1384 lines
35 KiB
C
1384 lines
35 KiB
C
/*
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* Copyright (c) 1995-1998 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 REGENTS 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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* $Id: uthread_kern.c,v 1.10 1998/04/29 09:59:02 jb Exp $
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*
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*/
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#include <errno.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <string.h>
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#include <unistd.h>
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#include <setjmp.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/socket.h>
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#include <sys/uio.h>
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#include <sys/syscall.h>
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#include <fcntl.h>
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#ifdef _THREAD_SAFE
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#include <pthread.h>
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#include "pthread_private.h"
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/* Static function prototype definitions: */
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static void
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_thread_kern_select(int wait_reqd);
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void
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_thread_kern_sched(struct sigcontext * scp)
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{
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#ifndef __alpha__
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char *fdata;
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#endif
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int i;
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int prio = -1;
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pthread_t pthread;
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pthread_t pthread_h = NULL;
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pthread_t pthread_nxt = NULL;
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pthread_t pthread_prv = NULL;
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pthread_t pthread_s = NULL;
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struct itimerval itimer;
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struct timespec ts;
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struct timespec ts1;
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struct timeval tv;
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struct timeval tv1;
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/*
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* Flag the pthread kernel as executing scheduler code
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* to avoid a scheduler signal from interrupting this
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* execution and calling the scheduler again.
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*/
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_thread_kern_in_sched = 1;
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/* Check if this function was called from the signal handler: */
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if (scp != NULL) {
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/*
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* Copy the signal context to the current thread's jump
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* buffer:
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*/
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memcpy(&_thread_run->saved_sigcontext, scp, sizeof(_thread_run->saved_sigcontext));
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#ifndef __alpha__
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/* Point to the floating point data in the running thread: */
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fdata = _thread_run->saved_fp;
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/* Save the floating point data: */
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__asm__("fnsave %0": :"m"(*fdata));
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#endif
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/* Flag the signal context as the last state saved: */
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_thread_run->sig_saved = 1;
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}
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/* Save the state of the current thread: */
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else if (setjmp(_thread_run->saved_jmp_buf) != 0) {
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/*
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* This point is reached when a longjmp() is called to
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* restore the state of a thread.
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*
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* This is the normal way out of the scheduler.
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*/
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_thread_kern_in_sched = 0;
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/*
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* There might be pending signals for this thread, so
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* dispatch any that aren't blocked:
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*/
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_dispatch_signals();
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return;
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} else {
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/* Flag the jump buffer was the last state saved: */
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_thread_run->sig_saved = 0;
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}
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/* Point to the first dead thread (if there are any): */
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pthread = _thread_dead;
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/* There is no previous dead thread: */
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pthread_prv = NULL;
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/* Enter a loop to cleanup after dead threads: */
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while (pthread != NULL) {
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/* Save a pointer to the next thread: */
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pthread_nxt = pthread->nxt;
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/* Check if this thread is one which is running: */
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if (pthread == _thread_run || pthread == _thread_initial) {
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/*
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* Don't destroy the running thread or the initial
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* thread.
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*/
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pthread_prv = pthread;
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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 & PTHREAD_DETACHED) != 0) {
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/* Check if there is no previous dead thread: */
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if (pthread_prv == NULL) {
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/*
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* The dead thread is at the head of the
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* list:
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*/
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_thread_dead = pthread_nxt;
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} else {
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/*
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* The dead thread is not at the head of the
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* list:
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*/
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pthread_prv->nxt = pthread->nxt;
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}
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/*
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* Check if the stack was not specified by the caller
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* to pthread_create and has not been destroyed yet:
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*/
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if (pthread->attr.stackaddr_attr == NULL && pthread->stack != NULL) {
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/* Free the stack of the dead thread: */
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free(pthread->stack);
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}
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/* Free the memory allocated to the thread structure: */
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free(pthread);
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} else {
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/*
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* This thread has not detached, so do not destroy
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* it:
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*/
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pthread_prv = pthread;
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/*
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* Check if the stack was not specified by the caller
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* to pthread_create and has not been destroyed yet:
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*/
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if (pthread->attr.stackaddr_attr == NULL && pthread->stack != NULL) {
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/* Free the stack of the dead thread: */
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free(pthread->stack);
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/*
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* NULL the stack pointer now that the memory
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* 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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/* Point to the next thread: */
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pthread = pthread_nxt;
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}
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/*
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* Enter a the scheduling loop that finds the next thread that is
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* ready to run. This loop completes when there are no more threads
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* in the global list or when a thread has its state restored by
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* either a sigreturn (if the state was saved as a sigcontext) or a
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* longjmp (if the state was saved by a setjmp).
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*/
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while (_thread_link_list != NULL) {
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/* Get the current time of day: */
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gettimeofday(&tv, NULL);
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TIMEVAL_TO_TIMESPEC(&tv, &ts);
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/*
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* Poll file descriptors to update the state of threads
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* waiting on file I/O where data may be available:
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*/
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_thread_kern_select(0);
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/*
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* Enter a loop to look for sleeping threads that are ready:
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*/
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for (pthread = _thread_link_list; pthread != NULL;
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pthread = pthread->nxt) {
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/* Check if this thread is to timeout: */
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if (pthread->state == PS_COND_WAIT ||
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pthread->state == PS_SLEEP_WAIT ||
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pthread->state == PS_FDR_WAIT ||
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pthread->state == PS_FDW_WAIT ||
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pthread->state == PS_SELECT_WAIT) {
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/* Check if this thread is to wait forever: */
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if (pthread->wakeup_time.tv_sec == -1) {
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}
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/*
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* Check if this thread is to wakeup
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* immediately or if it is past its wakeup
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* time:
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*/
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else if ((pthread->wakeup_time.tv_sec == 0 &&
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pthread->wakeup_time.tv_nsec == 0) ||
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(ts.tv_sec > pthread->wakeup_time.tv_sec) ||
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((ts.tv_sec == pthread->wakeup_time.tv_sec) &&
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(ts.tv_nsec >= pthread->wakeup_time.tv_nsec))) {
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/*
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* Check if this thread is waiting on
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* select:
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*/
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if (pthread->state == PS_SELECT_WAIT) {
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/*
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* The select has timed out,
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* so zero the file
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* descriptor sets:
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*/
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FD_ZERO(&pthread->data.select_data->readfds);
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FD_ZERO(&pthread->data.select_data->writefds);
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FD_ZERO(&pthread->data.select_data->exceptfds);
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pthread->data.select_data->nfds = 0;
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}
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/*
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* Return an error as an interrupted
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* wait:
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*/
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_thread_seterrno(pthread, EINTR);
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/*
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* Flag the timeout in the thread
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* structure:
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*/
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pthread->timeout = 1;
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/*
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* Change the threads state to allow
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* it to be restarted:
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*/
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PTHREAD_NEW_STATE(pthread,PS_RUNNING);
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}
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}
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}
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/* Check if there is a current thread: */
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if (_thread_run != &_thread_kern_thread) {
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/*
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* Save the current time as the time that the thread
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* became inactive:
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*/
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_thread_run->last_inactive.tv_sec = tv.tv_sec;
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_thread_run->last_inactive.tv_usec = tv.tv_usec;
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/*
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* Accumulate the number of microseconds that this
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* thread has run for:
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*/
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_thread_run->slice_usec += (_thread_run->last_inactive.tv_sec -
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_thread_run->last_active.tv_sec) * 1000000 +
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_thread_run->last_inactive.tv_usec -
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_thread_run->last_active.tv_usec;
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/*
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* Check if this thread has reached its allocated
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* time slice period:
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*/
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if (_thread_run->slice_usec > TIMESLICE_USEC) {
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/*
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* Flag the allocated time slice period as
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* up:
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*/
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_thread_run->slice_usec = -1;
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}
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}
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/* Check if an incremental priority update is required: */
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if (((tv.tv_sec - kern_inc_prio_time.tv_sec) * 1000000 +
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tv.tv_usec - kern_inc_prio_time.tv_usec) > INC_PRIO_USEC) {
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/*
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* Enter a loop to look for run-enabled threads that
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* have not run since the last time that an
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* incremental priority update was performed:
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*/
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for (pthread = _thread_link_list; pthread != NULL; pthread = pthread->nxt) {
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/* Check if this thread is unable to run: */
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if (pthread->state != PS_RUNNING) {
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}
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/*
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* Check if the last time that this thread
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* was run (as indicated by the last time it
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* became inactive) is before the time that
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* the last incremental priority check was
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* made:
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*/
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else if (timercmp(&_thread_run->last_inactive, &kern_inc_prio_time, <)) {
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/*
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* Increment the incremental priority
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* for this thread in the hope that
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* it will eventually get a chance to
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* run:
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*/
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(pthread->inc_prio)++;
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}
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}
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/* Save the new incremental priority update time: */
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kern_inc_prio_time.tv_sec = tv.tv_sec;
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kern_inc_prio_time.tv_usec = tv.tv_usec;
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}
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/*
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* Enter a loop to look for the first thread of the highest
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* priority that is ready to run:
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*/
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for (pthread = _thread_link_list; pthread != NULL; pthread = pthread->nxt) {
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/* Check if the current thread is unable to run: */
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if (pthread->state != PS_RUNNING) {
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}
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/*
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* Check if no run-enabled thread has been seen or if
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* the current thread has a priority higher than the
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* highest seen so far:
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*/
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else if (pthread_h == NULL || (pthread->pthread_priority + pthread->inc_prio) > prio) {
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/*
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* Save this thread as the highest priority
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* thread seen so far:
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*/
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pthread_h = pthread;
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prio = pthread->pthread_priority + pthread->inc_prio;
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}
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}
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/*
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* Enter a loop to look for a thread that: 1. Is run-enabled.
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* 2. Has the required agregate priority. 3. Has not been
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* allocated its allocated time slice. 4. Became inactive
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* least recently.
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*/
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for (pthread = _thread_link_list; pthread != NULL; pthread = pthread->nxt) {
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/* Check if the current thread is unable to run: */
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if (pthread->state != PS_RUNNING) {
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/* Ignore threads that are not ready to run. */
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}
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/*
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* Check if the current thread as an agregate
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* priority not equal to the highest priority found
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* above:
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*/
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else if ((pthread->pthread_priority + pthread->inc_prio) != prio) {
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/*
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* Ignore threads which have lower agregate
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* priority.
