StmtPool.cpp

/*
 * The CERN Tape Archive (CTA) project
 * Copyright (C) 2015  CERN
 *
 * 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, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include "common/exception/Exception.hpp"
#include "common/threading/MutexLocker.hpp"
#include "rdbms/wrapper/ConnWrapper.hpp"
#include "rdbms/StmtPool.hpp"

namespace cta {
namespace rdbms {

//------------------------------------------------------------------------------
// getStmt
//------------------------------------------------------------------------------
Stmt StmtPool::getStmt(wrapper::ConnWrapper &conn, const std::string &sql) {
  threading::MutexLocker locker(m_stmtsMutex);

  auto itor = m_stmts.find(sql);

  // If there is no prepared statement in the cache
  if(itor == m_stmts.end()) {
    auto stmt = conn.createStmt(sql);
    return Stmt(std::move(stmt), *this);
  } else {
    auto &stmtList = itor->second;
    if(stmtList.empty()) {
      throw exception::Exception(std::string(__FUNCTION__) + " failed: Unexpected empty list of cached statements");
    }
    auto stmt = std::move(stmtList.front());
    stmtList.pop_front();

    // If there are no more cached prepared statements then remove the empty list from the cache
    if(stmtList.empty()) {
      m_stmts.erase(itor);
    }

    return Stmt(std::move(stmt), *this);
  }
}

//------------------------------------------------------------------------------
// getNbStmts
//------------------------------------------------------------------------------
uint64_t StmtPool::getNbStmts() const {
  threading::MutexLocker locker(m_stmtsMutex);

  uint64_t nbStmts = 0;
  for(const auto &maplet: m_stmts) {
    auto &stmtList = maplet.second;
    nbStmts += stmtList.size();
  }
  return nbStmts;
}

//------------------------------------------------------------------------------
// returnStmt
//------------------------------------------------------------------------------
void StmtPool::returnStmt(std::unique_ptr<wrapper::StmtWrapper> stmt) {
  threading::MutexLocker locker(m_stmtsMutex);

  stmt->clear();

  m_stmts[stmt->getSql()].push_back(std::move(stmt));
}

//------------------------------------------------------------------------------
// clear
//------------------------------------------------------------------------------
void StmtPool::clear() {
  m_stmts.clear();
}

} // namespace rdbms
} // namespace cta