cds  2.2.0
cds::container::MichaelKVList< GC, Key, Value, Traits > Class Template Reference

Michael's ordered list for key-value pair. More...

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

Inheritance diagram for cds::container::MichaelKVList< GC, Key, Value, Traits >:
cds::intrusive::MichaelList< GC, implementation_defined, Traits >

Public Types

typedef Key key_type
 Key type.
 
typedef Value mapped_type
 Type of value stored in the list.
 
typedef std::pair< key_type const, mapped_typevalue_type
 key/value pair stored in the list
 
typedef base_class::gc gc
 Garbage collector used.
 
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_map< node_type, value_type > > guarded_ptr
 Guarded pointer.
 
typedef iterator_type< false > iterator
 Forward iterator. More...
 
typedef iterator_type< true > const_iterator
 Const forward iterator. More...
 

Public Member Functions

 MichaelKVList ()
 Default constructor. More...
 
 ~MichaelKVList ()
 List destructor. More...
 
template<typename K >
bool insert (K &&key)
 Inserts new node with key and default value. More...
 
template<typename K , typename V >
bool insert (K &&key, V &&val)
 Inserts new node with a key and a value. More...
 
template<typename K , typename Func >
bool insert_with (K &&key, Func func)
 Inserts new node and initialize it by a functor. More...
 
template<typename K , typename Func >
std::pair< bool, bool > update (K &&key, Func f, bool bAllowInsert=true)
 Updates data by key. More...
 
template<typename K , typename... Args>
bool emplace (K &&key, Args &&... args)
 Inserts a new node using move semantics. More...
 
template<typename K >
bool erase (K const &key)
 Deletes key from the list. More...
 
template<typename K , typename Less >
bool erase_with (K const &key, Less pred)
 Deletes the item from the list using pred predicate for searching. More...
 
template<typename K , typename Func >
bool erase (K const &key, Func f)
 Deletes key from the list. More...
 
template<typename K , typename Less , typename Func >
bool erase_with (K const &key, Less pred, Func f)
 Deletes the item from the list using pred predicate for searching. More...
 
template<typename K >
guarded_ptr extract (K const &key)
 Extracts the item from the list with specified key. More...
 
template<typename K , typename Less >
guarded_ptr extract_with (K 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 map contains key using pred predicate for searching. More...
 
template<typename Q , typename Func >
bool find (Q const &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 const &key, Less pred, Func f)
 Finds the key val using pred predicate for searching. More...
 
template<typename K >
guarded_ptr get (K const &key)
 Finds the key and return the item found. More...
 
template<typename K , typename Less >
guarded_ptr get_with (K const &key, Less pred)
 Finds the key and return the item found. More...
 
bool empty () const
 Checks if the list is empty.
 
size_t size () const
 Returns list's item count. More...
 
void clear ()
 Clears the list.
 
stat const & statistics () const
 Returns const reference to internal statistics.
 
Forward iterators (only for debugging purpose)
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 Public Attributes

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

Additional Inherited Members

- Protected Types inherited from cds::intrusive::MichaelList< GC, implementation_defined, Traits >
typedef node_type::atomic_marked_ptr atomic_node_ptr
 Atomic node pointer.
 
typedef node_type::marked_ptr marked_node_ptr
 Node marked pointer.
 
typedef atomic_node_ptr auxiliary_head
 Auxiliary head type (for split-list support)
 
typedef implementation_defined 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 used
 
typedef traits::stat stat
 Internal statistics.
 
typedef get_node_traits< value_type, node_type, hook >::type node_traits
 node traits
 
typedef michael_list::get_link_checker< node_type, traits::link_checker >::type link_checker
 link checker
 
typedef GC gc
 Garbage collector.
 
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
 Memory ordering. See cds::opt::memory_model option.
 
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::MichaelList< GC, implementation_defined, Traits >
 MichaelList ()
 Default constructor initializes empty list.
 
 ~MichaelList ()
 Destroys the list object.
 
bool insert (value_type &val)
 Inserts new node. More...
 
bool insert (value_type &val, Func f)
 Inserts new node. More...
 
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 list. More...
 
bool erase (Q const &key)
 Deletes the item from the list. More...
 
bool erase (Q const &key, Func func)
 Deletes the item from the list. More...
 
bool erase_with (Q const &key, Less pred)
 Deletes the item from the list using pred predicate for searching. More...
 
bool erase_with (Q const &key, Less pred, Func f)
 Deletes the item from the list using pred predicate for searching. More...
 
guarded_ptr extract (Q const &key)
 Extracts the item from the list with specified key. More...
 
guarded_ptr extract_with (Q const &key, Less pred)
 Extracts the item using compare functor pred. More...
 
bool find (Q &key, Func f)
 Finds key in the list. More...
 
bool find_with (Q &key, Less pred, Func f)
 Finds the key using pred predicate for searching. More...
 