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*/
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}
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/*
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* Check if the current thread reached its time slice
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* allocation last time it ran (or if it has not run
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* yet):
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*/
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else if (pthread->slice_usec == -1) {
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}
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/*
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* Check if an eligible thread has not been found
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* yet, or if the current thread has an inactive time
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* earlier than the last one seen:
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*/
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else if (pthread_s == NULL || timercmp(&pthread->last_inactive, &tv1, <)) {
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/*
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* Save the pointer to the current thread as
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* the most eligible thread seen so far:
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*/
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pthread_s = pthread;
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/*
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* Save the time that the selected thread
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* became inactive:
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*/
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tv1.tv_sec = pthread->last_inactive.tv_sec;
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tv1.tv_usec = pthread->last_inactive.tv_usec;
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}
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}
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/*
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* Check if no thread was selected according to incomplete
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* time slice allocation:
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*/
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if (pthread_s == NULL) {
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/*
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* Enter a loop to look for any other thread that: 1.
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* Is run-enabled. 2. Has the required agregate
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* priority. 3. Became inactive least recently.
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*/
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for (pthread = _thread_link_list; pthread != NULL; pthread = pthread->nxt) {
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/*
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* Check if the current thread is unable to
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* run:
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*/
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if (pthread->state != PS_RUNNING) {
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/*
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* Ignore threads that are not ready
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* to run.
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*/
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}
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/*
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* Check if the current thread as an agregate
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* priority not equal to the highest priority
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* found above:
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*/
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else if ((pthread->pthread_priority + pthread->inc_prio) != prio) {
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/*
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* Ignore threads which have lower
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* agregate priority.
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*/
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}
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/*
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* Check if an eligible thread has not been
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* found yet, or if the current thread has an
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* inactive time earlier than the last one
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* seen:
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*/
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else if (pthread_s == NULL || timercmp(&pthread->last_inactive, &tv1, <)) {
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/*
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* Save the pointer to the current
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* thread as the most eligible thread
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* seen so far:
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*/
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pthread_s = pthread;
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/*
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* Save the time that the selected
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* thread became inactive:
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*/
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tv1.tv_sec = pthread->last_inactive.tv_sec;
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tv1.tv_usec = pthread->last_inactive.tv_usec;
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}
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}
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}
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/* Check if there are no threads ready to run: */
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if (pthread_s == NULL) {
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/*
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* Lock the pthread kernel by changing the pointer to
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* the running thread to point to the global kernel
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* thread structure:
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*/
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_thread_run = &_thread_kern_thread;
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/*
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* There are no threads ready to run, so wait until
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* something happens that changes this condition:
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*/
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_thread_kern_select(1);
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} else {
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/* Make the selected thread the current thread: */
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_thread_run = pthread_s;
|
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/*
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* Save the current time as the time that the thread
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* became active:
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*/
|
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_thread_run->last_active.tv_sec = tv.tv_sec;
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_thread_run->last_active.tv_usec = tv.tv_usec;
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|
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/*
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* Check if this thread is running for the first time
|
|
* or running again after using its full time slice
|
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* allocation:
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*/
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if (_thread_run->slice_usec == -1) {
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/* Reset the accumulated time slice period: */
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_thread_run->slice_usec = 0;
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}
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/*
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* Reset the incremental priority now that this
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* thread has been given the chance to run:
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*/
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_thread_run->inc_prio = 0;
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|
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/* Check if there is more than one thread: */
|
|
if (_thread_run != _thread_link_list || _thread_run->nxt != NULL) {
|
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/*
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* Define the maximum time before a SIGVTALRM
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|
* is required:
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*/
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|
itimer.it_value.tv_sec = 0;
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itimer.it_value.tv_usec = TIMESLICE_USEC;
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|
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/*
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|
* The interval timer is not reloaded when it
|
|
* times out. The interval time needs to be
|
|
* calculated every time.
