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RetroArch/deps/pthreads/sem.c
twinaphex 9488e4e25a Add pthreads-emb implementation
2017-12-26 20:52:03 +01:00

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/*
* -------------------------------------------------------------
*
* Module: sem.c
*
* Purpose:
* Semaphores aren't actually part of the PThreads standard.
* They are defined by the POSIX Standard:
*
* POSIX 1003.1b-1993 (POSIX.1b)
*
* -------------------------------------------------------------
*
* --------------------------------------------------------------------------
*
* Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems
* Copyright(C) 2008 Jason Schmidlapp
*
* Contact Email: jschmidlapp@users.sourceforge.net
*
*
* Based upon Pthreads-win32 - POSIX Threads Library for Win32
* Copyright(C) 1998 John E. Bossom
* Copyright(C) 1999,2005 Pthreads-win32 contributors
*
* Contact Email: rpj@callisto.canberra.edu.au
*
* The original list of contributors to the Pthreads-win32 project
* is contained in the file CONTRIBUTORS.ptw32 included with the
* source code distribution. The list can also be seen at the
* following World Wide Web location:
* http://sources.redhat.com/pthreads-win32/contributors.html
*
* This 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 2 of the License, or (at your option) any later version.
*
* This 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 library in the file COPYING.LIB;
* if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <stdio.h>
#include <stdlib.h>
#include "pte_osal.h"
#include "pthread.h"
#include "semaphore.h"
#include "implement.h"
typedef struct
{
sem_t sem;
int * resultPtr;
} sem_timedwait_cleanup_args_t;
static void pte_sem_wait_cleanup(void * sem)
{
sem_t s = (sem_t) sem;
unsigned int timeout;
if (pthread_mutex_lock (&s->lock) == 0)
{
/*
* If sema is destroyed do nothing, otherwise:-
* If the sema is posted between us being cancelled and us locking
* the sema again above then we need to consume that post but cancel
* anyway. If we don't get the semaphore we indicate that we're no
* longer waiting.
*/
timeout = 0;
if (pte_osSemaphorePend(s->sem, &timeout) != PTE_OS_OK)
{
++s->value;
/*
* Don't release the W32 sema, it doesn't need adjustment
* because it doesn't record the number of waiters.
*/
}
(void) pthread_mutex_unlock (&s->lock);
}
}
static void pte_sem_timedwait_cleanup (void * args)
{
sem_timedwait_cleanup_args_t * a = (sem_timedwait_cleanup_args_t *)args;
sem_t s = a->sem;
if (pthread_mutex_lock (&s->lock) == 0)
{
/*
* We either timed out or were cancelled.
* If someone has posted between then and now we try to take the semaphore.
* Otherwise the semaphore count may be wrong after we
* return. In the case of a cancellation, it is as if we
* were cancelled just before we return (after taking the semaphore)
* which is ok.
*/
unsigned int timeout = 0;
if (pte_osSemaphorePend(s->sem, &timeout) == PTE_OS_OK)
{
/* We got the semaphore on the second attempt */
*(a->resultPtr) = 0;
}
else
{
/* Indicate we're no longer waiting */
s->value++;
/*
* Don't release the OS sema, it doesn't need adjustment
* because it doesn't record the number of waiters.
*/
}
(void) pthread_mutex_unlock (&s->lock);
}
}
int sem_close (sem_t * sem)
{
errno = ENOSYS;
return -1;
}
int sem_destroy (sem_t * sem)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function destroys an unnamed semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* DESCRIPTION
* This function destroys an unnamed semaphore.
*
* RESULTS
* 0 successfully destroyed semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* EBUSY threads (or processes) are currently
* blocked on 'sem'
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s = NULL;
if (sem == NULL || *sem == NULL)
result = EINVAL;
else
{
s = *sem;
if ((result = pthread_mutex_lock (&s->lock)) == 0)
{
if (s->value < 0)
{
(void) pthread_mutex_unlock (&s->lock);
result = EBUSY;
}
else
{
/* There are no threads currently blocked on this semaphore. */
pte_osResult osResult = pte_osSemaphoreDelete(s->sem);
if (osResult != PTE_OS_OK)
{
(void) pthread_mutex_unlock (&s->lock);
result = EINVAL;
}
else
{
/*
* Invalidate the semaphore handle when we have the lock.
