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firebird-mirror/extern/libcds/cds/container/striped_map.h
2022-10-08 20:46:39 +03:00

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40 KiB
C++

// Copyright (c) 2006-2018 Maxim Khizhinsky
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE or copy at http://www.boost.org/LICENSE_1_0.txt)
#ifndef CDSLIB_CONTAINER_STRIPED_MAP_H
#define CDSLIB_CONTAINER_STRIPED_MAP_H
#include <type_traits>
#include <cds/container/striped_set.h>
#include <cds/container/striped_set/adapter.h>
#include <cds/details/binary_functor_wrapper.h>
namespace cds { namespace container {
//@cond
namespace details {
template <class Container, typename... Options>
class make_striped_map
{
typedef StripedSet< Container, Options...> billet;
typedef typename billet::options billet_options;
typedef typename billet_options::hash billet_hash;
typedef typename Container::value_type pair_type;
typedef typename pair_type::first_type key_type;
struct options: public billet_options {
struct hash: public billet_hash {
size_t operator()( pair_type const& v ) const
{
return billet_hash::operator()( v.first );
}
template <typename Q>
size_t operator()( Q const& v ) const
{
return billet_hash::operator()( v );
}
};
};
public:
typedef StripedSet< Container, cds::opt::type_traits< options > > type ; ///< metafunction result
};
}
//@endcond
/// Striped hash map
/** @ingroup cds_nonintrusive_map
Source
- [2008] Maurice Herlihy, Nir Shavit "The Art of Multiprocessor Programming"
Lock striping is very simple technique.
The map consists of the bucket table and the array of locks.
Initially, the capacity of lock array and bucket table is the same.
When the map is resized, bucket table capacity will be doubled but lock array will not.
The lock \p i protects each bucket \p j, where <tt> j = i mod L </tt>,
where \p L - the size of lock array.
Template arguments:
- \p Container - the container class that is used as bucket entry. The \p Container class should support
an uniform interface described below.
- \p Options - options
The \p %StripedMap class does not exactly specify the type of container that should be used as a \p Container bucket.
Instead, the class supports different container type for the bucket, for exampe, \p std::list, \p std::map and others.
Remember that \p %StripedMap class algorithm ensures sequential blocking access to its bucket through the mutex type you specify
among \p Options template arguments.
The \p Options are:
- \p cds::opt::mutex_policy - concurrent access policy.
Available policies: \p striped_set::striping, \p striped_set::refinable.
Default is \p %striped_set::striping.
- \p cds::opt::hash - hash functor. Default option value see <tt>opt::v::hash_selector<opt::none> </tt>
which selects default hash functor for your compiler.
- \p cds::opt::compare - key comparison functor. No default functor is provided.
If the option is not specified, the \p %opt::less is used.
- \p cds::opt::less - specifies binary predicate used for key comparison. Default is \p std::less<T>.
- \p cds::opt::item_counter - item counter type. Default is \p atomicity::item_counter since some operation on the counter is performed
without locks. Note that item counting is an essential part of the map algorithm, so dummy counter
like as \p atomicity::empty_item_counter is not suitable.
- \p cds::opt::allocator - the allocator type using for memory allocation of bucket table and lock array. Default is \ref CDS_DEFAULT_ALLOCATOR.
- \p cds::opt::resizing_policy - the resizing policy that is a functor that decides when to resize the hash map.
Default option value depends on bucket container type:
for sequential containers like \p std::list, \p std::vector the resizing policy is <tt>striped_set::load_factor_resizing<4> </tt>;
for other type of containers like \p std::map, \p std::unordered_map the resizing policy is \p striped_set::no_resizing.
See \ref cds_striped_resizing_policy "available resizing policy".
Note that the choose of resizing policy depends of \p Container type:
for sequential containers like \p std::list, \p std::vector and so on, right choosing of the policy can
significantly improve performance.
For other, non-sequential types of \p Container (like a \p std::map)
the resizing policy is not so important.
- \p cds::opt::copy_policy - the copy policy which is used to copy items from the old map to the new one when resizing.
The policy can be optionally used in adapted bucket container for performance reasons of resizing.
The detail of copy algorithm depends on type of bucket container and explains below.
