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/*
* libmowgli: A collection of useful routines for programming.
* mowgli_spinlock.c: Spinlocks.
*
* Copyright (c) 2007 William Pitcock <nenolod -at- sacredspiral.co.uk>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice is present in all copies.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include "mowgli.h"
mowgli_spinlock_t *mowgli_spinlock_create(void)
{
mowgli_spinlock_t *out = mowgli_alloc(sizeof(mowgli_spinlock_t));
return out;
}
void mowgli_spinlock_lock(mowgli_spinlock_t *self, void *r, void *w)
{
return_if_fail(self != NULL);
if (r)
mowgli_spinlock_wait(self, MOWGLI_SPINLOCK_READ);
if (w)
mowgli_spinlock_wait(self, MOWGLI_SPINLOCK_WRITE);
if (r && (self->read_owner == NULL || self->read_owner == r))
self->read_owner = r;
if (w && (self->write_owner == NULL || self->write_owner == w))
self->write_owner = w;
}
void mowgli_spinlock_unlock(mowgli_spinlock_t *self, void *r, void *w)
{
return_if_fail(self != NULL);
if (r && self->read_owner == r)
self->read_owner = NULL;
if (w && self->write_owner == w)
self->write_owner = NULL;
}
void mowgli_spinlock_wait(mowgli_spinlock_t *self, mowgli_spinlock_lock_param_t param)
{
return_if_fail(self != NULL)
if (param == MOWGLI_SPINLOCK_READ)
while (self->read_owner != NULL)
usleep(1000); /* XXX: we'll want a more threadsafe function eventually. */
if (param == MOWGLI_SPINLOCK_WRITE)
while (self->write_owner != NULL)
usleep(1000);
if (param == MOWGLI_SPINLOCK_READWRITE)
while (self->write_owner != NULL || self->read_owner != NULL)
usleep(1000);
}
void mowgli_spinlock_timed_wait(mowgli_spinlock_t *self, mowgli_spinlock_lock_param_t param, struct timeval *tv)
{
struct timeval iter = {0};
return_if_fail(self != NULL)
return_if_fail(tv != NULL)
if (param == MOWGLI_SPINLOCK_READ)
while (self->read_owner != NULL && iter.tv_sec < tv->tv_sec && iter.tv_usec < tv->tv_usec)
{
gettimeofday(&iter, NULL);
usleep(1000); /* XXX: we'll want a more threadsafe function eventually. */
}
if (param == MOWGLI_SPINLOCK_WRITE)
while (self->write_owner != NULL && iter.tv_sec < tv->tv_sec && iter.tv_usec < tv->tv_usec)
{
gettimeofday(&iter, NULL);
usleep(1000);
}
if (param == MOWGLI_SPINLOCK_READWRITE)
while ((self->write_owner != NULL || self->read_owner != NULL) && iter.tv_sec < tv->tv_sec && iter.tv_usec < tv->tv_usec)
{
gettimeofday(&iter, NULL);
usleep(1000);
}
}
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