cds  2.2.0
cds::intrusive::MichaelHashSet< GC, OrderedList, Traits > Class Template Reference

Michael's hash set. More...

#include <cds/intrusive/michael_set.h>

Public Types

typedef GC gc
 Garbage collector.
 
typedef OrderedList ordered_list
 type of ordered list used as a bucket implementation
 
typedef Traits traits
 Set traits.
 
typedef ordered_list::value_type value_type
 type of value to be stored in the set
 
typedef ordered_list::key_comparator key_comparator
 key comparing functor
 
typedef ordered_list::disposer disposer
 Node disposer functor.
 
typedef ordered_list::stat stat
 Internal statistics.
 
typedef cds::opt::v::hash_selector< typename traits::hash >::type hash
 Hash functor for value_type and all its derivatives that you use.
 
typedef traits::item_counter item_counter
 Item counter type.
 
typedef traits::allocator allocator
 Bucket table allocator.
 
typedef ordered_list::guarded_ptr guarded_ptr
 Guarded pointer.
 

Public Member Functions

 MichaelHashSet (size_t nMaxItemCount, size_t nLoadFactor)
 Initializes hash set. More...
 
 ~MichaelHashSet ()
 Clears hash set object and destroys it.
 
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 element. More...
 
std::pair< bool, bool > upsert (value_type &val, bool bAllowInsert=true)
 Inserts or updates the node (only for IterableList) 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 predicate 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 predicate for searching. More...
 
template<typename Q >
guarded_ptr extract (Q const &key)
 Extracts the item with specified key. More...
 
template<typename Q , typename Less >
guarded_ptr extract_with (Q const &key, Less pred)
 Extracts the item using compare functor pred. More...
 
template<typename Q , typename Func >
bool find (Q &key, Func f)
 Finds the key key. More...
 
template<typename Q >
iterator find (Q &key)
 Finds key and returns iterator pointed to the item found (only for IterableList) 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 , typename Less >
iterator find_with (Q &key, Less pred)
 Finds key using pred predicate and returns iterator pointed to the item found (only for IterableList) 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 the key key and return the item found. More...
 
template<typename Q , typename Less >
guarded_ptr get_with (Q const &key, Less pred)
 Finds the key key and return the item found. More...
 
void clear ()
 Clears the set (non-atomic) More...
 
bool empty () const
 Checks if the set is empty. More...
 
size_t size () const
 Returns item count in the set.
 
stat const & statistics () const
 Returns const reference to internal statistics.
 
size_t bucket_count () const
 Returns the size of hash table. More...
 

Static Public Attributes

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

Forward iterators

typedef michael_set::details::iterator< internal_bucket_type, false > iterator
 Forward iterator. More...
 
typedef michael_set::details::iterator< internal_bucket_type, true > const_iterator
 Const forward iterator. More...
 
iterator begin ()
 Returns a forward iterator addressing the first element in a set. More...
 
iterator end ()
 Returns an iterator that addresses the location succeeding the last element in a set. More...
 
const_iterator begin () const
 Returns a forward const iterator addressing the first element in a set.
 
const_iterator cbegin () const
 Returns a forward const iterator addressing the first element in a set.
 
const_iterator end () const
 Returns an const iterator that addresses the location succeeding the last element in a set.
 
const_iterator cend () const
 Returns an const iterator that addresses the location succeeding the last element in a set.
 

Detailed Description

template<class GC, class OrderedList, class Traits = michael_set::traits>
class cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >

Michael's hash set.

Source:

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

Michael's hash table algorithm is based on lock-free ordered list and it is very simple. The main structure is an array T of size M. Each element in T is basically a pointer to a hash bucket, implemented as a singly linked list. The array of buckets cannot be dynamically expanded. However, each bucket may contain unbounded number of items.

Template parameters are:

  • GC - Garbage collector used. Note the GC must be the same as the GC used for OrderedList
  • OrderedList - ordered list implementation used as bucket for hash set, possible implementations: MichaelList, LazyList, IterableList. The intrusive ordered list implementation specifies the type T stored in the hash-set, the reclamation schema GC used by hash-set, the comparison functor for the type T and other features specific for the ordered list.
  • Traits - type traits. See michael_set::traits for explanation. Instead of defining Traits struct you can use option-based syntax with michael_set::make_traits metafunction.

