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

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 >:
cds::intrusive::EllenBinTree< 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_typeguarded_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 :

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

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 2.2.0 Developed by Maxim Khizhinsky aka khizmax 2007 - 2017
Autogenerated Wed Jan 4 2017 08:49:34 by Doxygen 1.8.12