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

Iterable ordered list. More...

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

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

Public Types

typedef T value_type
 Type of value stored in the list.
 
typedef Traits traits
 List traits.
 
typedef base_class::gc gc
 Garbage collector used.
 
typedef base_class::back_off back_off
 Back-off strategy used.
 
typedef maker::data_allocator_type allocator_type
 Allocator type used for allocate/deallocate data.
 
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 base_class::guarded_ptr guarded_ptr
 Guarded pointer.
 

Public Member Functions

 IterableList ()
 Default constructor. More...
 
 ~IterableList ()
 List destructor. More...
 
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 Q , typename Func >
std::pair< bool, bool > update (Q &&key, Func func, bool bAllowInsert=true)
 Updates data by key. More...
 
template<typename Q >
std::pair< bool, bool > upsert (Q &&key, bool bInsert=true)
 Insert or update. 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 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) const
 Checks whether the list contains key. More...
 
template<typename Q , typename Less >
bool contains (Q const &key, Less pred) const
 Checks whether the list contains key using pred predicate for searching. More...
 
template<typename Q , typename Func >
bool find (Q &key, Func f) const
 Finds key and perform an action with it. More...
 
template<typename Q >
iterator find (Q const &key) const
 Finds key in the list and returns iterator pointed to the item found. More...
 
template<typename Q , typename Less , typename Func >
bool find_with (Q &key, Less pred, Func f) const
 Finds key using pred predicate for searching. More...
 
template<typename Q , typename Less >
iterator find_with (Q const &key, Less pred) const
 Finds key in the list using pred predicate for searching and returns iterator pointed to the item found. More...
 
template<typename Q >
guarded_ptr get (Q const &key) const
 Finds key and return the item found. More...
 
template<typename Q , typename Less >
guarded_ptr get_with (Q const &key, Less pred) const
 Finds key and return the item found. More...
 
bool empty () const
 Checks if the list is empty. More...
 
size_t size () const
 Returns list's item count. More...
 
void clear ()
 Clears the list (thread safe, not atomic)
 
stat const & statistics () const
 Returns const reference to internal statistics.
 

Static Public Attributes

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

Thread-safe forward iterators

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::IterableList< GC, T, Traits >
typedef T value_type
 type of value stored in the list
 
typedef Traits traits
 Traits template parameter.
 
typedef iterable_list::node< value_typenode_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 for value_type
 
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 traits::node_allocator node_allocator
 Node allocator.
 
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::IterableList< GC, T, Traits >
 IterableList ()
 Default constructor initializes empty list.
 
 ~IterableList ()
 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 bInsert=true)
 Updates the node. More...
 
std::pair< bool, bool > upsert (value_type &val, bool bInsert=true)
 Insert or update. 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 (Q const &key, Func func)
 Deletes the item 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 using compare functor pred. More...
 
template<typename Q , typename Func >
bool find (Q &key, Func f) const
 Finds key in the list. More...
 
template<typename Q >
iterator find (Q const &key) const
 Finds key in the list and returns iterator pointed to the item found. More...
 
template<typename Q , typename Less , typename Func >
bool find_with (Q &key, Less pred, Func f) const
 Finds the key using pred predicate for searching. More...
 
template<typename Q , typename Less >
iterator find_with (Q const &key, Less pred) const
 Finds key in the list using pred predicate for searching and returns iterator pointed to the item found. More...
 
template<typename Q >
bool contains (Q const &key) const
 Checks whether the list contains key. More...
 
template<typename Q , typename Less >
bool contains (Q const &key, Less pred) const
 Checks whether the list contains key using pred predicate for searching. More...
 
template<typename Q >
guarded_ptr get (Q const &key) const
 Finds the key and return the item found. More...
 
template<typename Q , typename Less >
guarded_ptr get_with (Q const &key, Less pred) const
 Finds the key and return the item found. More...
 
void clear ()
 Clears the list (thread safe, not atomic)
 
bool empty () const
 Checks if the list is empty. More...
 
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 cbegin () const
 Returns a forward const iterator addressing the first element in a list.
 
const_iterator begin () 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::IterableList< 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 = iterable_list::traits>
class cds::container::IterableList< GC, T, Traits >

Iterable ordered list.

