cds  2.2.0
cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits > Class Template Reference

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

#include <cds/container/skip_list_set_rcu.h>

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

Public Types

typedef base_class::gc gc
 Garbage collector used.
 
typedef T value_type
 Value type stored in the set.
 
typedef Traits traits
 Options specified.
 
typedef base_class::back_off back_off
 Back-off strategy used.
 
typedef traits::allocator allocator_type
 Allocator type used for allocate/deallocate the skip-list nodes.
 
typedef base_class::item_counter item_counter
 Item counting policy used.
 
typedef maker::key_comparator key_comparator
 key compare functor
 
typedef base_class::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::stat stat
 internal statistics type
 
typedef traits::rcu_check_deadlock rcu_check_deadlock
 Deadlock checking policy.
 
typedef base_class::rcu_lock rcu_lock
 
using exempt_ptr = cds::urcu::exempt_ptr< gc, node_type, value_type, typename maker::intrusive_traits::disposer >
 pointer to extracted node
 
typedef cds::urcu::raw_ptr_adaptor< value_type, typename base_class::raw_ptr, raw_ptr_converter > raw_ptr
 Result of get(), get_with() functions - pointer to the node found.
 

Public Member Functions

 SkipListSet ()
 Default ctor.
 
 ~SkipListSet ()
 Destructor destroys the set object.
 
template<typename Q >
bool insert (Q const &val)
 Inserts new node. More...
 
template<typename Q , typename Func >
bool insert (Q const &val, Func f)
 Inserts new node. More...
 
template<typename Q , typename Func >
std::pair< bool, bool > update (const Q &val, Func func, bool bInsert=true)
 Updates the item. More...
 
template<typename... Args>
bool emplace (Args &&... args)
 Inserts data of type value_type constructed with std::forward<Args>(args)... More...
 
template<typename Q >
bool erase (Q const &key)
 Delete key from the set. More...
 
template<typename Q , typename Less >
bool erase_with (Q const &key, Less pred)
 Deletes the item from the set using pred predicate for searching. More...
 
template<typename Q , typename Func >
bool erase (Q const &key, Func f)
 Delete key from the set. More...
 
template<typename Q , typename Less , typename Func >
bool erase_with (Q const &key, Less pred, Func f)
 Deletes the item from the set using pred predicate for searching. 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 set. More...
 
exempt_ptr extract_max ()
 Extracts an item with maximal key from the set. More...
 
template<typename Q , typename Func >
bool find (Q &val, Func f)
 Find the key val. More...
 
template<typename Q , typename Less , typename Func >
bool find_with (Q &val, Less pred, Func f)
 Finds the key val using pred predicate for searching. 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 &val, Less pred)
 Finds the key val and return the item found. More...
 
void clear ()
 Clears the set (non-atomic). More...
 
bool empty () const
 Checks if the set is empty.
 
size_t size () const
 Returns item count in the set. More...
 
stat const & statistics () const
 Returns const reference to internal statistics.
 

Static Public Attributes

static constexpr const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal
 Group of extract_xxx functions do not require external locking.
 

Forward ordered iterators (thread-safe under RCU lock)

typedef skip_list::details::iterator< typename base_class::iterator > iterator
 Forward iterator. More...
 
typedef skip_list::details::iterator< typename base_class::const_iterator > 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.
 

Additional Inherited Members

- Protected Types inherited from cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >
typedef node_type::atomic_marked_ptr atomic_node_ptr
 Atomic marked node pointer.
 
typedef node_type::marked_ptr marked_node_ptr
 Node marked pointer.
 
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.
 
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.
 
- Protected Member Functions inherited from cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >
 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.
 
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.
 
- Static Protected Member Functions inherited from cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >
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.
 
- Protected Attributes inherited from cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >
skip_list::details::head_node< node_typem_Head
 head tower (max height)
 
item_counter m_ItemCounter
 item counter
 
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.
 
stat m_Stat
 internal statistics
 
- Static Protected Attributes inherited from cds::intrusive::SkipListSet< cds::urcu::gc< RCU >, T, Traits >
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...
 

Detailed Description

template<typename RCU, typename T, typename Traits = skip_list::traits>
class cds::container::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.
  • Traits - set traits, default is skip_list::traits for explanation.

It is possible to declare option-based list with cds::container::skip_list::make_traits metafunction istead of Traits template argument. Template argument list Options of cds::container::skip_list::make_traits metafunction are:

Note
Before including <cds/container/skip_list_set_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.

The requirement of RCU lock during iterating means that deletion of the elements (i.e. erase) 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/container/skip_list_set_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::continer::skip_list::traits
{
// ...
};
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
}
Warning
Due to concurrent nature of skip-list set it is not guarantee that you can iterate all elements in the set: any concurrent deletion can exclude the element pointed by the iterator from the set, and your iteration can be terminated before end of the set. Therefore, such iteration is more suitable for debugging purposes

The iterator class supports the following minimalistic interface:

struct iterator {
// Default ctor
// 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.

Member Typedef Documentation

§ iterator

template<typename RCU , typename T , typename Traits = skip_list::traits>
typedef skip_list::details::iterator< typename base_class::iterator > cds::container::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.