|
|
*/
|
|
itimer.it_interval.tv_sec = 0;
|
|
itimer.it_interval.tv_usec = 0;
|
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|
|
/*
|
|
* Enter a loop to look for threads waiting
|
|
* for a time:
|
|
*/
|
|
for (pthread = _thread_link_list; pthread != NULL; pthread = pthread->nxt) {
|
|
/*
|
|
* Check if this thread is to
|
|
* timeout:
|
|
*/
|
|
if (pthread->state == PS_COND_WAIT ||
|
|
pthread->state == PS_SLEEP_WAIT ||
|
|
pthread->state == PS_FDR_WAIT ||
|
|
pthread->state == PS_FDW_WAIT ||
|
|
pthread->state == PS_SELECT_WAIT) {
|
|
/*
|
|
* Check if this thread is to
|
|
* wait forever:
|
|
*/
|
|
if (pthread->wakeup_time.tv_sec == -1) {
|
|
}
|
|
/*
|
|
* Check if this thread is to
|
|
* wakeup immediately:
|
|
*/
|
|
else if (pthread->wakeup_time.tv_sec == 0 &&
|
|
pthread->wakeup_time.tv_nsec == 0) {
|
|
}
|
|
/*
|
|
* Check if the current time
|
|
* is after the wakeup time:
|
|
*/
|
|
else if ((ts.tv_sec > pthread->wakeup_time.tv_sec) ||
|
|
((ts.tv_sec == pthread->wakeup_time.tv_sec) &&
|
|
(ts.tv_nsec > pthread->wakeup_time.tv_nsec))) {
|
|
} else {
|
|
/*
|
|
* Calculate the time
|
|
* until this thread
|
|
* is ready, allowing
|
|
* for the clock
|
|
* resolution:
|
|
*/
|
|
ts1.tv_sec = pthread->wakeup_time.tv_sec - ts.tv_sec;
|
|
ts1.tv_nsec = pthread->wakeup_time.tv_nsec - ts.tv_nsec +
|
|
CLOCK_RES_NSEC;
|
|
|
|
/*
|
|
* Check for
|
|
* underflow of the
|
|
* nanosecond field:
|
|
*/
|
|
if (ts1.tv_nsec < 0) {
|
|
/*
|
|
* Allow for
|
|
* the
|
|
* underflow
|
|
* of the
|
|
* nanosecond
|
|
* field:
|
|
*/
|
|
ts1.tv_sec--;
|
|
ts1.tv_nsec += 1000000000;
|
|
}
|
|
/*
|
|
* Check for overflow
|
|
* of the nanosecond
|
|
* field:
|
|
*/
|
|
if (ts1.tv_nsec >= 1000000000) {
|
|
/*
|
|
* Allow for
|
|
* the
|
|
* overflow
|
|
* of the
|
|
* nanosecond
|
|
* field:
|
|
*/
|
|
ts1.tv_sec++;
|
|
ts1.tv_nsec -= 1000000000;
|
|
}
|
|
/*
|
|
* Convert the
|
|
* timespec structure
|
|
* to a timeval
|
|
* structure:
|
|
*/
|
|
TIMESPEC_TO_TIMEVAL(&tv, &ts1);
|
|
|
|
/*
|
|
* Check if the
|
|
* thread will be
|
|
* ready sooner than
|
|
* the earliest one
|
|
* found so far:
|
|
*/
|
|
if (timercmp(&tv, &itimer.it_value, <)) {
|
|
/*
|
|
* Update the
|
|
* time
|
|
* value:
|
|
*/
|
|
itimer.it_value.tv_sec = tv.tv_sec;
|
|
itimer.it_value.tv_usec = tv.tv_usec;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Start the interval timer for the
|
|
* calculated time interval:
|
|
*/
|
|
if (setitimer(ITIMER_VIRTUAL, &itimer, NULL) != 0) {
|
|
/*
|
|
* Cannot initialise the timer, so
|
|
* abort this process:
|
|
*/
|
|
PANIC("Cannot set virtual timer");
|
|
}
|
|
}
|
|
/* Check if a signal context was saved: */
|
|
if (_thread_run->sig_saved == 1) {
|
|
#ifndef __alpha__
|
|
/*
|
|
* Point to the floating point data in the
|
|
* running thread:
|
|
*/
|
|
fdata = _thread_run->saved_fp;
|
|
|
|
/* Restore the floating point state: */
|
|
__asm__("frstor %0": :"m"(*fdata));
|
|
#endif
|
|
|
|
/*
|
|
* Do a sigreturn to restart the thread that
|
|
* was interrupted by a signal:
|
|
*/
|
|
_thread_sys_sigreturn(&_thread_run->saved_sigcontext);
|
|
} else
|
|
/*
|
|
* Do a longjmp to restart the thread that
|
|
* was context switched out (by a longjmp to
|
|
* a different thread):
|
|
*/
|
|
longjmp(_thread_run->saved_jmp_buf, 1);
|
|
|
|
/* This point should not be reached. */
|
|
PANIC("Thread has returned from sigreturn or longjmp");
|
|
}
|
|
}
|
|
|
|
/* There are no more threads, so exit this process: */
|
|
exit(0);
|
|
}
|
|
|
|
void
|
|
_thread_kern_sched_state(enum pthread_state state, char *fname, int lineno)
|
|
{
|
|
/* Change the state of the current thread: */
|
|
_thread_run->state = state;
|
|
_thread_run->fname = fname;
|
|
_thread_run->lineno = lineno;
|
|
|
|
/* Schedule the next thread that is ready: */
|
|
_thread_kern_sched(NULL);
|
|
return;
|
|
}
|
|
|
|
static void
|
|
_thread_kern_select(int wait_reqd)
|
|
{
|
|
char bufr[128];
|
|
fd_set fd_set_except;
|
|
fd_set fd_set_read;
|
|
fd_set fd_set_write;
|
|
int count = 0;
|
|
int count_dec;
|
|
int found_one;
|
|
int i;
|
|
int nfds = -1;
