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