cpython.git - https://github.com/python/cpython.git

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/* Posix threads interface */ #include <stdlib.h> #include <string.h> #include <pthread.h> /* try to determine what version of the Pthread Standard is installed. * this is important, since all sorts of parameter types changed from * draft to draft and there are several (incompatible) drafts in * common use. these macros are a start, at least. * 12 May 1997 -- david arnold <davida@pobox.com> */ #if defined(__ultrix) && defined(__mips) && defined(_DECTHREADS_) /* _DECTHREADS_ is defined in cma.h which is included by pthread.h */ # define PY_PTHREAD_D4 #elif defined(__osf__) && defined (__alpha) /* _DECTHREADS_ is defined in cma.h which is included by pthread.h */ # if !defined(_PTHREAD_ENV_ALPHA) || defined(_PTHREAD_USE_D4) || defined(PTHREAD_USE_D4) # define PY_PTHREAD_D4 # else # define PY_PTHREAD_STD # endif #elif defined(_AIX) /* SCHED_BG_NP is defined if using AIX DCE pthreads * but it is unsupported by AIX 4 pthreads. Default * attributes for AIX 4 pthreads equal to NULL. For * AIX DCE pthreads they should be left unchanged. */ # if !defined(SCHED_BG_NP) # define PY_PTHREAD_STD # else # define PY_PTHREAD_D7 # endif #elif defined(__DGUX) # define PY_PTHREAD_D6 #elif defined(__hpux) && defined(_DECTHREADS_) # define PY_PTHREAD_D4 #else /* Default case */ # define PY_PTHREAD_STD #endif #ifdef USE_GUSI /* The Macintosh GUSI I/O library sets the stackspace to ** 20KB, much too low. We up it to 64K. */ #define THREAD_STACK_SIZE 0x10000 #endif /* set default attribute object for different versions */ #if defined(PY_PTHREAD_D4) || defined(PY_PTHREAD_D7) # define pthread_attr_default pthread_attr_default # define pthread_mutexattr_default pthread_mutexattr_default # define pthread_condattr_default pthread_condattr_default #elif defined(PY_PTHREAD_STD) || defined(PY_PTHREAD_D6) # define pthread_attr_default ((pthread_attr_t *)NULL) # define pthread_mutexattr_default ((pthread_mutexattr_t *)NULL) # define pthread_condattr_default ((pthread_condattr_t *)NULL) #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 <condition, mutex> 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 <cond, mutex> 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__) pthread_init(); #endif } #endif /* !_HAVE_BSDI */ /* * Thread support. */ int PyThread_start_new_thread(void (*func)(void *), void *arg) { pthread_t th; int success; #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED) pthread_attr_t attrs; #endif dprintf(("PyThread_start_new_thread called\n")); if (!initialized) PyThread_init_thread(); #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED) pthread_attr_init(&attrs); #endif #ifdef THREAD_STACK_SIZE pthread_attr_setstacksize(&attrs, THREAD_STACK_SIZE); #endif #ifdef PTHREAD_SYSTEM_SCHED_SUPPORTED pthread_attr_setscope(&attrs, PTHREAD_SCOPE_SYSTEM); #endif success = pthread_create(&th, #if defined(PY_PTHREAD_D4) pthread_attr_default, (pthread_startroutine_t)func, (pthread_addr_t)arg #elif defined(PY_PTHREAD_D6) pthread_attr_default, (void* (*)(void *))func, arg #elif defined(PY_PTHREAD_D7) pthread_attr_default, func, arg #elif defined(PY_PTHREAD_STD) #if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED) &attrs, #else (pthread_attr_t*)NULL, #endif (void* (*)(void *))func, (void *)arg #endif ); #ifdef THREAD_STACK_SIZE pthread_attr_destroy(&attrs); #endif if (success == 0) { #if defined(PY_PTHREAD_D4) || defined(PY_PTHREAD_D6) || defined(PY_PTHREAD_D7) pthread_detach(&th); #elif defined(PY_PTHREAD_STD) pthread_detach(th); #endif } return success != 0 ? 