\p %opt::compare or \p %opt::less options are used only in some \p Container class for searching an item.
\p %opt::compare option has the highest priority: if \p %opt::compare is specified, \p %opt::less is not used.
You can pass other option that would be passed to <tt>adapt</tt> metafunction, see below.
<b>Internal details</b>
The \p %StripedMap class cannot utilize the \p Container container specified directly, but only its adapted variant which
supports an unified interface. Internally, the adaptation is made via \p striped_set::adapt metafunction that wraps bucket container
and provides the unified bucket interface suitable for \p %StripedMap. Such adaptation is completely transparent for you -
you don't need to call \p adapt metafunction directly, \p %StripedMap class's internal machinery itself invokes appropriate
\p adapt metafunction to adjust your \p Container container class to \p %StripedMap bucket's internal interface.
All you need is to include a right header before <tt>striped_hash_map.h</tt>.
By default, <tt>striped_set::adapt<AnyContainer, Options...> </tt> metafunction does not make any wrapping to \p AnyContainer,
so, the result <tt>striped_set::adapt<AnyContainer, Options...>::type </tt> is the same as \p AnyContainer.
However, there are a lot of specializations of \p adapt for well-known containers, see table below.
Any of this specialization wraps corresponding container making it suitable for the map's bucket.
Remember, you should include the proper header file for \p adapt <b>before</b> <tt>striped_map.h</tt>.
<table>
<tr>
<th>Container</th>
<th>.h-file for \p adapt</th>
<th>Example</th>
<th>Notes</th>
</tr>
<tr>
<td> \p std::list</td>
<td><tt><cds/container/striped_map/std_list.h></tt></td>
<td>\code
#include <cds/container/striped_map/std_list.h>
#include <cds/container/striped_hash_map.h>
typedef cds::container::StripedMap<
std::list< std::pair< const Key, V > >,
cds::opt::less< std::less<Key> >
> striped_map;
\endcode
</td>
<td>
The type of values stored in the \p std::list must be <tt> std::pair< const Key, V > </tt>, where \p Key - key type, and \p V - value type
The list is ordered by key \p Key.
Template argument pack \p Options <b>must</b> contain \p cds::opt::less or \p cds::opt::compare for type \p Key stored in the list.
</td>
</tr>
<tr>
<td> \p std::map</td>
<td><tt><cds/container/striped_map/std_map.h></tt></td>
<td>\code
#include <cds/container/striped_map/std_map.h>
#include <cds/container/striped_hash_map.h>
typedef cds::container::StripedMap<
std::map< Key, T, std::less<Key> >
> striped_map;
\endcode
</td>
<td>
</td>
</tr>
<tr>
<td> \p std::unordered_map</td>
<td><tt><cds/container/striped_map/std_hash_map.h></tt></td>
<td>\code
#include <cds/container/striped_map/std_hash_map.h>
#include <cds/container/striped_hash_map.h>
typedef cds::container::StripedMap<
std::unordered_map<
Key, T,
std::hash<Key>,
std::equal_to<Key>
>
> striped_map;
\endcode
</td>
<td>
You should provide two different hash function \p h1 and \p h2 - one for std::unordered_map and other for \p %StripedMap.
For the best result, \p h1 and \p h2 must be orthogonal i.e. <tt> h1(X) != h2(X) </tt> for any value \p X of type \p Key.
</td>
</tr>
<tr>
<td> \p boost::container::slist</td>
<td><tt><cds/container/striped_map/boost_slist.h></tt></td>
<td>\code
#include <cds/container/hash_smap/boost_slist.h>
#include <cds/container/striped_hash_map.h>
typedef cds::container::StripedMap<
boost::container::slist< std::pair< const Key, T > >
> striped_map;
\endcode
</td>
<td>
The type of values stored in the \p boost::container::slist must be <tt> std::pair< const Key, T > </tt>,
where \p Key - key type, and \p T - value type. The list is ordered.
\p Options <b>must</b> contain \p cds::opt::less or \p cds::opt::compare.