|
|
int settimeout;
|
|
pthread_t pthread;
|
|
ssize_t num;
|
|
struct timespec ts;
|
|
struct timespec ts1;
|
|
struct timeval *p_tv;
|
|
struct timeval tv;
|
|
struct timeval tv1;
|
|
|
|
/* Zero the file descriptor sets: */
|
|
FD_ZERO(&fd_set_read);
|
|
FD_ZERO(&fd_set_write);
|
|
FD_ZERO(&fd_set_except);
|
|
|
|
/* Check if the caller wants to wait: */
|
|
if (wait_reqd) {
|
|
/*
|
|
* Add the pthread kernel pipe file descriptor to the read
|
|
* set:
|
|
*/
|
|
FD_SET(_thread_kern_pipe[0], &fd_set_read);
|
|
nfds = _thread_kern_pipe[0];
|
|
|
|
/* Get the current time of day: */
|
|
gettimeofday(&tv, NULL);
|
|
TIMEVAL_TO_TIMESPEC(&tv, &ts);
|
|
}
|
|
/* Initialise the time value structure: */
|
|
tv.tv_sec = 0;
|
|
tv.tv_usec = 0;
|
|
|
|
/*
|
|
* Enter a loop to process threads waiting on either file descriptors
|
|
* or times:
|
|
*/
|
|
for (pthread = _thread_link_list; pthread != NULL; pthread = pthread->nxt) {
|
|
/* Assume that this state does not time out: */
|
|
settimeout = 0;
|
|
|
|
/* Process according to thread state: */
|
|
switch (pthread->state) {
|
|
/*
|
|
* States which do not depend on file descriptor I/O
|
|
* operations or timeouts:
|
|
*/
|
|
case PS_DEAD:
|
|
case PS_FDLR_WAIT:
|
|
case PS_FDLW_WAIT:
|
|
case PS_FILE_WAIT:
|
|
case PS_JOIN:
|
|
case PS_MUTEX_WAIT:
|
|
case PS_RUNNING:
|
|
case PS_SIGTHREAD:
|
|
case PS_SIGWAIT:
|
|
case PS_STATE_MAX:
|
|
case PS_WAIT_WAIT:
|
|
case PS_SUSPENDED:
|
|
/* Nothing to do here. */
|
|
break;
|
|
|
|
/* File descriptor read wait: */
|
|
case PS_FDR_WAIT:
|
|
/* Add the file descriptor to the read set: */
|
|
FD_SET(pthread->data.fd.fd, &fd_set_read);
|
|
|
|
/*
|
|
* Check if this file descriptor is greater than any
|
|
* of those seen so far:
|
|
*/
|
|
if (pthread->data.fd.fd > nfds) {
|
|
/* Remember this file descriptor: */
|
|
nfds = pthread->data.fd.fd;
|
|
}
|
|
/* Increment the file descriptor count: */
|
|
count++;
|
|
|
|
/* This state can time out: */
|
|
settimeout = 1;
|
|
break;
|
|
|
|
/* File descriptor write wait: */
|
|
case PS_FDW_WAIT:
|
|
/* Add the file descriptor to the write set: */
|
|
FD_SET(pthread->data.fd.fd, &fd_set_write);
|
|
|
|
/*
|
|
* Check if this file descriptor is greater than any
|
|
* of those seen so far:
|
|
*/
|
|
if (pthread->data.fd.fd > nfds) {
|
|
/* Remember this file descriptor: */
|
|
nfds = pthread->data.fd.fd;
|
|
}
|
|
/* Increment the file descriptor count: */
|
|
count++;
|
|
|
|
/* This state can time out: */
|
|
settimeout = 1;
|
|
break;
|
|
|
|
/* States that time out: */
|
|
case PS_SLEEP_WAIT:
|
|
case PS_COND_WAIT:
|
|
/* Flag a timeout as required: */
|
|
settimeout = 1;
|
|
break;
|
|
|
|
/* Select wait: */
|
|
case PS_SELECT_WAIT:
|
|
/*
|
|
* Enter a loop to process each file descriptor in
|
|
* the thread-specific file descriptor sets:
|
|
*/
|
|
for (i = 0; i < pthread->data.select_data->nfds; i++) {
|
|
/*
|
|
* Check if this file descriptor is set for
|
|
* exceptions:
|
|
*/
|
|
if (FD_ISSET(i, &pthread->data.select_data->exceptfds)) {
|
|
/*
|
|
* Add the file descriptor to the
|
|
* exception set:
|
|
*/
|
|
FD_SET(i, &fd_set_except);
|
|
|
|
/*
|
|
* Increment the file descriptor
|
|
* count:
|
|
*/
|
|
count++;
|
|
|
|
/*
|
|
* Check if this file descriptor is
|
|
* greater than any of those seen so
|
|
* far:
|
|
*/
|
|
if (i > nfds) {
|
|
/*
|
|
* Remember this file
|
|
* descriptor:
|
|
*/
|
|
nfds = i;
|
|
}
|
|
}
|
|
/*
|
|
* Check if this file descriptor is set for
|
|
* write:
|
|
*/
|
|
if (FD_ISSET(i, &pthread->data.select_data->writefds)) {
|
|
/*
|
|
* Add the file descriptor to the
|
|
* write set:
|
|
*/
|
|
FD_SET(i, &fd_set_write);
|
|
|
|
/*
|
|
* Increment the file descriptor
|
|
* count:
|
|
*/
|
|
count++;
|
|
|
|
/*
|
|
* Check if this file descriptor is
|
|
* greater than any of those seen so
|
|
* far:
|
|
*/
|
|
if (i > nfds) {
|
|
/*
|
|
* Remember this file
|
|
* descriptor:
|
|
*/
|
|
nfds = i;
|
|
}
|
|
}
|
|
/*
|
|
* Check if this file descriptor is set for
|
|
* read:
|
|
*/
|
|
if (FD_ISSET(i, &pthread->data.select_data->readfds)) {
|
|
/*
|
|
