/* Copyright (C) 2014 InfiniDB, Inc.
   Copyright (C) 2016 MariaDB Corporation

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; version 2 of
   the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   MA 02110-1301, USA. */

/***************************************************************************
 *
 *   $Id: filebuffermgr.cpp 2045 2013-01-30 20:26:59Z pleblanc $
 *
 *   jrodriguez@calpont.com   *
 *                                                                         *
 ***************************************************************************/
/**
* 	InitialDBBCSize - the starting number of elements the unordered set used to store disk blocks.
        This does not instantiate InitialDBBCSize disk blocks but only the initial size of the unordered_set

**/

//#define NDEBUG
#include <cassert>
#include <limits>
#include <boost/thread.hpp>

#include <pthread.h>

#include "stats.h"
#include "configcpp.h"
#include "filebuffermgr.h"
#include "mcsconfig.h"

using namespace config;
using namespace boost;
using namespace std;
using namespace BRM;

extern dbbc::Stats* gPMStatsPtr;
extern bool gPMProfOn;
extern uint32_t gSession;

namespace dbbc
{
const uint32_t gReportingFrequencyMin(32768);

FileBufferMgr::FileBufferMgr(const uint32_t numBlcks, const uint32_t blkSz, const uint32_t deleteBlocks)
 : fMaxNumBlocks(numBlcks)
 , fBlockSz(blkSz)
 , fWLock()
 , fbSet()
 , fbList()
 , fCacheSize(0)
 , fFBPool()
 , fDeleteBlocks(deleteBlocks)
 , fEmptyPoolSlots()
 , fReportFrequency(0)
{
  fFBPool.reserve(numBlcks);
  fConfig = Config::makeConfig();
  setReportingFrequency(0);
  fLog.open(string(MCSLOGDIR) + "/trace/bc", ios_base::app | ios_base::ate);
}

FileBufferMgr::~FileBufferMgr()
{
  flushCache();
}

// param d is used as a togle only
void FileBufferMgr::setReportingFrequency(const uint32_t d)
{
  if (d == 0)
  {
    fReportFrequency = 0;
    return;
  }

  const string val = fConfig->getConfig("DBBC", "ReportFrequency");
  uint32_t temp = 0;

  if (val.length() > 0)
    temp = static_cast<int>(Config::fromText(val));

  if (temp > 0 && temp <= gReportingFrequencyMin)
    fReportFrequency = gReportingFrequencyMin;
  else
    fReportFrequency = temp;
}

void FileBufferMgr::flushCache()
{
  boost::mutex::scoped_lock lk(fWLock);
  {
    filebuffer_uset_t sEmpty;
    filebuffer_list_t lEmpty;
    emptylist_t vEmpty;

    fbList.swap(lEmpty);
    fbSet.swap(sEmpty);
    fEmptyPoolSlots.swap(vEmpty);
  }
  fCacheSize = 0;

  // the block pool should not be freed in the above block to allow us
  // to continue doing concurrent unprotected-but-"safe" memcpys
  // from that memory
  if (fReportFrequency)
  {
    fLog << "Clearing entire cache" << endl;
  }
  fFBPool.clear();
  //	fFBPool.reserve(fMaxNumBlocks);
}

void FileBufferMgr::flushOne(const BRM::LBID_t lbid, const BRM::VER_t ver)
{
  // similar in function to depleteCache()
  boost::mutex::scoped_lock lk(fWLock);

  filebuffer_uset_iter_t iter = fbSet.find(HashObject_t(lbid, ver, 0));

  if (iter != fbSet.end())
  {
    // remove it from fbList
    uint32_t idx = iter->poolIdx;
    fbList.erase(fFBPool[idx].listLoc());
    // add to fEmptyPoolSlots
    fEmptyPoolSlots.push_back(idx);
    // remove it from fbSet
    fbSet.erase(iter);
    // adjust fCacheSize
    fCacheSize--;
  }
}

void FileBufferMgr::flushMany(const LbidAtVer* laVptr, uint32_t cnt)
{
  boost::mutex::scoped_lock lk(fWLock);

