/* Posix threads interface */ #include #include #if defined(__APPLE__) || defined(HAVE_PTHREAD_DESTRUCTOR) #define destructor xxdestructor #endif #include #if defined(__APPLE__) || defined(HAVE_PTHREAD_DESTRUCTOR) #undef destructor #endif #include /* The POSIX spec requires that use of pthread_attr_setstacksize be conditional on _POSIX_THREAD_ATTR_STACKSIZE being defined. */ #ifdef _POSIX_THREAD_ATTR_STACKSIZE #ifndef THREAD_STACK_SIZE #define THREAD_STACK_SIZE 0 /* use default stack size */ #endif #if (defined(__APPLE__) || defined(__FreeBSD__)) && defined(THREAD_STACK_SIZE) && THREAD_STACK_SIZE == 0 /* The default stack size for new threads on OSX is small enough that * we'll get hard crashes instead of 'maximum recursion depth exceeded' * exceptions. * * The default stack size below is the minimal stack size where a * simple recursive function doesn't cause a hard crash. */ #undef THREAD_STACK_SIZE #define THREAD_STACK_SIZE 0x400000 #endif /* for safety, ensure a viable minimum stacksize */ #define THREAD_STACK_MIN 0x8000 /* 32kB */ #else /* !_POSIX_THREAD_ATTR_STACKSIZE */ #ifdef THREAD_STACK_SIZE #error "THREAD_STACK_SIZE defined but _POSIX_THREAD_ATTR_STACKSIZE undefined" #endif #endif /* The POSIX spec says that implementations supporting the sem_* family of functions must indicate this by defining _POSIX_SEMAPHORES. */ #ifdef _POSIX_SEMAPHORES /* On FreeBSD 4.x, _POSIX_SEMAPHORES is defined empty, so we need to add 0 to make it work there as well. */ #if (_POSIX_SEMAPHORES+0) == -1 #define HAVE_BROKEN_POSIX_SEMAPHORES #else #include #include #endif #endif /* Before FreeBSD 5.4, system scope threads was very limited resource in default setting. So the process scope is preferred to get enough number of threads to work. */ #ifdef __FreeBSD__ #include #if __FreeBSD_version >= 500000 && __FreeBSD_version < 504101 #undef PTHREAD_SYSTEM_SCHED_SUPPORTED #endif #endif #if !defined(pthread_attr_default) # define pthread_attr_default ((pthread_attr_t *)NULL) #endif #if !defined(pthread_mutexattr_default) # define pthread_mutexattr_default ((pthread_mutexattr_t *)NULL) #endif #if !defined(pthread_condattr_default) # define pthread_condattr_default ((pthread_condattr_t *)NULL) #endif /* Whether or not to use semaphores directly rather than emulating them with * mutexes and condition variables: */ #if defined(_POSIX_SEMAPHORES) && !defined(HAVE_BROKEN_POSIX_SEMAPHORES) # define USE_SEMAPHORES #else # undef USE_SEMAPHORES #endif /* On platforms that don't use standard POSIX threads pthread_sigmask() * isn't present. DEC threads uses sigprocmask() instead as do most * other UNIX International compliant systems that don't have the full * pthread implementation. */ #if defined(HAVE_PTHREAD_SIGMASK) && !defined(HAVE_BROKEN_PTHREAD_SIGMASK) # define SET_THREAD_SIGMASK pthread_sigmask #else # define SET_THREAD_SIGMASK sigprocmask #endif /* A pthread mutex isn't sufficient to model the Python lock type * because, according to Draft 5 of the docs (P1003.4a/D5), both of the * following are undefined: * -> a thread tries to lock a mutex it already has locked * -> a thread tries to unlock a mutex locked by a different thread * pthread mutexes are designed for serializing threads over short pieces * of code anyway, so wouldn't be an appropriate implementation of * Python's locks regardless. * * The pthread_lock struct implements a Python lock as a "locked?" bit * and a pair. In general, if the bit can be acquired * instantly, it is, else the pair is used to block the thread until the * bit is cleared. 9 May 1994 tim@ksr.com */ typedef struct { char locked; /* 0=unlocked, 1=locked */ /* a pair to handle an acquire of a locked lock */ pthread_cond_t lock_released; pthread_mutex_t mut; } pthread_lock; #define CHECK_STATUS(name) if (status != 0) { perror(name); error = 1; } /* * Initialization. */ #ifdef _HAVE_BSDI static void _noop(void) { } static void PyThread__init_thread(void) { /* DO AN INIT BY STARTING THE THREAD */ static int dummy = 0; pthread_t thread1; pthread_create(&thread1, NULL, (void *) _noop, &dummy); pthread_join(thread1, NULL); } #else /* !_HAVE_BSDI */ static void PyThread__init_thread(void) { #if defined(_AIX) && defined(__GNUC__) extern void pthread_init(void); pthread_init(); #endif } #endif /* !