/* Copyright (C) 2014 InfiniDB, Inc.

   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: sessionmanagerserver.cpp 1906 2013-06-14 19:15:32Z rdempsey $
 *
 ****************************************************************************/

/*
 * This class issues Transaction ID and keeps track of the current version ID
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <cerrno>
#include <fcntl.h>
#include <unistd.h>

#include <iostream>
#include <string>
#include <stdexcept>
#include <limits>
#ifdef _MSC_VER
#include <io.h>
#include <psapi.h>
#endif
using namespace std;

#include <boost/thread/mutex.hpp>
#include <boost/scoped_ptr.hpp>
using namespace boost;

#include "brmtypes.h"
#include "calpontsystemcatalog.h"
using namespace execplan;

#include "configcpp.h"
#include "atomicops.h"

#define SESSIONMANAGERSERVER_DLLEXPORT
#include "sessionmanagerserver.h"
#undef SESSIONMANAGERSERVER_DLLEXPORT

#ifndef O_BINARY
#define O_BINARY 0
#endif
#ifndef O_DIRECT
#define O_DIRECT 0
#endif
#ifndef O_LARGEFILE
#define O_LARGEFILE 0
#endif
#ifndef O_NOATIME
#define O_NOATIME 0
#endif

#include "IDBDataFile.h"
#include "IDBPolicy.h"
using namespace idbdatafile;

namespace BRM
{
const uint32_t SessionManagerServer::SS_READY = 1 << 0;  // Set by dmlProc one time when dmlProc is ready
const uint32_t SessionManagerServer::SS_SUSPENDED =
    1 << 1;  // Set by console when the system has been suspended by user.
const uint32_t SessionManagerServer::SS_SUSPEND_PENDING =
    1 << 2;  // Set by console when user wants to suspend, but writing is occuring.
const uint32_t SessionManagerServer::SS_SHUTDOWN_PENDING =
    1 << 3;  // Set by console when user wants to shutdown, but writing is occuring.
const uint32_t SessionManagerServer::SS_ROLLBACK =
    1 << 4;  // In combination with a PENDING flag, force a rollback as soom as possible.
const uint32_t SessionManagerServer::SS_FORCE =
    1 << 5;  // In combination with a PENDING flag, force a shutdown without rollback.
const uint32_t SessionManagerServer::SS_QUERY_READY =
    1 << 6;  // Set by ProcManager when system is ready for queries

SessionManagerServer::SessionManagerServer() : unique32(0), unique64(0)
{
  config::Config* conf;
  string stmp;
  const char* ctmp;

  conf = config::Config::makeConfig();

  try
  {
    stmp = conf->getConfig("SessionManager", "MaxConcurrentTransactions");
  }
  catch (const std::exception& e)
  {
    cout << e.what() << endl;
    stmp.clear();
  }

  if (stmp != "")
  {
    int64_t tmp;
    ctmp = stmp.c_str();
    tmp = config::Config::fromText(ctmp);

    if (tmp < 1)
      maxTxns = 1;
    else
      maxTxns = static_cast<int>(tmp);
  }
  else
    maxTxns = 1;

  txnidFilename = conf->getConfig("SessionManager", "TxnIDFile");

  semValue = maxTxns;
  _verID = 0;
  _sysCatVerID = 0;
  systemState = 0;

  try
  {
    loadState();
  }
  catch (...)
  {
    // first-time run most likely, ignore the error
  }
}

SessionManagerServer::~SessionManagerServer()
{
}
void SessionManagerServer::reset()
{
  mutex.try_lock();
  semValue = maxTxns;
  condvar.notify_all();
  activeTxns.clear();
  mutex.unlock();
}

void SessionManagerServer::loadState()
{
  int lastTxnID;
  int err;
  int lastSysCatVerId;

again:

  // There are now 3 pieces of info stored in the txnidfd file: last
  // transaction id, last system catalog version id, and the
  // system state flags. All these values are stored in shared, an
  // instance of struct Overlay.
  // If we fail to read a full four bytes for any value, then the
  // value isn't in the file, and we start with the default.

  if (IDBPolicy::exists(txnidFilename.c_str()))
  {
    scoped_ptr<IDBDataFile> txnidfp(IDBDataFile::open(
        IDBPolicy::getType(txnidFilename.c_str(), IDBPolicy::WRITEENG), txnidFilename.c_str(), "rb", 0));

    if (!txnidfp)
    {
      perror("SessionManagerServer(): open");
      throw runtime_error("SessionManagerServer: Could not open the transaction ID file");
    }

    // Last transaction id
    txnidfp->seek(0, SEEK_SET);
    err = txnidfp->read(&lastTxnID, 4);

    if (err < 0 && errno != EINTR)
    {
      perror("Sessionmanager::initSegment(): read");
      throw runtime_error("SessionManagerServer: read failed, aborting");
    }
    else if (err < 0)
      goto again;
    else if (err == sizeof(int))
      _verID = lastTxnID;

    // last system catalog version id
    err = txnidfp->read(&lastSysCatVerId, 4);

    if (err < 0 && errno != EINTR)
    {
      perror("Sessionmanager::initSegment(): read");
      throw runtime_error("SessionManagerServer: read failed, aborting");
    }
    else if (err < 0)
      goto again;
    else if (err == sizeof(int))
      _sysCatVerID = lastSysCatVerId;

    // System state. Contains flags regarding the suspend state of the system.
    err = txnidfp->read(&systemState, 4);

    if (err < 0 && errno == EINTR)
    {
      goto again;
    }
    else if (err == sizeof(int))
    {
      // Turn off the pending and force flags. They make no sense for a clean start.
      // Turn off the ready flag. DMLProc will set it back on when
      // initialized.
      systemState &=
          ~(SS_READY | SS_QUERY_READY | SS_SUSPEND_PENDING | SS_SHUTDOWN_PENDING | SS_ROLLBACK | SS_FORCE);
    }
    else
    {
      // else no problem. System state wasn't saved. Might be an upgraded system.
      systemState = 0;
    }
  }
}

/* Save the systemState flags of the Overlay
 * segment. This is saved in the third
 * word of txnid File
 */
void SessionManagerServer::saveSystemState()
{
  saveSMTxnIDAndState();
}

const QueryContext SessionManagerServer::verID()
{
  QueryContext ret;

  boost::mutex::scoped_lock lk(mutex);
  ret.currentScn = _verID;

  for (iterator i = activeTxns.begin(); i != activeTxns.end(); ++i)
    ret.currentTxns->push_back(i->second);

  return ret;
}

const QueryContext SessionManagerServer::sysCatVerID()
{
  QueryContext ret;

  boost::mutex::scoped_lock lk(mutex);
  ret.currentScn = _sysCatVerID;

  for (iterator i = activeTxns.begin(); i != activeTxns.end(); ++i)
    ret.currentTxns->push_back(i->second);

  return ret;
}

const TxnID SessionManagerServer::newTxnID(const SID session, bool block, bool isDDL)
{
  TxnID ret;  // ctor must set valid = false
  iterator it;

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

  // if it already has a txn...
  it = activeTxns.find(session);

  if (it != activeTxns.end())
  {
    ret.id = it->second;
    ret.valid = true;
    return ret;
  }

  if (!block && semValue == 0)
    return ret;
  else
    while (semValue == 0)
      condvar.wait(lk);

  semValue--;
  idbassert(semValue <= (uint32_t)maxTxns);

  ret.id = ++_verID;
  ret.valid = true;
  activeTxns[session] = ret.id;

  if (isDDL)
    ++_sysCatVerID;

  saveSMTxnIDAndState();

  return ret;
}

void SessionManagerServer::finishTransaction(TxnID& txn)
{
  iterator it;
  boost::mutex::scoped_lock lk(mutex);
  bool found = false;

  if (!txn.valid)
    throw invalid_argument("SessionManagerServer::finishTransaction(): transaction is invalid");

  for (it = activeTxns.begin(); it != activeTxns.end();)
  {
    if (it->second == txn.id)
    {
      activeTxns.erase(it++);
      txn.valid = false;
      found = true;
      // we could probably break at this point, but there won't be that many active txns, and,
      // even though it'd be an error to have multiple entries for the same txn, we might
      // well just get rid of them...
    }
    else
      ++it;
  }

  if (found)
  {
    semValue++;
    idbassert(semValue <= (uint32_t)maxTxns);
    condvar.notify_one();
  }
  else
    throw invalid_argument("SessionManagerServer::finishTransaction(): transaction doesn't exist");
}

const TxnID SessionManagerServer::getTxnID(const SID session)
{
  TxnID ret;
  iterator it;

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

  it = activeTxns.find(session);

  if (it != activeTxns.end())
  {
    ret.id = it->second;
    ret.valid = true;
  }

  return ret;
}

shared_array<SIDTIDEntry> SessionManagerServer::SIDTIDMap(int& len)
{
  int j;
  shared_array<SIDTIDEntry> ret;
  boost::mutex::scoped_lock lk(mutex);
  iterator it;

  ret.reset(new SIDTIDEntry[activeTxns.size()]);

  len = activeTxns.size();

  for (it = activeTxns.begin(), j = 0; it != activeTxns.end(); ++it, ++j)
  {
    ret[j].sessionid = it->first;
    ret[j].txnid.id = it->second;
    ret[j].txnid.valid = true;
  }

  return ret;
}

void SessionManagerServer::setSystemState(uint32_t state)
{
  boost::mutex::scoped_lock lk(mutex);

  systemState |= state;
  saveSystemState();
}

void SessionManagerServer::clearSystemState(uint32_t state)
{
  boost::mutex::scoped_lock lk(mutex);

  systemState &= ~state;
  saveSystemState();
}

uint32_t SessionManagerServer::getTxnCount()
{
  boost::mutex::scoped_lock lk(mutex);
  return activeTxns.size();
}

void SessionManagerServer::saveSMTxnIDAndState()
{
  // caller holds the lock
  scoped_ptr<IDBDataFile> txnidfp(IDBDataFile::open(
      IDBPolicy::getType(txnidFilename.c_str(), IDBPolicy::WRITEENG), txnidFilename.c_str(), "wb", 0));

  if (!txnidfp)
  {
    perror("SessionManagerServer(): open");
    throw runtime_error("SessionManagerServer: Could not open the transaction ID file");
  }

  int filedata[2];
  filedata[0] = _verID;
  filedata[1] = _sysCatVerID;

  int err = txnidfp->write(filedata, 8);

  if (err < 0)
  {
    perror("SessionManagerServer::newTxnID(): write(verid)");
    throw runtime_error("SessionManagerServer::newTxnID(): write(verid) failed");
  }

  uint32_t lSystemState = systemState;
  // We don't save the pending flags, the force flag or the ready flags.
  lSystemState &= ~(SS_READY | SS_QUERY_READY | SS_SUSPEND_PENDING | SS_SHUTDOWN_PENDING | SS_FORCE);
  err = txnidfp->write(&lSystemState, sizeof(int));

  if (err < 0)
  {
    perror("SessionManagerServer::saveSystemState(): write(systemState)");
    throw runtime_error("SessionManagerServer::saveSystemState(): write(systemState) failed");
  }

  txnidfp->flush();
}

}  // namespace BRM
