cds  2.2.0
cds::container::LazyList< GC, T, Traits > Class Template Reference

Lazy ordered list. More...

#include <cds/container/impl/lazy_list.h>

Inheritance diagram for cds::container::LazyList< GC, T, Traits >:
cds::intrusive::LazyList< GC, T, Traits >

Public Types

typedef GC gc
 Garbage collector used.
 
typedef T value_type
 Type of value stored in the list.
 
typedef Traits traits
 List traits.
 
typedef base_class::back_off back_off
 Back-off strategy used.
 
typedef maker::allocator_type allocator_type
 Allocator type used for allocate/deallocate the nodes.
 
typedef base_class::item_counter item_counter
 Item counting policy used.
 
typedef maker::key_comparator key_comparator
 key comparison functor
 
typedef base_class::memory_model memory_model
 Memory ordering. See cds::opt::memory_model option.
 
typedef base_class::stat stat
 Internal statistics.
 
typedef gc::template guarded_ptr< node_type, value_type, details::guarded_ptr_cast_set< node_type, value_type > > guarded_ptr
 Guarded pointer.
 

Public Member Functions

 LazyList ()
 Default constructor.
 
 ~LazyList ()
 Destructor clears the list.
 
template<typename Q >
bool insert (Q &&val)
 Inserts new node. More...
 
template<typename Q , typename Func >
bool insert (Q &&key, Func func)
 Inserts new node. More...
 
template<typename... Args>
bool emplace (Args &&... args)
 Inserts data of type value_type constructed from args. More...
 
template<typename Q , typename Func >
std::pair< bool, bool > update (Q const &key, Func func, bool bAllowInsert=true)
 Updates data by key. More...
 
template<typename Q >
bool erase (Q const &key)
 Deletes key from the list. More...
 
template<typename Q , typename Less >
bool erase_with (Q const &key, Less pred)
 Deletes the item from the list using pred predicate for searching. More...
 
template<typename Q , typename Func >
bool erase (Q const &key, Func f)
 Deletes key from the list. More...
 
template<typename Q , typename Less , typename Func >
bool erase_with (Q const &key, Less pred, Func f)
 Deletes the item from the list using pred predicate for searching. More...
 
template<typename Q >
guarded_ptr extract (Q const &key)
 Extracts the item from the list with specified key. More...
 
template<typename Q , typename Less >
guarded_ptr extract_with (Q const &key, Less pred)
 Extracts the item from the list with comparing functor pred. More...
 
template<typename Q >
bool contains (Q const &key)
 Checks whether the list contains key. More...
 
template<typename Q , typename Less >
bool contains (Q const &key, Less pred)
 Checks whether the list contains key using pred predicate for searching. More...
 
template<typename Q , typename Func >
bool find (Q &key, Func f)
 Finds the key key and performs an action with it. More...
 
template<typename Q , typename Less , typename Func >
bool find_with (Q &key, Less pred, Func f)
 Finds the key key using pred predicate for searching. More...
 
template<typename Q >
guarded_ptr get (Q const &key)
 Finds the key key and return the item found. More...
 
template<typename Q , typename Less >
guarded_ptr get_with (Q const &key, Less pred)
 Finds the key key and return the item found. More...
 
bool empty () const
 Checks whether the list is empty.
 
size_t size () const
 Returns list's item count. More...
 
stat const & statistics () const
 Returns const reference to internal statistics.
 
void clear ()
 Clears the list.
 

Static Public Attributes

static constexpr const size_t c_nHazardPtrCount = base_class::c_nHazardPtrCount
 Count of hazard pointer required for the algorithm.
 

Forward iterators (only for debugging purpose)

typedef iterator_type< false > iterator
 Forward iterator. More...
 
typedef iterator_type< true > const_iterator
 Const forward iterator. More...
 
iterator begin ()
 Returns a forward iterator addressing the first element in a list. More...
 
iterator end ()
 Returns an iterator that addresses the location succeeding the last element in a list. More...
 
const_iterator begin () const
 Returns a forward const iterator addressing the first element in a list.
 
const_iterator cbegin () const
 Returns a forward const iterator addressing the first element in a list.
 
const_iterator end () const
 Returns an const iterator that addresses the location succeeding the last element in a list.
 
const_iterator cend () const
 Returns an const iterator that addresses the location succeeding the last element in a list.
 

