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);
}
}
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);
}
static void*
altexecbuffered(Alt *a, int willreplace)
{
uchar *v;
Channel *c;
c = a->c;
/* use buffered channel queue */
if(a->op==CHANRCV && c->n > 0){
_threaddebug(DBGCHAN, "buffer recv alt %p chan %p", a, c);
v = c->v + c->e*(c->f%c->s);
if(!willreplace)
c->n--;
c->f++;
return v;
}
if(a->op==CHANSND && c->n < c->s){
_threaddebug(DBGCHAN, "buffer send alt %p chan %p", a, c);
v = c->v + c->e*((c->f+c->n)%c->s);
if(!willreplace)
c->n++;
return v;
}
abort();
return nil;
}
void
_threadnote(void *v, char *s)
{
Proc *p;
Note *n;
_threaddebug(DBGNOTE, "Got note %s", s);
if(strncmp(s, "sys:", 4) == 0)
noted(NDFLT);
if(_threadexitsallstatus){
_threaddebug(DBGNOTE, "Threadexitsallstatus = '%s'\n", _threadexitsallstatus);
_exits(_threadexitsallstatus);
}
if(strcmp(s, "threadint")==0)
noted(NCONT);
p = _threadgetproc();
if(p == nil)
noted(NDFLT);
for(n=notes; n<enotes; n++)
if(canlock(&n->inuse))
break;
if(n==enotes)
sysfatal("libthread: too many delayed notes");
utfecpy(n->s, n->s+ERRMAX, s);
n->proc = p;
p->pending = 1;
if(!p->splhi)
delayednotes(p, v);
noted(NCONT);
}
static void
delayednotes(Proc *p, void *v)
{
int i;
Note *n;
int (*fn)(void*, char*);
if(!p->pending)
return;
p->pending = 0;
for(n=notes; n<enotes; n++){
if(n->proc == p){
for(i=0; i<NFN; i++){
if(onnotepid[i]!=p->pid || (fn = onnote[i])==nil)
continue;
if((*fn)(v, n->s))
break;
}
if(i==NFN){
_threaddebug(DBGNOTE, "Unhandled note %s, proc %p\n", n->s, p);
if(v != nil)
noted(NDFLT);
else if(strncmp(n->s, "sys:", 4)==0)
abort();
threadexitsall(n->s);
}
n->proc = nil;
unlock(&n->inuse);
}
}
}
void
_schedexecwait(void)
{
int pid;
Channel *c;
Proc *p;
Thread *t;
Waitmsg *w;
p = _threadgetproc();
t = p->thread;
pid = t->ret;
_threaddebug(DBGEXEC, "_schedexecwait %d", t->ret);
rfork(RFCFDG);
for(;;){
w = wait();
if(w == nil)
break;
if(w->pid == pid)
break;
free(w);
}
if(w != nil){
if((c = _threadwaitchan) != nil)
sendp(c, w);
else
free(w);
}
threadexits("procexec");
}
/*
* Create and initialize a new Thread structure attached to a given proc.
*/
static int
newthread(Proc *p, void (*f)(void *arg), void *arg, uint stacksize,
char *name, int grp)
{
int id;
Thread *t;
if(stacksize < 32)
sysfatal("bad stacksize %d", stacksize);
t = _threadmalloc(sizeof(Thread), 1);
t->stksize = stacksize;
t->stk = _threadmalloc(stacksize, 0);
memset(t->stk, 0xFE, stacksize);
_threadinitstack(t, f, arg);
t->grp = grp;
if(name)
t->cmdname = strdup(name);
t->id = nextID();
id = t->id;
t->next = (Thread*)~0;
t->proc = p;
_threaddebug(DBGSCHED, "create thread %d.%d name %s", p->pid, t->id, name);
lock(&p->lock);
p->nthreads++;
if(p->threads.head == nil)
p->threads.head = t;
else
*p->threads.tail = t;
p->threads.tail = &t->nextt;
t->nextt = nil;
t->state = Ready;
_threadready(t);
unlock(&p->lock);
return id;
}
static void
efork(Execargs *e)
{
char buf[ERRMAX];
_threaddebug(DBGEXEC, "_schedexec %s", e->prog);
close(e->fd[0]);
exec(e->prog, e->args);
_threaddebug(DBGEXEC, "_schedexec failed: %r");
rerrstr(buf, sizeof buf);
if(buf[0]=='\0')
strcpy(buf, "exec failed");
write(e->fd[1], buf, strlen(buf));
close(e->fd[1]);
_exits(buf);
}
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;
}
static void
enqueue(Alt *a, Channel **c)
{
int i;
_threaddebug(DBGCHAN, "Queuing alt %p on channel %p", a, a->c);
a->tag = c;
i = emptyentry(a->c);
a->c->qentry[i] = a;
}
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();
}
Channel*
chancreate(int elemsize, int elemcnt)
{
Channel *c;
if(elemcnt < 0 || elemsize <= 0)
return nil;
c = _threadmalloc(sizeof(Channel)+elemsize*elemcnt, 1);
c->e = elemsize;
c->s = elemcnt;
_threaddebug(DBGCHAN, "chancreate %p", c);
return c;
}
int
chaninit(Channel *c, int elemsize, int elemcnt)
{
if(elemcnt < 0 || elemsize <= 0 || c == nil)
return -1;
c->f = 0;
c->n = 0;
c->closed = 0;
c->freed = 0;
c->e = elemsize;
c->s = elemcnt;
_threaddebug(DBGCHAN, "chaninit %p", c);
return 1;
}
static int
canexec(Alt *a)
{
int i, otherop;
Channel *c;
c = a->c;
/* are there senders or receivers blocked? */
otherop = (CHANSND+CHANRCV) - a->op;
for(i=0; i<c->nentry; i++)
if(c->qentry[i] && c->qentry[i]->op==otherop && *c->qentry[i]->tag==nil){
_threaddebug(DBGCHAN, "can rendez alt %p chan %p", a, c);
return 1;
}
/* is there room in the channel? */
if((a->op==CHANSND && c->n < c->s)
|| (a->op==CHANRCV && c->n > 0)){
_threaddebug(DBGCHAN, "can buffer alt %p chan %p", a, c);
return 1;
}
return 0;
}
static void
dequeue(Alt *a)
{
int i;
Channel *c;
c = a->c;
for(i=0; i<c->nentry; i++)
if(c->qentry[i]==a){
_threaddebug(DBGCHAN, "Dequeuing alt %p from channel %p", a, a->c);
c->qentry[i] = nil;
/* release if freed and not closing */
if(c->freed && c->closed != 1)
_chanfree(c);
return;
}
}
void
threadexitsall(char *exitstr)
{
Proc *p;
int pid[64];
int i, npid, mypid;
if(exitstr == nil)
exitstr = "";
_threadexitsallstatus = exitstr;
_threaddebug(DBGSCHED, "_threadexitsallstatus set to %p", _threadexitsallstatus);
mypid = _tos->pid; //getpid();
/*
* signal others.
