/* drop all threads (except for the currently active one) */
intern void pth_scheduler_drop(void)
{
pth_t t;
/* clear the new queue */
while ((t = pth_pqueue_delmax(&pth_NQ)) != NULL)
pth_tcb_free(t);
pth_pqueue_init(&pth_NQ);
/* clear the ready queue */
while ((t = pth_pqueue_delmax(&pth_RQ)) != NULL)
pth_tcb_free(t);
pth_pqueue_init(&pth_RQ);
/* clear the waiting queue */
while ((t = pth_pqueue_delmax(&pth_WQ)) != NULL)
pth_tcb_free(t);
pth_pqueue_init(&pth_WQ);
/* clear the suspend queue */
while ((t = pth_pqueue_delmax(&pth_SQ)) != NULL)
pth_tcb_free(t);
pth_pqueue_init(&pth_SQ);
/* clear the dead queue */
while ((t = pth_pqueue_delmax(&pth_DQ)) != NULL)
pth_tcb_free(t);
pth_pqueue_init(&pth_DQ);
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_gctx_get()->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_gctx_get()->pth_NQ; break;
case PTH_STATE_READY: q = &pth_gctx_get()->pth_RQ; break;
case PTH_STATE_WAITING: q = &pth_gctx_get()->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_gctx_get()->pth_DQ, PTH_PRIO_STD, thread);
}
}
return TRUE;
}
/* the heart of this library: the thread scheduler */
intern void *pth_scheduler(void *dummy)
{
sigset_t sigs;
pth_time_t running;
pth_time_t snapshot;
struct sigaction sa;
sigset_t ss;
int sig;
pth_t t;
/*
* bootstrapping
*/
pth_debug1("pth_scheduler: bootstrapping");
/* mark this thread as the special scheduler thread */
pth_sched->state = PTH_STATE_SCHEDULER;
/* block all signals in the scheduler thread */
sigfillset(&sigs);
pth_sc(sigprocmask)(SIG_SETMASK, &sigs, NULL);
/* initialize the snapshot time for bootstrapping the loop */
pth_time_set(&snapshot, PTH_TIME_NOW);
/*
* endless scheduler loop
*/
for (;;) {
/*
* Move threads from new queue to ready queue and optionally
* give them maximum priority so they start immediately.
*/
while ((t = pth_pqueue_tail(&pth_NQ)) != NULL) {
pth_pqueue_delete(&pth_NQ, t);
t->state = PTH_STATE_READY;
if (pth_favournew)
pth_pqueue_insert(&pth_RQ, pth_pqueue_favorite_prio(&pth_RQ), t);
else
pth_pqueue_insert(&pth_RQ, PTH_PRIO_STD, t);
pth_debug2("pth_scheduler: new thread \"%s\" moved to top of ready queue", t->name);
}
/* Calculate thread target runtime for ready queue */
pth_pqueue_calc_target(&pth_RQ);
/* Assign tikets to threads in ready queue */
pth_pqueue_issue_tk(&pth_RQ);
/*
* Update average scheduler load
*/
pth_scheduler_load(&snapshot);
/*
* Find next thread in ready queue
*/
/* generate lottery number randomly */
/* pth_current = pth_pqueue_delmax(&pth_RQ); */
int ltr_num = rand() % pth_RQ.total_tk;
pth_current = pth_pqueue_deltk(&pth_RQ, ltr_num);
if (pth_current == NULL) {
fprintf(stderr, "**Pth** SCHEDULER INTERNAL ERROR: "
"no more thread(s) available to schedule!?!?\n");
abort();
}
pth_debug4("pth_scheduler: thread \"%s\" selected (prio=%d, qprio=%d)",
pth_current->name, pth_current->prio, pth_current->q_prio);
/*
* Raise additionally thread-specific signals
* (they are delivered when we switch the context)
*
* Situation is ('#' = signal pending):
* process pending (pth_sigpending): ----####
* thread pending (pth_current->sigpending): --##--##
* Result has to be:
* process new pending: --######
*/
if (pth_current->sigpendcnt > 0) {
sigpending(&pth_sigpending);
for (sig = 1; sig < PTH_NSIG; sig++)
if (sigismember(&pth_current->sigpending, sig))
if (!sigismember(&pth_sigpending, sig))
kill(getpid(), sig);
}
/*
* Set running start time for new thread
* and perform a context switch to it
*/
pth_debug3("pth_scheduler: switching to thread 0x%lx (\"%s\")",
(unsigned long)pth_current, pth_current->name);
/* update thread times */
pth_time_set(&pth_current->lastran, PTH_TIME_NOW);
/* update scheduler times */
pth_time_set(&running, &pth_current->lastran);
pth_time_sub(&running, &snapshot);
pth_time_add(&pth_sched->running, &running);
/* ** ENTERING THREAD ** - by switching the machine context */
pth_current->dispatches++;
pth_mctx_switch(&pth_sched->mctx, &pth_current->mctx);
/* update scheduler times */
pth_time_set(&snapshot, PTH_TIME_NOW);
pth_debug3("pth_scheduler: cameback from thread 0x%lx (\"%s\")",
(unsigned long)pth_current, pth_current->name);
/*
* Calculate and update the time the previous thread was running
