source: trunk/src/gcc/boehm-gc/irix_threads.c@ 1289

/* 
 * Copyright (c) 1991-1995 by Xerox Corporation.  All rights reserved.
 * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
 * Copyright (c) 1999 by Hewlett-Packard Company. All rights reserved.
 *
 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
 *
 * Permission is hereby granted to use or copy this program
 * for any purpose,  provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 */
/*
 * Support code for Irix (>=6.2) Pthreads.  This relies on properties
 * not guaranteed by the Pthread standard.  It may or may not be portable
 * to other implementations.
 *
 * This now also includes an initial attempt at thread support for
 * HP/UX 11.
 *
 * Note that there is a lot of code duplication between linux_threads.c
 * and irix_threads.c; any changes made here may need to be reflected
 * there too.
 */

# if defined(GC_IRIX_THREADS)

# include "private/gc_priv.h"
# include <pthread.h>
# include <semaphore.h>
# include <time.h>
# include <errno.h>
# include <unistd.h>
# include <sys/mman.h>
# include <sys/time.h>

#undef pthread_create
#undef pthread_sigmask
#undef pthread_join
#undef pthread_detach

void GC_thr_init();

#if 0
void GC_print_sig_mask()
{
    sigset_t blocked;
    int i;

    if (pthread_sigmask(SIG_BLOCK, NULL, &blocked) != 0)
        ABORT("pthread_sigmask");
    GC_printf0("Blocked: ");
    for (i = 1; i <= MAXSIG; i++) {
        if (sigismember(&blocked, i)) { GC_printf1("%ld ",(long) i); }
    }
    GC_printf0("\n");
}
#endif

/* We use the allocation lock to protect thread-related data structures. */

/* The set of all known threads.  We intercept thread creation and      */
/* joins.  We never actually create detached threads.  We allocate all  */
/* new thread stacks ourselves.  These allow us to maintain this        */
/* data structure.                                                      */
/* Protected by GC_thr_lock.                                            */
/* Some of this should be declared volatile, but that's incosnsistent   */
/* with some library routine declarations.                              */
typedef struct GC_Thread_Rep {
    struct GC_Thread_Rep * next;  /* More recently allocated threads    */
                                  /* with a given pthread id come       */
                                  /* first.  (All but the first are     */
                                  /* guaranteed to be dead, but we may  */
                                  /* not yet have registered the join.) */
    pthread_t id;
    word stop;
#       define NOT_STOPPED 0
#       define PLEASE_STOP 1
#       define STOPPED 2
    word flags;
#       define FINISHED 1       /* Thread has exited.   */
#       define DETACHED 2       /* Thread is intended to be detached.   */
#       define CLIENT_OWNS_STACK        4
                                /* Stack was supplied by client.        */
    ptr_t stack;
    ptr_t stack_ptr;            /* Valid only when stopped. */
                                /* But must be within stack region at   */
                                /* all times.                           */
    size_t stack_size;          /* 0 for original thread.       */
    void * status;              /* Used only to avoid premature         */
                                /* reclamation of any data it might     */
                                /* reference.                           */
} * GC_thread;

GC_thread GC_lookup_thread(pthread_t id);

/*
 * The only way to suspend threads given the pthread interface is to send
 * signals.  Unfortunately, this means we have to reserve
 * a signal, and intercept client calls to change the signal mask.
 * We use SIG_SUSPEND, defined in gc_priv.h.
 */

pthread_mutex_t GC_suspend_lock = PTHREAD_MUTEX_INITIALIZER;
                                /* Number of threads stopped so far     */
pthread_cond_t GC_suspend_ack_cv = PTHREAD_COND_INITIALIZER;
pthread_cond_t GC_continue_cv = PTHREAD_COND_INITIALIZER;

void GC_suspend_handler(int sig)
{
    int dummy;
    GC_thread me;
    sigset_t all_sigs;
    sigset_t old_sigs;
    int i;

    if (sig != SIG_SUSPEND) ABORT("Bad signal in suspend_handler");
    me = GC_lookup_thread(pthread_self());
    /* The lookup here is safe, since I'm doing this on behalf  */
    /* of a thread which holds the allocation lock in order     */
    /* to stop the world.  Thus concurrent modification of the  */
    /* data structure is impossible.                            */
    if (PLEASE_STOP != me -> stop) {
        /* Misdirected signal.  */
        pthread_mutex_unlock(&GC_suspend_lock);
        return;
    }
    pthread_mutex_lock(&GC_suspend_lock);
    me -> stack_ptr = (ptr_t)(&dummy);
    me -> stop = STOPPED;
    pthread_cond_signal(&GC_suspend_ack_cv);
    pthread_cond_wait(&GC_continue_cv, &GC_suspend_lock);
    pthread_mutex_unlock(&GC_suspend_lock);
    /* GC_printf1("Continuing 0x%x\n", pthread_self()); */
}


GC_bool GC_thr_initialized = FALSE;

size_t GC_min_stack_sz;

# define N_FREE_LISTS 25
ptr_t GC_stack_free_lists[N_FREE_LISTS] = { 0 };
                /* GC_stack_free_lists[i] is free list for stacks of    */
                /* size GC_min_stack_sz*2**i.                           */
                /* Free lists are linked through first word.            */

/* Return a stack of size at least *stack_size.  *stack_size is */
/* replaced by the actual stack size.                           */
/* Caller holds allocation lock.                                */
ptr_t GC_stack_alloc(size_t * stack_size)
{
    register size_t requested_sz = *stack_size;
    register size_t search_sz = GC_min_stack_sz;
    register int index = 0;     /* = log2(search_sz/GC_min_stack_sz) */
    register ptr_t result;
    
    while (search_sz < requested_sz) {
        search_sz *= 2;
        index++;
    }