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raypcalls.c
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raypcalls.c
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#ifndef lint
static const char RCSid[] = "$Id: raypcalls.c,v 2.34 2020/06/16 17:58:11 greg Exp $";
#endif
/*
* raypcalls.c - interface for parallel rendering using Radiance
*
* External symbols declared in ray.h
*/
#include "copyright.h"
/*
* These calls are designed similarly to the ones in raycalls.c,
* but allow for multiple rendering processes on the same host
* machine. There is no sense in specifying more child processes
* than you have processor cores, but one child may help by allowing
* asynchronous ray computation in an interactive program, and
* will protect the caller from fatal rendering errors.
*
* You should first read and understand the header in raycalls.c,
* as some things are explained there that are not repated here.
*
* The first step is opening one or more rendering processes
* with a call to ray_pinit(oct, nproc). Before calling fork(),
* ray_pinit() loads the octree and data structures into the
* caller's memory, and ray_popen() synchronizes the ambient
* file, if any. Shared memory permits all sorts of queries
* that wouldn't be possible otherwise without causing any real
* memory overhead, since all the static data are shared
* between processes. Rays are traced using a simple
* queuing mechanism, explained below.
*
* The ray queue buffers RAYQLEN rays before sending to
* children, each of which may internally buffer RAYQLEN rays
* during evaluation. Rays are not returned in the order
* they are sent when multiple processes are open.
*
* Rays are queued and returned by a single
* ray_pqueue() call. A ray_pqueue() return
* value of 0 indicates that no rays are ready
* and the queue is not yet full. A return value of 1
* indicates that a ray was returned, though it is probably
* not the one you just requested. Rays may be identified by
* the rno member of the RAY struct, which is incremented
* by the rayorigin() call, or may be set explicitly by
* the caller. Below is an example call sequence:
*
* myRay.rorg = ( ray origin point )
* myRay.rdir = ( normalized ray direction )
* myRay.rmax = ( maximum length, or zero for no limit )
* rayorigin(&myRay, PRIMARY, NULL, NULL);
* myRay.rno = ( my personal ray identifier )
* if (ray_pqueue(&myRay) == 1)
* { do something with results }
*
* Note the differences between this and the simpler ray_trace()
* call. In particular, the call may or may not return a value
* in the passed ray structure. Also, you need to call rayorigin()
* yourself, which is normally called for you by ray_trace(). The
* benefit is that ray_pqueue() will trace rays faster in
* proportion to the number of CPUs you have available on your
* system. If the ray queue is full before the call, ray_pqueue()
* will block until a result is ready so it can queue this one.
* The global int ray_pnidle indicates the number of currently idle
* children. If you want to check for completed rays without blocking,
* or get the results from rays that have been queued without
* queuing any new ones, the ray_presult() call is for you:
*
* if (ray_presult(&myRay, 1) == 1)
* { do something with results }
*
* If the second argument is 1, the call won't block when
* results aren't ready, but will immediately return 0.
* If the second argument is 0, the call will block
* until a value is available, returning 0 only if the
* queue is completely empty. Setting the second argument
* to -1 returns 0 unless a ray is ready in the queue and
* no system calls are needed. A negative return value
* indicates that a rendering process died. If this
* happens, ray_pclose(0) is automatically called to close
* all child processes, and ray_pnprocs is set to zero.
*
* If you just want to fill the ray queue without checking for
* results, check ray_pnidle and call ray_psend():
*
* while (ray_pnidle) {
* ( set up ray )
* ray_psend(&myRay);
* }
*
* Note that it is a mistake to call ra_psend() when
* ray_pnidle is zero, and nothing will be sent in
* this case. Otherwise, the ray_presult() and/or ray_pqueue()
* functions may be called subsequently to read back the results
* of rays queued by ray_psend().
*
* When you are done, you may call ray_pdone(1) to close
* all child processes and clean up memory used by Radiance.
* Any queued ray calculations will be awaited and discarded.
* As with ray_done(), ray_pdone(0) hangs onto data files
* and fonts that are likely to be used in subsequent renderings.
* Whether you need to clean up memory or not, you should
* at least call ray_pclose(0) to await the child processes.
* The caller should define a quit() function that calls
* ray_pclose(0) if ray_pnprocs > 0.
