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Add semaphores API.

This commit is contained in:
Jonas 'Sortie' Termansen 2014-08-02 17:33:14 +02:00
parent 0329192ba8
commit 392472af5c
10 changed files with 389 additions and 2 deletions
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3
libc/include/unistd.h
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@ -96,8 +96,7 @@ __BEGIN_DECLS
TODO: Uncomment when regular expressions are implemented. */
/* #define _POSIX_SAVED_IDS 1
TODO: Uncomment when saved ids are implemented. I forgot if they already are. */
/* #define _POSIX_SEMAPHORES 200809L
TODO: Uncomment when named semaphores are implemented. */
#define _POSIX_SEMAPHORES 200809L
/*TODO: _POSIX_SHARED_MEMORY_OBJECTS - Research what this is. */
#define _POSIX_SHELL 1
/*TODO: _POSIX_SPAWN - Research what this is. */

7
libpthread/Makefile
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@ -56,6 +56,13 @@ pthread_rwlock_wrlock.o \
pthread_self.o \
pthread_setspecific.o \
pthread_sigmask.o \
sem_destroy.o \
sem_getvalue.o \
sem_init.o \
sem_post.o \
sem_timedwait.o \
sem_trywait.o \
sem_wait.o \
BINS:=libpthread.a

58
libpthread/include/semaphore.h Normal file
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@ -0,0 +1,58 @@
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2014.
This file is part of Sortix libpthread.
Sortix libpthread 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.
Sortix libpthread 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 Sortix libpthread. If not, see <http://www.gnu.org/licenses/>.
semaphore.h
Semaphore API.
*******************************************************************************/
#ifndef INCLUDE_SEMAPHORE_H
#define INCLUDE_SEMAPHORE_H
#include <features.h>
#include <sortix/timespec.h>
__BEGIN_DECLS
typedef struct
{
#if defined(__is_sortix_libpthread)
int value;
#else
int __value;
#endif
} sem_t;
#define SEM_FAILED ((sem_t*) 0)
/*int sem_close(sem_t*);*/
int sem_destroy(sem_t*);
int sem_getvalue(sem_t* __restrict, int* __restrict);
int sem_init(sem_t*, int, unsigned int);
/*sem_t* sem_open(const char*, int, ...);*/
int sem_post(sem_t*);
int sem_timedwait(sem_t* __restrict, const struct timespec* __restrict);
int sem_trywait(sem_t*);
/*int sem_unlink(const char*);*/
int sem_wait(sem_t*);
__END_DECLS
#endif

31
libpthread/sem_destroy.c++ Normal file
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@ -0,0 +1,31 @@
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2014.
This file is part of Sortix libpthread.
Sortix libpthread 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.
Sortix libpthread 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 Sortix libpthread. If not, see <http://www.gnu.org/licenses/>.
sem_destroy.c++
Destroy a semaphore.
*******************************************************************************/
#include <semaphore.h>
extern "C" int sem_destroy(sem_t* sem)
{
(void) sem;
return 0;
}

31
libpthread/sem_getvalue.c++ Normal file
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@ -0,0 +1,31 @@
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2014.
This file is part of Sortix libpthread.
Sortix libpthread 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.
Sortix libpthread 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 Sortix libpthread. If not, see <http://www.gnu.org/licenses/>.
sem_getvalue.c++
Get the value of a semaphore.
*******************************************************************************/
#include <semaphore.h>
extern "C" int sem_getvalue(sem_t* restrict sem, int* restrict value_ptr)
{
*value_ptr = __atomic_load_n(&sem->value, __ATOMIC_SEQ_CST);
return 0;
}

40
libpthread/sem_init.c++ Normal file
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@ -0,0 +1,40 @@
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2014.
This file is part of Sortix libpthread.
Sortix libpthread 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.
Sortix libpthread 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 Sortix libpthread. If not, see <http://www.gnu.org/licenses/>.
sem_init.c++
Initialize a semaphore.
*******************************************************************************/
#include <errno.h>
#include <limits.h>
#include <semaphore.h>
extern "C" int sem_init(sem_t* sem, int pshared, unsigned int value)
{
if ( pshared )
return errno = ENOSYS, -1;
if ( (unsigned int) INT_MAX < value )
return errno = EINVAL, -1;
sem->value = (int) value;
return 0;
}