* Other sema operations should test this after acquiring the lock
* to check that the sema is still valid, i.e. before performing any
* operations. This may only be necessary before the sema op routine
* returns so that the routine can return EINVAL - e.g. if setting
* s->value to SEM_VALUE_MAX below does force a fall-through.
*/
*sem = NULL;
/* Prevent anyone else actually waiting on or posting this sema.
*/
s->value = SEM_VALUE_MAX;
(void) pthread_mutex_unlock (&s->lock);
do
{
/* Give other threads a chance to run and exit any sema op
* routines. Due to the SEM_VALUE_MAX value, if sem_post or
* sem_wait were blocked by us they should fall through.
*/
pte_osThreadSleep(1);
}
while (pthread_mutex_destroy (&s->lock) == EBUSY);
}
}
}
}
if (result != 0)
{
errno = result;
return -1;
}
free (s);
return 0;
}
int
sem_getvalue (sem_t * sem, int *sval)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function stores the current count value of the
* semaphore.
* RESULTS
*
* Return value
*
* 0 sval has been set.
* -1 failed, error in errno
*
* in global errno
*
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS this function is not supported,
*
*
* PARAMETERS
*
* sem pointer to an instance of sem_t
*
* sval pointer to int.
*
* DESCRIPTION
* This function stores the current count value of the semaphore
* pointed to by sem in the int pointed to by sval.
*/
{
if (sem == NULL || *sem == NULL || sval == NULL)
{
errno = EINVAL;
return -1;
}
else
{
long value;
register sem_t s = *sem;
int result = 0;
if ((result = pthread_mutex_lock(&s->lock)) == 0)
{
if (*sem == NULL)
{
(void) pthread_mutex_unlock (&s->lock);
errno = EINVAL;
return -1;
}
value = s->value;
(void) pthread_mutex_unlock(&s->lock);
*sval = value;
}
return result;
}
}
int
sem_init (sem_t * sem, int pshared, unsigned int value)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function initializes a semaphore. The
* initial value of the semaphore is 'value'
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* pshared
* if zero, this semaphore may only be shared between
* threads in the same process.
* if nonzero, the semaphore can be shared between
* processes
*
* value
* initial value of the semaphore counter
*
* DESCRIPTION
* This function initializes a semaphore. The
* initial value of the semaphore is set to 'value'.
*
* RESULTS
* 0 successfully created semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore, or
* 'value' >= SEM_VALUE_MAX
* ENOMEM out of memory,
* ENOSPC a required resource has been exhausted,
* ENOSYS semaphores are not supported,
* EPERM the process lacks appropriate privilege
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s = NULL;
if (pshared != 0)
{
/*
* Creating a semaphore that can be shared between
* processes
*/
result = EPERM;
}
else if (value > (unsigned int)SEM_VALUE_MAX)
{
result = EINVAL;
}
else
{
s = (sem_t) calloc (1, sizeof (*s));
if (NULL == s)
{
result = ENOMEM;
}
else
{
s->value = value;
if (pthread_mutex_init(&s->lock, NULL) == 0)
{
pte_osResult osResult = pte_osSemaphoreCreate(0, &s->sem);
if (osResult != PTE_OS_OK)
{
(void) pthread_mutex_destroy(&s->lock);
result = ENOSPC;
}
}
else
{
result = ENOSPC;
}
if (result != 0)
{
free(s);
}
}
}
if (result != 0)
{
errno = result;
return -1;
}
*sem = s;
return 0;
}
int sem_open (const char *name, int oflag, mode_t mode, unsigned int value)
{
errno = ENOSYS;
return -1;
}
int
sem_post (sem_t * sem)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function posts a wakeup to a semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* DESCRIPTION
* This function posts a wakeup to a semaphore. If there
* are waiting threads (or processes), one is awakened;
* otherwise, the semaphore value is incremented by one.
