral_constant< unsigned int, skip_list::c_nHeightLimit >
        >::type::value

Max node height. The actual node height should be in range [0 .. c_nMaxHeight)

The max height is specified by random level generator constant m_nUpperBound but it should be no more than 32 (skip_list::c_nHeightLimit).

The documentation for this class was generated from the following file:

cds/intrusive/skip_list_rcu.h

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Types

Protected Attributes

Forward iterators (thread-safe under RCU lock)

Detailed Description

template<class RCU, typename T, typename Traits = skip_list::traits> class cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >

Member Typedef Documentation

◆ iterator

Member Function Documentation

◆ clear()

◆ contains() [1/2]

◆ contains() [2/2]

◆ erase() [1/2]

◆ erase() [2/2]

◆ erase_with() [1/2]

◆ erase_with() [2/2]

◆ extract()

◆ extract_max()

◆ extract_min()

◆ extract_with()

◆ find()

◆ find_with()

◆ get()

◆ get_with()

◆ insert() [1/2]

◆ insert() [2/2]

◆ size()

◆ unlink()

◆ update()

Field Documentation

◆ c_nMaxHeight

template<class RCU, typename T, typename Traits = skip_list::traits>
class cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >