-//$$CDS-header$$
+/*
+ This file is a part of libcds - Concurrent Data Structures library
+
+ (C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2016
+
+ Source code repo: http://github.com/khizmax/libcds/
+ Download: http://sourceforge.net/projects/libcds/files/
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice, this
+ list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright notice,
+ this list of conditions and the following disclaimer in the documentation
+ and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
#ifndef CDSLIB_CONTAINER_BRONSON_AVLTREE_MAP_RCU_H
#define CDSLIB_CONTAINER_BRONSON_AVLTREE_MAP_RCU_H
+#include <functional>
#include <cds/container/impl/bronson_avltree_map_rcu.h>
namespace cds { namespace container {
Source:
- [2010] N.Bronson, J.Casper, H.Chafi, K.Olukotun "A Practical Concurrent Binary Search Tree"
-
- bla-bla-bla
+ - <a href="http://github.com/nbronson/snaptree">Java implementation</a>
+
+ This is a concurrent AVL tree algorithm that uses hand-over-hand optimistic validation,
+ a concurrency control mechanism for searching and navigating a binary search tree.
+ This mechanism minimizes spurious retries when concurrent structural changes cannot
+ affect the correctness of the search or navigation result.
+ The algorithm is based on partially external trees, a simple scheme that simplifies deletions
+ by leaving a routing node in the tree when deleting a node that has two children,
+ then opportunistically unlinking routing nodes during rebalancing. As in external trees,
+ which store values only in leaf nodes, deletions can be performed locally while holding
+ a fixed number of locks. Partially external trees, however, require far fewer routing nodes
+ than an external tree for most sequences of insertions and deletions.
+ The algorithm uses optimistic concurrency control, but carefully manage the
+ tree in such a way that all atomic regions have fixed read and write sets
+ that are known ahead of time. This allows to reduce practical overheads by embedding
+ the concurrency control directly. To perform tree operations using only fixed sized
+ atomic regions the algo uses the following mechanisms: search operations overlap atomic blocks as
+ in the hand-over-hand locking technique; mutations perform rebalancing separately;
+ and deletions occasionally leave a routing node in the tree.
<b>Template arguments</b>:
- \p RCU - one of \ref cds_urcu_gc "RCU type"
It is possible to declare option-based tree with \p bronson_avltree::make_traits metafunction
instead of \p Traits template argument.
+ There is \ref cds_container_BronsonAVLTreeMap_rcu_ptr "a specialization" for "key -> value pointer" map.
+
@note Before including <tt><cds/container/bronson_avltree_map_rcu.h></tt> you should include appropriate RCU header file,
see \ref cds_urcu_gc "RCU type" for list of existing RCU class and corresponding header files.
*/
/// Enabled or disabled @ref bronson_avltree::relaxed_insert "relaxed insertion"
static bool const c_bRelaxedInsert = traits::relaxed_insert;
+
+ /// Group of \p extract_xxx functions does not require external locking
+ static CDS_CONSTEXPR const bool c_bExtractLockExternal = base_class::c_bExtractLockExternal;
+
typedef typename base_class::rcu_lock rcu_lock; ///< RCU scoped lock
/// Returned pointer to \p mapped_type of extracted node
) == update_flags::result_inserted;
}
- /// For key \p key inserts data of type \p mapped_type created in-place from \p args
+ /// For \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 )
{
- return base_class::do_update( key, key_comparator(),
- [&]( node_type * pNode ) -> mapped_type*
- {
- assert( pNode->m_pValue.load( memory_model::memory_order_relaxed ) == nullptr );
- CDS_UNUSED( pNode );
- return cxx_allocator().New( std::forward<Args>(args)...);
- },
- update_flags::allow_insert
- ) == update_flags::result_inserted;
+ struct scoped_ptr
+ {
+ mapped_type * pVal;
+ scoped_ptr( mapped_type * p ): pVal( p ) {}
+ ~scoped_ptr() { if ( pVal ) cxx_allocator().Delete( pVal ); }
+ void release() { pVal = nullptr; }
+ };
+
+ scoped_ptr p( cxx_allocator().MoveNew( std::forward<Args>( args )... ));
+ if ( base_class::insert( std::forward<K>( key ), p.pVal )) {
+ p.release();
+ return true;
+ }
+ return false;
}
- /// Ensures that the \p key exists in the map
+ /// Updates the value for \p key
/**
The operation performs inserting or changing data with lock-free manner.
If the \p key not found in the map, then the new item created from \p key
- is inserted into the map (note that in this case the \ref key_type should be
- constructible from type \p K).
+ will be inserted into the map iff \p bAllowInsert is \p true
+ (note that in this case the \ref key_type should be constructible from type \p K).
Otherwise, the functor \p func is called with item found.
