cpython/Python/thread_sgi.h

#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;
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 */
/*
 * Initialization.
 */
static void PyThread__init_thread(void)
{
#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 */
	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(void)
{
	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++;
	}
}

long PyThread_start_new_thread(void (*func)(void *), 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;
}

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

void PyThread_exit_thread(void)
{
	dprintf(("PyThread_exit_thread called\n"));
	if (!initialized)
		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;
		waiting_for_threads = 1;
		if (ussetlock(wait_lock) < 0)
			perror("ussetlock (wait_lock)");
		for (;;) {
			if (nthreads < 0) {
				dprintf(("really exit (%d)\n", exit_status));
				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)");
	}
	if (usunsetlock(count_lock) < 0)
		perror("usunsetlock (count_lock)");
	_exit(0);
}

/*
 * Lock support.
 */
PyThread_type_lock PyThread_allocate_lock(void)
{
	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(PyThread_type_lock lock)
{
	dprintf(("PyThread_free_lock(%p) called\n", lock));
	usfreelock((ulock_t) lock, shared_arena);
}

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