Additional Inherited Members

- Protected Types inherited from cds::intrusive::LazyList< GC, T, Traits >
typedef node_type::marked_ptr marked_node_ptr
 Node marked pointer.
 
typedef node_typeauxiliary_head
 Auxiliary head type (for split-list support)
 
typedef GC gc
 Garbage collector.
 
typedef T value_type
 type of value stored in the 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 opt::compare and opt::less option setter.
 
typedef traits::disposer disposer
 disposer
 
typedef get_node_traits< value_type, node_type, hook >::type node_traits
 node traits
 
typedef lazy_list::get_link_checker< node_type, traits::link_checker >::type link_checker
 link checker
 
typedef traits::back_off back_off
 back-off strategy
 
typedef traits::item_counter item_counter
 Item counting policy used.
 
typedef traits::memory_model memory_model
 C++ memory ordering (see lazy_list::traits::memory_model)
 
typedef traits::stat stat
 Internal statistics.
 
typedef gc::template guarded_ptr< value_typeguarded_ptr
 Guarded pointer.
 
typedef iterator_type< false > iterator
 Forward iterator. More...
 
typedef iterator_type< true > const_iterator
 Const forward iterator. More...
 
- Protected Member Functions inherited from cds::intrusive::LazyList< GC, T, Traits >
 LazyList ()
 Default constructor initializes empty list.
 
 ~LazyList ()
 Destroys the list object.
 
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 bAllowInsert=true)
 Updates the item. More...
 
bool unlink (value_type &val)
 Unlinks the item val from the list. More...
 
template<typename Q >
bool erase (Q const &key)
 Deletes the item from the list. More...
 
template<typename Q , typename Less >
bool erase_with (Q const &key, Less pred)
 Deletes the item from the list using pred predicate for searching. More...
 
template<typename Q , typename Func >
bool erase (const Q &key, Func func)
 Deletes the item from the list. More...
 
template<typename Q , typename Less , typename Func >
bool erase_with (const Q &key, Less pred, Func func)
 Deletes the item from the list using pred predicate for searching. More...
 
template<typename Q >
guarded_ptr extract (Q const &key)
 Extracts the item from the list with specified key. More...
 
template<typename Q , typename Less >
guarded_ptr extract_with (Q const &key, Less pred)
 Extracts the item from the list with comparing functor pred. More...
 
template<typename Q , typename Func >
bool find (Q &key, Func f)
 Finds the key key. More...
 
template<typename Q , typename Less , typename Func >
bool find_with (Q &key, Less pred, Func f)
 Finds the key key using pred predicate for searching. More...
 
template<typename Q >
bool contains (Q const &key)
 Checks whether the list contains key. More...
 
template<typename Q >
guarded_ptr get (Q const &key)
 
template<typename Q , typename Less >
guarded_ptr get_with (Q const &key, Less pred)
 Finds key and return the item found. More...
 
void clear ()
 Clears the list.
 
bool empty () const
 Checks if the list is empty.
 
size_t size () const
 Returns list's item count. More...
 
stat const & statistics () const
 Returns const reference to internal statistics.
 
iterator begin ()
 Returns a forward iterator addressing the first element in a list. More...
 
iterator end ()
 Returns an iterator that addresses the location succeeding the last element in a list. More...
 
const_iterator begin () const
 Returns a forward const iterator addressing the first element in a list.
 
const_iterator cbegin () const
 Returns a forward const iterator addressing the first element in a list.
 
const_iterator end () const
 Returns an const iterator that addresses the location succeeding the last element in a list.
 
const_iterator cend () const
 Returns an const iterator that addresses the location succeeding the last element in a list.
 
- Static Protected Attributes inherited from cds::intrusive::LazyList< GC, T, Traits >
static constexpr const size_t c_nHazardPtrCount = 4
 Count of hazard pointer required for the algorithm.
 

Detailed Description

template<typename GC, typename T, typename Traits = lazy_list::traits>
class cds::container::LazyList< GC, T, Traits >

Lazy ordered list.

Usually, ordered single-linked list is used as a building block for the hash table implementation. The complexity of searching is O(N).

Source:

  • [2005] Steve Heller, Maurice Herlihy, Victor Luchangco, Mark Moir, William N. Scherer III, and Nir Shavit "A Lazy Concurrent List-Based Set Algorithm"

The lazy list is based on an optimistic locking scheme for inserts and removes, eliminating the need to use the equivalent of an atomically markable reference. It also has a novel wait-free membership find() operation that does not need to perform cleanup operations and is more efficient.

It is non-intrusive version of cds::intrusive::LazyList class.