*
* RESULTS
* 0 successfully posted semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* ERANGE semaphore count is too big
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s = *sem;
if (s == NULL)
result = EINVAL;
else if ((result = pthread_mutex_lock (&s->lock)) == 0)
{
/* See sem_destroy.c
*/
if (*sem == NULL)
{
(void) pthread_mutex_unlock (&s->lock);
result = EINVAL;
return -1;
}
if (s->value < SEM_VALUE_MAX)
{
pte_osResult osResult = pte_osSemaphorePost(s->sem, 1);
if (++s->value <= 0
&& (osResult != PTE_OS_OK))
{
s->value--;
result = EINVAL;
}
}
else
result = ERANGE;
(void) pthread_mutex_unlock (&s->lock);
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
}
int
sem_post_multiple (sem_t * sem, int count)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function posts multiple wakeups to a semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* count
* counter, must be greater than zero.
*
* DESCRIPTION
* This function posts multiple wakeups to a semaphore. If there
* are waiting threads (or processes), n <= count are awakened;
* the semaphore value is incremented by count - n.
*
* RESULTS
* 0 successfully posted semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore
* or count is less than or equal to zero.
* ERANGE semaphore count is too big
*
* ------------------------------------------------------
*/
{
int result = 0;
long waiters;
sem_t s = *sem;
if (s == NULL || count <= 0)
result = EINVAL;
else if ((result = pthread_mutex_lock (&s->lock)) == 0)
{
/* See sem_destroy.c
*/
if (*sem == NULL)
{
(void) pthread_mutex_unlock (&s->lock);
result = EINVAL;
return -1;
}
if (s->value <= (SEM_VALUE_MAX - count))
{
waiters = -s->value;
s->value += count;
if (waiters > 0)
{
pte_osSemaphorePost(s->sem, (waiters<=count)?waiters:count);
result = 0;
}
/*
else
{
s->value -= count;
result = EINVAL;
}
*/
}
else
{
result = ERANGE;
}
(void) pthread_mutex_unlock (&s->lock);
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
}
int
sem_timedwait (sem_t * sem, const struct timespec *abstime)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function waits on a semaphore possibly until
* 'abstime' time.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* abstime
* pointer to an instance of struct timespec
*
* DESCRIPTION
* This function waits on a semaphore. If the
* semaphore value is greater than zero, it decreases
* its value by one. If the semaphore value is zero, then
* the calling thread (or process) is blocked until it can
* successfully decrease the value or until interrupted by
* a signal.
*
* If 'abstime' is a NULL pointer then this function will
* block until it can successfully decrease the value or
* until interrupted by a signal.
*
* RESULTS
* 0 successfully decreased semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* EINTR the function was interrupted by a signal,
* EDEADLK a deadlock condition was detected.
* ETIMEDOUT abstime elapsed before success.
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s = *sem;
pthread_testcancel();
if (sem == NULL)
result = EINVAL;
else
{
unsigned int milliseconds;
unsigned int *pTimeout;
if (abstime == NULL)
{
pTimeout = NULL;
}
else
{
/*
* Calculate timeout as milliseconds from current system time.
