Initial revision

src/libthread/sched.c

@@ -0,0 +1,192 @@
+#include "threadimpl.h"
+#include <signal.h>
+
+//static Thread	*runthread(Proc*);
+
+static char *_psstate[] = {
+	"Dead",
+	"Running",
+	"Ready",
+	"Rendezvous",
+};
+
+static char*
+psstate(int s)
+{
+	if(s < 0 || s >= nelem(_psstate))
+		return "unknown";
+	return _psstate[s];
+}
+
+void
+_schedinit(void *arg)
+{
+	Proc *p;
+	Thread *t;
+	extern void ignusr1(void), _threaddie(int);
+	ignusr1();
+	signal(SIGTERM, _threaddie);
+  
+
+
+	p = arg;
+	p->pid = _threadgetpid();
+	_threadsetproc(p);
+	while(_setlabel(&p->sched))
+		;
+	_threaddebug(DBGSCHED, "top of schedinit, _threadexitsallstatus=%p", _threadexitsallstatus);
+	if(_threadexitsallstatus)
+		exits(_threadexitsallstatus);
+	lock(&p->lock);
+	if((t=p->thread) != nil){
+		p->thread = nil;
+		if(t->moribund){
+			assert(t->moribund == 1);
+			t->state = Dead;
+			if(t->prevt)
+				t->prevt->nextt = t->nextt;
+			else
+				p->threads.head = t->nextt;
+			if(t->nextt)
+				t->nextt->prevt = t->prevt;
+			else
+				p->threads.tail = t->prevt;
+			unlock(&p->lock);
+			if(t->inrendez){
+				_threadflagrendez(t);
+				_threadbreakrendez();
+			}
+			_stackfree(t->stk);
+			free(t->cmdname);
+			free(t);	/* XXX how do we know there are no references? */
+			t = nil;
+			_sched();
+		}
+		if(p->needexec){
+			t->ret = _schedexec(&p->exec);
+			p->needexec = 0;
+		}
+		if(p->newproc){
+			t->ret = _schedfork(p->newproc);
+			if(t->ret < 0){
+//fprint(2, "_schedfork: %r\n");
+				abort();
+}
+			p->newproc = nil;
+		}
+		t->state = t->nextstate;
+		if(t->state == Ready)
+			_threadready(t);
+	}
+	unlock(&p->lock);
+	_sched();
+}
+
+static inline Thread*
+runthread(Proc *p)
+{
+	Thread *t;
+	Tqueue *q;
+
+	if(p->nthreads==0)
+		return nil;
+	q = &p->ready;
+	lock(&p->readylock);
+	if(q->head == nil){
+		q->asleep = 1;
+		_threaddebug(DBGSCHED, "sleeping for more work");
+		unlock(&p->readylock);
+		while(rendezvous((ulong)q, 0) == ~0){
+			if(_threadexitsallstatus)
+				exits(_threadexitsallstatus);
+		}
+		/* lock picked up from _threadready */
+	}
+	t = q->head;
+	q->head = t->next;
+	unlock(&p->readylock);
+	return t;
+}
+
+void
+_sched(void)
+{
+	Proc *p;
+	Thread *t;
+
+Resched:
+	p = _threadgetproc();
+//fprint(2, "p %p\n", p);
+	if((t = p->thread) != nil){
+		if((ulong)&p < (ulong)t->stk){	/* stack overflow */
+			fprint(2, "stack overflow %lux %lux\n", (ulong)&p, (ulong)t->stk);
+			abort();
+		}
+	//	_threaddebug(DBGSCHED, "pausing, state=%s set %p goto %p",
+	//		psstate(t->state), &t->sched, &p->sched);
+		if(_setlabel(&t->sched)==0)
+			_gotolabel(&p->sched);
+		return;
+	}else{
+		t = runthread(p);
+		if(t == nil){
+			_threaddebug(DBGSCHED, "all threads gone; exiting");
+			_threaddelproc();
+			_schedexit(p);
+		}
+	//	_threaddebug(DBGSCHED, "running %d.%d", t->proc->pid, t->id);
+		p->thread = t;
+		if(t->moribund){
+			_threaddebug(DBGSCHED, "%d.%d marked to die");
+			goto Resched;
+		}
+		t->state = Running;
+		t->nextstate = Ready;
+		_gotolabel(&t->sched);
+	}
+}
+
+long
+threadstack(void)
+{
+	Proc *p;
+	Thread *t;
+
+	p = _threadgetproc();
+	t = p->thread;
+	return (ulong)&p - (ulong)t->stk;
+}
+
+void
+_threadready(Thread *t)
+{
+	Tqueue *q;
+
+	assert(t->state == Ready);
+	_threaddebug(DBGSCHED, "readying %d.%d", t->proc->pid, t->id);
+	q = &t->proc->ready;
+	lock(&t->proc->readylock);
+	t->next = nil;
+	if(q->head==nil)
+		q->head = t;
+	else
+		q->tail->next = t;
+	q->tail = t;
+	if(q->asleep){
+		q->asleep = 0;
+		/* lock passes to runthread */
+		_threaddebug(DBGSCHED, "waking process %d", t->proc->pid);
+		while(rendezvous((ulong)q, 0) == ~0){
+			if(_threadexitsallstatus)
+				exits(_threadexitsallstatus);
+		}
+	}else
+		unlock(&t->proc->readylock);
+}
+
+void
+yield(void)
+{
+	_sched();
+}
+