Split-ordered list RCU specialization. More...

#include <cds/intrusive/split_list_rcu.h>

Public Types
typedef cds::urcu::gc< RCU >	gc
	RCU garbage collector.

typedef Traits	traits
	Traits template parameters.

typedef cds::opt::v::hash_selector< typename traits::hash >::type	hash
	Hash functor for value_type and all its derivatives that you use.

typedef OrderedList	ordered_list
	type of ordered list used as base for split-list

typedef ordered_list::value_type	value_type
	type of value stored in the split-list

typedef ordered_list::key_comparator	key_comparator
	key compare functor

typedef ordered_list::disposer	disposer
	Node disposer functor.

typedef ordered_list::rcu_lock	rcu_lock
	RCU scoped lock.

typedef ordered_list::exempt_ptr	exempt_ptr
	pointer to extracted node

typedef ordered_list::raw_ptr	raw_ptr

typedef traits::bit_reversal	bit_reversal
	Bit reversal algorithm, see `split_list::traits::bit_reversal`.

typedef traits::item_counter	item_counter
	Item counter type.

typedef traits::back_off	back_off
	back-off strategy for spinning

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

typedef traits::stat	stat
	Internal statistics.

Public Member Functions
	SplitListSet ()
	Initialize split-ordered list of default capacity. More...

	SplitListSet (size_t nItemCount, size_t nLoadFactor=1)
	Initialize split-ordered list. More...

	~SplitListSet ()
	Destroys split-list.

bool	insert (value_type &val)
	Inserts new node. More...

template<typename Func >
bool	insert (value_type &val, Func f)
	Inserts new node. More...

template<typename Func >
std::pair< bool, bool >	update (value_type &val, Func func, bool bAllowInsert=true)
	Updates the node. More...

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

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

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

template<typename Q , typename Func >
bool	erase (Q const &key, Func f)
	Deletes the item from the set. More...

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

template<typename Q >
exempt_ptr	extract (Q const &key)
	Extracts an item from the set. More...

template<typename Q , typename Less >
exempt_ptr	extract_with (Q const &key, Less pred)
	Extracts an item from the set using `pred` for searching. 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` with `pred` predicate for comparing. More...

template<typename Q >
bool	contains (Q const &key)
	Checks whether the set contains `key`. More...

template<typename Q , typename Less >
bool	contains (Q const &key, Less pred)
	Checks whether the set contains `key` using `pred` predicate for searching. More...

template<typename Q >
raw_ptr	get (Q const &key)
	Finds the key `key` and return the item found. More...

template<typename Q , typename Less >
raw_ptr	get_with (Q const &key, Less pred)
	Finds the key `key` and return the item found. More...

size_t	size () const
	Returns item count in the set.

bool	empty () const
	Checks if the set is empty. More...

void	clear ()
	Clears the set (not atomic)

stat const &	statistics () const
	Returns internal statistics.

OrderedList::stat const &	list_statistics () const
	Returns internal statistics for `OrderedList`.

Static Public Attributes
static constexpr const bool	c_bExtractLockExternal = ordered_list::c_bExtractLockExternal
	Group of `extract_xxx` functions require external locking if underlying ordered list requires that.

Forward iterators (thread-safe under RCU lock)
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 split-list. More...

iterator	end ()
	Returns an iterator that addresses the location succeeding the last element in a split-list. More...

const_iterator	begin () const
	Returns a forward const iterator addressing the first element in a split-list.

const_iterator	cbegin () const
	Returns a forward const iterator addressing the first element in a split-list.

const_iterator	end () const
	Returns an const iterator that addresses the location succeeding the last element in a split-list.

const_iterator	cend () const
	Returns an const iterator that addresses the location succeeding the last element in a split-list.

Detailed Description

template<class RCU, class OrderedList, class Traits = split_list::traits>
class cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >

Split-ordered list RCU specialization.

Hash table implementation based on split-ordered list algorithm discovered by Ori Shalev and Nir Shavit, see

[2003] Ori Shalev, Nir Shavit "Split-Ordered Lists - Lock-free Resizable Hash Tables"
[2008] Nir Shavit "The Art of Multiprocessor Programming"

The split-ordered list is a lock-free implementation of an extensible unbounded hash table. It uses original recursive split-ordering algorithm discovered by Ori Shalev and Nir Shavit that allows to split buckets without moving an item on resizing, see short algo description.

Implementation

Template parameters are:

RCU - one of RCU type
OrderedList - ordered list implementation used as bucket for hash set, for example, MichaelList, LazyList. The intrusive ordered list implementation specifies the type T stored in the hash-set, the comparing functor for the type T and other features specific for the ordered list.
Traits - set traits, default isd split_list::traits. Instead of defining Traits struct you can use option-based syntax provided by split_list::make_traits metafunction.