*/
pth_time_set(&running, &snapshot);
pth_time_sub(&running, &pth_current->lastran);
pth_time_add(&pth_current->running, &running);
/* Update actual time of all threads in ready queue */
pth_pqueue_update_a_rt(&pth_RQ);
pth_debug3("pth_scheduler: thread \"%s\" ran %.6f",
pth_current->name, pth_time_t2d(&running));
/* Additional debugging code */
pth_debug2("pth_scheduler: lottery number %d",
ltr_num);
pth_debug2("pth_scheduler: total ticket %d",
pth_RQ.total_tk);
pth_debug3("pth_scheduler: thread has %d offset and %d tickets",
(pth_current->tk).offset, (pth_current->tk).tk_num);
pth_debug3("pth_scheduler: thread has %.6f running time and %.6f lifetime",
pth_time_t2d(&pth_current->running), pth_time_t2d(&lifetime));
pth_debug2("pth_scheduler: thread has %.6f target runtime",
(pth_current->cpu_rt).target);
pth_debug2("pth_scheduler: thread has %.6f actual runtime",
(pth_current->cpu_rt).actual);
/*
* Remove still pending thread-specific signals
* (they are re-delivered next time)
*
* Situation is ('#' = signal pending):
* thread old pending (pth_current->sigpending): --##--##
* process old pending (pth_sigpending): ----####
* process still pending (sigstillpending): ---#-#-#
* Result has to be:
* process new pending: -----#-#
* thread new pending (pth_current->sigpending): ---#---#
*/
if (pth_current->sigpendcnt > 0) {
sigset_t sigstillpending;
sigpending(&sigstillpending);
for (sig = 1; sig < PTH_NSIG; sig++) {
if (sigismember(&pth_current->sigpending, sig)) {
if (!sigismember(&sigstillpending, sig)) {
/* thread (and perhaps also process) signal delivered */
sigdelset(&pth_current->sigpending, sig);
pth_current->sigpendcnt--;
}
else if (!sigismember(&pth_sigpending, sig)) {
/* thread signal not delivered */
pth_util_sigdelete(sig);
}
}
}
}
/*
* Check for stack overflow
*/
if (pth_current->stackguard != NULL) {
if (*pth_current->stackguard != 0xDEAD) {
pth_debug3("pth_scheduler: stack overflow detected for thread 0x%lx (\"%s\")",
(unsigned long)pth_current, pth_current->name);
/*
* if the application doesn't catch SIGSEGVs, we terminate
* manually with a SIGSEGV now, but output a reasonable message.
*/
if (sigaction(SIGSEGV, NULL, &sa) == 0) {
if (sa.sa_handler == SIG_DFL) {
fprintf(stderr, "**Pth** STACK OVERFLOW: thread pid_t=0x%lx, name=\"%s\"\n",
(unsigned long)pth_current, pth_current->name);
kill(getpid(), SIGSEGV);
sigfillset(&ss);
sigdelset(&ss, SIGSEGV);
sigsuspend(&ss);
abort();
}
}
/*
* else we terminate the thread only and send us a SIGSEGV
* which allows the application to handle the situation...
*/
pth_current->join_arg = (void *)0xDEAD;
pth_current->state = PTH_STATE_DEAD;
kill(getpid(), SIGSEGV);
}
}
/*
* If previous thread is now marked as dead, kick it out
*/
if (pth_current->state == PTH_STATE_DEAD) {
pth_debug2("pth_scheduler: marking thread \"%s\" as dead", pth_current->name);
if (!pth_current->joinable)
pth_tcb_free(pth_current);
else
pth_pqueue_insert(&pth_DQ, PTH_PRIO_STD, pth_current);
pth_current = NULL;
}
/*
* If thread wants to wait for an event
* move it to waiting queue now
*/
if (pth_current != NULL && pth_current->state == PTH_STATE_WAITING) {
pth_debug2("pth_scheduler: moving thread \"%s\" to waiting queue",
pth_current->name);
pth_pqueue_insert(&pth_WQ, pth_current->prio, pth_current);
pth_current = NULL;
}
/*
* migrate old treads in ready queue into higher
* priorities to avoid starvation and insert last running
* thread back into this queue, too.
*/
/* Disable this auto-increment mechanism */
/* pth_pqueue_increase(&pth_RQ); */
if (pth_current != NULL)
pth_pqueue_insert(&pth_RQ, pth_current->prio, pth_current);
/*
* Manage the events in the waiting queue, i.e. decide whether their
* events occurred and move them to the ready queue. But wait only if
* we have already no new or ready threads.
*/
if ( pth_pqueue_elements(&pth_RQ) == 0
&& pth_pqueue_elements(&pth_NQ) == 0)
/* still no NEW or READY threads, so we have to wait for new work */
pth_sched_eventmanager(&snapshot, FALSE /* wait */);
else
/* already NEW or READY threads exists, so just poll for even more work */
pth_sched_eventmanager(&snapshot, TRUE /* poll */);
}
/* NOTREACHED */
return NULL;
}