bool contains (Q const &key)
 Checks whether the list contains key. More...
 
bool contains (Q const &key, Less pred)
 Checks whether the list contains key using pred predicate for searching. More...
 
guarded_ptr get (Q const &key)
 Finds the key and return the item found. More...
 
guarded_ptr get_with (Q const &key, Less pred)
 Finds the key and return the item found. More...
 
void clear ()
 Clears the list. 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.
 
iterator begin ()
 Returns a forward iterator addressing the first element in a list. More...
 
const_iterator begin () const
 Returns a forward const iterator addressing the first element in a list.
 
iterator end ()
 Returns an iterator that addresses the location succeeding the last element in a list. More...
 
const_iterator end () const
 Returns an const iterator that addresses the location succeeding the last element in a list.
 
const_iterator cbegin () const
 Returns a forward const iterator addressing the first element in a list.
 
const_iterator cend () const
 Returns an const iterator that addresses the location succeeding the last element in a list.
 
- Protected Attributes inherited from cds::intrusive::MichaelList< GC, implementation_defined, Traits >
atomic_node_ptr m_pHead
 Head pointer.
 
item_counter m_ItemCounter
 Item counter.
 
stat m_Stat
 Internal statistics.
 
- Static Protected Attributes inherited from cds::intrusive::MichaelList< GC, implementation_defined, Traits >
static constexpr const size_t c_nHazardPtrCount
 Count of hazard pointer required for the algorithm.
 

Detailed Description

template<typename GC, typename Key, typename Value, typename Traits = michael_list::traits>
class cds::container::MichaelKVList< GC, Key, Value, Traits >

Michael's ordered list for key-value pair.

This is key-value variation of non-intrusive MichaelList. Like standard container, this implementation split a value stored into two part - constant key and alterable value.

Usually, ordered single-linked list is used as a building block for the hash table implementation. The complexity of searching is O(N) where N is the item count in the list, not in the hash table.

Template arguments:

  • GC - garbage collector used
  • Key - key type of an item stored in the list. It should be copy-constructible
  • Value - value type stored in a list
  • Traits - type traits, default is michael_list::traits

It is possible to declare option-based list with cds::container::michael_list::make_traits metafunction instead of Traits template argument. For example, the following traits-based declaration of gc::HP Michael's list

#include <cds/container/michael_kvlist_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::michael_list::traits
{
typedef my_compare compare;
};
// Declare traits-based list

is equivalent for the following option-based list

#include <cds/container/michael_kvlist_hp.h>
// my_compare is the same
// Declare option-based list
typedef cds::container::MichaelKVList< cds::gc::HP, int, int,
>::type
> option_based_list;
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:
    #include <cds/container/michael_kvlist_hp.h>
  • for gc::DHP:
    #include <cds/container/michael_kvlist_dhp.h>
  • for RCU:
    #include <cds/container/michael_kvlist_rcu.h>
  • for gc::nogc:
    #include <cds/container/michael_kvlist_nogc.h>

Member Typedef Documentation

§ const_iterator

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
typedef iterator_type<true> cds::container::MichaelKVList< GC, Key, Value, Traits >::const_iterator

Const forward iterator.

For iterator's features and requirements see iterator

§ iterator

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
typedef iterator_type<false> cds::container::MichaelKVList< GC, Key, Value, Traits >::iterator

Forward iterator.

The forward iterator for Michael's 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.
Warning
Use this iterator on the concurrent container for debugging purpose only.

The iterator interface to access item data:

  • operator -> - returns a pointer to value_type for iterator
  • operator * - returns a reference (a const reference for const_iterator) to value_type for iterator
  • const key_type& key() - returns a key reference for iterator
  • mapped_type& val() - retuns a value reference for iterator (const reference for const_iterator)

For both functions the iterator should not be equal to end()

Constructor & Destructor Documentation

§ MichaelKVList()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
cds::container::MichaelKVList< GC, Key, Value, Traits >::MichaelKVList ( )
inline

Default constructor.

Initializes empty list

§ ~MichaelKVList()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
cds::container::MichaelKVList< GC, Key, Value, Traits >::~MichaelKVList ( )
inline

List destructor.

Clears the list

Member Function Documentation

§ begin()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
iterator cds::container::MichaelKVList< GC, Key, Value, 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 Key , typename Value , typename Traits = michael_list::traits>
template<typename Q >
bool cds::container::MichaelKVList< GC, Key, Value, 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 Key , typename Value , typename Traits = michael_list::traits>
template<typename Q , typename Less >
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::contains ( Q const &  key,
Less  pred 
)
inline

Checks whether the map 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. Less must imply the same element order as the comparator used for building the list.

§ emplace()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
template<typename K , typename... Args>
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::emplace ( K &&  key,
Args &&...  args 
)
inline

Inserts a new node using move semantics.

key_type field of new item is constructed from key argument, mapped_type field is done from args.

