Set based on Ellen's et al binary search tree. More...

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

Inheritance diagram for cds::container::EllenBinTreeSet< GC, Key, T, Traits >:

Public Types
typedef GC	gc
	Garbage collector.

typedef Key	key_type
	type of a key to be stored in internal nodes; key is a part of `value_type`

typedef T	value_type
	type of value to be stored in the binary tree

typedef Traits	traits
	Traits template parameter.

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

typedef base_class::item_counter	item_counter
	Item counting policy used.

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

typedef base_class::stat	stat
	internal statistics type

typedef traits::key_extractor	key_extractor
	key extracting functor

typedef traits::back_off	back_off
	Back-off strategy.

typedef traits::allocator	allocator_type
	Allocator for leaf nodes.

typedef base_class::node_allocator	node_allocator
	Internal node allocator.

typedef base_class::update_desc_allocator	update_desc_allocator
	Update descriptor allocator.

typedef gc::template guarded_ptr< leaf_node, value_type, details::guarded_ptr_cast_set< leaf_node, value_type > >	guarded_ptr
	Guarded pointer.

Public Types inherited from cds::intrusive::EllenBinTree< GC, Key, T, Traits >
typedef GC	gc
	Garbage collector.

typedef Key	key_type
	type of a key to be stored in internal nodes; key is a part of `value_type`

typedef T	value_type
	type of value stored in the binary tree

typedef Traits	traits
	Traits template parameter.

typedef traits::hook	hook
	hook type

typedef hook::node_type	node_type
	node type

typedef traits::disposer	disposer
	leaf node disposer

typedef traits::back_off	back_off
	back-off strategy

typedef gc::template guarded_ptr< value_type >	guarded_ptr
	Guarded pointer.

typedef implementation_defined	key_comparator
	key compare functor based on `Traits::compare` and `Traits::less`

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

typedef traits::item_counter	item_counter
	Item counting policy.

typedef traits::memory_model	memory_model
	Memory ordering, see `cds::opt::memory_model`.

typedef traits::stat	stat
	internal statistics type

typedef traits::key_extractor	key_extractor
	key extracting functor

typedef traits::node_allocator	node_allocator
	Allocator for internal node.

typedef traits::update_desc_allocator	update_desc_allocator
	Update descriptor allocator.

Public Member Functions
	EllenBinTreeSet ()
	Default constructor.

	~EllenBinTreeSet ()
	Clears the set.

template<typename Q >
bool	insert (Q const &val)
	Inserts new node. More...

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

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

template<typename... Args>
bool	emplace (Args &&... args)
	Inserts data of type `value_type` created in-place from `args`. More...

template<typename Q >
bool	erase (Q const &key)
	Delete `key` 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` predicate for searching. More...

template<typename Q , typename Func >
bool	erase (Q const &key, Func f)
	Delete `key` 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` predicate for searching. More...

guarded_ptr	extract_min ()
	Extracts an item with minimal key from the set. More...

guarded_ptr	extract_max ()
	Extracts an item with maximal key from the set. More...

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

template<typename Q , typename Less >
guarded_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)
	Find the key `key`. More...

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

template<typename Q >
bool	contains (Q const &key)
	Checks whether the 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 >
guarded_ptr	get (Q const &key)
	Finds `key` and returns the item found. More...

template<typename Q , typename Less >
guarded_ptr	get_with (Q const &key, Less pred)
	Finds `key` with predicate `pred` and returns the item found. More...

void	clear ()
	Clears the set (not atomic) More...

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

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

stat const &	statistics () const
	Returns const reference to internal statistics.

bool	check_consistency () const
	Checks internal consistency (not atomic, not thread-safe) More...

Public Member Functions inherited from cds::intrusive::EllenBinTree< GC, Key, T, Traits >
	EllenBinTree ()
	Default constructor.

	~EllenBinTree ()
	Clears the tree.

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 tree. More...

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

template<typename Q , typename Less >
bool	erase_with (const Q &key, Less pred)
	Delete the item from the tree with comparing functor `pred`. More...

