ossp-pkg/pth/pth_cancel.c
1.31
/*
** GNU Pth - The GNU Portable Threads
** Copyright (c) 1999-2007 Ralf S. Engelschall <rse@engelschall.com>
**
** This file is part of GNU Pth, a non-preemptive thread scheduling
** library which can be found at http://www.gnu.org/software/pth/.
**
** This library is free software; you can redistribute it and/or
** modify it under the terms of the GNU Lesser General Public
** License as published by the Free Software Foundation; either
** version 2.1 of the License, or (at your option) any later version.
**
** This library is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
** Lesser General Public License for more details.
**
** You should have received a copy of the GNU Lesser General Public
** License along with this library; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
** USA, or contact Ralf S. Engelschall <rse@engelschall.com>.
**
** pth_cancel.c: Pth thread cancellation
*/
/* ``Study it forever and you'll still wonder.
Fly it once and you'll know.''
-- Henry Spencer */
#include "pth_p.h"
/* set cancellation state */
void pth_cancel_state(int newstate, int *oldstate)
{
if (oldstate != NULL)
*oldstate = pth_current->cancelstate;
if (newstate != 0)
pth_current->cancelstate = newstate;
return;
}
/* enter a cancellation point */
void pth_cancel_point(void)
{
if ( pth_current->cancelreq == TRUE
&& pth_current->cancelstate & PTH_CANCEL_ENABLE) {
/* avoid looping if cleanup handlers contain cancellation points */
pth_current->cancelreq = FALSE;
pth_debug2("pth_cancel_point: terminating cancelled thread \"%s\"", pth_current->name);
pth_exit(PTH_CANCELED);
}
return;
}
/* cancel a thread (the friendly way) */
int pth_cancel(pth_t thread)
{
pth_pqueue_t *q;
if (thread == NULL)
return pth_error(FALSE, EINVAL);
/* the current thread cannot be cancelled */
if (thread == pth_current)
return pth_error(FALSE, EINVAL);
/* the thread has to be at least still alive */
if (thread->state == PTH_STATE_DEAD)
return pth_error(FALSE, EPERM);
/* now mark the thread as cancelled */
thread->cancelreq = TRUE;
/* when cancellation is enabled in async mode we cancel the thread immediately */
if ( thread->cancelstate & PTH_CANCEL_ENABLE
&& thread->cancelstate & PTH_CANCEL_ASYNCHRONOUS) {
/* remove thread from its queue */
switch (thread->state) {
case PTH_STATE_NEW: q = &pth_NQ; break;
case PTH_STATE_READY: q = &pth_RQ; break;
case PTH_STATE_WAITING: q = &pth_WQ; break;
default: q = NULL;
}
if (q == NULL)
return pth_error(FALSE, ESRCH);
if (!pth_pqueue_contains(q, thread))
return pth_error(FALSE, ESRCH);
pth_pqueue_delete(q, thread);
/* execute cleanups */
pth_thread_cleanup(thread);
/* and now either kick it out or move it to dead queue */
if (!thread->joinable) {
pth_debug2("pth_cancel: kicking out cancelled thread \"%s\" immediately", thread->name);
pth_tcb_free(thread);
}
else {
pth_debug2("pth_cancel: moving cancelled thread \"%s\" to dead queue", thread->name);
thread->join_arg = PTH_CANCELED;
thread->state = PTH_STATE_DEAD;
pth_pqueue_insert(&pth_DQ, PTH_PRIO_STD, thread);
}
}
return TRUE;
}
/* abort a thread (the cruel way) */
int pth_abort(pth_t thread)
{
if (thread == NULL)
return pth_error(FALSE, EINVAL);
/* the current thread cannot be aborted */
if (thread == pth_current)
return pth_error(FALSE, EINVAL);
if (thread->state == PTH_STATE_DEAD && thread->joinable) {
/* if thread is already terminated, just join it */
if (!pth_join(thread, NULL))
return FALSE;
}
else {
/* else force it to be detached and cancel it asynchronously */
thread->joinable = FALSE;
thread->cancelstate = (PTH_CANCEL_ENABLE|PTH_CANCEL_ASYNCHRONOUS);
if (!pth_cancel(thread))
return FALSE;
}
return TRUE;
}