</td>
</tr>
<tr>
<td> \p boost::container::list</td>
<td><tt><cds/container/striped_map/boost_list.h></tt></td>
<td>\code
#include <cds/container/striped_map/boost_list.h>
#include <cds/container/striped_hash_map.h>
typedef cds::container::StripedMap<
boost::container::list< std::pair< const Key, T > >
> striped_map;
\endcode
</td>
<td>
The type of values stored in the \p boost::container::list must be <tt> std::pair< const Key, T > </tt>,
where \p Key - key type, and \p T - value type. The list is ordered.
\p Options <b>must</b> contain \p cds::opt::less or \p cds::opt::compare.
</td>
</tr>
<tr>
<td> \p boost::container::map</td>
<td><tt><cds/container/striped_map/boost_map.h></tt></td>
<td>\code
#include <cds/container/striped_map/boost_map.h>
#include <cds/container/striped_hash_map.h>
typedef cds::container::StripedMap<
boost::container::map< Key, T, std::less<Key> >
> striped_map;
\endcode
</td>
<td>
</td>
</tr>
<tr>
<td> \p boost::container::flat_map</td>
<td><tt><cds/container/striped_map/boost_flat_map.h></tt></td>
<td>\code
#include <cds/container/striped_map/boost_flat_map.h>
#include <cds/container/striped_hash_map.h>
typedef cds::container::StripedMap<
boost::container::flat_map< Key, T,
std::less< std::less<Key> >
>
> striped_map;
\endcode
</td>
<td>
</td>
</tr>
<tr>
<td> \p boost::unordered_map</td>
<td><tt><cds/container/striped_map/boost_unordered_map.h></tt></td>
<td>\code
#include <cds/container/striped_map/boost_unordered_map.h>
#include <cds/container/refinable_hash_map.h>
typedef cds::container::StripedMap<
boost::unordered_map< Key, T, boost::hash<Key>, std::equal_to<Key> >
> refinable_map;
\endcode
</td>
<td>
</td>
</tr>
</table>
You can use another container type as map's bucket.
Suppose, you have a container class \p MyBestContainer and you want to integrate it with \p %StripedMap as bucket type.
There are two possibility:
- either your \p MyBestContainer class has native support of bucket's interface;
in this case, you can use default <tt>striped_set::adapt</tt> metafunction;
- or your \p MyBestContainer class does not support bucket's interface; it means you should develop a specialization
<tt>cds::container::striped_set::adapt<MyBestContainer> </tt> metafunction providing necessary interface.
The <tt>striped_set::adapt< Container, Options... ></tt> metafunction has two template argument:
- \p Container is the class that should be used as the bucket, for example, <tt>std::list< std::pair< Key, T > ></tt>.
- \p Options pack is the options from \p %StripedMap declaration. The \p adapt metafunction can use
any option from \p Options for its internal use. For example, a \p compare option can be passed to \p adapt
metafunction via \p Options argument of \p %StripedMap declaration.
See \p striped_set::adapt metafunction for the description of interface that the bucket container must provide
to be \p %StripedMap compatible.
<b>Copy policy</b>
There are three predefined copy policy:
- \p cds::container::striped_set::copy_item - copy item from old bucket to new one when resizing using copy ctor. It is default policy for
any compiler that do not support move semantics
- \p cds::container::striped_set::move_item - move item from old bucket to new one when resizing using move semantics. It is default policy for
any compiler that support move semantics. If compiler does not support move semantics, the move policy is the same as \p copy_item
- \p cds::container::striped_set::swap_item - copy item from old bucket to new one when resizing using \p std::swap. Not all containers support
this copy policy, see details in table below.
You can define your own copy policy specifically for your case.
Note, right copy policy can significantly improve the performance of resizing.