Note: About required features of hash functor see SplitList general description.

How to use: Before including <cds/intrusive/split_list_rcu.h> you should include appropriate RCU header file, see RCU type for list of existing RCU class and corresponding header files. For example, for general-purpose buffered RCU and MichaelList-based split-list you should include:
#include <cds/urcu/general_buffered.h>

#include <cds/intrusive/michael_list_rcu.h>

#include <cds/intrusive/split_list_rcu.h>

// Declare Michael's list for type Foo and default traits:

typedef cds::intrusive::MichaelList< cds::urcu::gc< cds::urcu::general_buffered<> >, Foo > rcu_michael_list;

// Declare split-list based on rcu_michael_list

typedef cds::intrusive::SplitListSet< cds::urcu::gc< cds::urcu::general_buffered<> >, rcu_michael_list > rcu_split_list;

Member Typedef Documentation

template<class RCU , class OrderedList , class Traits = split_list::traits>

typedef iterator_type<true> cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::const_iterator

Const forward iterator.

For iterator's features and requirements see iterator

template<class RCU , class OrderedList , class Traits = split_list::traits>

typedef iterator_type<false> cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::iterator

Forward iterator.

The forward iterator for a split-list has some features:

it has no post-increment operator
it depends on iterator of underlying OrderedList

You may safely use iterators in multi-threaded environment only under RCU lock. Otherwise, a crash is possible if another thread deletes the element the iterator points to.

template<class RCU , class OrderedList , class Traits = split_list::traits>

typedef ordered_list::raw_ptr cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::raw_ptr

pointer to the node for get() function

Constructor & Destructor Documentation

template<class RCU , class OrderedList , class Traits = split_list::traits>

cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::SplitListSet ( )

inline

Initialize split-ordered list of default capacity.

The default capacity is defined in bucket table constructor. See split_list::expandable_bucket_table, split_list::static_ducket_table which selects by split_list::dynamic_bucket_table option.

template<class RCU , class OrderedList , class Traits = split_list::traits>

cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::SplitListSet	(	size_t	nItemCount,
		size_t	nLoadFactor = `1`
	)

inline

Initialize split-ordered list.

Parameters

nItemCount	estimate average of item count
nLoadFactor	load factor - average item count per bucket. Small integer up to 8, default is 1.

Member Function Documentation

template<class RCU , class OrderedList , class Traits = split_list::traits>

iterator cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::begin ( )

inline

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

For empty list

begin() == end()

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q >

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::contains ( Q const & key )

inline

Checks whether the set contains key.

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

Note the hash functor specified for class Traits template parameter should accept a parameter of type Q that can be not the same as value_type. Otherwise, you may use contains( Q const&, Less pred ) functions with explicit predicate for key comparing.

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q , typename Less >

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::contains	(	Q const &	key,
		Less	pred
	)

inline

Checks whether the set 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.

template<class RCU , class OrderedList , class Traits = split_list::traits>

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::empty ( ) const

inline

Checks if the set is empty.

Emptiness is checked by item counting: if item count is zero then the set is empty. Thus, the correct item counting feature is an important part of split-list set implementation.

template<class RCU , class OrderedList , class Traits = split_list::traits>

iterator cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::end ( )

inline

Returns an iterator that addresses the location succeeding the last element in a split-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 split-list. For empty list

begin() == end()

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q >

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::erase ( Q const & key )

inline

Deletes the item from the set.

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

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 key is an item of that set, i.e. the pointer to item found is equal to &key .

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

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

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q , typename Func >

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::erase	(	Q const &	key,
		Func	f
	)

inline

Deletes the item from the set.

The function searches an item with key equal to key in the set, call f functor with item found, unlinks it from the set, and returns true. The disposer specified by OrderedList class template parameter is called by garbage collector GC asynchronously.

The Func interface is

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

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

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

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

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q , typename Less >

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::erase_with	(	Q const &	key,
		Less	pred
	)

inline

Deletes the item from the set using pred for searching.

The function is an analog of erase(Q const&) but cmp is used for key compare. Less has the interface like std::less. pred must imply the same element order as the comparator used for building the set.

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q , typename Less , typename Func >

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::erase_with	(	Q const &	key,
		Less	pred,
		Func	f
	)

inline

Deletes the item from the set using pred for searching.

The function is an analog of erase(Q const&, Func) but cmp is used for key compare. Less has the interface like std::less. pred must imply the same element order as the comparator used for building the set.

