RepoMirrors
/
mpv
mirror of https://github.com/mpv-player/mpv
1
0
Fork 0
Code Issues Releases Wiki Activity
mpv/osdep/semaphore.h

38 lines
870 B
C
Raw Normal View History

osdep: add POSIX semaphore emulation for OSX OSX is POSIX conformant, but it's a sad joke: it provides the <semaphore.h> prototype as the standard demands, but they're empty wrappers, and all functions just return ENOSYS. Emulate them similar to how osdep/io.h emulate filesystem functions on Windows. By including the header, working sem_* functions become available. To make it async-signal safe, use a pipe for wakeup (write() is AS-safe, but mutexes can't be). Actually I'm not sure anymore if we really need AS-safety, but for now the emulation can do it. On Linux, the system provides a far more efficient and robust implementation. We definitely want to avoid using the emulation if possible, so this code is active on OSX only. For convenience we always build the source file though, even if the implementation is disabled and no actual code is generated. (Linux provides working semaphores, but is formally not POSIX conformant. On OSX it's the opposite. Is POSIX a complete joke?)
2014-09-10 01:09:41 +00:00
#ifndef MP_SEMAPHORE_H_
#define MP_SEMAPHORE_H_
osdep: hack to fix build with low quality pthreads-w32 headers When compiling semaphore_osx.c on win32, the following error happened: /usr/i686-w64-mingw32/include/semaphore.h:160:6: error: unknown type name 'mode_t' This is because this system header references symbols that are not not defined anywhere. This is clearly a bug in pthreads-w32, but has been known and unfixed since 2012, so add a hack to fix it. We build semaphore_osx.c this way because it saves us an extra configure check. On win32, Linux, etc. it's empty and contains "#include <semaphore.h>" only. Should fix #1108.
2014-09-20 02:18:40 +00:00
#include <sys/types.h>
osdep: add POSIX semaphore emulation for OSX OSX is POSIX conformant, but it's a sad joke: it provides the <semaphore.h> prototype as the standard demands, but they're empty wrappers, and all functions just return ENOSYS. Emulate them similar to how osdep/io.h emulate filesystem functions on Windows. By including the header, working sem_* functions become available. To make it async-signal safe, use a pipe for wakeup (write() is AS-safe, but mutexes can't be). Actually I'm not sure anymore if we really need AS-safety, but for now the emulation can do it. On Linux, the system provides a far more efficient and robust implementation. We definitely want to avoid using the emulation if possible, so this code is active on OSX only. For convenience we always build the source file though, even if the implementation is disabled and no actual code is generated. (Linux provides working semaphores, but is formally not POSIX conformant. On OSX it's the opposite. Is POSIX a complete joke?)
2014-09-10 01:09:41 +00:00
#include <semaphore.h>
various: make mentions of macOS consistent change all mentions and variations of OSX, OS X, MacOSX, MacOS X, etc consistent. use the official naming macOS.
2024-02-20 20:24:54 +00:00
// macOS provides non-working empty stubs, so we emulate them.
osdep: add POSIX semaphore emulation for OSX OSX is POSIX conformant, but it's a sad joke: it provides the <semaphore.h> prototype as the standard demands, but they're empty wrappers, and all functions just return ENOSYS. Emulate them similar to how osdep/io.h emulate filesystem functions on Windows. By including the header, working sem_* functions become available. To make it async-signal safe, use a pipe for wakeup (write() is AS-safe, but mutexes can't be). Actually I'm not sure anymore if we really need AS-safety, but for now the emulation can do it. On Linux, the system provides a far more efficient and robust implementation. We definitely want to avoid using the emulation if possible, so this code is active on OSX only. For convenience we always build the source file though, even if the implementation is disabled and no actual code is generated. (Linux provides working semaphores, but is formally not POSIX conformant. On OSX it's the opposite. Is POSIX a complete joke?)
2014-09-10 01:09:41 +00:00
// This should be AS-safe, but cancellation issues were ignored.
// sem_getvalue() is not provided.
// sem_post() won't always correctly return an error on overflow.
// Process-shared semantics are not provided.
#ifdef __APPLE__
#define MP_SEMAPHORE_EMULATION
ALL: use new mp_thread abstraction
2023-10-21 02:55:41 +00:00
#include "osdep/threads.h"
osdep: add POSIX semaphore emulation for OSX OSX is POSIX conformant, but it's a sad joke: it provides the <semaphore.h> prototype as the standard demands, but they're empty wrappers, and all functions just return ENOSYS. Emulate them similar to how osdep/io.h emulate filesystem functions on Windows. By including the header, working sem_* functions become available. To make it async-signal safe, use a pipe for wakeup (write() is AS-safe, but mutexes can't be). Actually I'm not sure anymore if we really need AS-safety, but for now the emulation can do it. On Linux, the system provides a far more efficient and robust implementation. We definitely want to avoid using the emulation if possible, so this code is active on OSX only. For convenience we always build the source file though, even if the implementation is disabled and no actual code is generated. (Linux provides working semaphores, but is formally not POSIX conformant. On OSX it's the opposite. Is POSIX a complete joke?)
2014-09-10 01:09:41 +00:00
#define MP_SEM_VALUE_MAX 4096
typedef struct {
int wakeup_pipe[2];
ALL: use new mp_thread abstraction
2023-10-21 02:55:41 +00:00
mp_mutex lock;
osdep: add POSIX semaphore emulation for OSX OSX is POSIX conformant, but it's a sad joke: it provides the <semaphore.h> prototype as the standard demands, but they're empty wrappers, and all functions just return ENOSYS. Emulate them similar to how osdep/io.h emulate filesystem functions on Windows. By including the header, working sem_* functions become available. To make it async-signal safe, use a pipe for wakeup (write() is AS-safe, but mutexes can't be). Actually I'm not sure anymore if we really need AS-safety, but for now the emulation can do it. On Linux, the system provides a far more efficient and robust implementation. We definitely want to avoid using the emulation if possible, so this code is active on OSX only. For convenience we always build the source file though, even if the implementation is disabled and no actual code is generated. (Linux provides working semaphores, but is formally not POSIX conformant. On OSX it's the opposite. Is POSIX a complete joke?)
2014-09-10 01:09:41 +00:00
// protected by lock
unsigned int count;
} mp_sem_t;
int mp_sem_init(mp_sem_t *sem, int pshared, unsigned int value);
int mp_sem_wait(mp_sem_t *sem);
int mp_sem_trywait(mp_sem_t *sem);
semaphore_osx: change mp_sem_timedwait to mp_time
2023-10-22 05:33:19 +00:00
int mp_sem_timedwait(mp_sem_t *sem, int64_t until);
osdep: add POSIX semaphore emulation for OSX OSX is POSIX conformant, but it's a sad joke: it provides the <semaphore.h> prototype as the standard demands, but they're empty wrappers, and all functions just return ENOSYS. Emulate them similar to how osdep/io.h emulate filesystem functions on Windows. By including the header, working sem_* functions become available. To make it async-signal safe, use a pipe for wakeup (write() is AS-safe, but mutexes can't be). Actually I'm not sure anymore if we really need AS-safety, but for now the emulation can do it. On Linux, the system provides a far more efficient and robust implementation. We definitely want to avoid using the emulation if possible, so this code is active on OSX only. For convenience we always build the source file though, even if the implementation is disabled and no actual code is generated. (Linux provides working semaphores, but is formally not POSIX conformant. On OSX it's the opposite. Is POSIX a complete joke?)
2014-09-10 01:09:41 +00:00
int mp_sem_post(mp_sem_t *sem);
int mp_sem_destroy(mp_sem_t *sem);
#endif
#endif