////////////////////////////////////////////////////////////////////////////////
/// @brief Write Locker
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2014 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Frank Celler
/// @author Achim Brandt
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2010-2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

#include "WriteLocker.h"

#ifdef TRI_SHOW_LOCK_TIME
#include "Basics/logging.h"
#endif

using namespace triagens::basics;

// -----------------------------------------------------------------------------
// --SECTION--                                      constructors and destructors
// -----------------------------------------------------------------------------


////////////////////////////////////////////////////////////////////////////////
/// @brief aquires a write-lock
///
/// The constructors aquires a write lock, the destructors unlocks the lock.
////////////////////////////////////////////////////////////////////////////////

#ifdef TRI_SHOW_LOCK_TIME

WriteLocker::WriteLocker (ReadWriteLock* readWriteLock, char const* file, int line)
  : _readWriteLock(readWriteLock), _file(file), _line(line) {

  double t = TRI_microtime();
  _readWriteLock->writeLock();
  _time = TRI_microtime() - t;
}

#else 

WriteLocker::WriteLocker (ReadWriteLock* readWriteLock)
  : _readWriteLock(readWriteLock) {
  
  _readWriteLock->writeLock();
}

#endif

////////////////////////////////////////////////////////////////////////////////
/// @brief aquires a write-lock, with periodic sleeps while not acquired
/// sleep time is specified in nanoseconds
////////////////////////////////////////////////////////////////////////////////

#ifdef TRI_SHOW_LOCK_TIME

WriteLocker::WriteLocker (ReadWriteLock* readWriteLock, 
                          uint64_t sleepTime,
                          char const* file,
                          int line) 
  : _readWriteLock(readWriteLock), _file(file), _line(line) {
  
  double t = TRI_microtime();
  while (! _readWriteLock->tryWriteLock()) {
#ifdef _WIN32
    usleep((unsigned long) sleepTime);
#else
    usleep((useconds_t) sleepTime);
#endif
  }
  _time = TRI_microtime() - t;
}

#else

WriteLocker::WriteLocker (ReadWriteLock* readWriteLock, 
                          uint64_t sleepTime) 
  : _readWriteLock(readWriteLock) {
  
  while (! _readWriteLock->tryWriteLock()) {
#ifdef _WIN32
    usleep((unsigned long) sleepTime);
#else
    usleep((useconds_t) sleepTime);
#endif
  }
}

#endif

////////////////////////////////////////////////////////////////////////////////
/// @brief releases the write-lock
////////////////////////////////////////////////////////////////////////////////

WriteLocker::~WriteLocker () {
  _readWriteLock->unlock();

#ifdef TRI_SHOW_LOCK_TIME
  if (_time > TRI_SHOW_LOCK_THRESHOLD) {
    LOG_WARNING("WriteLocker %s:%d took %f s", _file, _line, _time);
  }
#endif  
}

// -----------------------------------------------------------------------------
// --SECTION--                                                       END-OF-FILE
// -----------------------------------------------------------------------------

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