* copying all the pids first avoids other threads
* teardown procedures getting in the way.
*
* avoid mallocs since malloc can post a note which can
* call threadexitsall...
*/
for(;;){
lock(&_threadpq.lock);
npid = 0;
for(p = _threadpq.head; p && npid < nelem(pid); p=p->next){
if(p->threadint == 0 && p->pid != mypid){
pid[npid++] = p->pid;
p->threadint = 1;
}
}
unlock(&_threadpq.lock);
if(npid == 0)
break;
for(i=0; i<npid; i++)
postnote(PNPROC, pid[i], "threadint");
}
/* leave */
exits(exitstr);
}
void
procexec(Channel *pidc, char *prog, char *args[])
{
int n;
Proc *p;
Thread *t;
_threaddebug(DBGEXEC, "procexec %s", prog);
/* must be only thread in proc */
p = _threadgetproc();
t = p->thread;
if(p->threads.head != t || p->threads.head->nextt != nil){
werrstr("not only thread in proc");
Bad:
if(pidc)
sendul(pidc, ~0);
return;
}
/*
* We want procexec to behave like exec; if exec succeeds,
* never return, and if it fails, return with errstr set.
* Unfortunately, the exec happens in another proc since
* we have to wait for the exec'ed process to finish.
* To provide the semantics, we open a pipe with the
* write end close-on-exec and hand it to the proc that
* is doing the exec. If the exec succeeds, the pipe will
* close so that our read below fails. If the exec fails,
* then the proc doing the exec sends the errstr down the
* pipe to us.
*/
if(bind("#|", PIPEMNT, MREPL) < 0)
goto Bad;
if((p->exec.fd[0] = open(PIPEMNT "/data", OREAD)) < 0){
unmount(nil, PIPEMNT);
goto Bad;
}
if((p->exec.fd[1] = open(PIPEMNT "/data1", OWRITE|OCEXEC)) < 0){
close(p->exec.fd[0]);
unmount(nil, PIPEMNT);
goto Bad;
}
unmount(nil, PIPEMNT);
/* exec in parallel via the scheduler */
assert(p->needexec==0);
p->exec.prog = prog;
p->exec.args = args;
p->needexec = 1;
_sched();
close(p->exec.fd[1]);
if((n = read(p->exec.fd[0], p->exitstr, ERRMAX-1)) > 0){ /* exec failed */
p->exitstr[n] = '\0';
errstr(p->exitstr, ERRMAX);
close(p->exec.fd[0]);
goto Bad;
}
close(p->exec.fd[0]);
if(pidc)
sendul(pidc, t->ret);
/* wait for exec'ed program, then exit */
_schedexecwait();
}
static int
altexec(Alt *a, int spl)
{
volatile Alt *b;
int i, n, otherop;
Channel *c;
void *me, *waiter, *buf;
c = a->c;
/* rendezvous with others */
otherop = (CHANSND+CHANRCV) - a->op;
n = 0;
b = nil;
me = a->v;
for(i=0; i<c->nentry; i++)
if(c->qentry[i] && c->qentry[i]->op==otherop && *c->qentry[i]->tag==nil)
if(nrand(++n) == 0)
b = c->qentry[i];
if(b != nil){
_threaddebug(DBGCHAN, "rendez %s alt %p chan %p alt %p", a->op==CHANRCV?"recv":"send", a, c, b);
waiter = b->v;
if(c->s && c->n){
/*
* if buffer is full and there are waiters
* and we're meeting a waiter,
* we must be receiving.
*
* we use the value in the channel buffer,
* copy the waiter's value into the channel buffer
* on behalf of the waiter, and then wake the waiter.
*/
if(a->op!=CHANRCV)
abort();
buf = altexecbuffered(a, 1);
altcopy(me, buf, c->e);
altcopy(buf, waiter, c->e);
}else{
if(a->op==CHANRCV)
altcopy(me, waiter, c->e);
else
altcopy(waiter, me, c->e);
}
*b->tag = c; /* commits us to rendezvous */
_threaddebug(DBGCHAN, "unlocking the chanlock");
unlock(&chanlock);
_procsplx(spl);
_threaddebug(DBGCHAN, "chanlock is %lud", *(ulong*)&chanlock);
while(_threadrendezvous(b->tag, 0) == Intred)
;
return 1;
}
buf = altexecbuffered(a, 0);
if(a->op==CHANRCV)
altcopy(me, buf, c->e);
else
altcopy(buf, me, c->e);
unlock(&chanlock);
_procsplx(spl);
return 1;
}