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

template<typename Q , typename Less , typename Func >
bool	erase_with (Q const &key, Less pred, Func f)
	Delete the item from the tree with comparing functor `pred`. More...

guarded_ptr	extract_min ()
	Extracts an item with minimal key from the tree. More...

guarded_ptr	extract_max ()
	Extracts an item with maximal key from the tree. More...

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

template<typename Q , typename Less >
guarded_ptr	extract_with (Q const &key, Less pred)
	Extracts an item from the tree using `pred` for searching. More...

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

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

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

template<typename Q , typename Less , typename Func >
bool	find_with (Q &key, Less pred, Func f) const
	Finds the key `key` with comparing functor `pred`. More...

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

template<typename Q , typename Less >
guarded_ptr	get_with (Q const &key, Less pred) const
	Finds `key` with predicate `pred` and returns the item found. More...

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

void	clear ()
	Clears the tree (thread safe, not atomic) More...

void	unsafe_clear ()
	Clears the tree (not thread safe) More...

size_t	size () const
	Returns item count in the tree. More...

stat const &	statistics () const
	Returns const reference to internal statistics.

bool	check_consistency () const
	Checks internal consistency (not atomic, not thread-safe) More...

Additional Inherited Members
Static Public Attributes inherited from cds::intrusive::EllenBinTree< GC, Key, T, Traits >
static constexpr const size_t	c_nHazardPtrCount = 9
	Count of hazard pointer required for the algorithm.

Protected Attributes inherited from cds::intrusive::EllenBinTree< GC, Key, T, Traits >
item_counter	m_ItemCounter
	item counter

stat	m_Stat
	internal statistics

Detailed Description

template<class GC, typename Key, typename T, class Traits = ellen_bintree::traits>
class cds::container::EllenBinTreeSet< GC, Key, T, Traits >

Set based on Ellen's et al binary search tree.

Source:

[2010] F.Ellen, P.Fatourou, E.Ruppert, F.van Breugel "Non-blocking Binary Search Tree"

EllenBinTreeSet is an unbalanced leaf-oriented binary search tree that implements the set abstract data type. Nodes maintains child pointers but not parent pointers. Every internal node has exactly two children, and all data of type T currently in the tree are stored in the leaves. Internal nodes of the tree are used to direct find operation along the path to the correct leaf. The keys (of Key type) stored in internal nodes may or may not be in the set. Key type is a subset of T type. There should be exactly defined a key extracting functor for converting object of type T to object of type Key.

Due to extract_min and extract_max member functions the EllenBinTreeSet can act as a priority queue. In this case you should provide unique compound key, for example, the priority value plus some uniformly distributed random value.

Warning: Recall the tree is unbalanced. The complexity of operations is O(log N) for uniformly distributed random keys, but in the worst case the complexity is O(N).

Note: In the current implementation we do not use helping technique described in the original paper. In Hazard Pointer schema helping is too complicated and does not give any observable benefits. Instead of helping, when a thread encounters a concurrent operation it just spins waiting for the operation done. Such solution allows greatly simplify the implementation of tree.

Template arguments :

GC - safe memory reclamation (i.e. light-weight garbage collector) type, like cds::gc::HP, cds::gc::DHP
Key - key type, a subset of T
T - type to be stored in tree's leaf nodes.
Traits - set traits, default is ellen_bintree::traits It is possible to declare option-based tree with ellen_bintree::make_set_traits metafunction instead of Traits template argument.

Note

Do not include <cds/container/impl/ellen_bintree_set.h> header file directly. There are header file for each GC type:

<cds/container/ellen_bintree_set_hp.h> - for cds::gc::HP
<cds/container/ellen_bintree_set_dhp.h> - for cds::gc::DHP
<cds/container/ellen_bintree_set_rcu.h> - for RCU GC (see RCU-based EllenBinTreeSet)

