Import sources from 2011-03-30 iso image

1 files changed, 189 insertions, 0 deletions

diff --git a/sys/src/libthread/sched.c b/sys/src/libthread/sched.c
new file mode 100755
index 000000000..50603a3c4
--- /dev/null
+++ b/sys/src/libthread/sched.c
@@ -0,0 +1,189 @@
+#include <u.h>
+#include <libc.h>
+#include <thread.h>
+#include "threadimpl.h"
+#include <tos.h>
+
+static Thread	*runthread(Proc*);
+
+static char *_psstate[] = {
+	"Moribund",
+	"Dead",
+	"Exec",
+	"Fork",
+	"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, **l;
+
+	p = arg;
+	_threadsetproc(p);
+	p->pid = _tos->pid; //getpid();
+	while(setjmp(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){
+			t->state = Dead;
+			for(l=&p->threads.head; *l; l=&(*l)->nextt)
+				if(*l == t){
+					*l = t->nextt;
+					if(*l==nil)
+						p->threads.tail = l;
+					p->nthreads--;
+					break;
+				}
+			unlock(&p->lock);
+			if(t->inrendez){
+				_threadflagrendez(t);
+				_threadbreakrendez();
+			}
+			free(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);
+			p->newproc = nil;
+		}
+		t->state = t->nextstate;
+		if(t->state == Ready)
+			_threadready(t);
+	}
+	unlock(&p->lock);
+	_sched();
+}
+
+void
+needstack(int n)
+{
+	int x;
+	Proc *p;
+	Thread *t;
+	
+	p = _threadgetproc();
+	t = p->thread;
+	
+	if((uchar*)&x - n < (uchar*)t->stk){
+		fprint(2, "%s %lud: &x=%p n=%d t->stk=%p\n",
+			argv0, _tos->pid, &x, n, t->stk);
+		fprint(2, "%s %lud: stack overflow\n", argv0, _tos->pid);
+		abort();
+	}
+}
+
+void
+_sched(void)
+{
+	Proc *p;
+	Thread *t;
+
+Resched:
+	p = _threadgetproc();
+	if((t = p->thread) != nil){
+		needstack(128);
+		_threaddebug(DBGSCHED, "pausing, state=%s", psstate(t->state));
+		if(setjmp(t->sched)==0)
+			longjmp(p->sched, 1);
+		return;
+	}else{
+		t = runthread(p);
+		if(t == nil){
+			_threaddebug(DBGSCHED, "all threads gone; exiting");
+			_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;
+		longjmp(t->sched, 1);
+	}
+}
+
+static 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(q, 0) == (void*)~0){
+			if(_threadexitsallstatus)
+				exits(_threadexitsallstatus);
+		}
+		/* lock picked up from _threadready */
+	}
+	t = q->head;
+	q->head = t->next;
+	unlock(&p->readylock);
+	return t;
+}
+
+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 = t;
+	q->tail = &t->next;
+	if(q->asleep){
+		q->asleep = 0;
+		/* lock passes to runthread */
+		_threaddebug(DBGSCHED, "waking process %d", t->proc->pid);
+		while(rendezvous(q, 0) == (void*)~0){
+			if(_threadexitsallstatus)
+				exits(_threadexitsallstatus);
+		}
+	}else
+		unlock(&t->proc->readylock);
+}
+
+void
+yield(void)
+{
+	_sched();
+}
+