polardbxengine/extra/IS/consensus/algorithm/paxos_log_cache.cc

/************************************************************************
 *
 * Copyright (c) 2017 Alibaba.com, Inc. All Rights Reserved
 * $Id:  paxos_log_cache.cc,v 1.0 01/16/2017 07:03:27 PM yingqiang.zyq(yingqiang.zyq@alibaba-inc.com) $
 *
 ************************************************************************/

/**
 * @file paxos_log_cache.cc
 * @author yingqiang.zyq(yingqiang.zyq@alibaba-inc.com)
 * @date 01/16/2017 07:03:27 PM
 * @version 1.0
 * @brief paxos log cache
 *
 **/

#include "paxos_log_cache.h"

namespace alisql {

void PaxosLogCache::put(uint64_t beginIndex, uint64_t endIndex, ::google::protobuf::RepeatedPtrField<LogEntry>& entries)
{
  put(new PaxosLogCacheNode(beginIndex, endIndex, entries));
}

void PaxosLogCache::put(PaxosLogCacheNode *newNode)
{
  for (auto it= logCache_.begin(); it != logCache_.end();)
  {
    PaxosLogCacheNode *node= *it;
    if (node->endIndex < newNode->beginIndex)
    {
      if (node->endIndex + 1 != newNode->beginIndex)
      {
        ++ it;
        continue;
      }
      else
      {
        // continue append case
        byteSize_ -= node->getByteSize();
        node->entries.MergeFrom(newNode->entries);
        node->endIndex= newNode->endIndex;

        delete newNode;
        it= logCache_.erase(it);
        newNode= node;
        continue;
      }
    }
    else if(node->beginIndex > newNode->endIndex)
    {
      if (node->beginIndex != newNode->endIndex + 1)
      {
        byteSize_ += newNode->getByteSize();
        logCache_.insert(it, newNode);
        return;
      }
      else
      {
        // continue preppend case
        byteSize_ += newNode->getByteSize();
        newNode->entries.MergeFrom(node->entries);
        newNode->endIndex= node->endIndex;

        delete node;
        *it= newNode;
        return;
      }
    }
    else
    {
      //overlap case, need merge.
      int bs = (*it)->getByteSize();
      PaxosLogCacheNode *leftNode= node, *rightNode= newNode;

      if (node->beginIndex > newNode->beginIndex)
      {
        /*
        uint64_t tmp;
        node->entries.Swap(&(newNode->entries));
        tmp= newNode->beginIndex;
        newNode->beginIndex= node->beginIndex;
        node->beginIndex= tmp;
        tmp= newNode->endIndex;
        newNode->endIndex= node->endIndex;
        node->endIndex= tmp;
        */
        leftNode= newNode;
        rightNode= node;
      }
      else
      {
        //node->beginIndex <= newNode->beginIndex
      }

      assert(leftNode->beginIndex <= rightNode->beginIndex);
      assert(static_cast<uint64_t>(leftNode->entries.size()) == (leftNode->endIndex - leftNode->beginIndex + 1));
      assert(static_cast<uint64_t>(rightNode->entries.size()) == (rightNode->endIndex - rightNode->beginIndex + 1));

      if (leftNode->endIndex < rightNode->endIndex)
      {
        // exclude case
        rightNode->entries.DeleteSubrange(0, leftNode->endIndex - rightNode->beginIndex + 1);
        leftNode->entries.MergeFrom(rightNode->entries);
        leftNode->endIndex= rightNode->endIndex;
      }
      else
      {
        // include case
        if (node == leftNode)
        {
          delete rightNode;
          return;
        }
      }

      delete rightNode;
      byteSize_ -= bs;
      it= logCache_.erase(it);
      newNode= leftNode;
    }
  }
  byteSize_ += newNode->getByteSize();
  logCache_.push_back(newNode);
}

PaxosLogCacheNode *PaxosLogCache::get(uint64_t beginIndex)
{
  for (auto it= logCache_.begin(); it != logCache_.end();)
  {
    PaxosLogCacheNode *node= *it;
    if (node->beginIndex == beginIndex)
    {
      byteSize_ -= (*it)->getByteSize();
      logCache_.erase(it);
      return node;
    }
    else if (node->beginIndex < beginIndex)
    {
      if (node->endIndex < beginIndex)
      {
        byteSize_ -= (*it)->getByteSize();
        it= logCache_.erase(it);
        delete node;
      }
      else
      {
        byteSize_ -= (*it)->getByteSize();
        logCache_.erase(it);
        node->entries.DeleteSubrange(0, beginIndex - node->beginIndex);
        node->beginIndex= beginIndex;
        return node;
      }
    }
    else
    {
      //node->beginIndex > beginIndex
      return NULL;
    }

  }
  return NULL;
}

void PaxosLogCache::clear()
{
  for (auto& it : logCache_)
    delete it;
  byteSize_ = 0;
  logCache_.clear();
}

PaxosLogCacheNode *PaxosLogCache::debugGet(uint64_t i)
{
  uint64_t j= 0;
  for(auto& it : logCache_)
  {
    if (j == i)
      return it;

    ++j;
  }
  return NULL;
}

int PaxosLogCache::debugGetByteSize()
{
  int ret = 0;
  for (auto& it: logCache_)
  {
    ret += it->getByteSize();
  }
  return ret;
}

}