This lock-free list implementation supports thread-safe iterators.

Usually, ordered single-linked list is used as a building block for the hash table implementation. Iterable list is suitable for almost append-only hash table because the list doesn't delete its internal node when erasing a key but it is marked them as empty to be reused in the future. However, plenty of empty nodes degrades performance.

The complexity of searching is O(N).

Template arguments:

  • GC - Garbage collector used.
  • T - type to be stored in the list.
  • Traits - type traits, default is iterable_list::traits.

Unlike standard container, this implementation does not divide type T into key and value part and may be used as a main building block for hash set algorithms. The key is a function (or a part) of type T, and this function is specified by Traits::compare functor or Traits::less predicate.

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

It is possible to declare option-based list with cds::container::iterable_list::make_traits metafunction istead of Traits template argument. For example, the following traits-based declaration of gc::HP iterable list

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

is equivalent for the following option-based list

#include <cds/container/iterable_list_hp.h>
// my_compare is the same
// Declare option-based list
typedef cds::container::IterableList< cds::gc::HP, 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/iterable_list_hp.h>
  • for gc::DHP:
    #include <cds/container/iterable_list_dhp.h>
  • for RCU:
    #include <cds/container/iterable_list_rcu.h>

Member Typedef Documentation

§ const_iterator

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

Const forward iterator.

For iterator's features and requirements see iterator

§ iterator

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

Forward iterator.

The forward iterator for iterable list has some features:

  • it has no post-increment operator
  • to protect the value, the iterator contains a GC-specific guard. For some GC (like as gc::HP), a guard is a limited resource per thread, so an exception (or assertion) "no free guard" may be thrown if the limit of guard count per thread is exceeded.
  • The iterator cannot be moved across thread boundary since it contains thread-private GC's guard.
  • Iterator is thread-safe: even if an element the iterator points to is removed, the iterator stays valid because it contains the guard keeping the value from to be recycled.

The iterator interface:

class iterator {
public:
// Default constructor
// Copy constructor
iterator( iterator const& src );
// Dereference operator
value_type * operator ->() const;
// Dereference operator
value_type& operator *() const;
// Preincrement operator
iterator& operator ++();
// Assignment operator
iterator& operator = (iterator const& src);
// Equality operators
bool operator ==(iterator const& i ) const;
bool operator !=(iterator const& i ) const;
};
Note
For two iterators pointed to the same element the value can be different; this code
if ( it1 == it2 )
assert( &(*it1) == &(*it2));
can throw assertion. The point is that the iterator stores the value of element which can be modified later by other thread. The guard inside the iterator prevents recycling that value so the iterator's value remains valid even after such changing. Other iterator can observe modified value of the element.

Constructor & Destructor Documentation

§ IterableList()

template<typename GC, typename T, typename Traits = iterable_list::traits>
cds::container::IterableList< GC, T, Traits >::IterableList ( )
inline

Default constructor.

Initialize empty list

§ ~IterableList()

template<typename GC, typename T, typename Traits = iterable_list::traits>
cds::container::IterableList< GC, T, Traits >::~IterableList ( )
inline

List destructor.

Clears the list

Member Function Documentation

§ begin()

template<typename GC, typename T, typename Traits = iterable_list::traits>
iterator cds::container::IterableList< 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 = iterable_list::traits>
template<typename Q >
bool cds::container::IterableList< GC, T, Traits >::contains ( Q const &  key) const
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 = iterable_list::traits>
template<typename Q , typename Less >
bool cds::container::IterableList< GC, T, Traits >::contains ( Q const &  key,
Less  pred 
) const
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 = iterable_list::traits>
template<typename... Args>
bool cds::container::IterableList< GC, 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.

§ empty()

template<typename GC, typename T, typename Traits = iterable_list::traits>
bool cds::container::IterableList< GC, T, Traits >::empty ( ) const
inline

Checks if the list is empty.

Emptiness is checked by item counting: if item count is zero then the set is empty. Thus, if you need to use empty() you should provide appropriate (non-empty) iterable_list::traits::item_counter feature.