_HAVE_BSDI */ /* * Thread support. */ /* bpo-33015: pythread_callback struct and pythread_wrapper() cast "void func(void *)" to "void* func(void *)": always return NULL. PyThread_start_new_thread() uses "void func(void *)" type, whereas pthread_create() requires a void* return value. */ typedef struct { void (*func) (void *); void *arg; } pythread_callback; static void * pythread_wrapper(void *arg) { /* copy func and func_arg and free the temporary structure */ pythread_callback *callback = arg; void (*func)(void *) = callback->func; void *func_arg = callback->arg; free(arg); func(func_arg); return NULL; } long PyThread_start_new_thread(void (*func)(void *), void *arg) { pthread_t th; int status; #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED) pthread_attr_t attrs; #endif #if defined(THREAD_STACK_SIZE) size_t tss; #endif dprintf(("PyThread_start_new_thread called\n")); if (!initialized) PyThread_init_thread(); #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED) if (pthread_attr_init(&attrs) != 0) return -1; #endif #if defined(THREAD_STACK_SIZE) tss = (_pythread_stacksize != 0) ? _pythread_stacksize : THREAD_STACK_SIZE; if (tss != 0) { if (pthread_attr_setstacksize(&attrs, tss) != 0) { pthread_attr_destroy(&attrs); return -1; } } #endif #if defined(PTHREAD_SYSTEM_SCHED_SUPPORTED) pthread_attr_setscope(&attrs, PTHREAD_SCOPE_SYSTEM); #endif pythread_callback *callback = malloc(sizeof(pythread_callback)); if (callback == NULL) { return -1; } callback->func = func; callback->arg = arg; status = pthread_create(&th, #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED) &attrs, #else (pthread_attr_t*)NULL, #endif pythread_wrapper, callback); #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED) pthread_attr_destroy(&attrs); #endif if (status != 0) { free(callback); return -1; } pthread_detach(th); #if SIZEOF_PTHREAD_T <= SIZEOF_LONG return (long) th; #else return (long) *(long *) &th; #endif } /* XXX This implementation is considered (to quote Tim Peters) "inherently hosed" because: - It does not guarantee the promise that a non-zero integer is returned. - The cast to long is inherently unsafe. - It is not clear that the 'volatile' (for AIX?) and ugly casting in the latter return statement (for Alpha OSF/1) are any longer necessary. */ long PyThread_get_thread_ident(void) { volatile pthread_t threadid; if (!initialized) PyThread_init_thread(); /* Jump through some hoops for Alpha OSF/1 */ threadid = pthread_self(); #if SIZEOF_PTHREAD_T <= SIZEOF_LONG return (long) threadid; #else return (long) *(long *) &threadid; #endif } void PyThread_exit_thread(void) { dprintf(("PyThread_exit_thread called\n")); if (!initialized) { exit(0); } } #ifdef USE_SEMAPHORES /* * Lock support. */ PyThread_type_lock PyThread_allocate_lock(void) { sem_t *lock; int status, error = 0; dprintf(("PyThread_allocate_lock called\n")); if (!initialized) PyThread_init_thread(); lock = (sem_t *)malloc(sizeof(sem_t)); if (lock) { status = sem_init(lock,0,1); CHECK_STATUS("sem_init"); if (error) { free((void *)lock); lock = NULL; } } dprintf(("PyThread_allocate_lock() -> %p\n", lock)); return (PyThread_type_lock)lock; } void PyThread_free_lock(PyThread_type_lock lock) { sem_t *thelock = (sem_t *)lock; int status, error = 0; (void) error; /* silence unused-but-set-variable warning */ dprintf(("PyThread_free_lock(%p) called\n", lock)); if (!thelock) return; status = sem_destroy(thelock); CHECK_STATUS("sem_destroy"); free((void *)thelock); } /* * As of February 2002, Cygwin thread implementations mistakenly report error * codes in the return value of the sem_ calls (like the pthread_ functions). * Correct implementations return -1 and put the code in errno. This supports * either. */ static int fix_status(int status) { return (status == -1) ? errno : status; } int PyThread_acquire_lock(PyThread_type_lock lock, int waitflag) { int success; sem_t *thelock = (sem_t *)lock; int status, error = 0; (void) error; /* silence unused-but-set-variable warning */ dprintf(("PyThread_acquire_lock(%p, %d) called\n", lock, waitflag)); do { if (waitflag) status = fix_status(sem_wait(thelock)); else status = fix_status(sem_trywait(thelock)); } while (status == EINTR); /* Retry if interrupted by a signal */ if (waitflag) { CHECK_STATUS("sem_wait"); } else if (status != EAGAIN) { CHECK_STATUS("sem_trywait"); } success = (status == 0) ? 