Michael's lock-free ordered single-linked list. More...

#include <cds/intrusive/michael_list_impl.h>

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

Public Types
typedef T	value_type
	type of value stored in the list

typedef Traits	options
	Traits template parameter.

typedef options::hook	hook
	hook type

typedef hook::node_type	node_type
	node type

typedef implementation_defined	key_comparator
	key comparision functor based on opt::compare and opt::less option setter.

typedef options::disposer	disposer
	disposer used

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

typedef michael_list::get_link_checker < node_type, options::link_checker >::type	link_checker
	link checker

typedef GC	gc
	Garbage collector.

typedef options::back_off	back_off
	back-off strategy

typedef options::item_counter	item_counter
	Item counting policy used.

typedef options::memory_model	memory_model
	Memory ordering. See cds::opt::memory_model option.

typedef iterator_type< false >	iterator
	Forward iterator. More...

typedef iterator_type< true >	const_iterator
	Const forward iterator. More...

Public Member Functions
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 ()
	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 ()
	Returns an const iterator that addresses the location succeeding the last element in a list.

	MichaelList ()
	Default constructor initializes empty list.

	~MichaelList ()
	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 >	ensure (value_type &val, Func func)
	Ensures that the `item` exists in the list. More...

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

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

template<typename Q , typename Less >
bool	erase_with (Q const &val, Less pred)
	Deletes the item from the list using `pred` predicate for searching. More...

template<typename Q , typename Func >
bool	erase (Q const &val, Func func)
	Deletes the item from the list. More...

template<typename Q , typename Less , typename Func >
bool	erase_with (Q const &val, Less pred, Func f)
	Deletes the item from the list using `pred` predicate for searching. More...

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

template<typename Q , typename Less , typename Func >
bool	find_with (Q const &val, Less pred, Func f)
	Finds the key `val` using `pred` predicate for searching. More...

template<typename Q >
bool	find (Q const &val)
	Finds the key `val`. More...

template<typename Q , typename Less >
bool	find_with (Q const &val, Less pred)
	Finds the key `val` using `pred` predicate for searching. More...

void	clear ()
	Clears the list. More...

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

size_t	size () const
	Returns list's item count. More...

Protected Types
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)

Protected Attributes
atomic_node_ptr	m_pHead
	Head pointer.

item_counter	m_ItemCounter
	Item counter.

Detailed Description

template<class GC, typename T, class Traits = michael_list::type_traits>
class cds::intrusive::MichaelList< GC, T, Traits >

Michael's lock-free ordered single-linked list.

Usually, ordered single-linked list is used as a building block for the hash table implementation.

Source:

[2002] Maged Michael "High performance dynamic lock-free hash tables and list-based sets"

Template arguments:

GC - Garbage collector used. Note the GC must be the same as the GC used for item type T (see michael_list::node).
T - type to be stored in the list. The type must be based on michael_list::node (for michael_list::base_hook) or it must have a member of type michael_list::node (for michael_list::member_hook).
Traits - type traits. See michael_list::type_traits for explanation.

It is possible to declare option-based list with cds::intrusive::michael_list::make_traits metafunction istead of Traits template argument.

Template argument list Options of cds::intrusive::michael_list::make_traits metafunction are:

opt::hook - hook used. Possible values are: michael_list::base_hook, michael_list::member_hook, michael_list::traits_hook. If the option is not specified, michael_list::base_hook<> and gc::HP is used.
opt::compare - key comparison functor. No default functor is provided. If the option is not specified, the opt::less is used.
opt::less - specifies binary predicate used for key comparision. Default is std::less<T>.
opt::back_off - back-off strategy used. If the option is not specified, the cds::backoff::Default is used.
opt::disposer - the functor used for dispose removed items. Default is opt::v::empty_disposer. Due the nature of GC schema the disposer may be called asynchronously.
opt::link_checker - the type of node's link fields checking. Default is opt::debug_check_link
opt::item_counter - the type of item counting feature. Default is atomicity::empty_item_counter that is no item counting.
opt::memory_model - C++ memory ordering model. Can be opt::v::relaxed_ordering (relaxed memory model, the default) or opt::v::sequential_consistent (sequentially consisnent memory model).

