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Diffstat (limited to '')
| -rw-r--r-- | gc/irix_threads.c | 674 |
1 files changed, 674 insertions, 0 deletions
diff --git a/gc/irix_threads.c b/gc/irix_threads.c new file mode 100644 index 0000000..5efca21 --- /dev/null +++ b/gc/irix_threads.c @@ -0,0 +1,674 @@ +/* + * Copyright (c) 1994 by Xerox Corporation. All rights reserved. + * Copyright (c) 1996 by Silicon Graphics. 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. + * + * 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(IRIX_THREADS) + +# include "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 + +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. + */ +# define SIG_SUSPEND (SIGRTMIN + 6) + +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; + +size_t GC_page_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++; + } + if ((result = GC_stack_free_lists[index]) == 0 + && (result = GC_stack_free_lists[index+1]) != 0) { + /* Try next size up. */ + search_sz *= 2; index++; + } + if (result != 0) { + GC_stack_free_lists[index] = *(ptr_t *)result; + } else { + result = (ptr_t) GC_scratch_alloc(search_sz + 2*GC_page_sz); + result = (ptr_t)(((word)result + GC_page_sz) & ~(GC_page_sz - 1)); + /* Protect hottest page to detect overflow. */ + /* mprotect(result, GC_page_sz, PROT_NONE); */ + result += GC_page_sz; + } + *stack_size = search_sz; + return(result); +} + +/* Caller holds allocation lock. */ +void GC_stack_free(ptr_t stack, size_t size) +{ + register int index = 0; + register size_t search_sz = GC_min_stack_sz; + + while (search_sz < size) { + search_sz *= 2; + index++; + } + if (search_sz != size) ABORT("Bad stack size"); + *(ptr_t *)stack = GC_stack_free_lists[index]; + GC_stack_free_lists[index] = stack; +} + + + +# define THREAD_TABLE_SZ 128 /* Must be power of 2 */ +volatile GC_thread GC_threads[THREAD_TABLE_SZ]; + +/* Add a thread to GC_threads. We assume it wasn't already there. */ +/* Caller holds allocation lock. */ +GC_thread GC_new_thread(pthread_t id) +{ + int hv = ((word)id) % THREAD_TABLE_SZ; + GC_thread result; + static struct GC_Thread_Rep first_thread; + static GC_bool first_thread_used = FALSE; + + if (!first_thread_used) { + result = &first_thread; + first_thread_used = TRUE; + /* Dont acquire allocation lock, since we may already hold it. */ + } else { + result = (struct GC_Thread_Rep *) + GC_generic_malloc_inner(sizeof(struct GC_Thread_Rep), NORMAL); + } + if (result == 0) return(0); + result -> id = id; + result -> next = GC_threads[hv]; + GC_threads[hv] = result; + /* result -> flags = 0; */ + /* result -> stop = 0; */ + return(result); +} + +/* Delete a thread from GC_threads. We assume it is there. */ +/* (The code intentionally traps if it wasn't.) */ +/* Caller holds allocation lock. */ +void GC_delete_thread(pthread_t id) +{ + int hv = ((word)id) % THREAD_TABLE_SZ; + register GC_thread p = GC_threads[hv]; + register GC_thread prev = 0; + + while (!pthread_equal(p -> id, id)) { + prev = p; + p = p -> next; + } + if (prev == 0) { + GC_threads[hv] = p -> next; + } else { + prev -> next = p -> next; + } +} + +/* If a thread has been joined, but we have not yet */ +/* been notified, then there may be more than one thread */ +/* in the table with the same pthread id. */ +/* This is OK, but we need a way to delete a specific one. */ +void GC_delete_gc_thread(pthread_t id, GC_thread gc_id) +{ + int hv = ((word)id) % THREAD_TABLE_SZ; + register GC_thread p = GC_threads[hv]; + register GC_thread prev = 0; + + while (p != gc_id) { + prev = p; + p = p -> next; + } + if (prev == 0) { + GC_threads[hv] = p -> next; + } else { + prev -> next = p -> next; + } +} + +/* Return