cpython/Python/thread_sgi.h

/***********************************************************
Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,
The Netherlands.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted,
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in
supporting documentation, and that the names of Stichting Mathematisch
Centrum or CWI or Corporation for National Research Initiatives or
CNRI not be used in advertising or publicity pertaining to
distribution of the software without specific, written prior
permission.

While CWI is the initial source for this software, a modified version
is made available by the Corporation for National Research Initiatives
(CNRI) at the Internet address ftp://ftp.python.org.

STICHTING MATHEMATISCH CENTRUM AND CNRI DISCLAIM ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH
CENTRUM OR CNRI BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.

******************************************************************/

#ifdef WITH_SGI_DL
#define USE_DL
#endif

#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/prctl.h>
#include <ulocks.h>
#include <errno.h>

#define HDR_SIZE	2680	/* sizeof(ushdr_t) */
#define MAXPROC		100	/* max # of threads that can be started */

static usptr_t *shared_arena;
static ulock_t count_lock;	/* protection for some variables */
static ulock_t wait_lock;	/* lock used to wait for other threads */
static int waiting_for_threads;	/* protected by count_lock */
static int nthreads;		/* protected by count_lock */
static int exit_status;
#ifndef NO_EXIT_PROG
static int do_exit;		/* indicates that the program is to exit */
#endif
static int exiting;		/* we're already exiting (for maybe_exit) */
static pid_t my_pid;		/* PID of main thread */
static struct pidlist {
	pid_t parent;
	pid_t child;
} pidlist[MAXPROC];	/* PIDs of other threads; protected by count_lock */
static int maxpidindex;		/* # of PIDs in pidlist */

#ifndef NO_EXIT_PROG
/*
 * This routine is called as a signal handler when another thread
 * exits.  When that happens, we must see whether we have to exit as
 * well (because of an PyThread_exit_prog()) or whether we should continue on.
 */
static void exit_sig _P0()
{
	d2printf(("exit_sig called\n"));
	if (exiting && getpid() == my_pid) {
		d2printf(("already exiting\n"));
		return;
	}
	if (do_exit) {
		d2printf(("exiting in exit_sig\n"));
#ifdef Py_DEBUG
		if ((thread_debug & 8) == 0)
			thread_debug &= ~1; /* don't produce debug messages */
#endif
		PyThread_exit_thread();
	}
}

/*
 * This routine is called when a process calls exit().  If that wasn't
 * done from the library, we do as if an PyThread_exit_prog() was intended.
 */
static void maybe_exit _P0()
{
	dprintf(("maybe_exit called\n"));
	if (exiting) {
		dprintf(("already exiting\n"));
		return;
	}
	PyThread_exit_prog(0);
}
#endif /* NO_EXIT_PROG */

/*
 * Initialization.
 */
static void PyThread__init_thread _P0()
{
#ifndef NO_EXIT_PROG
	struct sigaction s;
#endif /* NO_EXIT_PROG */
#ifdef USE_DL
	long addr, size;
#endif /* USE_DL */


