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// Copyright 2016 Proyectos y Sistemas de Mantenimiento SL (eProsima).
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
/**
* @file SkipList.cpp
*
*/
#include "SkipList.h"
#include <cstdlib>
#include <ctime>
namespace eprosima {
namespace fastrtps{
namespace rtps {
template<class Obj>
SkipNode<Obj>::~SkipNode()
{
delete [] mp_fwdNodes;
}
template<class Obj>
SkipNode<Obj>::SkipNode(Obj* obj,uint32_t level):m_height(level),
mp_data(obj)
{
mp_fwdNodes = new SkipNode<Obj>* [m_height];
for(int x = 0;x<m_height;++x)
mp_fwdNodes[x] = nullptr;
}
template <class Obj>
SkipNode<Obj>::SkipNode(uint32_t level):m_height(level),
mp_data(nullptr)
{
mp_fwdNodes = new SkipNode<Obj>* [m_height];
for(int x = 0;x<m_height;++x)
mp_fwdNodes[x] = nullptr;
}
//SKIP LIST
template <class Obj>
SkipList<Obj>::SkipList(float probability,uint32_t maxHeight): m_maxHeight(maxHeight),
m_currHeight(0),
m_probability(probability),
mp_head(nullptr),
mp_tails(nullptr)
{
srand (time(NULL));
mp_head = new SkipNode<Obj>(m_maxHeight);
mp_tails = new SkipNode<Obj>* [m_maxHeight];
for ( int x = 0; x < m_maxHeight; x++ )
{
mp_head->mp_fwdNodes[x] = nullptr;
mp_tails[x] = mp_head;
}
}
template <class Obj>
SkipList<Obj>::~SkipList() {
// Walk 0 level nodes and delete all
SkipNode<Obj>* tmp;
SkipNode<Obj>* nxt;
tmp = mp_head;
while ( tmp )
{
nxt = tmp->mp_fwdNodes[0];
delete tmp;
tmp = nxt;
}
delete [] mp_tails;
}
template <class Obj>
bool SkipList<Obj>::insert_at_end(Obj* obj)
{
SkipNode<Obj>* tmp = new SkipNode<Obj>(obj,newLevel());
for(int x = 0;x<tmp->m_height;++x)
{
mp_tails[x]->mp_fwdNodes[x] = tmp;
mp_tails[x] = tmp;
}
return true;
}
template <class Obj>
bool SkipList<Obj>::insert(Obj* obj)
{
int lvl = 0, h = 0;
SkipNode<Obj>** updateVec = new SkipNode<Obj>* [m_maxHeight];
SkipNode<Obj>* tmp = mp_head;
// Figure out where new node goes
for ( h = m_currHeight; h >= 0; h-- )
{
while (tmp->mp_fwdNodes[h] != nullptr && *tmp->mp_fwdNodes[h]->mp_data < *obj )
{
tmp = tmp->fwdNodes[h];
}
updateVec[h] = tmp;
}
tmp = tmp->fwdNodes[0]; //Element just before the one we are inserting.
// If dup, return false
if ( *tmp->mp_data == *obj )
{
return false;
}
else
{
// Perform an insert
lvl = newLevel();
if ( lvl > m_currHeight )
{
for ( int i = m_currHeight; i <= lvl; i++ )
updateVec[i] = mp_head;
m_currHeight = lvl;
}
// Insert new element
tmp = new SkipNode<Obj>(obj, lvl);
for ( int i = 0; i < lvl; i++ )
{
tmp->fwdNodes[i] = updateVec[i]->fwdNodes[i];
updateVec[i]->fwdNodes[i] = tmp;
}
}
return true;
}
template <class Obj>
bool SkipList<Obj>::remove(Obj* obj)
{
}
template <class Obj>
uint32_t SkipList<Obj>::newLevel()
{
uint32_t tmpLvl = 1;
// Develop a random number between 1 and maxLvl (node height).
while ((rand01() < m_probability) &&
(tmpLvl < m_maxHeight))
tmpLvl++;
return tmpLvl;
}
template <class Obj>
float SkipList<Obj>::rand01()
{
return static_cast <float> (rand()) / static_cast <float> (RAND_MAX);
}
}
} /* namespace rtps */
} /* namespace eprosima */
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