// ------------------------------------------------------------------------
// kvu_threads.cpp: Various pthread related helper functions.
// Copyright (C) 2002,2004 Kai Vehmanen
//
// 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
// ------------------------------------------------------------------------

#include <sys/time.h> /* gettimeofday() */
#include <errno.h> /* ETIMEDOUT */

#include "kvu_threads.h"

using std::string;

/**
 * A variant of the standard pthread_mutex_lock. This routine is
 * originally from Quasimodo CVS-tree, from the libpbd library, Written 
 * by Paul Davis. This version of the routine adds a second
 * argument, 'spinlimit' which specifies the number of loops spent
 * spinning, before blocking with the standard pthread_mutex_lock() call.
 */
int kvu_pthread_mutex_spinlock (pthread_mutex_t *mp, long int spinlimit)
{
  int err = EBUSY;
  unsigned int i;
  
  i = spinlimit;
  
  while (i > 0 && ((err = pthread_mutex_trylock (mp)) == EBUSY))
    i--;
  
  if (err == EBUSY) {
    err = pthread_mutex_lock (mp);
  }
  
  return err;
}

/**
 * Waits for condition to occur.
 *
 * @return 0 on success, 
 *         -ETIMEDOUT if timeout occured, 
 *	   other nonzero value on other errors
 */
int kvu_pthread_timed_wait(pthread_mutex_t* mutex, pthread_cond_t* cond, long int seconds)
{
   struct timeval now;
   gettimeofday(&now, 0);
   struct timespec sleepcount;
   sleepcount.tv_sec = now.tv_sec + seconds;
   sleepcount.tv_nsec = now.tv_usec * 1000;
   int ret = 0;
    
   pthread_mutex_lock(mutex);
   ret = pthread_cond_timedwait(cond, 
				mutex,
				&sleepcount);
   pthread_mutex_unlock(mutex);

   return(ret);
}

/**
 * Returns a string explaning the error code 
 * returned by kvu_pthread_timed_wait().
 */
string kvu_pthread_timed_wait_result(int result, const string& prefix)
{
  if (result != 0) {
    if (result == -ETIMEDOUT)
      return(prefix + " failed; timeout");
    else
      return(prefix + " failed");
  }
  return(prefix + " ok");
}