<table>
<tr>
<th>Container</th>
<th>Policies</th>
</tr>
<tr>
<td>
- \p std::list
- \p boost::list
</td>
<td>\code
struct copy_item {
void operator()(
std::list< std::pair<const Key, T> >& list,
std::list<std::pair<const Key, T> >::iterator itInsert,
std::list<std::pair<const Key, T> >::iterator itWhat )
{
list.insert( itInsert, *itWhat );
}
} \endcode
\code
// The type T stored in the list must be swappable
struct swap_item {
void operator()(
std::list< std::pair<const Key, T> >& list,
std::list<std::pair<const Key, T> >::iterator itInsert,
std::list<std::pair<const Key, T> >::iterator itWhat )
{
std::pair<Key, T> newVal( itWhat->first, T());
std::swap( list.insert( itInsert, newVal )->second, itWhat->second );
}
} \endcode
\code
struct move_item {
void operator()(
std::list< std::pair<const Key, T> >& list,
std::list<std::pair<const Key, T> >::iterator itInsert,
std::list<std::pair<const Key, T> >::iterator itWhat )
{
list.insert( itInsert, std::move( *itWhat ));
}
} \endcode
</td>
</tr>
<tr>
<td>
- \p std::map
- \p std::unordered_map
- \p boost::container::map
- \p boost::container::flat_map
- \p boost::unordered_map
</td>
<td>\code
struct copy_item {
void operator()( std::map< Key, T>& map, std::map<Key, T>::iterator itWhat )
{
map.insert( *itWhat );
}
} \endcode
\code
struct swap_item {
void operator()( std::map< Key, T>& map, std::map<Key, T>::iterator itWhat )
{
std::swap(
map.insert(
std::map::value_type( itWhat->first, T())).first->second
, itWhat->second
));
}
} \endcode
\p T type must be swappable.
\code
struct move_item {
void operator()( std::map< Key, T>& map, std::map<Key, T>::iterator itWhat )
{
map.insert( std::move( *itWhat ));
}
} \endcode
</tr>
<tr>
<td> \p boost::container::slist</td>
<td>\code
struct copy_item {
void operator()(
bc::slist< std::pair<const Key, T> >& list,
bc::slist<std::pair<const Key, T> >::iterator itInsert,
bc::slist<std::pair<const Key, T> >::iterator itWhat )
{
list.insert_after( itInsert, *itWhat );
}
} \endcode
\code
// The type T stored in the list must be swappable
struct swap_item {
void operator()(
bc::slist< std::pair<const Key, T> >& list,
bc::slist<std::pair<const Key, T> >::iterator itInsert,
bc::slist<std::pair<const Key, T> >::iterator itWhat )
{
std::pair<Key, T> newVal( itWhat->first, T());
std::swap( list.insert( itInsert, newVal )->second, itWhat->second );
}
} \endcode
\code
struct move_item {
void operator()(
bc::slist< std::pair<const Key, T> >& list,
bc::slist<std::pair<const Key, T> >::iterator itInsert,
bc::slist<std::pair<const Key, T> >::iterator itWhat )
{
list.insert_after( itInsert, std::move( *itWhat ));
}
} \endcode
</td>
</tr>
</table>
<b>Advanced functions</b>
The library provides some advanced functions like \p erase_with(), \p find_with(),
that cannot be supported by all underlying containers.
The table below shows whether underlying container supports those functions
(the sign "+" means "container supports the function"):
<table>
<tr>
<th>Container</th>
<th>\p find_with</th>
<th>\p erse_with</th>
</tr>
<tr>
<td> \p std::list</td>
<td>+</td>
<td>+</td>
</tr>
<tr>
<td> \p std::map</td>
<td>-</td>
<td>-</td>
</tr>
<tr>
<td> \p std::unordered_map</td>
<td>-</td>
<td>-</td>
</tr>
<tr>
<td> \p boost::container::slist</td>
<td>+</td>
<td>+</td>
</tr>
<tr>
<td> \p boost::container::list</td>
<td>+</td>
<td>+</td>
</tr>
<tr>
<td> \p boost::container::map</td>
<td>-</td>
<td>-</td>
</tr>
<tr>
<td> \p boost::container::flat_map</td>
<td>-</td>
<td>-</td>
</tr>
<tr>
<td> \p boost::unordered_map</td>
<td>-</td>
<td>-</td>
</tr>
</table>
**/
template <class Container, typename... Options>
class StripedMap
#ifdef CDS_DOXYGEN_INVOKED
: protected StripedSet<Container, Options...>
#else
: protected details::make_striped_map< Container, Options...>::type
#endif
{
//@cond
typedef typename details::make_striped_map< Container, Options...>::type base_class;
//@endcond
public:
//@cond
typedef typename base_class::default_options default_options;
typedef typename base_class::options options;
//@endcond
typedef Container underlying_container_type ; ///< original intrusive container type for the bucket
typedef typename base_class::bucket_type bucket_type ; ///< container type adapted for hash set
typedef typename bucket_type::value_type value_type ; ///< pair type (<tt> std::pair<key_type const, mapped_type> </tt>)
typedef typename value_type::first_type key_type ; ///< key type
typedef typename value_type::second_type mapped_type ; ///< mapped type
typedef typename base_class::hash hash ; ///< Hash functor
typedef typename base_class::item_counter item_counter ; ///< Item counter
typedef typename base_class::resizing_policy resizing_policy ; ///< Resizing policy
typedef typename base_class::allocator_type allocator_type ; ///< allocator type specified in options.