§ rcu_lock

template<typename RCU , typename T , typename Traits = skip_list::traits>
typedef base_class::rcu_lock cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::rcu_lock

RCU scoped lock

Member Function Documentation

§ clear()

template<typename RCU , typename T , typename Traits = skip_list::traits>
void cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::clear ( )
inline

Clears the set (non-atomic).

The function deletes 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 provided by Traits template parameter will be called.

§ contains() [1/2]

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q >
bool cds::container::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<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q , typename Less >
bool cds::container::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.

§ emplace()

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename... Args>
bool cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::emplace ( Args &&...  args)
inline

Inserts data of type value_type constructed with std::forward<Args>(args)...

Returns true if inserting successful, false otherwise.

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

§ erase() [1/2]

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q >
bool cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::erase ( Q const &  key)
inline

Delete key from the set.

The item comparator should be able to compare the type value_type and the type Q.

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

Return true if key is found and deleted, false otherwise

§ erase() [2/2]

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q , typename Func >
bool cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::erase ( Q const &  key,
Func  f 
)
inline

Delete key from the set.

The function searches an item with key key, calls f functor and deletes the item. If key is not found, the functor is not called.

The functor Func interface:

struct extractor {
void operator()(value_type const& val);
};

Since the key of MichaelHashSet's value_type is not explicitly specified, template parameter Q defines the key type searching in the list. The list item comparator should be able to compare the type T of list item and the type Q.

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

Return true if key is found and deleted, false otherwise

See also: erase

§ erase_with() [1/2]

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q , typename Less >
bool cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::erase_with ( Q const &  key,
Less  pred 
)
inline

Deletes the item from the set using pred predicate for searching.

The function is an analog of erase(Q const&) 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_with() [2/2]

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q , typename Less , typename Func >
bool cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::erase_with ( Q const &  key,
Less  pred,
Func  f 
)
inline

Deletes the item from the set using pred predicate for searching.

The function is an analog of erase(Q const&, Func) 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.

§ extract()

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q >
exempt_ptr cds::container::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 is not found the function returns an empty exempt_ptr

Note the compare functor from Traits class' template argument 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 free the item found. The item will be implicitly freed when the returned object is destroyed or when its release() member function is called.

§ extract_max()

template<typename RCU , typename T , typename Traits = skip_list::traits>
exempt_ptr cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::extract_max ( )
inline

Extracts an item with maximal key from the set.

The function searches an item with maximal key, unlinks it from the set, 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 free the item found. The item will be implicitly freed when the returned object is destroyed or when its release() member function is called.

§ extract_min()

template<typename RCU , typename T , typename Traits = skip_list::traits>
exempt_ptr cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::extract_min ( )
inline

Extracts an item with minimal key from the set.

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 free the item found. The item will be implicitly freed when the returned object is destroyed or when its release() member function is called.

§ extract_with()

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q , typename Less >
exempt_ptr cds::container::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 semantics like std::less. pred must imply the same element order as the comparator used for building the set.

§ find()

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q , typename Func >
bool cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::find ( Q &  val,
Func  f 
)
inline

Find the key val.

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

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

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

The functor may 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's item. If such access is possible you must provide your own synchronization schema on item level to exclude unsafe item modifications.

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

Note the hash functor specified for class Traits template parameter should accept a parameter of type Q that may be not the same as value_type.

The function applies RCU lock internally.

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

§ find_with()

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q , typename Less , typename Func >
bool cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::find_with ( Q &  val,
Less  pred,
Func  f 
)
inline

Finds the key val using pred predicate for searching.

The function is an analog of find(Q&, Func) 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.

§ get()

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q >
raw_ptr cds::container::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 in Traits class' template argument 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:

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<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q , typename Less >
raw_ptr cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::get_with ( Q const &  val,
Less  pred 
)
inline

Finds the key val 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<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q >
bool cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::insert ( Q const &  val)
inline

Inserts new node.

The function creates a node with copy of val value and then inserts the node created into the set.

The type Q should contain as minimum the complete key for the node. The object of value_type should be constructible from a value of type Q. In trivial case, Q is equal to value_type.

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

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

§ insert() [2/2]

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q , typename Func >
bool cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::insert ( Q const &  val,
Func  f 
)
inline

Inserts new node.

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-fields 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<typename RCU , typename T , typename Traits = skip_list::traits>
size_t cds::container::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. If it is atomicity::empty_item_counter this function always returns 0. Therefore, the function is not suitable for checking the set emptiness, use empty member function for this purpose.

§ update()

template<typename RCU , typename T , typename Traits = skip_list::traits>
template<typename Q , typename Func >
std::pair<bool, bool> cds::container::SkipListSet< cds::urcu::gc< RCU >, T, Traits >::update ( const Q &  val,
Func  func,
bool  bInsert = true 
)
inline

Updates the item.

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

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

struct my_functor {
void operator()( bool bNew, value_type& item, const Q& val );
};

where:

  • bNew - true if the item has been inserted, false otherwise
  • item - an item of the set
  • val - argument val passed into the update() function

The functor may 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, second is true if new item has been added or false if the item with key already exists.


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

cds 2.2.0 Developed by Maxim Khizhinsky aka khizmax 2007 - 2017
Autogenerated Wed Jan 4 2017 08:49:41 by Doxygen 1.8.12