There are several specializations of MichaelHashSet for each GC. You should include:

Hash functor

Some member functions of Michael's hash set accept the key parameter of type Q which differs from value_type. It is expected that type Q contains full key of value_type, and for equal keys of type Q and value_type the hash values of these keys must be equal. The hash functor Traits::hash should accept parameters of both type:

// Our node type
struct Foo {
std::string key_; // key field
// ... other fields
};
// Hash functor
struct fooHash {
size_t operator()( const std::string& s ) const
{
return std::hash( s );
}
size_t operator()( const Foo& f ) const
{
return (*this)( f.key_ );
}
};

How to use

First, you should define ordered list type to use in your hash set:

// For gc::HP-based MichaelList implementation
#include <cds/intrusive/michael_list_hp.h>
// cds::intrusive::MichaelHashSet declaration
#include <cds/intrusive/michael_set.h>
// Type of hash-set items
struct Foo: public cds::intrusive::michael_list::node< cds::gc::HP >
{
std::string key_ ; // key field
unsigned val_ ; // value field
// ... other value fields
};
// Declare comparator for the item
struct FooCmp
{
int operator()( const Foo& f1, const Foo& f2 ) const
{
return f1.key_.compare( f2.key_ );
}
};
// Declare bucket type for Michael's hash set
// The bucket type is any ordered list type like MichaelList, LazyList
typedef cds::intrusive::MichaelList< cds::gc::HP, Foo,
// hook option
// item comparator option
>::type
> Foo_bucket;

Second, you should declare Michael's hash set container:

// Declare hash functor
// Note, the hash functor accepts parameter type Foo and std::string
struct FooHash {
size_t operator()( const Foo& f ) const
{
return cds::opt::v::hash<std::string>()( f.key_ );
}
size_t operator()( const std::string& f ) const
{
return cds::opt::v::hash<std::string>()( f );
}
};
// Michael's set typedef
cds::gc::HP
,Foo_bucket
>::type
> Foo_set;

Now, you can use Foo_set in your application.

Like other intrusive containers, you may build several containers on single item structure:

#include <cds/intrusive/michael_list_hp.h>
#include <cds/intrusive/michael_list_dhp.h>
#include <cds/intrusive/michael_set.h>
struct tag_key1_idx;
struct tag_key2_idx;
// Your two-key data
// The first key is maintained by gc::HP, second key is maintained by gc::DHP garbage collectors
// (I don't know what is needed for, but it is correct)
struct Foo
: public cds::intrusive::michael_list::node< cds::gc::HP, tag_key1_idx >
, public cds::intrusive::michael_list::node< cds::gc::DHP, tag_key2_idx >
{
std::string key1_ ; // first key field
unsigned int key2_ ; // second key field
// ... value fields and fields for controlling item's lifetime
};
// Declare comparators for the item
struct Key1Cmp
{
int operator()( const Foo& f1, const Foo& f2 ) const { return f1.key1_.compare( f2.key1_ ) ; }
};
struct Key2Less
{
bool operator()( const Foo& f1, const Foo& f2 ) const { return f1.key2_ < f2.key1_ ; }
};
// Declare bucket type for Michael's hash set indexed by key1_ field and maintained by gc::HP
typedef cds::intrusive::MichaelList< cds::gc::HP, Foo,
// hook option
cds::intrusive::opt::hook< cds::intrusive::michael_list::base_hook< cds::opt::gc< cds::gc::HP >, tag_key1_idx > >
// item comparator option
>::type
> Key1_bucket;
// Declare bucket type for Michael's hash set indexed by key2_ field and maintained by gc::DHP
typedef cds::intrusive::MichaelList< cds::gc::DHP, Foo,
// hook option
// item comparator option
>::type
> Key2_bucket;
// Declare hash functor
struct Key1Hash {
size_t operator()( const Foo& f ) const { return cds::opt::v::hash<std::string>()( f.key1_ ) ; }
size_t operator()( const std::string& s ) const { return cds::opt::v::hash<std::string>()( s ) ; }
};
inline size_t Key2Hash( const Foo& f ) { return (size_t) f.key2_ ; }
// Michael's set indexed by key1_ field
cds::gc::HP
,Key1_bucket
>::type
> key1_set;
// Michael's set indexed by key2_ field
cds::gc::DHP
,Key2_bucket
>::type
> key2_set;

Member Typedef Documentation

§ const_iterator

template<class GC , class OrderedList , class Traits = michael_set::traits>
typedef michael_set::details::iterator< internal_bucket_type, true > cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::const_iterator

Const forward iterator.