*/
milliseconds = pte_relmillisecs (abstime);
pTimeout = &milliseconds;
}
if ((result = pthread_mutex_lock (&s->lock)) == 0)
{
int v;
/* See sem_destroy.c
*/
if (*sem == NULL)
{
(void) pthread_mutex_unlock (&s->lock);
errno = EINVAL;
return -1;
}
v = --s->value;
(void) pthread_mutex_unlock (&s->lock);
if (v < 0)
{
{
sem_timedwait_cleanup_args_t cleanup_args;
cleanup_args.sem = s;
cleanup_args.resultPtr = &result;
/* Must wait */
pthread_cleanup_push(pte_sem_timedwait_cleanup, (void *) &cleanup_args);
result = pte_cancellable_wait(s->sem,pTimeout);
pthread_cleanup_pop(result);
}
}
}
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
}
int sem_trywait (sem_t * sem)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function tries to wait on a semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* DESCRIPTION
* This function tries to wait on a semaphore. If the
* semaphore value is greater than zero, it decreases
* its value by one. If the semaphore value is zero, then
* this function returns immediately with the error EAGAIN
*
* RESULTS
* 0 successfully decreased semaphore,
* -1 failed, error in errno
* ERRNO
* EAGAIN the semaphore was already locked,
* EINVAL 'sem' is not a valid semaphore,
* ENOTSUP sem_trywait is not supported,
* EINTR the function was interrupted by a signal,
* EDEADLK a deadlock condition was detected.
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s = *sem;
if (s == NULL)
result = EINVAL;
else if ((result = pthread_mutex_lock (&s->lock)) == 0)
{
/* See sem_destroy.c
*/
if (*sem == NULL)
{
(void) pthread_mutex_unlock (&s->lock);
errno = EINVAL;
return -1;
}
if (s->value > 0)
s->value--;
else
result = EAGAIN;
(void) pthread_mutex_unlock (&s->lock);
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
}
int sem_unlink (const char *name)
{
errno = ENOSYS;
return -1;
}
int sem_wait (sem_t * sem)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function waits on a semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* DESCRIPTION
* This function waits on a semaphore. If the
* semaphore value is greater than zero, it decreases
* its value by one. If the semaphore value is zero, then
* the calling thread (or process) is blocked until it can
* successfully decrease the value or until interrupted by
* a signal.
*
* RESULTS
* 0 successfully decreased semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* EINTR the function was interrupted by a signal,
* EDEADLK a deadlock condition was detected.
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s = *sem;
pthread_testcancel();
if (s == NULL)
{
result = EINVAL;
}
else
{
if ((result = pthread_mutex_lock (&s->lock)) == 0)
{
int v;
/* See sem_destroy.c
*/
if (*sem == NULL)
{
(void) pthread_mutex_unlock (&s->lock);
errno = EINVAL;
return -1;
}
v = --s->value;
(void) pthread_mutex_unlock (&s->lock);
if (v < 0)
{
/* Must wait */
pthread_cleanup_push(pte_sem_wait_cleanup, (void *) s);
result = pte_cancellable_wait(s->sem,NULL);
/* Cleanup if we're canceled or on any other error */
pthread_cleanup_pop(result);
// Wait was cancelled, indicate that we're no longer waiting on this semaphore.
/*
if (result == PTE_OS_INTERRUPTED)
{
result = EINTR;
++s->value;
}
*/
}
}
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
} /* sem_wait */
int
sem_wait_nocancel (sem_t * sem)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function waits on a semaphore, and doesn't
* allow cancellation.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* DESCRIPTION
* This function waits on a semaphore. If the
* semaphore value is greater than zero, it decreases
* its value by one. If the semaphore value is zero, then
* the calling thread (or process) is blocked until it can
* successfully decrease the value or until interrupted by
* a signal.
*
* RESULTS
* 0 successfully decreased semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* EINTR the function was interrupted by a signal,
* EDEADLK a deadlock condition was detected.
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s = *sem;
pthread_testcancel();
if (s == NULL)
{
result = EINVAL;
}
else
{
if ((result = pthread_mutex_lock (&s->lock)) == 0)
{
int v;
/* See sem_destroy.c
*/
if (*sem == NULL)
{
(void) pthread_mutex_unlock (&s->lock);
errno = EINVAL;
return -1;
}
v = --s->value;
(void) pthread_mutex_unlock (&s->lock);
if (v < 0)
{
pte_osSemaphorePend(s->sem, NULL);
}
}
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
}
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