For example, the following traits-based declaration of gc::HP Michael's list

#include <cds/intrusive/michael_list_hp.h>
// Declare item stored in your list
struct item: public cds::intrusive::michael_list::node< cds::gc::HP >
{
    int nKey    ;
    // .... other data
};
// Declare comparator for the item
struct my_compare {
    int operator()( item const& i1, item const& i2 ) const
    {
        return i1.nKey - i2.nKey ;
    }
};
// Declare type_traits
struct my_traits: public cds::intrusive::michael_list::type_traits
{
    typedef cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::HP > >   hook    ;
    typedef my_compare compare ;
};
// Declare traits-based list
typedef cds::intrusive::MichaelList< cds::gc::HP, item, my_traits >     traits_based_list   ;

is equivalent for the following option-based list

#include <cds/intrusive/michael_list_hp.h>
// item struct and my_compare are the same
// Declare option-based list
typedef cds::intrusive::MichaelList< cds::gc::HP, item,
    typename cds::intrusive::michael_list::make_traits<
        cds::intrusive::opt::hook< cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::HP > > >    // hook option
        ,cds::intrusive::opt::compare< my_compare >     // item comparator option
    >::type
>     option_based_list   ;

Usage

There are different specializations of this template for each garbage collecting schema used. You should select GC needed and include appropriate .h-file:

for gc::HP:
#include <cds/intrusive/michael_list_hp.h>
for gc::PTB:
#include <cds/intrusive/michael_list_ptb.h>
for gc::HRC:
#include <cds/intrusive/michael_list_hrc.h>
for RCU type - see RCU-based MichaelList
for gc::nogc:
#include <cds/intrusive/michael_list_nogc.h>

See non-GC MichaelList

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

Example for gc::PTB and base hook:

// Include GC-related Michael's list specialization
#include <cds/intrusive/michael_list_ptb.h>
// Data stored in Michael's list
struct my_data: public cds::intrusive::michael_list::node< cds::gc::PTB >
{
    // key field
    std::string     strKey  ;
    // other data
    // ...
}   ;
// my_data comparing functor
struct my_data_cmp {
    int operator()( const my_data& d1, const my_data& d2 )
    {
        return d1.strKey.compare( d2.strKey )   ;
    }
    int operator()( const my_data& d, const std::string& s )
    {
        return d.strKey.compare(s)   ;
    }
    int operator()( const std::string& s, const my_data& d )
    {
        return s.compare( d.strKey )    ;
    }
} ;
// Declare type_traits
struct my_traits: public cds::intrusive::michael_list::type_traits
{
    typedef cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::PTB > >   hook    ;
    typedef my_data_cmp compare ;
};
// Declare list type
typedef cds::intrusive::MichaelList< cds::gc::PTB, my_data, my_traits >     traits_based_list   ;

Equivalent option-based code:

// GC-related specialization
#include <cds/intrusive/michael_list_ptb.h>
struct my_data {
    // see above
}   ;
struct compare {
    // see above
}   ;
// Declare option-based list
typedef cds::intrusive::MichaelList< cds::gc::PTB
    ,my_data
    , typename cds::intrusive::michael_list::make_traits<
        cds::intrusive::opt::hook< cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::PTB > > >
        ,cds::intrusive::opt::compare< my_data_cmp >
    >::type
> option_based_list   ;

Member Typedef Documentation

template<class GC, typename T, class Traits = michael_list::type_traits>

typedef iterator_type<true> cds::intrusive::MichaelList< GC, T, Traits >::const_iterator

Const forward iterator.

For iterator's features and requirements see iterator

template<class GC, typename T, class Traits = michael_list::type_traits>

typedef iterator_type<false> cds::intrusive::MichaelList< GC, T, 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, gc::HRC), 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.

Therefore, the use of iterators in concurrent environment is not good idea. Use the iterator on the concurrent container for debug purpose only.

Member Function Documentation

template<class GC, typename T, class Traits = michael_list::type_traits>

iterator cds::intrusive::MichaelList< GC, T, Traits >::begin ( )

inline

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

For empty list

begin() == end()

template<class GC, typename T, class Traits = michael_list::type_traits>

void cds::intrusive::MichaelList< GC, T, Traits >::clear ( )

inline

Clears the list.

The function unlink all items from the list.

template<class GC, typename T, class Traits = michael_list::type_traits>

iterator cds::intrusive::MichaelList< 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 NULL.