1 : 0; dprintf(("PyThread_acquire_lock(%p, %d) -> %d\n", lock, waitflag, success)); return success; } void PyThread_release_lock(PyThread_type_lock lock) { sem_t *thelock = (sem_t *)lock; int status, error = 0; (void) error; /* silence unused-but-set-variable warning */ dprintf(("PyThread_release_lock(%p) called\n", lock)); status = sem_post(thelock); CHECK_STATUS("sem_post"); } #else /* USE_SEMAPHORES */ /* * Lock support. */ PyThread_type_lock PyThread_allocate_lock(void) { pthread_lock *lock; int status, error = 0; dprintf(("PyThread_allocate_lock called\n")); if (!initialized) PyThread_init_thread(); lock = (pthread_lock *) malloc(sizeof(pthread_lock)); if (lock) { memset((void *)lock, '\0', sizeof(pthread_lock)); lock->locked = 0; status = pthread_mutex_init(&lock->mut, pthread_mutexattr_default); CHECK_STATUS("pthread_mutex_init"); status = pthread_cond_init(&lock->lock_released, pthread_condattr_default); CHECK_STATUS("pthread_cond_init"); if (error) { free((void *)lock); lock = 0; } } dprintf(("PyThread_allocate_lock() -> %p\n", lock)); return (PyThread_type_lock) lock; } void PyThread_free_lock(PyThread_type_lock lock) { pthread_lock *thelock = (pthread_lock *)lock; int status, error = 0; (void) error; /* silence unused-but-set-variable warning */ dprintf(("PyThread_free_lock(%p) called\n", lock)); status = pthread_mutex_destroy( &thelock->mut ); CHECK_STATUS("pthread_mutex_destroy"); status = pthread_cond_destroy( &thelock->lock_released ); CHECK_STATUS("pthread_cond_destroy"); free((void *)thelock); } int PyThread_acquire_lock(PyThread_type_lock lock, int waitflag) { int success = 0; pthread_lock *thelock = (pthread_lock *)lock; int status, error = 0; dprintf(("PyThread_acquire_lock(%p, %d) called\n", lock, waitflag)); if (waitflag) { status = pthread_mutex_lock( &thelock->mut ); CHECK_STATUS("pthread_mutex_lock[1]"); } else { status = pthread_mutex_trylock( &thelock->mut ); if (status != EBUSY) CHECK_STATUS("pthread_mutex_trylock[1]"); } if (status == 0) { success = thelock->locked == 0; if ( !success && waitflag ) { /* continue trying until we get the lock */ /* mut must be locked by me -- part of the condition * protocol */ while ( thelock->locked ) { status = pthread_cond_wait(&thelock->lock_released, &thelock->mut); CHECK_STATUS("pthread_cond_wait"); } success = 1; } if (success) thelock->locked = 1; status = pthread_mutex_unlock( &thelock->mut ); CHECK_STATUS("pthread_mutex_unlock[1]"); } if (error) success = 0; dprintf(("PyThread_acquire_lock(%p, %d) -> %d\n", lock, waitflag, success)); return success; } void PyThread_release_lock(PyThread_type_lock lock) { pthread_lock *thelock = (pthread_lock *)lock; int status, error = 0; (void) error; /* silence unused-but-set-variable warning */ dprintf(("PyThread_release_lock(%p) called\n", lock)); status = pthread_mutex_lock( &thelock->mut ); CHECK_STATUS("pthread_mutex_lock[3]"); thelock->locked = 0; status = pthread_mutex_unlock( &thelock->mut ); CHECK_STATUS("pthread_mutex_unlock[3]"); /* wake up someone (anyone, if any) waiting on the lock */ status = pthread_cond_signal( &thelock->lock_released ); CHECK_STATUS("pthread_cond_signal"); } #endif /* USE_SEMAPHORES */ /* set the thread stack size. * Return 0 if size is valid, -1 if size is invalid, * -2 if setting stack size is not supported. */ static int _pythread_pthread_set_stacksize(size_t size) { #if defined(THREAD_STACK_SIZE) pthread_attr_t attrs; size_t tss_min; int rc = 0; #endif /* set to default */ if (size == 0) { _pythread_stacksize = 0; return 0; } #if defined(THREAD_STACK_SIZE) #if defined(PTHREAD_STACK_MIN) tss_min = PTHREAD_STACK_MIN > THREAD_STACK_MIN ? PTHREAD_STACK_MIN : THREAD_STACK_MIN; #else tss_min = THREAD_STACK_MIN; #endif if (size >= tss_min) { /* validate stack size by setting thread attribute */ if (pthread_attr_init(&attrs) == 0) { rc = pthread_attr_setstacksize(&attrs, size); pthread_attr_destroy(&attrs); if (rc == 0) { _pythread_stacksize = size; return 0; } } } return -1; #else return -2; #endif } #define THREAD_SET_STACKSIZE(x) _pythread_pthread_set_stacksize(x)