typedef typename base_class::mutex_policy mutex_policy ; ///< Mutex policy
protected:
//@cond
typedef typename base_class::scoped_cell_lock scoped_cell_lock;
typedef typename base_class::scoped_full_lock scoped_full_lock;
typedef typename base_class::scoped_resize_lock scoped_resize_lock;
//@endcond
private:
//@cond
struct key_accessor {
key_type const& operator()( value_type const& p ) const
{
return p.first;
}
};
//@endcond
public:
/// Default ctor. The initial capacity is 16.
StripedMap()
: base_class()
{}
/// Ctor with initial capacity specified
StripedMap(
size_t nCapacity ///< Initial size of bucket table and lock array. Must be power of two, the minimum is 16.
) : base_class( nCapacity )
{}
/// Ctor with resizing policy (copy semantics)
/**
This constructor initializes m_ResizingPolicy member with copy of \p resizingPolicy parameter
*/
StripedMap(
size_t nCapacity ///< Initial size of bucket table and lock array. Must be power of two, the minimum is 16.
,resizing_policy const& resizingPolicy ///< Resizing policy
) : base_class( nCapacity, resizingPolicy )
{}
/// Ctor with resizing policy (move semantics)
/**
This constructor initializes m_ResizingPolicy member moving \p resizingPolicy parameter
Move semantics is used. Available only for the compilers that supports C++11 rvalue reference.
*/
StripedMap(
size_t nCapacity ///< Initial size of bucket table and lock array. Must be power of two, the minimum is 16.
,resizing_policy&& resizingPolicy ///< Resizing policy
) : base_class( nCapacity, std::forward<resizing_policy>(resizingPolicy))
{}
/// Destructor destroys internal data
~StripedMap()
{}
public:
/// Inserts new node with key and default value
/**
The function creates a node with \p key and default value, and then inserts the node created into the map.
Preconditions:
- The \p key_type should be constructible from a value of type \p K.
In trivial case, \p K is equal to \p key_type.
- The \p mapped_type should be default-constructible.
Returns \p true if inserting successful, \p false otherwise.
*/
template <typename K>
bool insert( K const& key )
{
return insert_with( key, [](value_type&){} );
}
/// Inserts new node
/**
The function creates a node with copy of \p val value
and then inserts the node created into the map.
Preconditions:
- The \p key_type should be constructible from \p key of type \p K.
- The \p mapped_type should be constructible from \p val of type \p V.
Returns \p true if \p val is inserted into the set, \p false otherwise.
*/
template <typename K, typename V>
bool insert( K const& key, V const& val )
{
return insert_with( key, [&val](value_type& item) { item.second = val ; } );
}
/// Inserts new node and initialize it by a functor
/**
This function inserts new node with key \p key and if inserting is successful then it calls
\p func functor with signature
\code
struct functor {
void operator()( value_type& item );
};
\endcode
The argument \p item of user-defined functor \p func is the reference
to the map's item inserted:
- <tt>item.first</tt> is a const reference to item's key that cannot be changed.
- <tt>item.second</tt> is a reference to item's value that may be changed.
The key_type should be constructible from value of type \p K.
The function allows to split creating of new item into two part:
- create item from \p key;
- insert new item into the map;
- if inserting is successful, initialize the value of item by calling \p func functor
This can be useful if complete initialization of object of \p mapped_type is heavyweight and
it is preferable that the initialization should be completed only if inserting is successful.