Predicate requirements

Traits::less, Traits::compare and other predicates using with member fuctions should accept at least parameters of type T and Key in any combination. For example, for Foo struct with std::string key field the appropiate less functor is:

struct Foo
{
    std::string m_strKey;
    ...
};
struct less {
    bool operator()( Foo const& v1, Foo const& v2 ) const
    { return v1.m_strKey < v2.m_strKey ; }
    bool operator()( Foo const& v, std::string const& s ) const
    { return v.m_strKey < s ; }
    bool operator()( std::string const& s, Foo const& v ) const
    { return s < v.m_strKey ; }
    // Support comparing std::string and char const *
    bool operator()( std::string const& s, char const * p ) const
    { return s.compare(p) < 0 ; }
    bool operator()( Foo const& v, char const * p ) const
    { return v.m_strKey.compare(p) < 0 ; }
    bool operator()( char const * p, std::string const& s ) const
    { return s.compare(p) > 0; }
    bool operator()( char const * p, Foo const& v ) const
    { return v.m_strKey.compare(p) > 0; }
};

Member Function Documentation

◆ check_consistency()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::check_consistency ( ) const

inline

Checks internal consistency (not atomic, not thread-safe)

The debugging function to check internal consistency of the tree.

◆ clear()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

void cds::container::EllenBinTreeSet< GC, Key, T, Traits >::clear ( )

inline

Clears the set (not atomic)

The function unlink all items from the tree. The function is not atomic, thus, in multi-threaded environment with parallel insertions this sequence

set.clear();

assert( set.empty());

the assertion could be raised.

For each leaf the disposer will be called after unlinking.

◆ contains() [1/2]

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q >

bool cds::container::EllenBinTreeSet< GC, Key, T, 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.

◆ contains() [2/2]

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q , typename Less >

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::contains	(	Q const &	key,
		Less	pred
	)

inline

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

The function is similar to 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 set.

◆ emplace()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename... Args>

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::emplace ( Args &&... args )

inline

Inserts data of type value_type created in-place from args.

Returns true if inserting successful, false otherwise.

◆ erase() [1/2]

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q >

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::erase ( Q const & key )

inline

Delete key from the set.

The 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<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q , typename Func >

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::erase	(	Q const &	key,
		Func	f
	)

inline

Delete key from the set.

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 const& val);
};

Since the key of MichaelHashSet's value_type is not explicitly specified, template parameter Q defines the key type searching in the list. The list item comparator should be able to compare the type T of list item and the type Q.

Return true if key is found and deleted, false otherwise

◆ erase_with() [1/2]

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q , typename Less >

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::erase_with	(	Q const &	key,
		Less	pred
	)

inline

Deletes the item from the set 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. Less must imply the same element order as the comparator used for building the set.

◆ erase_with() [2/2]

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q , typename Less , typename Func >

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::erase_with	(	Q const &	key,
		Less	pred,
		Func	f
	)

inline

Deletes the item from the set 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. Less must imply the same element order as the comparator used for building the set.

◆ extract()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q >

guarded_ptr cds::container::EllenBinTreeSet< GC, Key, T, Traits >::extract ( Q const & key )

inline

Extracts an item from the tree.

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

The guarded pointer prevents deallocation of returned item, see cds::gc::guarded_ptr for explanation.

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

◆ extract_max()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

guarded_ptr cds::container::EllenBinTreeSet< GC, Key, T, Traits >::extract_max ( )

inline

Extracts an item with maximal key from the set.

If the set is not empty, the function returns a guarded pointer to maximal value. If the set is empty, the function returns an empty guarded_ptr.

Note: Due the concurrent nature of the set, the function extracts nearly maximal key. It means that the function gets rightmost leaf of the tree and tries to unlink it. During unlinking, a concurrent thread may insert an item with key great than leftmost item's key. So, the function returns the item with maximum key at the moment of tree traversing.

The guarded pointer prevents deallocation of returned item, see cds::gc::guarded_ptr for explanation.

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

◆ extract_min()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

guarded_ptr cds::container::EllenBinTreeSet< GC, Key, T, Traits >::extract_min ( )

inline

Extracts an item with minimal key from the set.

If the set is not empty, the function returns a guarded pointer to minimum value. If the set is empty, the function returns an empty guarded_ptr.