0 : 1; } /* XXX This implementation is considered (to quote Tim Peters) "inherently hosed" because: - It does not guanrantee 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 } static void do_PyThread_exit_thread(int no_cleanup) { dprintf(("PyThread_exit_thread called\n")); if (!initialized) { if (no_cleanup) _exit(0); else exit(0); } } void PyThread_exit_thread(void) { do_PyThread_exit_thread(0); } void PyThread__exit_thread(void) { do_PyThread_exit_thread(1); } #ifndef NO_EXIT_PROG static void do_PyThread_exit_prog(int status, int no_cleanup) { dprintf(("PyThread_exit_prog(%d) called\n", status)); if (!initialized) if (no_cleanup) _exit(status); else exit(status); } void PyThread_exit_prog(int status) { do_PyThread_exit_prog(status, 0); } void PyThread__exit_prog(int status) { do_PyThread_exit_prog(status, 1); } #endif /* NO_EXIT_PROG */ /* * 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)); memset((void *)lock, '\0', sizeof(pthread_lock)); if (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; 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; pthread_lock *thelock = (pthread_lock *)lock; int status, error = 0; dprintf(("PyThread_acquire_lock(%p, %d) called\n", lock, waitflag)); status = pthread_mutex_lock( &thelock->mut ); CHECK_STATUS("pthread_mutex_lock[1]"); success = thelock->locked == 0; if (success) thelock->locked = 1; status = pthread_mutex_unlock( &thelock->mut ); CHECK_STATUS("pthread_mutex_unlock[1]"); if ( !success && waitflag ) { /* continue trying until we get the lock */ /* mut must be locked by me -- part of the condition * protocol */ status = pthread_mutex_lock( &thelock->mut ); CHECK_STATUS("pthread_mutex_lock[2]"); while ( thelock->locked ) { status = pthread_cond_wait(&thelock->lock_released, &thelock->mut); CHECK_STATUS("pthread_cond_wait"); } thelock->locked = 1; status = pthread_mutex_unlock( &thelock->mut ); CHECK_STATUS("pthread_mutex_unlock[2]"); success = 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; 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"); } /* * Semaphore support. */ struct semaphore { pthread_mutex_t mutex; pthread_cond_t cond; int value; }; PyThread_type_sema PyThread_allocate_sema(int value) { struct semaphore *sema; int status, error = 0; dprintf(("PyThread_allocate_sema called\n")); if (!initialized) PyThread_init_thread(); sema = (struct semaphore *) malloc(sizeof(struct semaphore)); if (sema != NULL) { sema->value = value; status = pthread_mutex_init(&sema->mutex, pthread_mutexattr_default); CHECK_STATUS("pthread_mutex_init"); status = pthread_cond_init(&sema->cond, pthread_condattr_default); CHECK_STATUS("pthread_cond_init"); if (error) { free((void *) sema); sema = NULL; } } dprintf(("PyThread_allocate_sema() -> %p\n", sema)); return (PyThread_type_sema) sema; } void PyThread_free_sema(PyThread_type_sema sema) { int status, error = 0; struct semaphore *thesema = (struct semaphore *) sema; dprintf(("PyThread_free_sema(%p) called\n", sema)); status = pthread_cond_destroy(&thesema->cond); CHECK_STATUS("pthread_cond_destroy"); status = pthread_mutex_destroy(&thesema->mutex); CHECK_STATUS("pthread_mutex_destroy"); free((void *) thesema); } int PyThread_down_sema(PyThread_type_sema sema, int waitflag) { int status, error = 0, success; struct semaphore *thesema = (struct semaphore *) sema; dprintf(("PyThread_down_sema(%p, %d) called\n", sema, waitflag)); status = pthread_mutex_lock(&thesema->mutex); CHECK_STATUS("pthread_mutex_lock"); if (waitflag) { while (!error && thesema->value <= 0) { status = pthread_cond_wait(&thesema->cond, &thesema->mutex); CHECK_STATUS("pthread_cond_wait"); } } if (error) success = 0; else if (thesema->value > 0) { thesema->value--; success = 1; } else success = 0; status = pthread_mutex_unlock(&thesema->mutex); CHECK_STATUS("pthread_mutex_unlock"); dprintf(("PyThread_down_sema(%p) return\n", sema)); return success; } void PyThread_up_sema(PyThread_type_sema sema) { int status, error = 0; struct semaphore *thesema = (struct semaphore *) sema; dprintf(("PyThread_up_sema(%p)\n", sema)); status = pthread_mutex_lock(&thesema->mutex); CHECK_STATUS("pthread_mutex_lock"); thesema->value++; status = pthread_cond_signal(&thesema->cond); CHECK_STATUS("pthread_cond_signal"); status = pthread_mutex_unlock(&thesema->mutex); CHECK_STATUS("pthread_mutex_unlock"); }


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