  BRM::LBID_t lbid;
  BRM::VER_t ver;
  filebuffer_uset_iter_t iter;
  if (fReportFrequency)
  {
    fLog << "flushMany " << cnt << " items: ";
    for (uint32_t j = 0; j < cnt; j++)
    {
      fLog << "lbid: " << laVptr[j].LBID << " ver: " << laVptr[j].Ver << ", ";
    }
    fLog << endl;
  }
  for (uint32_t j = 0; j < cnt; j++)
  {
    lbid = static_cast<BRM::LBID_t>(laVptr->LBID);
    ver = static_cast<BRM::VER_t>(laVptr->Ver);
    iter = fbSet.find(HashObject_t(lbid, ver, 0));

    if (iter != fbSet.end())
    {
      if (fReportFrequency)
      {
        fLog << "flushMany hit, lbid: " << lbid << " index: " << iter->poolIdx << endl;
      }
      // remove it from fbList
      uint32_t idx = iter->poolIdx;
      fbList.erase(fFBPool[idx].listLoc());
      // add to fEmptyPoolSlots
      fEmptyPoolSlots.push_back(idx);
      // remove it from fbSet
      fbSet.erase(iter);
      // adjust fCacheSize
      fCacheSize--;
    }

    ++laVptr;
  }
}

void FileBufferMgr::flushManyAllversion(const LBID_t* laVptr, uint32_t cnt)
{
  filebuffer_uset_t::iterator it, tmpIt;
  tr1::unordered_set<LBID_t> uniquer;
  tr1::unordered_set<LBID_t>::iterator uit;

  boost::mutex::scoped_lock lk(fWLock);

  if (fReportFrequency)
  {
    fLog << "flushManyAllversion " << cnt << " items: ";
    for (uint32_t i = 0; i < cnt; i++)
    {
      fLog << laVptr[i] << ", ";
    }
    fLog << endl;
  }

  if (fCacheSize == 0 || cnt == 0)
    return;

  for (uint32_t i = 0; i < cnt; i++)
    uniquer.insert(laVptr[i]);

  for (it = fbSet.begin(); it != fbSet.end();)
  {
    if (uniquer.find(it->lbid) != uniquer.end())
    {
      if (fReportFrequency)
      {
        fLog << "flushManyAllversion hit: " << it->lbid << " index: " << it->poolIdx << endl;
      }
      const uint32_t idx = it->poolIdx;
      fbList.erase(fFBPool[idx].listLoc());
      fEmptyPoolSlots.push_back(idx);
      tmpIt = it;
      ++it;
      fbSet.erase(tmpIt);
      fCacheSize--;
    }
    else
      ++it;
  }
}

void FileBufferMgr::flushOIDs(const uint32_t* oids, uint32_t count)
{
  DBRM dbrm;
  uint32_t i;
  vector<EMEntry> extents;
  int err;
  uint32_t currentExtent;
  LBID_t currentLBID;
  typedef tr1::unordered_multimap<LBID_t, filebuffer_uset_t::iterator> byLBID_t;
  byLBID_t byLBID;
  pair<byLBID_t::iterator, byLBID_t::iterator> itList;
  filebuffer_uset_t::iterator it;

  if (fReportFrequency)
  {
    fLog << "flushOIDs " << count << " items: ";
    for (uint32_t i = 0; i < count; i++)
    {
      fLog << oids[i] << ", ";
    }
    fLog << endl;
  }

  // If there are more than this # of extents to drop, the whole cache will be cleared
  const uint32_t clearThreshold = 50000;

  boost::mutex::scoped_lock lk(fWLock);

  if (fCacheSize == 0 || count == 0)
    return;

  /* Index the cache by LBID */
  for (it = fbSet.begin(); it != fbSet.end(); it++)
    byLBID.insert(pair<LBID_t, filebuffer_uset_t::iterator>(it->lbid, it));

  for (i = 0; i < count; i++)
  {
    extents.clear();
    err = dbrm.getExtents(oids[i], extents, true, true, true);  // @Bug 3838 Include outofservice extents

    if (err < 0 || (i == 0 && (extents.size() * count) > clearThreshold))
    {
      // (The i == 0 should ensure it's not a dictionary column)
      lk.unlock();
      flushCache();
      return;
    }

    for (currentExtent = 0; currentExtent < extents.size(); currentExtent++)
    {
      EMEntry& range = extents[currentExtent];
      LBID_t lastLBID = range.range.start + (range.range.size * 1024);