45
libpthread/sem_post.c++ Normal file
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@ -0,0 +1,45 @@
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2014.
This file is part of Sortix libpthread.
Sortix libpthread 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.
Sortix libpthread 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 Sortix libpthread. If not, see <http://www.gnu.org/licenses/>.
sem_post.c++
Unlock a semaphore.
*******************************************************************************/
#include <errno.h>
#include <limits.h>
#include <semaphore.h>
extern "C" int sem_post(sem_t* sem)
{
while ( true )
{
int old_value = __atomic_load_n(&sem->value, __ATOMIC_SEQ_CST);
if ( old_value == INT_MAX )
return errno = EOVERFLOW;
int new_value = old_value + 1;
if ( !__atomic_compare_exchange_n(&sem->value, &old_value, new_value,
false,
__ATOMIC_SEQ_CST, __ATOMIC_RELAXED) )
continue;
return 0;
}
}

76
libpthread/sem_timedwait.c++ Normal file
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@ -0,0 +1,76 @@
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2014.
This file is part of Sortix libpthread.
Sortix libpthread 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.
Sortix libpthread 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 Sortix libpthread. If not, see <http://www.gnu.org/licenses/>.
sem_timedwait.c++
Lock a semaphore.
*******************************************************************************/
#include <errno.h>
#include <sched.h>
#include <semaphore.h>
#include <signal.h>
#include <stddef.h>
#include <time.h>
#include <timespec.h>
extern "C"
int sem_timedwait(sem_t* restrict sem, const struct timespec* restrict abstime)
{
if ( sem_trywait(sem) == 0 )
return 0;
if ( errno != EAGAIN )
return -1;
sigset_t old_set_mask;
sigset_t old_set_allowed;
sigset_t all_signals;
sigfillset(&all_signals);
sigprocmask(SIG_SETMASK, &all_signals, &old_set_mask);
signotset(&old_set_allowed, &old_set_mask);
while ( sem_trywait(sem) != 0 )
{
// TODO: Using CLOCK_REALTIME for this is bad as it is not monotonic. We
// need to enchance the semaphore API so a better clock can be
// used instead.
if ( errno == EAGAIN )
{
struct timespec now;
clock_gettime(CLOCK_REALTIME, &now);
if ( timespec_le(*abstime, now) )
errno = ETIMEDOUT;
}
if ( errno == EAGAIN && sigpending(&old_set_allowed) )
errno = EINTR;
if ( errno != EAGAIN )
{
sigprocmask(SIG_SETMASK, &old_set_mask, NULL);
return -1;
}
sched_yield();
}
sigprocmask(SIG_SETMASK, &old_set_mask, NULL);
return 0;
}

38
libpthread/sem_trywait.c++ Normal file
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@ -0,0 +1,38 @@
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2014.
This file is part of Sortix libpthread.
Sortix libpthread 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.
Sortix libpthread 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 Sortix libpthread. If not, see <http://www.gnu.org/licenses/>.
sem_trywait.c++
Lock a semaphore.
*******************************************************************************/
#include <errno.h>
#include <semaphore.h>
extern "C" int sem_trywait(sem_t* sem)
{
int old_value = __atomic_load_n(&sem->value, __ATOMIC_SEQ_CST);
if ( old_value <= 0 )
return errno = EAGAIN, -1;
int new_value = old_value - 1;
if ( !__atomic_compare_exchange_n(&sem->value, &old_value, new_value, false,
__ATOMIC_SEQ_CST, __ATOMIC_RELAXED) )
return errno = EAGAIN, -1;
return 0;
}

62
libpthread/sem_wait.c++ Normal file
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@ -0,0 +1,62 @@
/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2014.
This file is part of Sortix libpthread.
Sortix libpthread 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.
Sortix libpthread 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 Sortix libpthread. If not, see <http://www.gnu.org/licenses/>.
sem_wait.c++
Lock a semaphore.
*******************************************************************************/
#include <errno.h>
#include <sched.h>
#include <semaphore.h>
#include <signal.h>
#include <stddef.h>
extern "C" int sem_wait(sem_t* sem)
{
if ( sem_trywait(sem) == 0 )
return 0;
if ( errno != EAGAIN )
return -1;
sigset_t old_set_mask;
sigset_t old_set_allowed;
sigset_t all_signals;
sigfillset(&all_signals);
sigprocmask(SIG_SETMASK, &all_signals, &old_set_mask);
signotset(&old_set_allowed, &old_set_mask);
while ( sem_trywait(sem) != 0 )
{
if ( errno == EAGAIN && sigpending(&old_set_allowed) )
errno = EINTR;
if ( errno != EAGAIN )
{
sigprocmask(SIG_SETMASK, &old_set_mask, NULL);
return -1;
}
sched_yield();
}
sigprocmask(SIG_SETMASK, &old_set_mask, NULL);
return 0;
}