openh264/codec/common/inc/WelsList.h

/*!
 * \copy
 *     Copyright (c)  2009-2015, Cisco Systems
 *     All rights reserved.
 *
 *     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.
 *
 *
 * \file    WelsList
 *
 * \brief   for the list function needed in ThreadPool
 *
 * \date    9/27/2015 Created
 *
 *************************************************************************************
 */


#ifndef _WELS_LIST_H_
#define _WELS_LIST_H_

#include "typedefs.h"

namespace WelsCommon {

template<typename TNodeType>
struct SNode {
  TNodeType* pPointer;
  SNode* pPrevNode;
  SNode* pNextNode;
};

template<typename TNodeType>
class CWelsList {
 public:
  CWelsList() {
    m_iCurrentNodeCount = 0;
    m_iMaxNodeCount = 50;
    m_pCurrentList = static_cast<SNode<TNodeType>*> (malloc (m_iMaxNodeCount * sizeof (SNode<TNodeType>)));
    //here using array storage to simulate list is to avoid the frequent malloc/free of Nodes which may cause fragmented memory
    ResetStorage();
  };
  ~CWelsList() {
    free (m_pCurrentList);
  };

  int32_t size() {
    return m_iCurrentNodeCount;
  }

  bool push_back (TNodeType* pNode) {
    m_pCurrent->pPointer = pNode;
    if (0 == m_iCurrentNodeCount) {
      m_pFirst = m_pCurrent;
    }

    m_iCurrentNodeCount++;
    if (m_iCurrentNodeCount == m_iMaxNodeCount) {
      if (!ExpandList()) {
        return false;
      }
    }

    SNode<TNodeType>* pNext = FindNextStorage();
    m_pCurrent->pNextNode = pNext;
    pNext->pPrevNode = m_pCurrent;
    m_pCurrent = pNext;

    return true;
  }

  TNodeType* begin() {
    if (m_pFirst) {
      return m_pFirst->pPointer;
    }
    return NULL;
  }

  void pop_front() {
    if (m_iCurrentNodeCount == 0) {
      return;
    }

    SNode<TNodeType>* pTemp = m_pFirst;
    if (m_iCurrentNodeCount > 0) {
      m_iCurrentNodeCount --;
    }

    if (0 == m_iCurrentNodeCount) {
      ResetStorage();
    } else {
      m_pFirst = m_pFirst->pNextNode;
      m_pFirst->pPrevNode = NULL;

      CleanOneNode (pTemp);
    }
  }

  bool erase (TNodeType* pNode) {
    if (0 == m_iCurrentNodeCount) {
      return false;
    }

    SNode<TNodeType>* pTemp = m_pFirst;
    do {
      if (pNode == pTemp->pPointer) {
        if (pTemp->pPrevNode) {
          pTemp->pPrevNode->pNextNode = pTemp->pNextNode;
        } else {
          m_pFirst = pTemp->pNextNode;
        }

        if (pTemp->pNextNode) {
          pTemp->pNextNode->pPrevNode = pTemp->pPrevNode;
        }

        CleanOneNode (pTemp);
        m_iCurrentNodeCount --;
        return true;
      }

      if (pTemp->pNextNode) {
        pTemp = pTemp->pNextNode;
      } else {
        break;
      }
    } while (pTemp->pPointer && pTemp->pNextNode);
    return false;
  }

 private:
  bool ExpandList() {
    SNode<TNodeType>* tmpCurrentList = static_cast<SNode<TNodeType>*> (malloc (m_iMaxNodeCount * 2 * sizeof (
                                         SNode<TNodeType>)));
    if (tmpCurrentList == NULL) {
      return false;
    }
    InitStorage (tmpCurrentList, (m_iMaxNodeCount * 2) - 1);

    SNode<TNodeType>* pTemp = m_pFirst;
    for (int i = 0; ((i < m_iMaxNodeCount) && pTemp); i++) {
      tmpCurrentList[i].pPointer = pTemp->pPointer;
      pTemp = pTemp->pNextNode;
    }

    free (m_pCurrentList);
    m_pCurrentList = tmpCurrentList;
    m_iCurrentNodeCount = m_iMaxNodeCount;
    m_iMaxNodeCount = m_iMaxNodeCount * 2;
    m_pFirst = m_pCurrentList;
    m_pCurrent = & (m_pCurrentList[m_iCurrentNodeCount - 1]);
    return true;
  }

  void InitStorage (SNode<TNodeType>* pList, const int32_t iMaxIndex) {
    pList[0].pPrevNode = NULL;
    pList[0].pPointer = NULL;
    pList[0].pNextNode = & (pList[1]);
    for (int i = 1; i < iMaxIndex; i++) {
      pList[i].pPrevNode = & (pList[i - 1]);
      pList[i].pPointer = NULL;
      pList[i].pNextNode = & (pList[i + 1]);
    }
    pList[iMaxIndex].pPrevNode = & (pList[iMaxIndex - 1]);
    pList[iMaxIndex].pPointer = NULL;
    pList[iMaxIndex].pNextNode = NULL;
  }

  SNode<TNodeType>* FindNextStorage() {

    if (NULL != m_pCurrent->pNextNode) {
      if (NULL == m_pCurrent->pNextNode->pPointer) {
        return (m_pCurrent->pNextNode);
      }
    }

    for (int32_t i = 0; i < m_iMaxNodeCount; i++) {
      if (NULL == m_pCurrentList[i].pPointer) {
        return (&m_pCurrentList[i]);
      }
    }
    return NULL;
  }

  void CleanOneNode (SNode<TNodeType>* pSNode) {
    pSNode->pPointer = NULL;
    pSNode->pPrevNode = NULL;
    pSNode->pNextNode = NULL;
  }

  void ResetStorage() {
    m_pFirst = NULL;
    m_pCurrent = m_pCurrentList;
    InitStorage (m_pCurrentList, m_iMaxNodeCount - 1);
  }

  int32_t m_iCurrentNodeCount;
  int32_t m_iMaxNodeCount;
  SNode<TNodeType>* m_pCurrentList;
  SNode<TNodeType>* m_pFirst;
  SNode<TNodeType>* m_pCurrent;
};

}


#endif