* Add the file descriptor to the
|
|
* read set:
|
|
*/
|
|
FD_SET(i, &fd_set_read);
|
|
|
|
/*
|
|
* Increment the file descriptor
|
|
* count:
|
|
*/
|
|
count++;
|
|
|
|
/*
|
|
* Check if this file descriptor is
|
|
* greater than any of those seen so
|
|
* far:
|
|
*/
|
|
if (i > nfds) {
|
|
/*
|
|
* Remember this file
|
|
* descriptor:
|
|
*/
|
|
nfds = i;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* This state can time out: */
|
|
settimeout = 1;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Check if the caller wants to wait and if the thread state
|
|
* is one that times out:
|
|
*/
|
|
if (wait_reqd && settimeout) {
|
|
/* Check if this thread wants to wait forever: */
|
|
if (pthread->wakeup_time.tv_sec == -1) {
|
|
}
|
|
/* Check if this thread doesn't want to wait at all: */
|
|
else if (pthread->wakeup_time.tv_sec == 0 &&
|
|
pthread->wakeup_time.tv_nsec == 0) {
|
|
/* Override the caller's request to wait: */
|
|
wait_reqd = 0;
|
|
} else {
|
|
/*
|
|
* Calculate the time until this thread is
|
|
* ready, allowing for the clock resolution:
|
|
*/
|
|
ts1.tv_sec = pthread->wakeup_time.tv_sec - ts.tv_sec;
|
|
ts1.tv_nsec = pthread->wakeup_time.tv_nsec - ts.tv_nsec +
|
|
CLOCK_RES_NSEC;
|
|
|
|
/*
|
|
* Check for underflow of the nanosecond
|
|
* field:
|
|
*/
|
|
if (ts1.tv_nsec < 0) {
|
|
/*
|
|
* Allow for the underflow of the
|
|
* nanosecond field:
|
|
*/
|
|
ts1.tv_sec--;
|
|
ts1.tv_nsec += 1000000000;
|
|
}
|
|
/*
|
|
* Check for overflow of the nanosecond
|
|
* field:
|
|
*/
|
|
if (ts1.tv_nsec >= 1000000000) {
|
|
/*
|
|
* Allow for the overflow of the
|
|
* nanosecond field:
|
|
*/
|
|
ts1.tv_sec++;
|
|
ts1.tv_nsec -= 1000000000;
|
|
}
|
|
/*
|
|
* Convert the timespec structure to a
|
|
* timeval structure:
|
|
*/
|
|
TIMESPEC_TO_TIMEVAL(&tv1, &ts1);
|
|
|
|
/*
|
|
* Check if no time value has been found yet,
|
|
* or if the thread will be ready sooner that
|
|
* the earliest one found so far:
|
|
*/
|
|
if ((tv.tv_sec == 0 && tv.tv_usec == 0) || timercmp(&tv1, &tv, <)) {
|
|
/* Update the time value: */
|
|
tv.tv_sec = tv1.tv_sec;
|
|
tv.tv_usec = tv1.tv_usec;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Check if the caller wants to wait: */
|
|
if (wait_reqd) {
|
|
/* Check if no threads were found with timeouts: */
|
|
if (tv.tv_sec == 0 && tv.tv_usec == 0) {
|
|
/* Wait forever: */
|
|
p_tv = NULL;
|
|
} else {
|
|
/*
|
|
* Point to the time value structure which contains
|
|
* the earliest time that a thread will be ready:
|
|
*/
|
|
p_tv = &tv;
|
|
}
|
|
|
|
/*
|
|
* Flag the pthread kernel as in a select. This is to avoid
|
|
* the window between the next statement that unblocks
|
|
* signals and the select statement which follows.
|
|
*/
|
|
_thread_kern_in_select = 1;
|
|
|
|
/*
|
|
* Wait for a file descriptor to be ready for read, write, or
|
|
* an exception, or a timeout to occur:
|
|
*/
|
|
count = _thread_sys_select(nfds + 1, &fd_set_read, &fd_set_write, &fd_set_except, p_tv);
|
|
|
|
/* Reset the kernel in select flag: */
|
|
_thread_kern_in_select = 0;
|
|
|
|
/*
|
|
* Check if it is possible that there are bytes in the kernel
|
|
* read pipe waiting to be read:
|
|
*/
|
|
if (count < 0 || FD_ISSET(_thread_kern_pipe[0], &fd_set_read)) {
|
|
/*
|
|
* Check if the kernel read pipe was included in the
|
|
* count:
|
|
*/
|
|
if (count > 0) {
|
|
/*
|
|
* Remove the kernel read pipe from the
|
|
* count:
|
|
*/
|
|
FD_CLR(_thread_kern_pipe[0], &fd_set_read);
|
|
|
|
/* Decrement the count of file descriptors: */
|
|
count--;
|
|
}
|
|
/*
|
|
* Enter a loop to read (and trash) bytes from the
|
|
* pthread kernel pipe:
|
|
*/
|
|
while ((num = _thread_sys_read(_thread_kern_pipe[0], bufr, sizeof(bufr))) > 0) {
|
|
/*
|
|
* The buffer read contains one byte per
|
|
* signal and each byte is the signal number.
|
|
* This data is not used, but the fact that
|
|
* the signal handler wrote to the pipe *is*
|
|
* used to cause the _select call
|
|
* to complete if the signal occurred between
|
|
* the time when signals were unblocked and
|
|
* the _select select call being
|
|
* made.