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

begin() == end()

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Func >

std::pair<bool, bool> cds::intrusive::MichaelList< GC, T, Traits >::ensure	(	value_type &	val,
		Func	func
	)

inline

Ensures that the item exists in the list.

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

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

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

with arguments:

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

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.

You may pass func argument by reference using boost::ref or cds::ref.

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

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Q >

bool cds::intrusive::MichaelList< GC, T, Traits >::erase ( Q const & val )

inline

Deletes the item from the list.

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

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Q , typename Func >

bool cds::intrusive::MichaelList< GC, T, Traits >::erase	(	Q const &	val,
		Func	func
	)

inline

Deletes the item from the list.

The function searches an item with key equal to val in the list, call func functor with item found, unlinks it from the list, and returns true. The Func interface is

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

The functor may be passed by reference using boost:ref

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

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Q , typename Less >

bool cds::intrusive::MichaelList< GC, T, Traits >::erase_with	(	Q const &	val,
		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.

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Q , typename Less , typename Func >

bool cds::intrusive::MichaelList< GC, T, Traits >::erase_with	(	Q const &	val,
		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.

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Q , typename Func >

bool cds::intrusive::MichaelList< GC, T, Traits >::find	(	Q &	val,
		Func	f
	)

inline

Finds 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.

You may pass f argument by reference using boost::ref or cds::ref.

The functor may change non-key fields of item. Note that the function is only guarantee that item cannot be disposed 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 val 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 val is found, false otherwise.

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Q , typename Func >

bool cds::intrusive::MichaelList< GC, T, Traits >::find	(	Q const &	val,
		Func	f
	)

inline

Finds 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 const& val ) ;
};

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

You may pass f argument by reference using boost::ref or cds::ref.

The functor may change non-key fields of item. Note that the function is only guarantee that item cannot be disposed 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 val is found, false otherwise.

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Q >

bool cds::intrusive::MichaelList< GC, T, Traits >::find ( Q const & val )

inline

Finds the key val.

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

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Q , typename Less , typename Func >

bool cds::intrusive::MichaelList< GC, 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. pred must imply the same element order as the comparator used for building the list.

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Q , typename Less , typename Func >

bool cds::intrusive::MichaelList< GC, T, Traits >::find_with	(	Q const &	val,
		Less	pred,
		Func	f
	)

inline

Finds the key val using pred predicate for searching.

The function is an analog of find(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.

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Q , typename Less >

bool cds::intrusive::MichaelList< GC, T, Traits >::find_with	(	Q const &	val,
		Less	pred
	)

inline

Finds the key val using pred predicate for searching.

The function is an analog of find(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.

template<class GC, typename T, class Traits = michael_list::type_traits>

bool cds::intrusive::MichaelList< GC, T, Traits >::insert ( value_type & val )

inline

Inserts new node.

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

Returns true if val is linked into the list, false otherwise.

template<class GC, typename T, class Traits = michael_list::type_traits>

template<typename Func >

bool cds::intrusive::MichaelList< GC, T, Traits >::insert	(	value_type &	val,
		Func	f
	)

inline

Inserts new node.

This function is intended for derived non-intrusive containers.

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

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

The functor signature is:

void func( value_type& val ) ;

where val is the item inserted. User-defined functor f should guarantee that during changing val no any other changes could be made on this list's item by concurrent threads. The user-defined functor is called only if the inserting is success and may be passed by reference using boost::ref.

template<class GC, typename T, class Traits = michael_list::type_traits>

size_t cds::intrusive::MichaelList< GC, T, Traits >::size ( ) const

inline

Returns list's item count.

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

Warning: 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.

template<class GC, typename T, class Traits = michael_list::type_traits>

bool cds::intrusive::MichaelList< GC, T, Traits >::unlink ( value_type & val )

inline

Unlinks the item val from the list.

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

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

The function returns true if success and false otherwise.

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

cds/intrusive/michael_list_impl.h

Public Types

Public Member Functions

Protected Types

Protected Attributes

Detailed Description

template<class GC, typename T, class Traits = michael_list::type_traits> class cds::intrusive::MichaelList< GC, T, Traits >

Member Typedef Documentation

Member Function Documentation

template<class GC, typename T, class Traits = michael_list::type_traits>
class cds::intrusive::MichaelList< GC, T, Traits >