§ end()

template<typename GC, typename T, typename Traits = iterable_list::traits>
iterator cds::container::IterableList< 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. 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 T, typename Traits = iterable_list::traits>
template<typename Q >
bool cds::container::IterableList< GC, T, Traits >::erase ( Q const &  key)
inline

Delete key from the list.

Since the key of IterableList's item type value_type is not explicitly specified, template parameter Q sould contain the complete key to search in the list. The list item comparator should be able to compare the type value_type and the type Q.

Return true if key is found and deleted, false otherwise

§ erase() [2/2]

template<typename GC, typename T, typename Traits = iterable_list::traits>
template<typename Q , typename Func >
bool cds::container::IterableList< 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 it. 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 IterableList's item type value_type is not explicitly specified, template parameter Q should contain the complete key to search in the list. The list item comparator should be able to compare the type value_type of list item and the type Q.

Return true if key is found and deleted, false otherwise

§ erase_with() [1/2]

template<typename GC, typename T, typename Traits = iterable_list::traits>
template<typename Q , typename Less >
bool cds::container::IterableList< 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 = iterable_list::traits>
template<typename Q , typename Less , typename Func >
bool cds::container::IterableList< 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 = iterable_list::traits>
template<typename Q >
guarded_ptr cds::container::IterableList< 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 = iterable_list::traits>
template<typename Q , typename Less >
guarded_ptr cds::container::IterableList< 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 it should accept 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() [1/2]

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

Finds key and perform 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 function returns true if key is found, false otherwise.

§ find() [2/2]

template<typename GC, typename T, typename Traits = iterable_list::traits>
template<typename Q >
iterator cds::container::IterableList< GC, T, Traits >::find ( Q const &  key) const
inline

Finds key in the list and returns iterator pointed to the item found.

If key is not found the function returns end().

§ find_with() [1/2]

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

Finds 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.

§ find_with() [2/2]

template<typename GC, typename T, typename Traits = iterable_list::traits>
template<typename Q , typename Less >
iterator cds::container::IterableList< GC, T, Traits >::find_with ( Q const &  key,
Less  pred 
) const
inline

Finds key in the list using pred predicate for searching and returns iterator pointed to the item found.

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

If key is not found the function returns end().

§ get()

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

Finds 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 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 = iterable_list::traits>
template<typename Q , typename Less >
guarded_ptr cds::container::IterableList< GC, T, Traits >::get_with ( Q const &  key,
Less  pred 
) const
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 accept 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 = iterable_list::traits>
template<typename Q >
bool cds::container::IterableList< 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 least 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 = iterable_list::traits>
template<typename Q , typename Func >
bool cds::container::IterableList< 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& data );

The argument data of user-defined functor func is the reference to the list's item inserted. 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 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

The method 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.

Warning
See insert item troubleshooting

§ size()

template<typename GC, typename T, typename Traits = iterable_list::traits>
size_t cds::container::IterableList< GC, T, 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.

§ update()

template<typename GC, typename T, typename Traits = iterable_list::traits>
template<typename Q , typename Func >
std::pair<bool, bool> cds::container::IterableList< GC, T, Traits >::update ( Q &&  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 is called after inserting or replacing, it signature is:

void func( value_type& val, value_type * old );

where

  • val - a new data constructed from key
  • old - old value that will be retired. If new item has been inserted then old is nullptr.

The functor may change non-key fields of val; 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 such key already exists.

Warning
See insert item troubleshooting

§ upsert()

template<typename GC, typename T, typename Traits = iterable_list::traits>
template<typename Q >
std::pair<bool, bool> cds::container::IterableList< GC, T, Traits >::upsert ( Q &&  key,
bool  bInsert = true 
)
inline

Insert or update.

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

If the item key is not found in the list, then key is inserted iff bInsert is true. Otherwise, the current element is changed to key, the old element will be retired later.

value_type should be constructible from key.

Returns std::pair<bool, bool> where first is true if operation is successful, second is true if key has been added or false if the item with that key already in the list.


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 08:49:36 by Doxygen 1.8.12