#ifdef USE_DL
	if ((size = usconfig(CONF_INITSIZE, 64*1024)) < 0)
		perror("usconfig - CONF_INITSIZE (check)");
	if (usconfig(CONF_INITSIZE, size) < 0)
		perror("usconfig - CONF_INITSIZE (reset)");
	addr = (long) dl_getrange(size + HDR_SIZE);
	dprintf(("trying to use addr %p-%p for shared arena\n", addr, addr+size));
	errno = 0;
	if ((addr = usconfig(CONF_ATTACHADDR, addr)) < 0 && errno != 0)
		perror("usconfig - CONF_ATTACHADDR (set)");
#endif /* USE_DL */
	if (usconfig(CONF_INITUSERS, 16) < 0)
		perror("usconfig - CONF_INITUSERS");
	my_pid = getpid();	/* so that we know which is the main thread */
#ifndef NO_EXIT_PROG
	atexit(maybe_exit);
	s.sa_handler = exit_sig;
	sigemptyset(&s.sa_mask);
	/*sigaddset(&s.sa_mask, SIGUSR1);*/
	s.sa_flags = 0;
	sigaction(SIGUSR1, &s, 0);
	if (prctl(PR_SETEXITSIG, SIGUSR1) < 0)
		perror("prctl - PR_SETEXITSIG");
#endif /* NO_EXIT_PROG */
	if (usconfig(CONF_ARENATYPE, US_SHAREDONLY) < 0)
		perror("usconfig - CONF_ARENATYPE");
	usconfig(CONF_LOCKTYPE, US_DEBUG); /* XXX */
#ifdef Py_DEBUG
	if (thread_debug & 4)
		usconfig(CONF_LOCKTYPE, US_DEBUGPLUS);
	else if (thread_debug & 2)
		usconfig(CONF_LOCKTYPE, US_DEBUG);
#endif /* Py_DEBUG */
	if ((shared_arena = usinit(tmpnam(0))) == 0)
		perror("usinit");
#ifdef USE_DL
	if (usconfig(CONF_ATTACHADDR, addr) < 0) /* reset address */
		perror("usconfig - CONF_ATTACHADDR (reset)");
#endif /* USE_DL */
	if ((count_lock = usnewlock(shared_arena)) == NULL)
		perror("usnewlock (count_lock)");
	(void) usinitlock(count_lock);
	if ((wait_lock = usnewlock(shared_arena)) == NULL)
		perror("usnewlock (wait_lock)");
	dprintf(("arena start: %p, arena size: %ld\n",  shared_arena, (long) usconfig(CONF_GETSIZE, shared_arena)));
}

/*
 * Thread support.
 */

static void clean_threads _P0()
{
	int i, j;
	pid_t mypid, pid;

	/* clean up any exited threads */
	mypid = getpid();
	i = 0;
	while (i < maxpidindex) {
		if (pidlist[i].parent == mypid && (pid = pidlist[i].child) > 0) {
			pid = waitpid(pid, 0, WNOHANG);
			if (pid > 0) {
				/* a thread has exited */
				pidlist[i] = pidlist[--maxpidindex];
				/* remove references to children of dead proc */
				for (j = 0; j < maxpidindex; j++)
					if (pidlist[j].parent == pid)
						pidlist[j].child = -1;
				continue; /* don't increment i */
			}
		}
		i++;
	}
	/* clean up the list */
	i = 0;
	while (i < maxpidindex) {
		if (pidlist[i].child == -1) {
			pidlist[i] = pidlist[--maxpidindex];
			continue; /* don't increment i */
		}
		i++;
	}
}

int PyThread_start_new_thread _P2(func, void (*func) _P((void *)), arg, void *arg)
{
#ifdef USE_DL
	long addr, size;
	static int local_initialized = 0;
#endif /* USE_DL */
	int success = 0;	/* init not needed when SOLARIS_THREADS and */
				/* C_THREADS implemented properly */

	dprintf(("PyThread_start_new_thread called\n"));
	if (!initialized)
		PyThread_init_thread();
	switch (ussetlock(count_lock)) {
	case 0: return 0;
	case -1: perror("ussetlock (count_lock)");
	}
	if (maxpidindex >= MAXPROC)
		success = -1;
	else {
#ifdef USE_DL
		if (!local_initialized) {
			if ((size = usconfig(CONF_INITSIZE, 64*1024)) < 0)
				perror("usconfig - CONF_INITSIZE (check)");
			if (usconfig(CONF_INITSIZE, size) < 0)
				perror("usconfig - CONF_INITSIZE (reset)");
			addr = (long) dl_getrange(size + HDR_SIZE);
			dprintf(("trying to use addr %p-%p for sproc\n",
				 addr, addr+size));
			errno = 0;
			if ((addr = usconfig(CONF_ATTACHADDR, addr)) < 0 &&
			    errno != 0)
				perror("usconfig - CONF_ATTACHADDR (set)");
		}
#endif /* USE_DL */
		clean_threads();
		if ((success = sproc(func, PR_SALL, arg)) < 0)
			perror("sproc");
#ifdef USE_DL
		if (!local_initialized) {
			if (usconfig(CONF_ATTACHADDR, addr) < 0)
				/* reset address */
				perror("usconfig - CONF_ATTACHADDR (reset)");
			local_initialized = 1;
		}
#endif /* USE_DL */
		if (success >= 0) {
			nthreads++;
			pidlist[maxpidindex].parent = getpid();
			pidlist[maxpidindex++].child = success;
			dprintf(("pidlist[%d] = %d\n",
				 maxpidindex-1, success));
		}
	}
	if (usunsetlock(count_lock) < 0)
		perror("usunsetlock (count_lock)");
	return success < 0 ? 0 : 1;
}