*
* Warning: You cannot affect any of the rendering processes
* by changing global parameter values onece ray_pinit() has
* been called. Changing global parameters will have no effect
* until the next call to ray_pinit(), which restarts everything.
* If you just want to reap children so that you can alter the
* rendering parameters without reloading the scene, use the
* ray_pclose(0) and ray_popen(nproc) calls to close
* then restart the child processes after the changes are made.
*
* Note: These routines are written to coordinate with the
* definitions in raycalls.c, and in fact depend on them.
* If you want to trace a ray and get a result synchronously,
* use the ray_trace() call to compute it in the parent process.
* This will not interfere with any subprocess calculations,
* but beware that a fatal error may end with a call to quit().
*
* Note: One of the advantages of using separate processes
* is that it gives the calling program some immunity from
* fatal rendering errors. As discussed in raycalls.c,
* Radiance tends to throw up its hands and exit at the
* first sign of trouble, calling quit() to return control
* to the top level. Although you can avoid exit() with
* your own longjmp() in quit(), the cleanup afterwards
* is always suspect. Through the use of subprocesses,
* we avoid this pitfall by closing the processes and
* returning a negative value from ray_pqueue() or
* ray_presult(). If you get a negative value from either
* of these calls, you can assume that the processes have
* been cleaned up with a call to ray_pclose(), though you
* will have to call ray_pdone() yourself if you want to
* free memory. Obviously, you cannot continue rendering
* without risking further errors, but otherwise your
* process should not be compromised.
*/
#include "rtprocess.h"
#include "ray.h"
#include "ambient.h"
#include <sys/types.h>
#include <sys/wait.h>
#include "selcall.h"
#ifndef RAYQLEN
#define RAYQLEN 24 /* # rays to send at once */
#endif
#ifndef MAX_RPROCS
#if (FD_SETSIZE/2-4 < 64)
#define MAX_NPROCS (FD_SETSIZE/2-4)
#else
#define MAX_NPROCS 64 /* max. # rendering processes */
#endif
#endif
extern char *shm_boundary; /* boundary of shared memory */
int ray_pnprocs = 0; /* number of child processes */
int ray_pnidle = 0; /* number of idle children */
static struct child_proc {
RT_PID pid; /* child process id */
int fd_send; /* write to child here */
int fd_recv; /* read from child here */
int npending; /* # rays in process */
RNUMBER rno[RAYQLEN]; /* working on these rays */
} r_proc[MAX_NPROCS]; /* our child processes */
static RAY r_queue[2*RAYQLEN]; /* ray i/o buffer */
static int r_send_next = 0; /* next send ray placement */
static int r_recv_first = RAYQLEN; /* position of first unreported ray */
static int r_recv_next = RAYQLEN; /* next received ray placement */
static int samplestep = 1; /* sample step size */
#define sendq_full() (r_send_next >= RAYQLEN)
static int ray_pflush(void);
static void ray_pchild(int fd_in, int fd_out);
void
ray_pinit( /* initialize ray-tracing processes */
char *otnm,
int nproc
)
{
if (nobjects > 0) /* close old calculation */
ray_pdone(0);
ray_init(otnm); /* load the shared scene */
ray_popen(nproc); /* fork children */
}
static int
ray_pflush(void) /* send queued rays to idle children */
{
int nc, n, nw, i, sfirst;
if ((ray_pnidle <= 0) | (r_send_next <= 0))
return(0); /* nothing we can send */
sfirst = 0; /* divvy up labor */
nc = ray_pnidle;
for (i = ray_pnprocs; nc && i--; ) {
if (r_proc[i].npending > 0)
continue; /* child looks busy */
n = (r_send_next - sfirst) / nc--;
if (!n)
continue;