      for (currentLBID = range.range.start; currentLBID < lastLBID; currentLBID++)
      {
        itList = byLBID.equal_range(currentLBID);

        for (byLBID_t::iterator tmpIt = itList.first; tmpIt != itList.second; tmpIt++)
        {
          fbList.erase(fFBPool[tmpIt->second->poolIdx].listLoc());
          fEmptyPoolSlots.push_back(tmpIt->second->poolIdx);
          fbSet.erase(tmpIt->second);
          fCacheSize--;
        }
      }
    }
  }
}

void FileBufferMgr::flushPartition(const vector<OID_t>& oids, const set<BRM::LogicalPartition>& partitions)
{
  DBRM dbrm;
  uint32_t i;
  vector<EMEntry> extents;
  int err;
  uint32_t currentExtent;
  LBID_t currentLBID;
  typedef tr1::unordered_multimap<LBID_t, filebuffer_uset_t::iterator> byLBID_t;
  byLBID_t byLBID;
  pair<byLBID_t::iterator, byLBID_t::iterator> itList;
  filebuffer_uset_t::iterator it;
  uint32_t count = oids.size();

  boost::mutex::scoped_lock lk(fWLock);

  if (fReportFrequency)
  {
    std::set<BRM::LogicalPartition>::iterator sit;
    fLog << "flushPartition oids: ";
    for (uint32_t i = 0; i < count; i++)
    {
      fLog << oids[i] << ", ";
    }
    fLog << "flushPartition partitions: ";
    for (sit = partitions.begin(); sit != partitions.end(); ++sit)
    {
      fLog << (*sit).toString() << ", ";
    }
    fLog << endl;
  }

  if (fCacheSize == 0 || oids.size() == 0 || partitions.size() == 0)
    return;

  /* Index the cache by LBID */
  for (it = fbSet.begin(); it != fbSet.end(); it++)
    byLBID.insert(pair<LBID_t, filebuffer_uset_t::iterator>(it->lbid, it));

  for (i = 0; i < count; i++)
  {
    extents.clear();
    err = dbrm.getExtents(oids[i], extents, true, true, true);  // @Bug 3838 Include outofservice extents

    if (err < 0)
    {
      lk.unlock();
      flushCache();  // better than returning an error code to the user
      return;
    }

    for (currentExtent = 0; currentExtent < extents.size(); currentExtent++)
    {
      EMEntry& range = extents[currentExtent];

      LogicalPartition logicalPartNum(range.dbRoot, range.partitionNum, range.segmentNum);

      if (partitions.find(logicalPartNum) == partitions.end())
        continue;

      LBID_t lastLBID = range.range.start + (range.range.size * 1024);

      for (currentLBID = range.range.start; currentLBID < lastLBID; currentLBID++)
      {
        itList = byLBID.equal_range(currentLBID);

        for (byLBID_t::iterator tmpIt = itList.first; tmpIt != itList.second; tmpIt++)
        {
          fbList.erase(fFBPool[tmpIt->second->poolIdx].listLoc());
          fEmptyPoolSlots.push_back(tmpIt->second->poolIdx);
          fbSet.erase(tmpIt->second);
          fCacheSize--;
        }
      }
    }
  }
}

bool FileBufferMgr::exists(const BRM::LBID_t& lbid, const BRM::VER_t& ver) const
{
  const HashObject_t fb(lbid, ver, 0);
  const bool b = exists(fb);
  return b;
}

FileBuffer* FileBufferMgr::findPtr(const HashObject_t& keyFb)
{
  boost::mutex::scoped_lock lk(fWLock);

  filebuffer_uset_iter_t it = fbSet.find(keyFb);

  if (fbSet.end() != it)
  {
    FileBuffer* fb = &(fFBPool[it->poolIdx]);
    fFBPool[it->poolIdx].listLoc()->hits++;
    fbList.splice(fbList.begin(), fbList, (fFBPool[it->poolIdx]).listLoc());
    return fb;
  }

  return NULL;
}

bool FileBufferMgr::find(const HashObject_t& keyFb, FileBuffer& fb)
{
  bool ret = false;

  boost::mutex::scoped_lock lk(fWLock);

