https://github.com/python/cpython
Tip revision: 1da43e5e916949c8e849e656d9d05fa4b9d6836c authored by Benjamin Peterson on 26 June 2009, 13:21:52 UTC
rearrange the sections of the README, so they'll hopefully be more in the order people will interested in
rearrange the sections of the README, so they'll hopefully be more in the order people will interested in
Tip revision: 1da43e5
thread_pthread.h
/* Posix threads interface */
#include <stdlib.h>
#include <string.h>
#if defined(__APPLE__) || defined(HAVE_PTHREAD_DESTRUCTOR)
#define destructor xxdestructor
#endif
#include <pthread.h>
#if defined(__APPLE__) || defined(HAVE_PTHREAD_DESTRUCTOR)
#undef destructor
#endif
#include <signal.h>
/* 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
/* 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 <semaphore.h>
#include <errno.h>
#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 <osreldate.h>
#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 <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.
*/
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
status = pthread_create(&th,
#if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
&attrs,
#else
(pthread_attr_t*)NULL,
#endif
(void* (*)(void *))func,
(void *)arg
);
#if defined(THREAD_STACK_SIZE) || defined(PTHREAD_SYSTEM_SCHED_SUPPORTED)
pthread_attr_destroy(&attrs);
#endif
if (status != 0)
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
}
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 */
#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;
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;
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;
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;
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 && 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;
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)