ArMutex_LIN.cpp

/*
MobileRobots Advanced Robotics Interface for Applications (ARIA)
Copyright (C) 2004, 2005 ActivMedia Robotics LLC
Copyright (C) 2006, 2007 MobileRobots 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; either version 2 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, write to the Free Software
     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

If you wish to redistribute ARIA under different terms, contact 
MobileRobots for information about a commercial version of ARIA at 
robots@mobilerobots.com or 
MobileRobots Inc, 19 Columbia Drive, Amherst, NH 03031; 800-639-9481
*/

#include "ArExport.h"
#include <errno.h>
#include "ariaOSDef.h"
#include "ArMutex.h"
#include "ArLog.h"
#include "ArThread.h"

#include <sys/types.h>
#include <unistd.h>     // for getpid()

ArMutex::ArMutex() :
  myFailedInit(false),
  myMutex()
{
  myLog = false;
  if (pthread_mutex_init(&myMutex, 0) < 0)
  {
    myFailedInit=true;
    ArLog::logNoLock(ArLog::Terse, "ArMutex::ArMutex: Failed to initialize mutex");
  }
  else
    unlock();

  myStrMap[STATUS_FAILED_INIT]="Failed to initialize";
  myStrMap[STATUS_FAILED]="General failure";
  myStrMap[STATUS_ALREADY_LOCKED]="Mutex already locked";
}

ArMutex::~ArMutex()
{
  if (!myFailedInit && (pthread_mutex_destroy(&myMutex) < 0))
  {
    if (errno == EBUSY)
      ArLog::logNoLock(ArLog::Terse, "ArMutex::~ArMutex: Failed to destroy mutex. A thread is currently blocked waiting for this mutex.");
    else
      ArLog::logNoLock(ArLog::Terse, "ArMutex::~ArMutex: Failed to destroy mutex. Unknown error.");
  }      
}

int ArMutex::lock() 
{
  if (myLog && ArThread::self() != NULL)
    ArLog::log(ArLog::Terse, "Locking %s from thread %s %d pid %d", 
           myLogName.c_str(),
           ArThread::self()->getThreadName(), 
           *(ArThread::self()->getThread()), getpid());
  else if (myLog)
    ArLog::log(ArLog::Terse, 
           "Locking %s probably from pid %d", myLogName.c_str(), getpid());
  if (myFailedInit)
  {
    ArLog::logNoLock(ArLog::Terse, "ArMutex::lock: Initialization of mutex failed, failed lock");
    return(STATUS_FAILED_INIT);
  }

  if (pthread_mutex_lock(&myMutex) < 0)
  {
    if (errno == EDEADLK)
    {
      ArLog::logNoLock(ArLog::Terse, "ArMutex::lock: Trying to lock a mutex which is already locked by this thread");
      return(STATUS_ALREADY_LOCKED);
    }
    else
    {
      ArLog::logNoLock(ArLog::Terse, "ArMutex::lock: Failed to lock due to an unknown error");
      return(STATUS_FAILED);
    }
  }

  return(0);
}

int ArMutex::tryLock() 
{
  if (myFailedInit)
  {
    ArLog::logNoLock(ArLog::Terse, "ArMutex::tryLock: Initialization of mutex failed, failed trylock");
    return(STATUS_FAILED_INIT);
  }

  if (pthread_mutex_trylock(&myMutex) < 0)
  {
    if (errno == EBUSY)
    {
      ArLog::logNoLock(ArLog::Terse, "ArMutex::tryLock: Could not lock mutex because it is already locked");
      return(STATUS_ALREADY_LOCKED);
    }
    else
    {
      ArLog::logNoLock(ArLog::Terse, "ArMutex::trylock: Failed to trylock due to an unknown error");
      return(STATUS_FAILED);
    }
  }

  return(0);
}

int ArMutex::unlock() 
{
  if (myLog && ArThread::self() != NULL)
    ArLog::log(ArLog::Terse, "Unlocking %s from thread %s %d pid %d", 
           myLogName.c_str(),
           ArThread::self()->getThreadName(), 
           *(ArThread::self()->getThread()), getpid());
  else if (myLog)
    ArLog::log(ArLog::Terse, 
           "Unlocking %s probably from pid %d", myLogName.c_str(), getpid());
  if (myFailedInit)
  {
    ArLog::logNoLock(ArLog::Terse, "ArMutex::unlock: Initialization of mutex failed, failed unlock");
    return(STATUS_FAILED_INIT);
  }

  if (pthread_mutex_unlock(&myMutex) < 0)
  {
    if (errno == EPERM)
    {
      ArLog::logNoLock(ArLog::Terse, "ArMutex::unlock: Trying to unlock a mutex which this thread does not own");
      return(STATUS_ALREADY_LOCKED);
    }
    else
    {
      ArLog::logNoLock(ArLog::Terse, "ArMutex::unlock: Failed to unlock due to an unknown error");
      return(STATUS_FAILED);
    }
  }

  return(0);
}

AREXPORT const char *ArMutex::getError(int messageNumber) const
{
  ArStrMap::const_iterator it;
  if ((it = myStrMap.find(messageNumber)) != myStrMap.end())
    return (*it).second.c_str();
  else
    return NULL;
}

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