Returns true if inserting successful, false otherwise.

§ end()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
iterator cds::container::MichaelKVList< GC, Key, Value, 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. Internally, end returning value equals to nullptr.

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 Key , typename Value , typename Traits = michael_list::traits>
template<typename K >
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::erase ( K const &  key)
inline

Deletes key from the list.

Returns true if key is found and has been deleted, false otherwise

§ erase() [2/2]

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
template<typename K , typename Func >
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::erase ( K const &  key,
Func  f 
)
inline

Deletes key from the list.

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& val) { ... }
};

Return true if key is found and deleted, false otherwise

See also: erase

§ erase_with() [1/2]

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
template<typename K , typename Less >
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::erase_with ( K const &  key,
Less  pred 
)
inline

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

The function is an analog of erase(K 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 Key , typename Value , typename Traits = michael_list::traits>
template<typename K , typename Less , typename Func >
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::erase_with ( K 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(K 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 Key , typename Value , typename Traits = michael_list::traits>
template<typename K >
guarded_ptr cds::container::MichaelKVList< GC, Key, Value, Traits >::extract ( K 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 K that can be not the same as key_type.

The disposer specified in Traits class template parameter is called automatically by garbage collector GC specified in class' template parameters when returned guarded_ptr object will be destroyed or released.

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
}

§ extract_with()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
template<typename K , typename Less >
guarded_ptr cds::container::MichaelKVList< GC, Key, Value, Traits >::extract_with ( K const &  key,
Less  pred 
)
inline

Extracts the item from the list with comparing functor pred.

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

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

§ find()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
template<typename Q , typename Func >
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::find ( Q const &  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 );
};

where item is the item found.

The functor may change item.second that is reference to value of node. 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 function returns true if key is found, false otherwise.

§ find_with()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
template<typename Q , typename Less , typename Func >
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::find_with ( Q const &  key,
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. pred must imply the same element order as the comparator used for building the list.

§ get()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
template<typename K >
guarded_ptr cds::container::MichaelKVList< GC, Key, Value, Traits >::get ( K const &  key)
inline

Finds the key and return the item found.

The function searches the item with key equal to key and returns it 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
}

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

§ get_with()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
template<typename K , typename Less >
guarded_ptr cds::container::MichaelKVList< GC, Key, Value, Traits >::get_with ( K const &  key,
Less  pred 
)
inline

Finds the key and return the item found.

The function is an analog of get( guarded_ptr& ptr, K const&) but pred is used for comparing the keys.

Less functor has the semantics like std::less but should take arguments of type key_type and K 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 Key , typename Value , typename Traits = michael_list::traits>
template<typename K >
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::insert ( K &&  key)
inline

Inserts new node with key and default value.

The function creates a node with key and default value, and then inserts the node created into the list.

Preconditions:

  • The key_type should be constructible from value of type K. In trivial case, K is equal to key_type.
  • The mapped_type should be default-constructible.

Returns true if inserting successful, false otherwise.

§ insert() [2/2]

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
template<typename K , typename V >
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::insert ( K &&  key,
V &&  val 
)
inline

Inserts new node with a key and a value.

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

Preconditions:

  • The key_type should be constructible from key of type K.
  • The mapped_type should be constructible from val of type V.

Returns true if inserting successful, false otherwise.

§ insert_with()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
template<typename K , typename Func >
bool cds::container::MichaelKVList< GC, Key, Value, Traits >::insert_with ( K &&  key,
Func  func 
)
inline

Inserts new node and initialize it by a functor.

This function inserts new node with key key and if inserting is successful then it calls func functor with signature

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

The argument item of user-defined functor func is the reference to the item inserted. item.second is a reference to item's value that may be changed. User-defined functor func should guarantee that during changing item's value no any other changes could be made on this list's item by concurrent threads. The user-defined functor is called only if inserting is successful.

The key_type should be constructible from value of type K.

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

  • create a new item from key;
  • insert the new item into the list;
  • if inserting is successful, initialize the value of item by calling func functor

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

Warning
See insert item troubleshooting

§ size()

template<typename GC , typename Key , typename Value , typename Traits = michael_list::traits>
size_t cds::container::MichaelKVList< GC, Key, Value, Traits >::size ( ) const
inline

Returns list's item count.

The value returned depends on item counter provided by Traits. 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 Key , typename Value , typename Traits = michael_list::traits>
template<typename K , typename Func >
std::pair<bool, bool> cds::container::MichaelKVList< GC, Key, Value, Traits >::update ( K &&  key,
Func  f,
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. (note that in this case the key_type should be constructible from type K). 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 );
};

with arguments:

  • bNew - true if the item has been inserted, false otherwise
  • item - the item found or inserted

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

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.

Warning
See insert item troubleshooting

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 08:49:38 by Doxygen 1.8.12