Template arguments:

  • GC - garbage collector: gc::HP, gp::DHP
  • T - type to be stored in the list.
  • Traits - type traits, default is lazy_list::traits. It is possible to declare option-based list with lazy_list::make_traits metafunction istead of Traits template argument. For example, the following traits-based declaration of gc::HP lazy list
    #include <cds/container/lazy_list_hp.h>
    // Declare comparator for the item
    struct my_compare {
    int operator ()( int i1, int i2 )
    {
    return i1 - i2;
    }
    };
    // Declare traits
    struct my_traits: public cds::container::lazy_list::traits
    {
    typedef my_compare compare;
    };
    // Declare traits-based list
    is equal to the following option-based list:
    #include <cds/container/lazy_list_hp.h>
    // my_compare is the same
    // Declare option-based list
    typedef cds::container::LazyList< cds::gc::HP, int,
    >::type
    > option_based_list;

Unlike standard container, this implementation does not divide type T into key and value part and may be used as main building block for hash set algorithms.

The key is a function (or a part) of type T, and the comparing function is specified by Traits::compare functor or Traits::less predicate.

LazyKVList is a key-value version of lazy non-intrusive list that is closer to the C++ std library approach.

Usage
There are different specializations of this template for each garbage collecting schema used. You should include appropriate .h-file depending on GC you are using:
  • for gc::HP: <cds/container/lazy_list_hp.h>
  • for gc::DHP: <cds/container/lazy_list_dhp.h>
  • for RCU: <cds/container/lazy_list_rcu.h>
  • for gc::nogc: <cds/container/lazy_list_nogc.h>

Member Typedef Documentation

§ const_iterator

template<typename GC , typename T , typename Traits = lazy_list::traits>
typedef iterator_type<true> cds::container::LazyList< GC, T, Traits >::const_iterator

Const forward iterator.

For iterator's features and requirements see iterator

§ iterator

template<typename GC , typename T , typename Traits = lazy_list::traits>
typedef iterator_type<false> cds::container::LazyList< GC, T, Traits >::iterator

Forward iterator.

The forward iterator for lazy list has some features:

  • it has no post-increment operator
  • to protect the value, the iterator contains a GC-specific guard + another guard is required locally for increment operator. For some GC (gc::HP), a guard is limited resource per thread, so an exception (or assertion) "no free guard" may be thrown if a limit of guard count per thread is exceeded.
  • The iterator cannot be moved across thread boundary since it contains GC's guard that is thread-private GC data.
  • Iterator ensures thread-safety even if you delete the item that iterator points to. However, in case of concurrent deleting operations it is no guarantee that you iterate all item in the list. Moreover, a crash is possible when you try to iterate the next element that has been deleted by concurrent thread.
Warning
Use this iterator on the concurrent container for debugging purpose only.

Member Function Documentation

§ begin()

template<typename GC , typename T , typename Traits = lazy_list::traits>
iterator cds::container::LazyList< GC, T, Traits >::begin ( )
inline

Returns a forward iterator addressing the first element in a list.

For empty list

begin() == end()

§ contains() [1/2]

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q >
bool cds::container::LazyList< GC, T, Traits >::contains ( Q const &  key)
inline

Checks whether the list contains key.

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

§ contains() [2/2]

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q , typename Less >
bool cds::container::LazyList< GC, T, Traits >::contains ( Q const &  key,
Less  pred 
)
inline

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

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

§ emplace()

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename... Args>
bool cds::container::LazyList< GC, T, Traits >::emplace ( Args &&...  args)
inline

Inserts data of type value_type constructed from args.

Returns true if inserting successful, false otherwise.

§ end()

template<typename GC , typename T , typename Traits = lazy_list::traits>
iterator cds::container::LazyList< GC, T, Traits >::end ( )
inline

Returns an iterator that addresses the location succeeding the last element in a list.

Do not use the value returned by end function to access any item.

The returned value can be used only to control reaching the end of the list. For empty list

begin() == end()

§ erase() [1/2]

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q >
bool cds::container::LazyList< GC, T, Traits >::erase ( Q const &  key)
inline

Deletes key from the list.

Since the key of LazyList's item type T 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.

Return true if key is found and deleted, false otherwise

§ erase() [2/2]

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q , typename Func >
bool cds::container::LazyList< GC, T, Traits >::erase ( Q const &  key,
Func  f 
)
inline

Deletes key from the list.

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

The functor Func interface:

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

Since the key of LazyList's item type T 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.

Return true if key is found and deleted, false otherwise

See also: erase

§ erase_with() [1/2]

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q , typename Less >
bool cds::container::LazyList< GC, T, Traits >::erase_with ( Q const &  key,
Less  pred 
)
inline

Deletes the item from the list 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. pred must imply the same element order as the comparator used for building the list.

§ erase_with() [2/2]

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q , typename Less , typename Func >
bool cds::container::LazyList< GC, T, Traits >::erase_with ( Q const &  key,
Less  pred,
Func  f 
)
inline

Deletes the item from the list 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. pred must imply the same element order as the comparator used for building the list.