|
|
*/
|
|
}
|
|
}
|
|
}
|
|
/* Check if there are file descriptors to poll: */
|
|
else if (count > 0) {
|
|
/*
|
|
* Point to the time value structure which has been zeroed so
|
|
* that the call to _select will not wait:
|
|
*/
|
|
p_tv = &tv;
|
|
|
|
/* Poll file descrptors without wait: */
|
|
count = _thread_sys_select(nfds + 1, &fd_set_read, &fd_set_write, &fd_set_except, p_tv);
|
|
}
|
|
|
|
/*
|
|
* Check if any file descriptors are ready:
|
|
*/
|
|
if (count > 0) {
|
|
/*
|
|
* Enter a loop to look for threads waiting on file
|
|
* descriptors that are flagged as available by the
|
|
* _select syscall:
|
|
*/
|
|
for (pthread = _thread_link_list; pthread != NULL; pthread = pthread->nxt) {
|
|
/* Process according to thread state: */
|
|
switch (pthread->state) {
|
|
/*
|
|
* States which do not depend on file
|
|
* descriptor I/O operations:
|
|
*/
|
|
case PS_RUNNING:
|
|
case PS_COND_WAIT:
|
|
case PS_DEAD:
|
|
case PS_FDLR_WAIT:
|
|
case PS_FDLW_WAIT:
|
|
case PS_FILE_WAIT:
|
|
case PS_JOIN:
|
|
case PS_MUTEX_WAIT:
|
|
case PS_SIGWAIT:
|
|
case PS_SLEEP_WAIT:
|
|
case PS_WAIT_WAIT:
|
|
case PS_SIGTHREAD:
|
|
case PS_STATE_MAX:
|
|
case PS_SUSPENDED:
|
|
/* Nothing to do here. */
|
|
break;
|
|
|
|
/* File descriptor read wait: */
|
|
case PS_FDR_WAIT:
|
|
/*
|
|
* Check if the file descriptor is available
|
|
* for read:
|
|
*/
|
|
if (FD_ISSET(pthread->data.fd.fd, &fd_set_read)) {
|
|
/*
|
|
* Change the thread state to allow
|
|
* it to read from the file when it
|
|
* is scheduled next:
|
|
*/
|
|
pthread->state = PS_RUNNING;
|
|
}
|
|
break;
|
|
|
|
/* File descriptor write wait: */
|
|
case PS_FDW_WAIT:
|
|
/*
|
|
* Check if the file descriptor is available
|
|
* for write:
|
|
*/
|
|
if (FD_ISSET(pthread->data.fd.fd, &fd_set_write)) {
|
|
/*
|
|
* Change the thread state to allow
|
|
* it to write to the file when it is
|
|
* scheduled next:
|
|
*/
|
|
pthread->state = PS_RUNNING;
|
|
}
|
|
break;
|
|
|
|
/* Select wait: */
|
|
case PS_SELECT_WAIT:
|
|
/*
|
|
* Reset the flag that indicates if a file
|
|
* descriptor is ready for some type of
|
|
* operation:
|
|
*/
|
|
count_dec = 0;
|
|
|
|
/*
|
|
* Enter a loop to search though the
|
|
* thread-specific select file descriptors
|
|
* for the first descriptor that is ready:
|
|
*/
|
|
for (i = 0; i < pthread->data.select_data->nfds && count_dec == 0; i++) {
|
|
/*
|
|
* Check if this file descriptor does
|
|
* not have an exception:
|
|
*/
|
|
if (FD_ISSET(i, &pthread->data.select_data->exceptfds) && FD_ISSET(i, &fd_set_except)) {
|
|
/*
|
|
* Flag this file descriptor
|
|
* as ready:
|
|
*/
|
|
count_dec = 1;
|
|
}
|
|
/*
|
|
* Check if this file descriptor is
|
|
* not ready for write:
|
|
*/
|
|
if (FD_ISSET(i, &pthread->data.select_data->writefds) && FD_ISSET(i, &fd_set_write)) {
|
|
/*
|
|
* Flag this file descriptor
|
|
* as ready:
|
|
*/
|
|
count_dec = 1;
|
|
}
|
|
/*
|
|
* Check if this file descriptor is
|
|
* not ready for read:
|
|
*/
|
|
if (FD_ISSET(i, &pthread->data.select_data->readfds) && FD_ISSET(i, &fd_set_read)) {
|
|
/*
|
|
* Flag this file descriptor
|
|
* as ready:
|
|
*/
|
|
count_dec = 1;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Check if any file descriptors are ready
|
|
* for the current thread:
|
|
*/
|
|
if (count_dec) {
|
|
/*
|
|
* Reset the count of file
|
|
* descriptors that are ready for
|
|
* this thread:
|
|
*/
|
|
found_one = 0;
|
|
|
|
/*
|
|
* Enter a loop to search though the
|
|
* thread-specific select file
|
|
* descriptors:
|
|
*/
|
|
for (i = 0; i < pthread->data.select_data->nfds; i++) {
|
|
/*
|
|
* Reset the count of
|
|
* operations for which the
|
|
* current file descriptor is
|
|
* ready:
|
|
*/
|
|
count_dec = 0;
|
|
|
|
/*