long PyThread_get_thread_ident _P0()
{
	return getpid();
}

static void do_PyThread_exit_thread _P1(no_cleanup, int no_cleanup)
{
	dprintf(("PyThread_exit_thread called\n"));
	if (!initialized)
		if (no_cleanup)
			_exit(0);
		else
			exit(0);
	if (ussetlock(count_lock) < 0)
		perror("ussetlock (count_lock)");
	nthreads--;
	if (getpid() == my_pid) {
		/* main thread; wait for other threads to exit */
		exiting = 1;
#ifndef NO_EXIT_PROG
		if (do_exit) {
			int i;

			/* notify other threads */
			clean_threads();
			if (nthreads >= 0) {
				dprintf(("kill other threads\n"));
				for (i = 0; i < maxpidindex; i++)
					if (pidlist[i].child > 0)
						(void) kill(pidlist[i].child,
							    SIGKILL);
				_exit(exit_status);
			}
		}
#endif /* NO_EXIT_PROG */
		waiting_for_threads = 1;
		if (ussetlock(wait_lock) < 0)
			perror("ussetlock (wait_lock)");
		for (;;) {
			if (nthreads < 0) {
				dprintf(("really exit (%d)\n", exit_status));
				if (no_cleanup)
					_exit(exit_status);
				else
					exit(exit_status);
			}
			if (usunsetlock(count_lock) < 0)
				perror("usunsetlock (count_lock)");
			dprintf(("waiting for other threads (%d)\n", nthreads));
			if (ussetlock(wait_lock) < 0)
				perror("ussetlock (wait_lock)");
			if (ussetlock(count_lock) < 0)
				perror("ussetlock (count_lock)");
		}
	}
	/* not the main thread */
	if (waiting_for_threads) {
		dprintf(("main thread is waiting\n"));
		if (usunsetlock(wait_lock) < 0)
			perror("usunsetlock (wait_lock)");
	}
#ifndef NO_EXIT_PROG
	else if (do_exit)
		(void) kill(my_pid, SIGUSR1);
#endif /* NO_EXIT_PROG */
	if (usunsetlock(count_lock) < 0)
		perror("usunsetlock (count_lock)");
	_exit(0);
}

void PyThread_exit_thread _P0()
{
	do_PyThread_exit_thread(0);
}

void PyThread__exit_thread _P0()
{
	do_PyThread_exit_thread(1);
}

#ifndef NO_EXIT_PROG
static void do_PyThread_exit_prog _P2(status, int status, no_cleanup, int no_cleanup)
{
	dprintf(("PyThread_exit_prog(%d) called\n", status));
	if (!initialized)
		if (no_cleanup)
			_exit(status);
		else
			exit(status);
	do_exit = 1;
	exit_status = status;
	do_PyThread_exit_thread(no_cleanup);
}

void PyThread_exit_prog _P1(status, int status)
{
	do_PyThread_exit_prog(status, 0);
}

void PyThread__exit_prog _P1(status, int status)
{
	do_PyThread_exit_prog(status, 1);
}
#endif /* NO_EXIT_PROG */

/*
 * Lock support.
 */
PyThread_type_lock PyThread_allocate_lock _P0()
{
	ulock_t lock;

	dprintf(("PyThread_allocate_lock called\n"));
	if (!initialized)
		PyThread_init_thread();

	if ((lock = usnewlock(shared_arena)) == NULL)
		perror("usnewlock");
	(void) usinitlock(lock);
	dprintf(("PyThread_allocate_lock() -> %p\n", lock));
	return (PyThread_type_lock) lock;
}

void PyThread_free_lock _P1(lock, PyThread_type_lock lock)
{
	dprintf(("PyThread_free_lock(%p) called\n", lock));
	usfreelock((ulock_t) lock, shared_arena);
}