For iterator's features and requirements see iterator

§ iterator

template<class GC , class OrderedList , class Traits = michael_set::traits>
typedef michael_set::details::iterator< internal_bucket_type, false > cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::iterator

Forward iterator.

The forward iterator for Michael's set is based on OrderedList forward iterator and has some features:

  • it has no post-increment operator
  • it iterates items in unordered fashion
  • The iterator cannot be moved across thread boundary because it may contain GC's guard that is thread-private GC data.

Iterator thread safety depends on type of OrderedList:

  • for MichaelList and LazyList: iterator guarantees safety even if you delete the item that iterator points to because that item is guarded by hazard pointer. However, in case of concurrent deleting operations it is no guarantee that you iterate all item in the set. Moreover, a crash is possible when you try to iterate the next element that has been deleted by concurrent thread. Use this iterator on the concurrent container for debugging purpose only.
  • for IterableList: iterator is thread-safe. You may use it freely in concurrent environment.

Constructor & Destructor Documentation

§ MichaelHashSet()

template<class GC , class OrderedList , class Traits = michael_set::traits>
cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::MichaelHashSet ( size_t  nMaxItemCount,
size_t  nLoadFactor 
)
inline

Initializes hash set.

The Michael's hash set is an unbounded container, but its hash table is non-expandable. At construction time you should pass estimated maximum item count and a load factor. The load factor is average size of one bucket - a small number between 1 and 10. The bucket is an ordered single-linked list, searching in the bucket has linear complexity O(nLoadFactor). The constructor defines hash table size as rounding nMaxItemCount / nLoadFactor up to nearest power of two.

Parameters
nMaxItemCountestimation of max item count in the hash set
nLoadFactorload factor: estimation of max number of items in the bucket. Small integer up to 10.

Member Function Documentation

§ begin()

template<class GC , class OrderedList , class Traits = michael_set::traits>
iterator cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::begin ( )
inline

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

For empty set

begin() == end()

§ bucket_count()

template<class GC , class OrderedList , class Traits = michael_set::traits>
size_t cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::bucket_count ( ) const
inline

Returns the size of hash table.

Since MichaelHashSet cannot dynamically extend the hash table size, the value returned is an constant depending on object initialization parameters, see MichaelHashSet::MichaelHashSet.

§ clear()

template<class GC , class OrderedList , class Traits = michael_set::traits>
void cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::clear ( )
inline

Clears the set (non-atomic)

The function unlink all items from the set. The function is not atomic. It cleans up each bucket and then resets the item counter to zero. If there are a thread that performs insertion while clear() is working the result is undefined in general case: empty() may return true but the set may contain item(s). Therefore, clear() may be used only for debugging purposes.

For each item the disposer is called after unlinking.

§ contains() [1/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q >
bool cds::intrusive::MichaelHashSet< GC, 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 the key 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.

§ contains() [2/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q , typename Less >
bool cds::intrusive::MichaelHashSet< GC, 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 set.

§ empty()

template<class GC , class OrderedList , class Traits = michael_set::traits>
bool cds::intrusive::MichaelHashSet< GC, 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 Michael's set implementation.

§ end()

template<class GC , class OrderedList , class Traits = michael_set::traits>
iterator cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::end ( )
inline

Returns an iterator that addresses the location succeeding the last element in a set.

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 set. For empty set

begin() == end()

§ erase() [1/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q >
bool cds::intrusive::MichaelHashSet< GC, 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, and returns true. If the item with key equal to key is not found the function return false.