§ extract()

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q >
guarded_ptr cds::container::LazyList< GC, T, Traits >::extract ( Q const &  key)
inline

Extracts the item from the list with specified key.

The function searches an item with key equal to key, unlinks it from the list, and returns it as guarded_ptr. If key is not found the function returns an empty guarded pointer.

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

Note
Each guarded_ptr object uses the GC's guard that can be limited resource.

Usage:

ord_list theList;
// ...
{
ord_list::guarded_ptr gp(theList.extract( 5 ));
if ( gp ) {
// Deal with gp
// ...
}
// Destructor of gp releases internal HP guard and frees the item
}

§ extract_with()

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q , typename Less >
guarded_ptr cds::container::LazyList< GC, T, Traits >::extract_with ( Q const &  key,
Less  pred 
)
inline

Extracts the item from the list with comparing functor pred.

The function is an analog of extract(Q const&) but pred predicate is used for key comparing.

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 list.

§ find()

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q , typename Func >
bool cds::container::LazyList< GC, T, Traits >::find ( Q &  key,
Func  f 
)
inline

Finds the key key and performs an action with it.

The function searches an item with key equal to key and calls the functor f for the 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 may change non-key fields of item. Note that the function is only guarantee that item cannot be deleted during functor is executing. The function does not serialize simultaneous access to the list item. If such access is possible you must provide your own synchronization schema to exclude unsafe item modifications.

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

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

§ find_with()

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q , typename Less , typename Func >
bool cds::container::LazyList< GC, T, Traits >::find_with ( Q &  key,
Less  pred,
Func  f 
)
inline

Finds the key key 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. pred must imply the same element order as the comparator used for building the list.

§ get()

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q >
guarded_ptr cds::container::LazyList< GC, T, Traits >::get ( Q const &  key)
inline

Finds the key key and return the item found.

The function searches the item with key equal to key and returns the item found as guarded_ptr. If key is not found the function returns an empty guarded pointer.

Note
Each guarded_ptr object uses one GC's guard which can be limited resource.

Usage:

ord_list theList;
// ...
{
ord_list::guarded_ptr gp( theList.get( 5 ));
if ( gp ) {
// Deal with gp
//...
}
// Destructor of guarded_ptr releases internal HP guard and frees the item
}

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

§ get_with()

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q , typename Less >
guarded_ptr cds::container::LazyList< GC, T, Traits >::get_with ( Q const &  key,
Less  pred 
)
inline

Finds the key 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 list.

§ insert() [1/2]

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q >
bool cds::container::LazyList< GC, T, Traits >::insert ( Q &&  val)
inline

Inserts new node.

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

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

Returns true if inserting successful, false otherwise.

§ insert() [2/2]

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q , typename Func >
bool cds::container::LazyList< GC, T, Traits >::insert ( Q &&  key,
Func  func 
)
inline

Inserts new node.

This function inserts new node with default-constructed value and then it calls func functor with signature

void func( value_type& item ) ;

The argument item of user-defined functor func is the reference to the list's item inserted. When func is called it has exclusive access to the item. The user-defined functor is called only if the inserting is success.

The type Q should contain the complete key of the node. The object of value_type should be constructible from key of type Q.

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

  • create item from key with initializing key-fields only;
  • insert new item into the list;
  • if inserting is successful, initialize non-key fields of item by calling func functor

This can be useful if complete initialization of object of value_type is heavyweight and it is preferable that the initialization should be completed only if inserting is successful.

§ size()

template<typename GC , typename T , typename Traits = lazy_list::traits>
size_t cds::container::LazyList< GC, T, Traits >::size ( ) const
inline

Returns list's item count.

The value returned depends on Traits::item_counter type. For atomicity::empty_item_counter, this function always returns 0.

Note
Even if you use real item counter and it returns 0, this fact is not mean that the list is empty. To check list emptyness use empty() method.

§ update()

template<typename GC , typename T , typename Traits = lazy_list::traits>
template<typename Q , typename Func >
std::pair<bool, bool> cds::container::LazyList< GC, T, Traits >::update ( Q const &  key,
Func  func,
bool  bAllowInsert = true 
)
inline

Updates data by key.

The operation performs inserting or replacing the element with lock-free manner.

If the key not found in the list, then the new item created from key will be inserted iff bAllowInsert is true. Otherwise, if key is found, the functor func is called with item found.

The functor Func signature is:

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

with arguments:

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

The functor may change non-key fields of the item; during func call item is locked so it is safe to modify the item in multi-threaded environment.

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 files:

cds 2.2.0 Developed by Maxim Khizhinsky aka khizmax 2007 - 2017
Autogenerated Wed Jan 4 2017 08:49:37 by Doxygen 1.8.12