diff options
Diffstat (limited to 'lib/libpthread/thread/thr_gc.c')
| -rw-r--r-- | lib/libpthread/thread/thr_gc.c | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/lib/libpthread/thread/thr_gc.c b/lib/libpthread/thread/thr_gc.c new file mode 100644 index 0000000..9c93028 --- /dev/null +++ b/lib/libpthread/thread/thr_gc.c @@ -0,0 +1,219 @@ +/* + * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by John Birrell. + * 4. Neither the name of the author nor the names of any co-contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + * + * Garbage collector thread. Frees memory allocated for dead threads. + * + */ +#include <sys/param.h> +#include <errno.h> +#include <time.h> +#include <stdlib.h> +#include <unistd.h> +#include <sys/types.h> +#include <pthread.h> +#include "pthread_private.h" + +pthread_addr_t +_thread_gc(pthread_addr_t arg) +{ + struct pthread *curthread = _get_curthread(); + int f_debug; + int f_done = 0; + int ret; + sigset_t mask; + pthread_t pthread; + pthread_t pthread_cln; + struct timespec abstime; + void *p_stack; + + /* Block all signals */ + sigfillset(&mask); + pthread_sigmask(SIG_BLOCK, &mask, NULL); + + /* Mark this thread as a library thread (not a user thread). */ + curthread->flags |= PTHREAD_FLAGS_PRIVATE; + + /* Set a debug flag based on an environment variable. */ + f_debug = (getenv("LIBC_R_DEBUG") != NULL); + + /* Set the name of this thread. */ + pthread_set_name_np(curthread,"GC"); + + while (!f_done) { + /* Check if debugging this application. */ + if (f_debug) + /* Dump thread info to file. */ + _thread_dump_info(); + + /* + * Defer signals to protect the scheduling queues from + * access by the signal handler: + */ + _thread_kern_sig_defer(); + + /* Check if this is the last running thread: */ + if (TAILQ_FIRST(&_thread_list) == curthread && + TAILQ_NEXT(curthread, tle) == NULL) + /* + * This is the last thread, so it can exit + * now. + */ + f_done = 1; + + /* + * Undefer and handle pending signals, yielding if + * necessary: + */ + _thread_kern_sig_undefer(); + + /* No stack of thread structure to free yet: */ + p_stack = NULL; + pthread_cln = NULL; + + /* + * Lock the garbage collector mutex which ensures that + * this thread sees another thread exit: + */ + if (pthread_mutex_lock(&_gc_mutex) != 0) + PANIC("Cannot lock gc mutex"); + + /* + * Enter a loop to search for the first dead thread that + * has memory to free. + */ + for (pthread = TAILQ_FIRST(&_dead_list); + p_stack == NULL && pthread_cln == NULL && pthread != NULL; + pthread = TAILQ_NEXT(pthread, dle)) { + /* Check if the initial thread: */ + if (pthread == _thread_initial) { + /* Don't destroy the initial thread. */ + } + /* + * Check if this thread has detached: + */ + else if ((pthread->attr.flags & + PTHREAD_DETACHED) != 0) { + /* Remove this thread from the dead list: */ + TAILQ_REMOVE(&_dead_list, pthread, dle); + + /* + * Check if the stack was not specified by + * the caller to pthread_create() and has not + * been destroyed yet: + */ + if (pthread->attr.stackaddr_attr == NULL && + pthread->stack != NULL) { + _thread_stack_free(pthread->stack, + pthread->attr.stacksize_attr, + pthread->attr.guardsize_attr); + } + + /* + * Point to the thread structure that must + * be freed outside the locks: + */ + pthread_cln = pthread; + + } else { + /* + * This thread has not detached, so do + * not destroy it. + * + * Check if the stack was not specified by + * the caller to pthread_create() and has not + * been destroyed yet: + */ + if (pthread->attr.stackaddr_attr == NULL && + pthread->stack != NULL) { + _thread_stack_free(pthread->stack, + pthread->attr.stacksize_attr, + pthread->attr.guardsize_attr); + + /* + * NULL the stack pointer now that the + * memory has been freed: + */ + pthread->stack = NULL; + } + } + } + + /* + * Check if this is not the last thread and there is no + * memory to free this time around. + */ + if (!f_done && p_stack == NULL && pthread_cln == NULL) { + /* Get the current time. */ + if (clock_gettime(CLOCK_REALTIME,&abstime) != 0) + PANIC("gc cannot get time"); + + /* + * Do a backup poll in 10 seconds if no threads + * die before then. + */ + abstime.tv_sec += 10; + + /* + * Wait for a signal from a dying thread or a + * timeout (for a backup poll). + */ + if ((ret = pthread_cond_timedwait(&_gc_cond, + &_gc_mutex, &abstime)) != 0 && ret != ETIMEDOUT) + PANIC("gc cannot wait for a signal"); + } + + /* Unlock the garbage collector mutex: */ + if (pthread_mutex_unlock(&_gc_mutex) != 0) + PANIC("Cannot unlock gc mutex"); + + /* + * If there is memory to free, do it now. The call to + * free() might block, so this must be done outside the + * locks. + */ + if (p_stack != NULL) + free(p_stack); + if (pthread_cln != NULL) { + if (pthread_cln->name != NULL) { + /* Free the thread name string. */ + free(pthread_cln->name); + } + /* + * Free the memory allocated for the thread + * structure. + */ + free(pthread_cln); + } + } + return (NULL); +} |