  filebuffer_uset_iter_t it = fbSet.find(keyFb);

  if (fbSet.end() != it)
  {
    fFBPool[it->poolIdx].listLoc()->hits++;
    fbList.splice(fbList.begin(), fbList, (fFBPool[it->poolIdx]).listLoc());
    fb = fFBPool[it->poolIdx];
    ret = true;
  }

  return ret;
}

bool FileBufferMgr::find(const HashObject_t& keyFb, void* bufferPtr)
{
  bool ret = false;

  if (gPMProfOn && gPMStatsPtr)
    gPMStatsPtr->markEvent(keyFb.lbid, pthread_self(), gSession, 'L');
  boost::mutex::scoped_lock lk(fWLock);

  if (gPMProfOn && gPMStatsPtr)
    gPMStatsPtr->markEvent(keyFb.lbid, pthread_self(), gSession, 'M');
  filebuffer_uset_iter_t it = fbSet.find(keyFb);

  if (fbSet.end() != it)
  {
    uint32_t idx = it->poolIdx;

    //@bug 669 LRU cache, move block to front of list as last recently used.
    fFBPool[idx].listLoc()->hits++;
    fbList.splice(fbList.begin(), fbList, (fFBPool[idx]).listLoc());
    lk.unlock();
    memcpy(bufferPtr, (fFBPool[idx]).getData(), 8192);

    if (gPMProfOn && gPMStatsPtr)
      gPMStatsPtr->markEvent(keyFb.lbid, pthread_self(), gSession, 'U');
    ret = true;
  }

  return ret;
}

uint32_t FileBufferMgr::bulkFind(const BRM::LBID_t* lbids, const BRM::VER_t* vers, uint8_t** buffers,
                                 bool* wasCached, uint32_t count)
{
  uint32_t i, ret = 0;
  filebuffer_uset_iter_t* it = (filebuffer_uset_iter_t*)alloca(count * sizeof(filebuffer_uset_iter_t));
  uint32_t* indexes = (uint32_t*)alloca(count * 4);

  if (gPMProfOn && gPMStatsPtr)
  {
    for (i = 0; i < count; i++)
    {
      gPMStatsPtr->markEvent(lbids[i], pthread_self(), gSession, 'L');
    }
  }

  boost::mutex::scoped_lock lk(fWLock);

  if (gPMProfOn && gPMStatsPtr)
  {
    for (i = 0; i < count; i++)
    {
      gPMStatsPtr->markEvent(lbids[i], pthread_self(), gSession, 'M');
    }
  }

  for (i = 0; i < count; i++)
  {
    new ((void*)&it[i]) filebuffer_uset_iter_t();
    it[i] = fbSet.find(HashObject_t(lbids[i], vers[i], 0));

    if (it[i] != fbSet.end())
    {
      indexes[i] = it[i]->poolIdx;
      wasCached[i] = true;
      fFBPool[it[i]->poolIdx].listLoc()->hits++;
      fbList.splice(fbList.begin(), fbList, (fFBPool[it[i]->poolIdx]).listLoc());
    }
    else
    {
      wasCached[i] = false;
      indexes[i] = 0;
    }
  }

  lk.unlock();

  for (i = 0; i < count; i++)
  {
    if (wasCached[i])
    {
      memcpy(buffers[i], fFBPool[indexes[i]].getData(), 8192);
      ret++;

      if (gPMProfOn && gPMStatsPtr)
      {
        gPMStatsPtr->markEvent(lbids[i], pthread_self(), gSession, 'U');
      }
    }

    it[i].filebuffer_uset_iter_t::~filebuffer_uset_iter_t();
  }

  return ret;
}

bool FileBufferMgr::exists(const HashObject_t& fb) const
{
  bool find_bool = false;
  boost::mutex::scoped_lock lk(fWLock);

  filebuffer_uset_iter_t it = fbSet.find(fb);

  if (it != fbSet.end())
  {
    find_bool = true;
    fFBPool[it->poolIdx].listLoc()->hits++;
    fbList.splice(fbList.begin(), fbList, (fFBPool[it->poolIdx]).listLoc());
  }

  return find_bool;
}

// default insert operation.
// add a new fb into fbMgr and to fbList
// add to the front and age out from the back
// so add new fbs to the front of the list
//@bug 665: keep filebuffer in a vector. HashObject keeps the index of the filebuffer

int FileBufferMgr::insert(const BRM::LBID_t lbid, const BRM::VER_t ver, const uint8_t* data)
{
  int ret = 0;

  if (gPMProfOn && gPMStatsPtr)
    gPMStatsPtr->markEvent(lbid, pthread_self(), gSession, 'I');

  boost::mutex::scoped_lock lk(fWLock);