Note: Due the concurrent nature of the set, the function extracts nearly minimum key. It means that the function gets leftmost leaf of the tree and tries to unlink it. During unlinking, a concurrent thread may insert an item with key less than leftmost item's key. So, the function returns the item with minimum key at the moment of tree traversing.

The guarded pointer prevents deallocation of returned item, see cds::gc::guarded_ptr for explanation.

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

◆ extract_with()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q , typename Less >

guarded_ptr cds::container::EllenBinTreeSet< GC, Key, T, 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 has the interface like std::less. pred must imply the same element order as the comparator used for building the set.

◆ find()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q , typename Func >

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::find	(	Q &	key,
		Func	f
	)

inline

Find 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 may 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's 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 may be not the same as value_type.

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

◆ find_with()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q , typename Less , typename Func >

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::find_with	(	Q &	key,
		Less	pred,
		Func	f
	)

inline

Finds the key key using pred predicate for searching.

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

◆ get()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q >

guarded_ptr cds::container::EllenBinTreeSet< GC, Key, T, Traits >::get ( Q const & key )

inline

Finds key and returns the item found.

The function searches the item with key equal to key and returns the item found as an guarded pointer. The function returns true if key is found, false otherwise.

The guarded pointer prevents deallocation of returned item, see cds::gc::guarded_ptr for explanation.

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

◆ get_with()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q , typename Less >

guarded_ptr cds::container::EllenBinTreeSet< GC, Key, T, Traits >::get_with	(	Q const &	key,
		Less	pred
	)

inline

Finds key with predicate pred and returns the item found.

The function is an analog of get(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 set.

◆ insert() [1/2]

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q >

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::insert ( Q const & val )

inline

Inserts new node.

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

The type Q should contain at least the complete key for the node. The object of value_type should be constructible from a value of type Q. In trivial case, Q is equal to value_type.

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

◆ insert() [2/2]

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q , typename Func >

bool cds::container::EllenBinTreeSet< GC, Key, T, Traits >::insert	(	Q const &	val,
		Func	f
	)

inline

Inserts new node.

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-fields 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 set's item by concurrent threads. The user-defined functor is called only if the inserting is success.

◆ size()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

size_t cds::container::EllenBinTreeSet< GC, Key, T, Traits >::size ( ) const

inline

Returns item count in the set.

Only leaf nodes containing user data are counted.

The value returned depends on item counter type provided by Traits template parameter. If it is atomicity::empty_item_counter this function always returns 0.

The function is not suitable for checking the tree emptiness, use empty() member function for this purpose.

◆ update()

template<class GC , typename Key , typename T , class Traits = ellen_bintree::traits>

template<typename Q , typename Func >

std::pair<bool, bool> cds::container::EllenBinTreeSet< GC, Key, T, Traits >::update	(	const Q &	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 into the set iff bAllowInsert is true. Otherwise, the functor func is called with item found. The functor func signature is:

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

with arguments: with arguments:

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

The functor can 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.

Returns std::pair<bool, bool> where first is true if operation is successful, i.e. the node has been inserted or updated, 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 file:

cds/container/impl/ellen_bintree_set.h

Public Types

Public Member Functions

Additional Inherited Members

Detailed Description

template<class GC, typename Key, typename T, class Traits = ellen_bintree::traits> class cds::container::EllenBinTreeSet< GC, Key, T, Traits >

Member Function Documentation

◆ check_consistency()

◆ clear()

◆ contains() [1/2]

◆ contains() [2/2]

◆ emplace()

◆ erase() [1/2]

◆ erase() [2/2]

◆ erase_with() [1/2]

◆ erase_with() [2/2]

◆ extract()

◆ extract_max()

◆ extract_min()

◆ extract_with()

◆ find()

◆ find_with()

◆ get()

◆ get_with()

◆ insert() [1/2]

◆ insert() [2/2]

◆ size()

◆ update()

template<class GC, typename Key, typename T, class Traits = ellen_bintree::traits>
class cds::container::EllenBinTreeSet< GC, Key, T, Traits >