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q >

exempt_ptr cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::extract ( Q const & key )

inline

Extracts an item from the set.

The function searches an item with key equal to key in the set, unlinks it, and returns exempt_ptr pointer to the item found. If the item with the key equal to key is not found the function returns an empty exempt_ptr.

Depends on bucket_type you should or should not lock RCU before calling of this function:

for the set based on MichaelList RCU should not be locked
for the set based on LazyList RCU should be locked See ordered list implementation for details.

typedef cds::urcu::gc< general_buffered<> > rcu;
typedef cds::intrusive::MichaelList< rcu, Foo > rcu_michael_list;
typedef cds::intrusive::SplitListSet< rcu, rcu_michael_list, foo_traits > rcu_splitlist_set;
rcu_splitlist_set theSet;
// ...
rcu_splitlist_set::exempt_ptr p;
// For MichaelList we should not lock RCU
// Now, you can apply extract function
// Note that you must not delete the item found inside the RCU lock
p = theList.extract( 10 );
if ( p ) {
    // do something with p
    ...
}
// We may safely release p here
// release() passes the pointer to RCU reclamation cycle:
// it invokes RCU retire_ptr function with the disposer you provided for rcu_michael_list.
p.release();

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q , typename Less >

exempt_ptr cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::extract_with	(	Q const &	key,
		Less	pred
	)

inline

Extracts an item from the set using pred for searching.

The function is an analog of extract(Q const&) but pred is used for key compare. Less functor has the interface like std::less. pred must imply the same element order as the comparator used for building the set.

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q , typename Func >

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::find	(	Q &	key,
		Func	f
	)

inline

Finds the key key.

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

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

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

The function applies RCU lock internally.

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

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q , typename Less , typename Func >

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::find_with	(	Q &	key,
		Less	pred,
		Func	f
	)

inline

Finds the key key with pred predicate for comparing.

The function is an analog of find(Q&, Func) but cmp is used for key compare. Less has the interface like std::less. cmp must imply the same element order as the comparator used for building the set.

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q >

raw_ptr cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, 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 pointer to item found. If key is not found it returns nullptr.

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

RCU should be locked before call of this function. Returned item is valid only while RCU is locked:

typedef cds::intrusive::SplitListSet< your_template_parameters > set_class;
set_class theSet;
// ...
typename set_class::raw_ptr rp;
{
    // Lock RCU
    hash_set::rcu_lock lock;
    rp = theSet.get( 5 );
    if ( rp ) {
        // Deal with rp
        //...
    }
    // Unlock RCU by rcu_lock destructor
    // rp can be retired by disposer at any time after RCU has been unlocked
}

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Q , typename Less >

raw_ptr cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, 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 set.

template<class RCU , class OrderedList , class Traits = split_list::traits>

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::insert ( value_type & val )

inline

Inserts new node.

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

The function makes RCU lock internally.

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

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Func >

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, 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 creating of new item into two part:

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

The functor signature is:

void func( value_type& val );

where val is the item inserted.

The function makes RCU lock internally.

Warning: For MichaelList as the bucket see insert item troubleshooting. LazyList provides exclusive access to inserted item and does not require any node-level synchronization.

template<class RCU , class OrderedList , class Traits = split_list::traits>

bool cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::unlink ( value_type & val )

inline

Unlinks the item val from the set.

The function searches the item val in the set and unlinks it from the set if it is found and 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 set, i.e. the pointer to item found is equal to &val .

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

The function returns true if success and false otherwise.

template<class RCU , class OrderedList , class Traits = split_list::traits>

template<typename Func >

std::pair<bool, bool> cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >::update	(	value_type &	val,
		Func	func,
		bool	bAllowInsert = `true`
	)

inline

Updates the node.

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

If the item val is not found in the set, then val is inserted iff bAllowInsert is true. 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 set
val - argument val passed into the update() function If new item has been inserted (i.e. bNew is true) then item and val arguments refers to the same stuff.

The functor may change non-key fields of the item.

The function applies RCU lock internally.

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 is in the list.

Warning: For MichaelList as the bucket see insert item troubleshooting. LazyList provides exclusive access to inserted item and does not require any node-level synchronization.

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

cds/intrusive/split_list_rcu.h

Public Types

Public Member Functions

Static Public Attributes

Forward iterators (thread-safe under RCU lock)

Detailed Description

template<class RCU, class OrderedList, class Traits = split_list::traits> class cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >

Member Typedef Documentation

Constructor & Destructor Documentation

Member Function Documentation

template<class RCU, class OrderedList, class Traits = split_list::traits>
class cds::intrusive::SplitListSet< cds::urcu::gc< RCU >, OrderedList, Traits >