*/
template <typename K, typename Func>
bool insert_with( const K& key, Func func )
{
return base_class::insert( key, func );
}
/// For key \p key inserts data of type \p mapped_type created in-place from \p args
/**
Returns \p true if inserting successful, \p false otherwise.
*/
template <typename K, typename... Args>
bool emplace( K&& key, Args&&... args )
{
bool bOk;
bool bResize;
size_t nHash = base_class::hashing( std::forward<K>(key));
bucket_type * pBucket;
{
scoped_cell_lock sl( base_class::m_MutexPolicy, nHash );
pBucket = base_class::bucket( nHash );
bOk = pBucket->emplace( std::forward<K>(key), std::forward<Args>(args)...);
bResize = bOk && base_class::m_ResizingPolicy( ++base_class::m_ItemCounter, *this, *pBucket );
}
if ( bResize )
base_class::resize();
return bOk;
}
/// Updates the node
/**
The operation performs inserting or changing data with lock-free manner.
If \p key is not found in the map, then \p key is inserted iff \p bAllowInsert is \p true.
Otherwise, the functor \p func is called with item found.
The functor signature is:
\code
struct my_functor {
void operator()( bool bNew, value_type& item );
};
\endcode
with arguments:
- \p bNew - \p true if the item has been inserted, \p false otherwise
- \p item - item of the map
Returns <tt> std::pair<bool, bool> </tt> where \p first is true if operation is successful,
\p second is true if new item has been added or \p false if the item with \p key
already is in the map.
*/
template <typename K, typename Func>
std::pair<bool, bool> update( K const& key, Func func, bool bAllowInsert = true )
{
std::pair<bool, bool> result;
bool bResize;
size_t nHash = base_class::hashing( key );
bucket_type * pBucket;
{
scoped_cell_lock sl( base_class::m_MutexPolicy, nHash );
pBucket = base_class::bucket( nHash );
result = pBucket->update( key, func, bAllowInsert );
bResize = result.first && result.second && base_class::m_ResizingPolicy( ++base_class::m_ItemCounter, *this, *pBucket );
}
if ( bResize )
base_class::resize();
return result;
}
//@cond
template <typename K, typename Func>
CDS_DEPRECATED("ensure() is deprecated, use update() instead")
std::pair<bool, bool> ensure( K const& key, Func func )
{
return update( key, func, true );
}
//@endcond
/// Delete \p key from the map
/** \anchor cds_nonintrusive_StripedMap_erase
Return \p true if \p key is found and deleted, \p false otherwise
*/
template <typename K>
bool erase( K const& key )
{
return base_class::erase( key );
}
/// Deletes the item from the map using \p pred predicate for searching
/**
The function is an analog of \ref cds_nonintrusive_StripedMap_erase "erase(K const&)"
but \p pred is used for key comparing.
\p Less functor has the interface like \p std::less.
\p pred must imply the same element order as the comparator used for building the map.
@note This function is enabled if the compiler supports C++11
default template arguments for function template <b>and</b> the underlying container
supports \p %erase_with feature.
*/
template < typename K, typename Less
,typename Bucket = bucket_type, typename = typename std::enable_if< Bucket::has_erase_with >::type >
bool erase_with( K const& key, Less pred )
{
return erase_with( key, pred, [](value_type const&) {} );
}
/// Delete \p key from the map
/** \anchor cds_nonintrusive_StripedMap_erase_func
The function searches an item with key \p key, calls \p f functor
and deletes the item. If \p key is not found, the functor is not called.
The functor \p Func interface:
\code
struct extractor {
void operator()(value_type& item) { ... }
};
\endcode
Return \p true if key is found and deleted, \p false otherwise
*/
template <typename K, typename Func>
bool erase( K const& key, Func f )
{
return base_class::erase( key, f );
}
/// Deletes the item from the map using \p pred predicate for searching
/**
The function is an analog of \ref cds_nonintrusive_StripedMap_erase_func "erase(K const&, Func)"
but \p pred is used for key comparing.
\p Less functor has the interface like \p std::less.
\p pred must imply the same element order as the comparator used for building the map.