- The functor \p Func may be a functor:
+ The functor \p Func signature is:
\code
struct my_functor {
void operator()( bool bNew, key_type const& key, mapped_type& item );
- \p bNew - \p true if the item has been inserted, \p false otherwise
- \p item - value
- The functor may change any fields of the \p item. The functor is called under the node lock.
+ The functor may change any fields of the \p item. The functor is called under the node lock,
+ the caller can change any field of \p item.
RCU \p synchronize() method can be called. RCU should not be locked.
- Returns <tt> std::pair<bool, bool> </tt> where \p first is \p true if operation is successfull,
+ Returns <tt> std::pair<bool, bool> </tt> where \p first is \p true if operation is successful,
\p second is \p true if new item has been added or \p false if the item with \p key
- already is in the tree.
+ already exists.
*/
template <typename K, typename Func>
- std::pair<bool, bool> update( K const& key, Func func )
+ std::pair<bool, bool> update( K const& key, Func func, bool bAllowInsert = true )
{
int result = base_class::do_update( key, key_comparator(),
- [&func]( node_type * pNode ) -> mapped_type*
+ [&func]( node_type * pNode ) -> mapped_type*
{
mapped_type * pVal = pNode->m_pValue.load( memory_model::memory_order_relaxed );
if ( !pVal ) {
func( false, pNode->m_key, *pVal );
return pVal;
},
- update_flags::allow_insert | update_flags::allow_update
+ (bAllowInsert ? update_flags::allow_insert : 0) | update_flags::allow_update
);
return std::make_pair( result != 0, (result & update_flags::result_inserted) != 0 );
}
+
/// Delete \p key from the map
/**
RCU \p synchronize() method can be called. RCU should not be locked.
The functor \p Func interface:
\code
struct extractor {
- void operator()(mapped_type& item) { ... }
+ void operator()(key_type const& key, mapped_type& item) { ... }
};
\endcode
return base_class::extract_min();
}
- /// Extracts minimal key key and corresponding value
+ /// Extracts minimal key and corresponding value
/**
Returns \p exempt_ptr to the leftmost item.
If the tree is empty, returns empty \p exempt_ptr.
return base_class::extract_min( f );
}
- /// Extracts minimal key key and corresponding value
+ /// Extracts minimal key and corresponding value
/**
This function is a shortcut for the following call:
\code
key_type key;
exempt_ptr xp = theTree.extract_min( [&key]( key_type const& k ) { key = k; } );
- \endode
+ \endcode
\p key_type should be copy-assignable. The copy of minimal key
is returned in \p min_key argument.
*/
If the set is empty, returns empty \p exempt_ptr.
Note that the function returns only the value for maximal key.
- To retrieve its key use \p extract_max( Func ) member function.
+ To retrieve its key use \p extract_max( Func ) or \p extract_max_key(key_type&) member function.
@note Due the concurrent nature of the map, the function extracts <i>nearly</i> maximal key.
It means that the function gets rightmost leaf of the tree and tries to unlink it.
\code
key_type key;
exempt_ptr xp = theTree.extract_max( [&key]( key_type const& k ) { key = k; } );
- \endode
+ \endcode
\p key_type should be copy-assignable. The copy of maximal key
is returned in \p max_key argument.
*/
return base_class::find_with( key, pred, f );
}
- /// Find the key \p key
+ /// 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.
The function applies RCU lock internally.
*/
template <typename K>
- bool find( K const& key )
+ bool contains( K const& key )
{
- return base_class::find( key );
+ return base_class::contains( key );
}
- /// Finds the key \p val using \p pred predicate for searching
+ /// Checks whether the map contains \p key using \p pred predicate for searching
/**
- The function is an analog of \p find(K const&)
- but \p pred is used for key comparing.
+ 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 map.
+ \p Less must imply the same element order as the comparator used for building the set.
*/
template <typename K, typename Less>
- bool find_with( K const& key, Less pred )
+ bool contains( K const& key, Less pred )
{
- return base_class::find_with( key, pred );
+ return base_class::contains( key, pred );
}
/// Clears the map
return base_class::statistics();
}
+ /// Returns reference to \p sync_monitor object
+ sync_monitor& monitor()
+ {
+ return base_class::monitor();
+ }
+ //@cond
+ sync_monitor const& monitor() const
+ {
+ return base_class::monitor();
+ }
+ //@endcond
+
/// Checks internal consistency (not atomic, not thread-safe)
/**
The debugging function to check internal consistency of the tree.
void operator()( size_t nLevel, size_t hLeft, size_t hRight );
};
\endcode
- where
+ where
- \p nLevel - the level where the violation is found
- \p hLeft - the height of left subtree
- \p hRight - the height of right subtree
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