  HashObject_t fbIndex(lbid, ver, 0);
  filebuffer_pair_t pr = fbSet.insert(fbIndex);

  if (pr.second)
  {
    // It was inserted (it wasn't there before)
    // Right now we have an invalid cache: we have inserted an entry with a -1 index.
    // We need to fix this quickly...
    fCacheSize++;
    FBData_t fbdata = {lbid, ver, 0};
    fbList.push_front(fbdata);
    fBlksLoaded++;

    if (fReportFrequency && (fBlksLoaded % fReportFrequency) == 0)
    {
      struct timespec tm;
      clock_gettime(CLOCK_MONOTONIC, &tm);
      fLog << "insert: " << left << fixed << ((double)(tm.tv_sec + (1.e-9 * tm.tv_nsec))) << " " << right
           << setw(12) << fBlksLoaded << " " << right << setw(12) << fBlksNotUsed << endl;
    }
  }
  else
  {
    // if it's a duplicate there's nothing to do
    if (gPMProfOn && gPMStatsPtr)
      gPMStatsPtr->markEvent(lbid, pthread_self(), gSession, 'D');
    return ret;
  }

  uint32_t pi = numeric_limits<int>::max();

  if (fCacheSize > maxCacheSize())
  {
    // If the insert above caused the cache to exceed its max size, find the lru block in
    // the cache and use its pool index to store the block data.
    FBData_t& fbdata = fbList.back();  // the lru block
    HashObject_t lastFB(fbdata.lbid, fbdata.ver, 0);
    filebuffer_uset_iter_t iter = fbSet.find(lastFB);  // should be there

    idbassert(iter != fbSet.end());
    pi = iter->poolIdx;
    idbassert(pi < maxCacheSize());
    idbassert(pi < fFBPool.size());

    // set iters are always const. We are not changing the hash here, and this gets us
    // the pointer we need cheaply...
    HashObject_t& ref = const_cast<HashObject_t&>(*pr.first);
    ref.poolIdx = pi;

    // replace the lru block with this block
    FileBuffer fb(lbid, ver, NULL, 0);
    fFBPool[pi] = fb;
    fFBPool[pi].setData(data, 8192);
    fbSet.erase(iter);

    if (fbList.back().hits == 0)
      fBlksNotUsed++;

    fbList.pop_back();
    fCacheSize--;
    depleteCache();
    ret = 1;
  }
  else
  {
    if (!fEmptyPoolSlots.empty())
    {
      pi = fEmptyPoolSlots.front();
      fEmptyPoolSlots.pop_front();
      FileBuffer fb(lbid, ver, NULL, 0);
      fFBPool[pi] = fb;
      fFBPool[pi].setData(data, 8192);
    }
    else
    {
      pi = fFBPool.size();
      FileBuffer fb(lbid, ver, NULL, 0);
      fFBPool.push_back(fb);
      fFBPool[pi].setData(data, 8192);
    }

    // See comment above
    HashObject_t& ref = const_cast<HashObject_t&>(*pr.first);
    ref.poolIdx = pi;
    ret = 1;
  }

  idbassert(pi < fFBPool.size());
  fFBPool[pi].listLoc(fbList.begin());

  if (gPMProfOn && gPMStatsPtr)
    gPMStatsPtr->markEvent(lbid, pthread_self(), gSession, 'J');

  idbassert(fCacheSize <= maxCacheSize());
  // 	idbassert(fCacheSize == fbSet.size());
  // 	idbassert(fCacheSize == fbList.size());
  return ret;
}

void FileBufferMgr::depleteCache()
{
  for (uint32_t i = 0; i < fDeleteBlocks && !fbList.empty(); ++i)
  {
    FBData_t fbdata(fbList.back());  // the lru block
    HashObject_t lastFB(fbdata.lbid, fbdata.ver, 0);
    filebuffer_uset_iter_t iter = fbSet.find(lastFB);