@note This function is enabled if the compiler supports C++11
default template arguments for function template <b>and</b> the underlying container
supports \p %erase_with feature.
*/
template <typename K, typename Less, typename Func
,typename Bucket = bucket_type, typename = typename std::enable_if< Bucket::has_erase_with >::type >
bool erase_with( K const& key, Less pred, Func f )
{
CDS_UNUSED( pred );
return base_class::erase_with( key, cds::details::predicate_wrapper< value_type, Less, key_accessor >(), f );
}
/// Find the key \p key
/** \anchor cds_nonintrusive_StripedMap_find_func
The function searches the item with key equal to \p key and calls the functor \p f for item found.
The interface of \p Func functor is:
\code
struct functor {
void operator()( value_type& item );
};
\endcode
where \p item is the item found.
The functor may change \p item.second.
The function returns \p true if \p key is found, \p false otherwise.
*/
template <typename K, typename Func>
bool find( K const& key, Func f )
{
return base_class::find( key, [&f]( value_type& pair, K const& ) mutable { f(pair); } );
}
/// Find the key \p val using \p pred predicate
/**
The function is an analog of \ref cds_nonintrusive_StripedMap_find_func "find(K const&, Func)"
but \p pred is used for key comparing
\p Less has the interface like \p std::less.
\p pred must imply the same element order as the comparator used for building the set.
@note This function is enabled if the compiler supports C++11
default template arguments for function template <b>and</b> the underlying container
supports \p %find_with feature.
*/
template <typename K, typename Less, typename Func
,typename Bucket = bucket_type, typename = typename std::enable_if< Bucket::has_find_with >::type >
bool find_with( K const& key, Less pred, Func f )
{
CDS_UNUSED( pred );
return base_class::find_with( key, cds::details::predicate_wrapper< value_type, Less, key_accessor >(),
[&f]( value_type& pair, K const& ) mutable { f(pair); } );
}
/// Checks whether the map contains \p key
/**
The function searches the item with key equal to \p key
and returns \p true if it is found, and \p false otherwise.
*/
template <typename K>
bool contains( K const& key )
{
return base_class::contains( key );
}
//@cond
template <typename K>
CDS_DEPRECATED("use contains()")
bool find( K const& key )
{
return contains( key );
}
//@endcond
/// Checks whether the set contains \p key using \p pred predicate for searching
/**
The function is similar to <tt>contains( key )</tt> but \p pred is used for key comparing.
\p Less functor has the interface like \p std::less.
\p Less must imply the same element order as the comparator used for building the set.
@note This function is enabled if the compiler supports C++11
default template arguments for function template <b>and</b> the underlying container
supports \p %contains() feature.
*/
template <typename K, typename Less
,typename Bucket = bucket_type, typename = typename std::enable_if< Bucket::has_find_with >::type >
bool contains( K const& key, Less pred )
{
CDS_UNUSED( pred );
return base_class::contains( key, cds::details::predicate_wrapper< value_type, Less, key_accessor >());
}
//@cond
template <typename K, typename Less
,typename Bucket = bucket_type, typename = typename std::enable_if< Bucket::has_find_with >::type >
CDS_DEPRECATED("use contains()")
bool find_with( K const& key, Less pred )
{
return contains( key, pred );
}
//@endcond
/// Clears the map
void clear()
{
base_class::clear();
}
/// Checks if the map is empty
/**
Emptiness is checked by item counting: if item count is zero then the map is empty.
*/
bool empty() const
{
return base_class::empty();
}
/// Returns item count in the map
size_t size() const
{
return base_class::size();
}
/// Returns the size of hash table
/**
The hash table size is non-constant and can be increased via resizing.
*/
size_t bucket_count() const
{
return base_class::bucket_count();
}
/// Returns lock array size
/**
The lock array size is constant.
*/
size_t lock_count() const
{
return base_class::lock_count();
}
/// Returns resizing policy object
resizing_policy& get_resizing_policy()
{
return base_class::get_resizing_policy();
}
/// Returns resizing policy (const version)
resizing_policy const& get_resizing_policy() const
{
return base_class::get_resizing_policy();
}
};
}} // namespace cds::container
#endif // #ifndef CDSLIB_CONTAINER_STRIPED_MAP_H