87 lines
3.9 KiB
C++
87 lines
3.9 KiB
C++
/*
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This file is a part of libcds - Concurrent Data Structures library
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(C) Copyright Maxim Khizhinsky (libcds.dev@gmail.com) 2006-2017
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Source code repo: http://github.com/khizmax/libcds/
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Download: http://sourceforge.net/projects/libcds/files/
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef CDSLIB_ALGO_ELIMINATION_H
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#define CDSLIB_ALGO_ELIMINATION_H
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#include <cds/algo/elimination_tls.h>
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#include <cds/algo/elimination_opt.h>
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#include <cds/algo/atomic.h>
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#include <cds/threading/model.h>
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namespace cds { namespace algo {
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/// Elimination technique
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/** @anchor cds_elimination_description
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Elimination technique allows highly distributed coupling and execution of operations with reverse
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semantics like the pushes and pops on a stack. If a push followed by a pop are performed
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on a stack, the data structure's state does not change (similarly for a pop followed by a push).
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This means that if one can cause pairs of pushes and pops to meet and pair up in
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separate locations, the threads can exchange values without having to touch a centralized structure
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since they have anyhow "eliminated" each other's effect on it. Elimination can be implemented
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by using a collision array in which threads pick random locations in order to try and collide.
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Pairs of threads that "collide" in some location run through a synchronization protocol,
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and all such disjoint collisions can be performed in parallel. If a thread has not met another
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in the selected location or if it met a thread with an operation that cannot be eliminated
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(such as two push operations), an alternative scheme must be used.
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*/
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namespace elimination {
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/// Base class describing an operation for eliminating
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/**
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This class contains some debugng info.
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Actual operation descriptor depends on real container and its interface.
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*/
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struct operation_desc
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{
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record * pOwner; ///< Owner of the descriptor
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};
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/// Acquires elimination record for the current thread
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template <typename OperationDesc>
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static inline record * init_record( OperationDesc& op )
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{
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record& rec = cds::threading::elimination_record();
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assert( rec.is_free());
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op.pOwner = &rec;
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rec.pOp = static_cast<operation_desc *>( &op );
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return &rec;
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}
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/// Releases elimination record for the current thread
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static inline void clear_record()
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{
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cds::threading::elimination_record().pOp = nullptr;
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}
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} // namespace elimination
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}} // namespace cds::algo
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#endif // CDSLIB_ALGO_ELIMINATION_H
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