/* 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 /* The default stack size for new threads on OSX and BSD is small enough that * we'll get hard crashes instead of 'maximum recursion depth exceeded' * exceptions. * * The default stack sizes below are the empirically determined minimal stack * sizes where a simple recursive function doesn't cause a hard crash. */ #if defined(__APPLE__) && defined(THREAD_STACK_SIZE) && THREAD_STACK_SIZE == 0 #undef THREAD_STACK_SIZE #define THREAD_STACK_SIZE 0x500000 #endif #if defined(__FreeBSD__) && defined(THREAD_STACK_SIZE) && THREAD_STACK_SIZE == 0 #undef THREAD_STACK_SIZE #define THREAD_STACK_SIZE 0x400000 #endif /* for safety, ensure a viable minimum stacksize */ #define THREAD_STACK_MIN 0x8000 /* 32 KiB */ #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 #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) && \ defined(HAVE_SEM_TIMEDWAIT)) # 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 /* We assume all modern POSIX systems have gettimeofday() */ #ifdef GETTIMEOFDAY_NO_TZ #define GETTIMEOFDAY(ptv) gettimeofday(ptv) #else #define GETTIMEOFDAY(ptv) gettimeofday(ptv, (struct timezone *)NULL) #endif #define MICROSECONDS_TO_TIMESPEC(microseconds, ts) \ do { \ struct timeval tv; \ GETTIMEOFDAY(&tv); \ tv.tv_usec += microseconds % 1000000; \ tv.tv_sec += microseconds / 1000000; \ tv.tv_sec += tv.tv_usec / 1000000; \ tv.tv_usec %= 1000000; \ ts.tv_sec = tv.tv_sec; \ ts.tv_nsec = tv.tv_usec * 1000; \ } while(0) /* 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; } #define CHECK_STATUS_PTHREAD(name) if (status != 0) { fprintf(stderr, \ "%s: %s\n", name, strerror(status)); error = 1; } /* * Initialization. */ static void PyThread__init_thread(void) { #if defined(_AIX) && defined(__GNUC__) extern void pthread_init(void); pthread_init(); #endif } /* * 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; PyMem_RawFree(arg); func(func_arg); return NULL; } unsigned 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 PYTHREAD_INVALID_THREAD_ID; #endif #if defined(THREAD_STACK_SIZE) PyThreadState *tstate = PyThreadState_GET(); size_t stacksize = tstate ? tstate->interp->pythread_stacksize : 0; tss = (stacksize != 0) ? stacksize : THREAD_STACK_SIZE; if (tss != 0) { if (pthread_attr_setstacksize(&attrs, tss) != 0) { pthread_attr_destroy(&attrs); return PYTHREAD_INVALID_THREAD_ID; } } #endif #if defined(PTHREAD_SYSTEM_SCHED_SUPPORTED) pthread_attr_setscope(&attrs, PTHREAD_SCOPE_SYSTEM); #endif pythread_callback *callback = PyMem_RawMalloc(sizeof(pythread_callback)); if (callback == NULL) { return PYTHREAD_INVALID_THREAD_ID; } 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) { PyMem_RawFree(callback); return PYTHREAD_INVALID_THREAD_ID; } pthread_detach(th); #if SIZEOF_PTHREAD_T <= SIZEOF_LONG return (unsigned long) th; #else return (unsigned long) *(unsigned 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 unsigned long is inherently unsafe. - It is not clear that the 'volatile' (for AIX?) are any longer necessary. */ unsigned long PyThread_get_thread_ident(void) { volatile pthread_t threadid; if (!initialized) PyThread_init_thread(); threadid = pthread_self(); return (unsigned long) threadid; } void PyThread_exit_thread(void) { dprintf(("PyThread_exit_thread called\n")); if (!initialized) exit(0); pthread_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 *)PyMem_RawMalloc(sizeof(sem_t)); if (lock) { status = sem_init(lock,0,1); CHECK_STATUS("sem_init"); if (error) { PyMem_RawFree((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"); PyMem_RawFree((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; } PyLockStatus PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds, int intr_flag) { PyLockStatus success; sem_t *thelock = (sem_t *)lock; int status, error = 0; struct timespec ts; _PyTime_t deadline = 0; (void) error; /* silence unused-but-set-variable warning */ dprintf(("PyThread_acquire_lock_timed(%p, %lld, %d) called\n", lock, microseconds, intr_flag)); if (microseconds > PY_TIMEOUT_MAX) { Py_FatalError("Timeout larger than PY_TIMEOUT_MAX"); } if (microseconds > 0) { MICROSECONDS_TO_TIMESPEC(microseconds, ts); if (!intr_flag) { /* cannot overflow thanks to (microseconds > PY_TIMEOUT_MAX) check done above */ _PyTime_t timeout = _PyTime_FromNanoseconds(microseconds * 1000); deadline = _PyTime_GetMonotonicClock() + timeout; } } while (1) { if (microseconds > 0) { status = fix_status(sem_timedwait(thelock, &ts)); } else if (microseconds == 0) { status = fix_status(sem_trywait(thelock)); } else { status = fix_status(sem_wait(thelock)); } /* Retry if interrupted by a signal, unless the caller wants to be notified. */ if (intr_flag || status != EINTR) { break; } if (microseconds > 0) { /* wait interrupted by a signal (EINTR): recompute the timeout */ _PyTime_t dt = deadline - _PyTime_GetMonotonicClock(); if (dt < 0) { status = ETIMEDOUT; break; } else if (dt > 0) { _PyTime_t realtime_deadline = _PyTime_GetSystemClock() + dt; if (_PyTime_AsTimespec(realtime_deadline, &ts) < 0) { /* Cannot occur thanks to (microseconds > PY_TIMEOUT_MAX) check done above */ Py_UNREACHABLE(); } /* no need to update microseconds value, the code only care if (microseconds > 0 or (microseconds == 0). */ } else { microseconds = 0; } } } /* Don't check the status if we're stopping because of an interrupt. */ if (!(intr_flag && status == EINTR)) { if (microseconds > 0) { if (status != ETIMEDOUT) CHECK_STATUS("sem_timedwait"); } else if (microseconds == 0) { if (status != EAGAIN) CHECK_STATUS("sem_trywait"); } else { CHECK_STATUS("sem_wait"); } } if (status == 0) { success = PY_LOCK_ACQUIRED; } else if (intr_flag && status == EINTR) { success = PY_LOCK_INTR; } else { success = PY_LOCK_FAILURE; } dprintf(("PyThread_acquire_lock_timed(%p, %lld, %d) -> %d\n", lock, microseconds, intr_flag, 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 *) PyMem_RawMalloc(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("pthread_mutex_init"); /* Mark the pthread mutex underlying a Python mutex as pure happens-before. We can't simply mark the Python-level mutex as a mutex because it can be acquired and released in different threads, which will cause errors. */ _Py_ANNOTATE_PURE_HAPPENS_BEFORE_MUTEX(&lock->mut); status = pthread_cond_init(&lock->lock_released, pthread_condattr_default); CHECK_STATUS_PTHREAD("pthread_cond_init"); if (error) { PyMem_RawFree((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)); /* some pthread-like implementations tie the mutex to the cond * and must have the cond destroyed first. */ status = pthread_cond_destroy( &thelock->lock_released ); CHECK_STATUS_PTHREAD("pthread_cond_destroy"); status = pthread_mutex_destroy( &thelock->mut ); CHECK_STATUS_PTHREAD("pthread_mutex_destroy"); PyMem_RawFree((void *)thelock); } PyLockStatus PyThread_acquire_lock_timed(PyThread_type_lock lock, PY_TIMEOUT_T microseconds, int intr_flag) { PyLockStatus success = PY_LOCK_FAILURE; pthread_lock *thelock = (pthread_lock *)lock; int status, error = 0; dprintf(("PyThread_acquire_lock_timed(%p, %lld, %d) called\n", lock, microseconds, intr_flag)); if (microseconds == 0) { status = pthread_mutex_trylock( &thelock->mut ); if (status != EBUSY) CHECK_STATUS_PTHREAD("pthread_mutex_trylock[1]"); } else { status = pthread_mutex_lock( &thelock->mut ); CHECK_STATUS_PTHREAD("pthread_mutex_lock[1]"); } if (status == 0) { if (thelock->locked == 0) { success = PY_LOCK_ACQUIRED; } else if (microseconds != 0) { struct timespec ts; if (microseconds > 0) MICROSECONDS_TO_TIMESPEC(microseconds, ts); /* continue trying until we get the lock */ /* mut must be locked by me -- part of the condition * protocol */ while (success == PY_LOCK_FAILURE) { if (microseconds > 0) { status = pthread_cond_timedwait( &thelock->lock_released, &thelock->mut, &ts); if (status == ETIMEDOUT) break; CHECK_STATUS_PTHREAD("pthread_cond_timed_wait"); } else { status = pthread_cond_wait( &thelock->lock_released, &thelock->mut); CHECK_STATUS_PTHREAD("pthread_cond_wait"); } if (intr_flag && status == 0 && thelock->locked) { /* We were woken up, but didn't get the lock. We probably received * a signal. Return PY_LOCK_INTR to allow the caller to handle * it and retry. */ success = PY_LOCK_INTR; break; } else if (status == 0 && !thelock->locked) { success = PY_LOCK_ACQUIRED; } } } if (success == PY_LOCK_ACQUIRED) thelock->locked = 1; status = pthread_mutex_unlock( &thelock->mut ); CHECK_STATUS_PTHREAD("pthread_mutex_unlock[1]"); } if (error) success = PY_LOCK_FAILURE; dprintf(("PyThread_acquire_lock_timed(%p, %lld, %d) -> %d\n", lock, microseconds, intr_flag, 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("pthread_mutex_lock[3]"); thelock->locked = 0; /* wake up someone (anyone, if any) waiting on the lock */ status = pthread_cond_signal( &thelock->lock_released ); CHECK_STATUS_PTHREAD("pthread_cond_signal"); status = pthread_mutex_unlock( &thelock->mut ); CHECK_STATUS_PTHREAD("pthread_mutex_unlock[3]"); } #endif /* USE_SEMAPHORES */ int PyThread_acquire_lock(PyThread_type_lock lock, int waitflag) { return PyThread_acquire_lock_timed(lock, waitflag ? -1 : 0, /*intr_flag=*/0); } /* 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) { PyThreadState_GET()->interp->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) { PyThreadState_GET()->interp->pythread_stacksize = size; return 0; } } } return -1; #else return -2; #endif } #define THREAD_SET_STACKSIZE(x) _pythread_pthread_set_stacksize(x) /* Thread Local Storage (TLS) API This API is DEPRECATED since Python 3.7. See PEP 539 for details. */ /* Issue #25658: On platforms where native TLS key is defined in a way that cannot be safely cast to int, PyThread_create_key returns immediately a failure status and other TLS functions all are no-ops. This indicates clearly that the old API is not supported on platforms where it cannot be used reliably, and that no effort will be made to add such support. Note: PTHREAD_KEY_T_IS_COMPATIBLE_WITH_INT will be unnecessary after removing this API. */ int PyThread_create_key(void) { #ifdef PTHREAD_KEY_T_IS_COMPATIBLE_WITH_INT pthread_key_t key; int fail = pthread_key_create(&key, NULL); if (fail) return -1; if (key > INT_MAX) { /* Issue #22206: handle integer overflow */ pthread_key_delete(key); errno = ENOMEM; return -1; } return (int)key; #else return -1; /* never return valid key value. */ #endif } void PyThread_delete_key(int key) { #ifdef PTHREAD_KEY_T_IS_COMPATIBLE_WITH_INT pthread_key_delete(key); #endif } void PyThread_delete_key_value(int key) { #ifdef PTHREAD_KEY_T_IS_COMPATIBLE_WITH_INT pthread_setspecific(key, NULL); #endif } int PyThread_set_key_value(int key, void *value) { #ifdef PTHREAD_KEY_T_IS_COMPATIBLE_WITH_INT int fail = pthread_setspecific(key, value); return fail ? -1 : 0; #else return -1; #endif } void * PyThread_get_key_value(int key) { #ifdef PTHREAD_KEY_T_IS_COMPATIBLE_WITH_INT return pthread_getspecific(key); #else return NULL; #endif } void PyThread_ReInitTLS(void) { } /* Thread Specific Storage (TSS) API Platform-specific components of TSS API implementation. */ int PyThread_tss_create(Py_tss_t *key) { assert(key != NULL); /* If the key has been created, function is silently skipped. */ if (key->_is_initialized) { return 0; } int fail = pthread_key_create(&(key->_key), NULL); if (fail) { return -1; } key->_is_initialized = 1; return 0; } void PyThread_tss_delete(Py_tss_t *key) { assert(key != NULL); /* If the key has not been created, function is silently skipped. */ if (!key->_is_initialized) { return; } pthread_key_delete(key->_key); /* pthread has not provided the defined invalid value for the key. */ key->_is_initialized = 0; } int PyThread_tss_set(Py_tss_t *key, void *value) { assert(key != NULL); int fail = pthread_setspecific(key->_key, value); return fail ? -1 : 0; } void * PyThread_tss_get(Py_tss_t *key) { assert(key != NULL); return pthread_getspecific(key->_key); }