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/*************************************************************************
* Copyright (C) 2009-2013 Tavian Barnes <tavianator@tavianator.com> *
* *
* This file is part of The Dimension Library. *
* *
* The Dimension Library is free software; you can redistribute it and/ *
* or modify it under the terms of the GNU Lesser General Public License *
* as published by the Free Software Foundation; either version 3 of the *
* License, or (at your option) any later version. *
* *
* The Dimension Library 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 *
* Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with this program. If not, see *
* <http://www.gnu.org/licenses/>. *
*************************************************************************/
/**
* @file
* Future objects.
*/
#include "dimension-internal.h"
#include <pthread.h>
/**
* Since C doesn't support anything like C++'s mutable, we fake it by casting
* away the constness. This is okay since all valid dmnsn_futures live on the
* heap, so cannot be const.
*/
#define MUTATE(future) ((dmnsn_future *)future)
/* Allocate a new dmnsn_future* */
dmnsn_future *
dmnsn_new_future(void)
{
dmnsn_future *future = dmnsn_malloc(sizeof(dmnsn_future));
future->progress = 0;
future->total = 1;
dmnsn_initialize_mutex(&future->mutex);
dmnsn_initialize_cond(&future->cond);
future->min_wait = 1.0;
return future;
}
/* Join the worker thread and delete `future'. */
int
dmnsn_future_join(dmnsn_future *future)
{
void *ptr;
int retval = -1;
if (future) {
/* Get the thread's return value */
dmnsn_join_thread(future->thread, &ptr);
if (ptr && ptr != PTHREAD_CANCELED) {
retval = *(int *)ptr;
dmnsn_free(ptr);
}
/* Free the future object */
dmnsn_destroy_cond(&future->cond);
dmnsn_destroy_mutex(&future->mutex);
dmnsn_free(future);
}
return retval;
}
/* Cancel a background thread */
void
dmnsn_future_cancel(dmnsn_future *future)
{
pthread_cancel(future->thread);
}
/**
* Get the current progress, without locking anything.
*
* future->mutex must be locked for this call to be safe.
*/
static inline double
dmnsn_future_progress_unlocked(const dmnsn_future *future)
{
return (double)future->progress/future->total;
}
/* Get the current progress of the worker thread, in [0.0, 1.0] */
double
dmnsn_future_progress(const dmnsn_future *future)
{
dmnsn_future *mfuture = MUTATE(future);
double progress;
dmnsn_lock_mutex(&mfuture->mutex);
progress = dmnsn_future_progress_unlocked(mfuture);
dmnsn_unlock_mutex(&mfuture->mutex);
return progress;
}
/* Wait until dmnsn_future_progress(future) >= progress */
void
dmnsn_future_wait(const dmnsn_future *future, double progress)
{
dmnsn_future *mfuture = MUTATE(future);
dmnsn_lock_mutex(&mfuture->mutex);
while (dmnsn_future_progress_unlocked(mfuture) < progress) {
/* Set the minimum waited-on value */
if (progress < mfuture->min_wait)
mfuture->min_wait = progress;
dmnsn_cond_wait(&mfuture->cond, &mfuture->mutex);
}
dmnsn_unlock_mutex(&mfuture->mutex);
}
/* Set the total number of loop iterations */
void
dmnsn_future_set_total(dmnsn_future *future, size_t total)
{
dmnsn_lock_mutex(&future->mutex);
future->total = total;
dmnsn_unlock_mutex(&future->mutex);
}
/* Increment the number of completed loop iterations */
void
dmnsn_future_increment(dmnsn_future *future)
{
/* Allow a thread to be canceled whenever it increments a future object --
this is close to PTHREAD_CANCEL_ASYNCHRONOUS but allows consistent state
on cancellation */
pthread_testcancel();
dmnsn_lock_mutex(&future->mutex);
++future->progress;
if (dmnsn_future_progress_unlocked(future) >= future->min_wait) {
future->min_wait = 1.0;
dmnsn_cond_broadcast(&future->cond);
}
dmnsn_unlock_mutex(&future->mutex);
}
/* Immediately set to 100% completion */
void
dmnsn_future_done(dmnsn_future *future)
{
dmnsn_lock_mutex(&future->mutex);
future->progress = future->total;
dmnsn_cond_broadcast(&future->cond);
dmnsn_unlock_mutex(&future->mutex);
}
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