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

§ erase() [2/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q , typename Func >
bool cds::intrusive::MichaelHashSet< GC, 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, and unlinks it from the set. The disposer specified in 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.

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

§ erase_with() [1/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q , typename Less >
bool cds::intrusive::MichaelHashSet< GC, OrderedList, 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. pred must imply the same element order as the comparator used for building the set.

§ erase_with() [2/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q , typename Less , typename Func >
bool cds::intrusive::MichaelHashSet< GC, OrderedList, 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. pred must imply the same element order as the comparator used for building the set.

§ extract()

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q >
guarded_ptr cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::extract ( Q const &  key)
inline

Extracts the item with specified key.

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

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

The disposer specified in OrderedList class' template parameter is called automatically by garbage collector GC when returned guarded_ptr object will be destroyed or released.

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

Usage:

michael_set theSet;
// ...
{
michael_set::guarded_ptr gp( theSet.extract( 5 ));
if ( gp ) {
// Deal with gp
// ...
}
// Destructor of gp releases internal HP guard
}

§ extract_with()

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q , typename Less >
guarded_ptr cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::extract_with ( Q const &  key,
Less  pred 
)
inline

Extracts the item using compare functor pred.

The function is an analog of extract(Q const&) but pred predicate is used for key comparing.

Less functor has the semantics like std::less but 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 list.

§ find() [1/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q , typename Func >
bool cds::intrusive::MichaelHashSet< GC, 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 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 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 may 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 returns true if key is found, false otherwise.

§ find() [2/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q >
iterator cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::find ( Q &  key)
inline

Finds key and returns iterator pointed to the item found (only for IterableList)

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

Note
This function is supported only for the set based on IterableList

§ find_with() [1/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q , typename Less , typename Func >
bool cds::intrusive::MichaelHashSet< GC, OrderedList, 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. pred must imply the same element order as the comparator used for building the set.

§ find_with() [2/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q , typename Less >
iterator cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::find_with ( Q &  key,
Less  pred 
)
inline

Finds key using pred predicate and returns iterator pointed to the item found (only for IterableList)

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

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

Note
This function is supported only for the set based on IterableList

§ get()

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q >
guarded_ptr cds::intrusive::MichaelHashSet< GC, 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 guarded pointer to the item found. If key is not found the function returns an empty guarded_ptr.

Note
Each guarded_ptr object uses one GC's guard which can be limited resource.

Usage:

michael_set theSet;
// ...
{
michael_set::guarded_ptr gp( theSet.get( 5 ));
if ( theSet.get( 5 )) {
// Deal with gp
//...
}
// Destructor of guarded_ptr releases internal HP guard
}

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

§ get_with()

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Q , typename Less >
guarded_ptr cds::intrusive::MichaelHashSet< GC, 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.

§ insert() [1/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
bool cds::intrusive::MichaelHashSet< GC, 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.

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

§ insert() [2/2]

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Func >
bool cds::intrusive::MichaelHashSet< GC, 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 user-defined functor is called only if the inserting is success.

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.

§ unlink()

template<class GC , class OrderedList , class Traits = michael_set::traits>
bool cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::unlink ( value_type val)
inline

Unlinks the item val from the set.

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

The function returns true if success and false otherwise.

§ update()

template<class GC , class OrderedList , class Traits = michael_set::traits>
template<typename Func >
std::pair<bool, bool> cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::update ( value_type val,
Func  func,
bool  bAllowInsert = true 
)
inline

Updates the element.

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

If the item val 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 depends of the type of OrderedList:

for MichaelList, LazyList

struct functor {
void operator()( 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 thing.

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

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.

for IterableList

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

where

  • val - argument val passed into the update() function
  • old - old value that will be retired. If new item has been inserted then old is nullptr.

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 set.

§ upsert()

template<class GC , class OrderedList , class Traits = michael_set::traits>
std::pair<bool, bool> cds::intrusive::MichaelHashSet< GC, OrderedList, Traits >::upsert ( value_type val,
bool  bAllowInsert = true 
)
inline

Inserts or updates the node (only for IterableList)

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 current element is changed to val, the old element will be retired later by call Traits::disposer.

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


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 08:49:51 by Doxygen 1.8.12