a GC_thread corresponding to a given thread_t. */ +/* Returns 0 if it's not there. */ +/* Caller holds allocation lock or otherwise inhibits */ +/* updates. */ +/* If there is more than one thread with the given id we */ +/* return the most recent one. */ +GC_thread GC_lookup_thread(pthread_t id) +{ + int hv = ((word)id) % THREAD_TABLE_SZ; + register GC_thread p = GC_threads[hv]; + + while (p != 0 && !pthread_equal(p -> id, id)) p = p -> next; + return(p); +} + + +/* Caller holds allocation lock. */ +void GC_stop_world() +{ + pthread_t my_thread = pthread_self(); + register int i; + register GC_thread p; + register int result; + struct timespec timeout; + + for (i = 0; i < THREAD_TABLE_SZ; i++) { + for (p = GC_threads[i]; p != 0; p = p -> next) { + if (p -> id != my_thread) { + if (p -> flags & FINISHED) { + p -> stop = STOPPED; + continue; + } + p -> stop = PLEASE_STOP; + result = pthread_kill(p -> id, SIG_SUSPEND); + /* GC_printf1("Sent signal to 0x%x\n", p -> id); */ + switch(result) { + case ESRCH: + /* Not really there anymore. Possible? */ + p -> stop = STOPPED; + break; + case 0: + break; + default: + ABORT("pthread_kill failed"); + } + } + } + } + pthread_mutex_lock(&GC_suspend_lock); + for (i = 0; i < THREAD_TABLE_SZ; i++) { + for (p = GC_threads[i]; p != 0; p = p -> next) { + while (p -> id != my_thread && p -> stop != STOPPED) { + clock_gettime(CLOCK_REALTIME, &timeout); + timeout.tv_nsec += 50000000; /* 50 msecs */ + if (timeout.tv_nsec >= 1000000000) { + timeout.tv_nsec -= 1000000000; + ++timeout.tv_sec; + } + result = pthread_cond_timedwait(&GC_suspend_ack_cv, + &GC_suspend_lock, + &timeout); + if (result == ETIMEDOUT) { + /* Signal was lost or misdirected. Try again. */ + /* Duplicate signals should be benign. */ + result = pthread_kill(p -> id, SIG_SUSPEND); + } + } + } + } + pthread_mutex_unlock(&GC_suspend_lock); + /* GC_printf1("World stopped 0x%x\n", pthread_self()); */ +} + +/* Caller holds allocation lock. */ +void GC_start_world() +{ + GC_thread p; + unsigned i; + + /* GC_printf0("World starting\n"); */ + for (i = 0; i < THREAD_TABLE_SZ; i++) { + for (p = GC_threads[i]; p != 0; p = p -> next) { + p -> stop = NOT_STOPPED; + } + } + pthread_mutex_lock(&GC_suspend_lock); + /* All other threads are at pthread_cond_wait in signal handler. */ + /* Otherwise we couldn't have acquired the lock. */ + pthread_mutex_unlock(&GC_suspend_lock); + pthread_cond_broadcast(&GC_continue_cv); +} + +# ifdef MMAP_STACKS +--> not really supported yet. +int GC_is_thread_stack(ptr_t addr) +{ + register int i; + register GC_thread p; + + for (i = 0; i < THREAD_TABLE_SZ; i++) { + for (p = GC_threads[i]; p != 0; p = p -> next) { + if (p -> stack_size != 0) { + if (p -> stack <= addr && + addr < p -> stack + p -> stack_size) + return 1; + } + } + } + return 0; +} +# endif + +/* We hold allocation lock. We assume the world is stopped. */ +void GC_push_all_stacks() +{ + register int i; + register GC_thread p; + register ptr_t sp = GC_approx_sp(); + register ptr_t lo, hi; + pthread_t me = pthread_self(); + + if (!GC_thr_initialized) GC_thr_init(); + /* GC_printf1("Pushing stacks from thread 0x%x\n", me); */ + for (i = 0; i < THREAD_TABLE_SZ; i++) { + for (p = GC_threads[i]; p != 0; p = p -> next) { + if (p -> flags & FINISHED) continue; + if (pthread_equal(p -> id, me)) { + lo = GC_approx_sp(); + } else { + lo = p -> stack_ptr; + } + if (p -> stack_size != 0) { + hi = p -> stack + p -> stack_size; + } else { + /* The original stack. */ + hi = GC_stackbottom; + } + GC_push_all_stack(lo, hi); + } + } +} + + +/* We hold the allocation lock. */ +void GC_thr_init() +{ + GC_thread t; + struct sigaction act; + + if (GC_thr_initialized) return; + GC_thr_initialized = TRUE; + GC_min_stack_sz = HBLKSIZE; + GC_page_sz = sysconf(_SC_PAGESIZE); + (void) sigaction(SIG_SUSPEND, 0, &act); + if (act.sa_handler != SIG_DFL) + ABORT("Previously installed SIG_SUSPEND handler"); + /* Install handler. */ + act.sa_handler = GC_suspend_handler; + act.sa_flags = SA_RESTART; + (void) sigemptyset(&act.sa_mask); + if (0 != sigaction(SIG_SUSPEND, &act, 0)) + ABORT("Failed to install SIG_SUSPEND handler"); + /* Add the initial thread, so we can stop it. */ + t = GC_new_thread(pthread_self()); + t -> stack_size = 0; + t -> stack_ptr = (ptr_t)(&t); + t -> flags = DETACHED; +} + +int GC_pthread_sigmask(int how, const sigset_t *set, sigset_t *oset) +{ + sigset_t fudged_set; + + if (set != NULL && (how == SIG_BLOCK || how == SIG_SETMASK)) { + fudged_set = *set; + sigdelset(&fudged_set, SIG_SUSPEND); + set = &fudged_set; + } + return(pthread_sigmask(how, set, oset)); +} + +struct start_info { + void *(*start_routine)(void *); + void *arg; + word flags; + ptr_t stack; + size_t stack_size; + sem_t registered; /* 1 ==> in our thread table, but */ + /* parent hasn't yet noticed. */ +}; + +void GC_thread_exit_proc(void *arg) +{ + GC_thread me; + + LOCK(); + me = GC_lookup_thread(pthread_self()); + if (me -> flags & DETACHED) { + GC_delete_thread(pthread_self()); + } else { + me -> flags |= FINISHED; + } + UNLOCK(); +} + +int GC_pthread_join(pthread_t thread, void **retval) +{ + int result; + GC_thread thread_gc_id; + + LOCK(); + thread_gc_id = GC_lookup_thread(thread); + /* This is guaranteed to be the intended one, since the thread id */ + /* cant have been recycled by pthreads. */ + UNLOCK(); + result = pthread_join(thread, retval); + /* Some versions of the Irix pthreads library can erroneously */ + /* return EINTR when the call succeeds. */ + if (EINTR == result) result = 0; + LOCK(); + /* Here the pthread thread id may have been recycled. */ + GC_delete_gc_thread(thread, thread_gc_id); + UNLOCK(); + return result; +} + +void * GC_start_routine(void * arg) +{ + struct start_info * si = arg; + void * result; + GC_thread me; + pthread_t my_pthread; + void *(*start)(void *); + void *start_arg; + + my_pthread = pthread_self(); + /* If a GC occurs before the thread is registered, that GC will */ + /* ignore this thread. That's fine, since it will block trying to */ + /* acquire the allocation lock, and won't yet hold interesting */ + /* pointers. */ + LOCK(); + /* We register the thread here instead of in the parent, so that */ + /* we don't need to hold the allocation lock during pthread_create. */ + /* Holding the allocation lock there would make REDIRECT_MALLOC */ + /* impossible. It probably still doesn't work, but we're a little */ + /* closer ... */ + /* This unfortunately means that we have to be careful the parent */ + /* doesn't try to do a pthread_join before we're registered. */ + me = GC_new_thread(my_pthread); + me -> flags = si -> flags; + me -> stack = si -> stack; + me -> stack_size = si -> stack_size; + me -> stack_ptr = (ptr_t)si -> stack + si -> stack_size - sizeof(word); + UNLOCK(); + start = si -> start_routine; + start_arg = si -> arg; + sem_post(&(si -> registered)); + pthread_cleanup_push(GC_thread_exit_proc, 0); + result = (*start)(start_arg); + me -> status = result; + me -> flags |= FINISHED; + pthread_cleanup_pop(1); + /* This involves acquiring the lock, ensuring that we can't exit */ + /* while a collection that thinks we're alive is trying to stop */ + /* us. */ + return(result); +} + +int +GC_pthread_create(pthread_t *new_thread, + const pthread_attr_t *attr, + void *(*start_routine)(void *), void *arg) +{ + int result; + GC_thread t; + void * stack; + size_t stacksize; + pthread_attr_t new_attr; + int detachstate; + word my_flags = 0; + struct start_info * si = GC_malloc(sizeof(struct start_info)); + /* This is otherwise saved only in an area mmapped by the thread */ + /* library, which isn't visible to the collector. */ + + if (0 == si) return(ENOMEM); + sem_init(&(si -> registered), 0, 0); + si -> start_routine = start_routine; + si -> arg = arg; + LOCK(); + if (!GC_thr_initialized) GC_thr_init(); + if (NULL == attr) { + stack = 0; + (void) pthread_attr_init(&new_attr); + } else { + new_attr = *attr; + pthread_attr_getstackaddr(&new_attr, &stack); + } + pthread_attr_getstacksize(&new_attr, &stacksize); + pthread_attr_getdetachstate(&new_attr, &detachstate); + if (stacksize < GC_min_stack_sz) ABORT("Stack too small"); + if (0 == stack) { + stack = (void *)GC_stack_alloc(&stacksize); + if (0 == stack) { + UNLOCK(); + return(ENOMEM); + } + pthread_attr_setstackaddr(&new_attr, stack); + } else { + my_flags |= CLIENT_OWNS_STACK; + } + if (PTHREAD_CREATE_DETACHED == detachstate) my_flags |= DETACHED; + si -> flags = my_flags; + si -> stack = stack; + si -> stack_size = stacksize; + result = pthread_create(new_thread, &new_attr, GC_start_routine, si); + if (0 == new_thread && !(my_flags & CLIENT_OWNS_STACK)) { + GC_stack_free(stack, stacksize); + } + UNLOCK(); + /* Wait until child has been added to the thread table. */ + /* This also ensures that we hold onto si until the child is done */ + /* with it. Thus it doesn't matter whether it is otherwise */ + /* visible to the collector. */ + if (0 != sem_wait(&(si -> registered))) ABORT("sem_wait failed"); + sem_destroy(&(si -> registered)); + /* pthread_attr_destroy(&new_attr); */ + return(result); +} + +GC_bool GC_collecting = 0; /* A hint that we're in the collector and */ + /* holding the allocation lock for an */ + /* extended period. */ + +/* Reasonably fast spin locks. Basically the same implementation */ +/* as STL alloc.h. This isn't really the right way to do this. */ +/* but until the POSIX scheduling mess gets straightened out ... */ + +unsigned long GC_allocate_lock = 0; + +#define SLEEP_THRESHOLD 3 + +void GC_lock() +{ +# define low_spin_max 30 /* spin cycles if we suspect uniprocessor */ +# define high_spin_max 1000 /* spin cycles for multiprocessor */ + static unsigned spin_max = low_spin_max; + unsigned my_spin_max; + static unsigned last_spins = 0; + unsigned my_last_spins; + volatile unsigned junk; +# define PAUSE junk *= junk; junk *= junk; junk *= junk; junk *= junk + int i; + + if (!GC_test_and_set(&GC_allocate_lock, 1)) { + return; + } + junk = 0; + my_spin_max = spin_max; + my_last_spins = last_spins; + for (i = 0; i < my_spin_max; i++) { + if (GC_collecting) goto yield; + if (i < my_last_spins/2 || GC_allocate_lock) { + PAUSE; + continue; + } + if (!GC_test_and_set(&GC_allocate_lock, 1)) { + /* + * got it! + * Spinning worked. Thus we're probably not being scheduled + * against the other process with which we were contending. + * Thus it makes sense to spin longer the next time. + */ + last_spins = i; + spin_max = high_spin_max; + return; + } + } + /* We are probably being scheduled against the other process. Sleep. */ + spin_max = low_spin_max; +yield: + for (i = 0;; ++i) { + if (!GC_test_and_set(&GC_allocate_lock, 1)) { + return; + } + if (i < SLEEP_THRESHOLD) { + sched_yield(); + } else { + struct timespec ts; + + if (i > 26) i = 26; + /* Don't wait for more than about 60msecs, even */ + /* under extreme contention. */ + ts.tv_sec = 0; + ts.tv_nsec = 1 << i; + nanosleep(&ts, 0); + } + } +} + + + +# else + +#ifndef LINT + int GC_no_Irix_threads; +#endif + +# endif /* IRIX_THREADS */ + |