int PyThread_acquire_lock _P2(lock, PyThread_type_lock lock, waitflag, int waitflag)
{
	int success;

	dprintf(("PyThread_acquire_lock(%p, %d) called\n", lock, waitflag));
	errno = 0;		/* clear it just in case */
	if (waitflag)
		success = ussetlock((ulock_t) lock);
	else
		success = uscsetlock((ulock_t) lock, 1); /* Try it once */
	if (success < 0)
		perror(waitflag ? "ussetlock" : "uscsetlock");
	dprintf(("PyThread_acquire_lock(%p, %d) -> %d\n", lock, waitflag, success));
	return success;
}

void PyThread_release_lock _P1(lock, PyThread_type_lock lock)
{
	dprintf(("PyThread_release_lock(%p) called\n", lock));
	if (usunsetlock((ulock_t) lock) < 0)
		perror("usunsetlock");
}

/*
 * Semaphore support.
 */
PyThread_type_sema PyThread_allocate_sema _P1(value, int value)
{
	usema_t *sema;
	dprintf(("PyThread_allocate_sema called\n"));
	if (!initialized)
		PyThread_init_thread();

	if ((sema = usnewsema(shared_arena, value)) == NULL)
		perror("usnewsema");
	dprintf(("PyThread_allocate_sema() -> %p\n",  sema));
	return (PyThread_type_sema) sema;
}

void PyThread_free_sema _P1(sema, PyThread_type_sema sema)
{
	dprintf(("PyThread_free_sema(%p) called\n",  sema));
	usfreesema((usema_t *) sema, shared_arena);
}

int PyThread_down_sema _P2(sema, PyThread_type_sema sema, waitflag, int waitflag)
{
	int success;

	dprintf(("PyThread_down_sema(%p) called\n",  sema));
	if (waitflag)
		success = uspsema((usema_t *) sema);
	else
		success = uscpsema((usema_t *) sema);
	if (success < 0)
		perror(waitflag ? "uspsema" : "uscpsema");
	dprintf(("PyThread_down_sema(%p) return\n",  sema));
	return success;
}

void PyThread_up_sema _P1(sema, PyThread_type_sema sema)
{
	dprintf(("PyThread_up_sema(%p)\n",  sema));
	if (usvsema((usema_t *) sema) < 0)
		perror("usvsema");
}

/*
 * Per-thread data ("key") support.
 */

struct key {
	struct key *next;
	long id;
	int key;
	void *value;
};

static struct key *keyhead = NULL;
static int nkeys = 0;
static PyThread_type_lock keymutex = NULL;

static struct key *find_key _P2(key, int key, value, void *value)
{
	struct key *p;
	long id = PyThread_get_thread_ident();
	for (p = keyhead; p != NULL; p = p->next) {
		if (p->id == id && p->key == key)
			return p;
	}
	if (value == NULL)
		return NULL;
	p = (struct key *)malloc(sizeof(struct key));
	if (p != NULL) {
		p->id = id;
		p->key = key;
		p->value = value;
		PyThread_acquire_lock(keymutex, 1);
		p->next = keyhead;
		keyhead = p;
		PyThread_release_lock(keymutex);
	}
	return p;
}

int PyThread_create_key _P0()
{
	if (keymutex == NULL)
		keymutex = PyThread_allocate_lock();
	return ++nkeys;
}

void PyThread_delete_key _P1(key, int key)
{
	struct key *p, **q;
	PyThread_acquire_lock(keymutex, 1);
	q = &keyhead;
	while ((p = *q) != NULL) {
		if (p->key == key) {
			*q = p->next;
			free((void *)p);
			/* NB This does *not* free p->value! */
		}
		else
			q = &p->next;
	}
	PyThread_release_lock(keymutex);
}

int PyThread_set_key_value _P2(key, int key, value, void *value)
{
	struct key *p = find_key(key, value);
	if (p == NULL)
		return -1;
	else
		return 0;
}

void *PyThread_get_key_value _P1(key, int key)
{
	struct key *p = find_key(key, NULL);
	if (p == NULL)
		return NULL;
	else
		return p->value;
}