|
|
* Check if this file
|
|
* descriptor is selected for
|
|
* exceptions:
|
|
*/
|
|
if (FD_ISSET(i, &pthread->data.select_data->exceptfds)) {
|
|
/*
|
|
* Check if this file
|
|
* descriptor has an
|
|
* exception:
|
|
*/
|
|
if (FD_ISSET(i, &fd_set_except)) {
|
|
/*
|
|
* Increment
|
|
* the count
|
|
* for this
|
|
* file:
|
|
*/
|
|
count_dec++;
|
|
} else {
|
|
/*
|
|
* Clear the
|
|
* file
|
|
* descriptor
|
|
* in the
|
|
* thread-spec
|
|
* ific file
|
|
* descriptor
|
|
* set:
|
|
*/
|
|
FD_CLR(i, &pthread->data.select_data->exceptfds);
|
|
}
|
|
}
|
|
/*
|
|
* Check if this file
|
|
* descriptor is selected for
|
|
* write:
|
|
*/
|
|
if (FD_ISSET(i, &pthread->data.select_data->writefds)) {
|
|
/*
|
|
* Check if this file
|
|
* descriptor is
|
|
* ready for write:
|
|
*/
|
|
if (FD_ISSET(i, &fd_set_write)) {
|
|
/*
|
|
* Increment
|
|
* the count
|
|
* for this
|
|
* file:
|
|
*/
|
|
count_dec++;
|
|
} else {
|
|
/*
|
|
* Clear the
|
|
* file
|
|
* descriptor
|
|
* in the
|
|
* thread-spec
|
|
* ific file
|
|
* descriptor
|
|
* set:
|
|
*/
|
|
FD_CLR(i, &pthread->data.select_data->writefds);
|
|
}
|
|
}
|
|
/*
|
|
* Check if this file
|
|
* descriptor is selected for
|
|
* read:
|
|
*/
|
|
if (FD_ISSET(i, &pthread->data.select_data->readfds)) {
|
|
/*
|
|
* Check if this file
|
|
* descriptor is
|
|
* ready for read:
|
|
*/
|
|
if (FD_ISSET(i, &fd_set_read)) {
|
|
/*
|
|
* Increment
|
|
* the count
|
|
* for this
|
|
* file:
|
|
*/
|
|
count_dec++;
|
|
} else {
|
|
/*
|
|
* Clear the
|
|
* file
|
|
* descriptor
|
|
* in the
|
|
* thread-spec
|
|
* ific file
|
|
* descriptor
|
|
* set:
|
|
*/
|
|
FD_CLR(i, &pthread->data.select_data->readfds);
|
|
}
|
|
}
|
|
/*
|
|
* Check if the current file
|
|
* descriptor is ready for
|
|
* any one of the operations:
|
|
*/
|
|
if (count_dec > 0) {
|
|
/*
|
|
* Increment the
|
|
* count of file
|
|
* descriptors that
|
|
* are ready for the
|
|
* current thread:
|
|
*/
|
|
found_one++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Return the number of file
|
|
* descriptors that are ready:
|
|
*/
|
|
pthread->data.select_data->nfds = found_one;
|
|
|
|
/*
|
|
* Change the state of the current
|
|
* thread to run:
|
|
*/
|
|
pthread->state = PS_RUNNING;
|
|
}
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Nothing to return. */
|
|
return;
|
|
}
|
|
|
|
void
|
|
_thread_kern_set_timeout(struct timespec * timeout)
|
|
{
|
|
struct timespec current_time;
|
|
struct timeval tv;
|
|
|
|
/* Reset the timeout flag for the running thread: */
|
|
_thread_run->timeout = 0;
|
|
|
|
/* Check if the thread is to wait forever: */
|
|
if (timeout == NULL) {
|
|
/*
|
|
* Set the wakeup time to something that can be recognised as
|
|
* different to an actual time of day:
|
|
*/
|
|
_thread_run->wakeup_time.tv_sec = -1;
|
|
_thread_run->wakeup_time.tv_nsec = -1;
|
|
}
|
|
/* Check if no waiting is required: */
|
|
else if (timeout->tv_sec == 0 && timeout->tv_nsec == 0) {
|
|
/* Set the wake up time to 'immediately': */
|
|
_thread_run->wakeup_time.tv_sec = 0;
|
|
_thread_run->wakeup_time.tv_nsec = 0;
|
|
} else {
|
|
/* Get the current time: */
|
|
gettimeofday(&tv, NULL);
|
|
TIMEVAL_TO_TIMESPEC(&tv, ¤t_time);
|
|
|
|
/* Calculate the time for the current thread to wake up: */
|
|
_thread_run->wakeup_time.tv_sec = current_time.tv_sec + timeout->tv_sec;
|
|
_thread_run->wakeup_time.tv_nsec = current_time.tv_nsec + timeout->tv_nsec;
|
|
|
|
/* Check if the nanosecond field needs to wrap: */
|
|
if (_thread_run->wakeup_time.tv_nsec >= 1000000000) {
|
|
/* Wrap the nanosecond field: */
|
|
_thread_run->wakeup_time.tv_sec += 1;
|
|
_thread_run->wakeup_time.tv_nsec -= 1000000000;
|
|
}
|
|
}
|
|
return;
|
|
}
|
|
#endif
|