    idbassert(iter != fbSet.end());
    uint32_t idx = iter->poolIdx;
    idbassert(idx < fFBPool.size());
    // Save position in FileBuffer pool for reuse.
    fEmptyPoolSlots.push_back(idx);
    fbSet.erase(iter);

    if (fbList.back().hits == 0)
      fBlksNotUsed++;

    fbList.pop_back();
    fCacheSize--;
  }
}

ostream& FileBufferMgr::formatLRUList(ostream& os) const
{
  filebuffer_list_t::const_iterator iter = fbList.begin();
  filebuffer_list_t::const_iterator end = fbList.end();

  while (iter != end)
  {
    os << iter->lbid << '\t' << iter->ver << endl;
    ++iter;
  }

  return os;
}

// puts the new entry at the front of the list
void FileBufferMgr::updateLRU(const FBData_t& f)
{
  if (fCacheSize > maxCacheSize())
  {
    list<FBData_t>::iterator last = fbList.end();
    last--;
    FBData_t& fbdata = *last;
    HashObject_t lastFB(fbdata.lbid, fbdata.ver, 0);
    filebuffer_uset_iter_t iter = fbSet.find(lastFB);
    fEmptyPoolSlots.push_back(iter->poolIdx);

    if (fbdata.hits == 0)
      fBlksNotUsed++;

    fbSet.erase(iter);
    fbList.splice(fbList.begin(), fbList, last);
    fbdata = f;
    fCacheSize--;
    // cout << "booted an entry\n";
  }
  else
  {
    // cout << "new entry\n";
    fbList.push_front(f);
  }
}

uint32_t FileBufferMgr::doBlockCopy(const BRM::LBID_t& lbid, const BRM::VER_t& ver, const uint8_t* data)
{
  uint32_t poolIdx;

  if (!fEmptyPoolSlots.empty())
  {
    poolIdx = fEmptyPoolSlots.front();
    fEmptyPoolSlots.pop_front();
  }
  else
  {
    poolIdx = fFBPool.size();
    fFBPool.resize(poolIdx + 1);  // shouldn't trigger a 'real' resize b/c of the reserve call
  }

  fFBPool[poolIdx].Lbid(lbid);
  fFBPool[poolIdx].Verid(ver);
  fFBPool[poolIdx].setData(data);
  return poolIdx;
}

int FileBufferMgr::bulkInsert(const vector<CacheInsert_t>& ops)
{
  uint32_t i;
  int32_t pi;
  int ret = 0;

  boost::mutex::scoped_lock lk(fWLock);

  if (fReportFrequency)
  {
    fLog << "bulkInsert: ";
  }

  for (i = 0; i < ops.size(); i++)
  {
    const CacheInsert_t& op = ops[i];

    if (gPMProfOn && gPMStatsPtr)
      gPMStatsPtr->markEvent(op.lbid, pthread_self(), gSession, 'I');

    HashObject_t fbIndex(op.lbid, op.ver, 0);
    filebuffer_pair_t pr = fbSet.insert(fbIndex);

    if (!pr.second)
    {
      if (gPMProfOn && gPMStatsPtr)
        gPMStatsPtr->markEvent(op.lbid, pthread_self(), gSession, 'D');
      continue;
    }

    if (fReportFrequency)
    {
      fLog << op.lbid << " " << op.ver << ", ";
    }
    fCacheSize++;
    fBlksLoaded++;
    FBData_t fbdata = {op.lbid, op.ver, 0};
    updateLRU(fbdata);
    pi = doBlockCopy(op.lbid, op.ver, op.data);

    HashObject_t& ref = const_cast<HashObject_t&>(*pr.first);
    ref.poolIdx = pi;
    fFBPool[pi].listLoc(fbList.begin());

    if (gPMProfOn && gPMStatsPtr)
      gPMStatsPtr->markEvent(op.lbid, pthread_self(), gSession, 'J');
    ret++;
  }
  if (fReportFrequency)
  {
    fLog << endl;
  }
  idbassert(fCacheSize <= maxCacheSize());

  return ret;
}

}  // namespace dbbc