/* smuggle set size in crtype */
r_queue[sfirst].crtype = n;
nw = writebuf(r_proc[i].fd_send, (char *)&r_queue[sfirst],
sizeof(RAY)*n);
if (nw != sizeof(RAY)*n)
return(-1); /* write error */
r_proc[i].npending = n;
while (n--) /* record ray IDs */
r_proc[i].rno[n] = r_queue[sfirst+n].rno;
sfirst += r_proc[i].npending;
ray_pnidle--; /* now she's busy */
}
if (sfirst != r_send_next)
error(CONSISTENCY, "code screwup in ray_pflush()");
r_send_next = 0;
return(sfirst); /* return total # sent */
}
int
ray_psend( /* add a ray to our send queue */
RAY *r
)
{
int rv;
if ((r == NULL) | (ray_pnidle <= 0))
return(0);
/* flush output if necessary */
if (sendq_full() && (rv = ray_pflush()) <= 0)
return(rv);
r_queue[r_send_next++] = *r;
return(1);
}
int
ray_pqueue( /* queue a ray for computation */
RAY *r
)
{
if (r == NULL)
return(0);
/* check for full send queue */
if (sendq_full()) {
RAY mySend = *r;
/* wait for a result */
if (ray_presult(r, 0) <= 0)
return(-1);
/* put new ray in queue */
r_queue[r_send_next++] = mySend;
return(1);
}
/* else add ray to send queue */
r_queue[r_send_next++] = *r;
/* check for returned ray... */
if (r_recv_first >= r_recv_next)
return(0);
/* ...one is sitting in queue */
*r = r_queue[r_recv_first++];
return(1);
}
int
ray_presult( /* check for a completed ray */
RAY *r,
int poll
)
{
static struct timeval tpoll; /* zero timeval struct */
static fd_set readset, errset;
int n, ok;
int pn;
if (r == NULL)
return(0);
/* check queued results first */
if (r_recv_first < r_recv_next) {
*r = r_queue[r_recv_first++];
return(1);
}
if (poll < 0) /* immediate polling mode? */
return(0);
n = ray_pnprocs - ray_pnidle; /* pending before flush? */
if (ray_pflush() < 0) /* send new rays to process */
return(-1);
/* reset receive queue */
r_recv_first = r_recv_next = RAYQLEN;
if (!poll) /* count newly sent unless polling */
n = ray_pnprocs - ray_pnidle;
if (n <= 0) /* return if nothing to await */
return(0);
if (!poll && ray_pnprocs == 1) /* one process -> skip select() */
FD_SET(r_proc[0].fd_recv, &readset);
getready: /* any children waiting for us? */
for (pn = ray_pnprocs; pn--; )
if (FD_ISSET(r_proc[pn].fd_recv, &readset) ||
FD_ISSET(r_proc[pn].fd_recv, &errset))
break;
/* call select() if we must */
if (pn < 0) {
FD_ZERO(&readset); FD_ZERO(&errset); n = 0;
for (pn = ray_pnprocs; pn--; ) {
if (r_proc[pn].npending > 0)
FD_SET(r_proc[pn].fd_recv, &readset);
FD_SET(r_proc[pn].fd_recv, &errset);
if (r_proc[pn].fd_recv >= n)
n = r_proc[pn].fd_recv + 1;
}
/* find out who is ready */
while ((n = select(n, &readset, (fd_set *)NULL, &errset,
poll ? &tpoll : (struct timeval *)NULL)) < 0)
if (errno != EINTR) {
error(WARNING,
"select call failed in ray_presult()");
ray_pclose(0);
return(-1);
}
if (n > 0) /* go back and get it */
goto getready;
return(0); /* else poll came up empty */
}
if (r_recv_next + r_proc[pn].npending > sizeof(r_queue)/sizeof(RAY))
error(CONSISTENCY, "buffer shortage in ray_presult()");
/* read rendered ray data */
n = readbuf(r_proc[pn].fd_recv, (char *)&r_queue[r_recv_next],
sizeof(RAY)*r_proc[pn].npending);
if (n > 0) {
r_recv_next += n/sizeof(RAY);
ok = (n == sizeof(RAY)*r_proc[pn].npending);
} else
ok = 0;
/* reset child's status */
FD_CLR(r_proc[pn].fd_recv, &readset);
if (n <= 0)
FD_CLR(r_proc[pn].fd_recv, &errset);
r_proc[pn].npending = 0;
ray_pnidle++;
/* check for rendering errors */
if (!ok) {
ray_pclose(0); /* process died -- clean up */
return(-1);
}
/* preen returned rays */
for (n = r_recv_next - r_recv_first; n--; ) {
RAY *rp = &r_queue[r_recv_first + n];
rp->rno = r_proc[pn].rno[n];
rp->parent = NULL;
rp->newcset = rp->clipset = NULL;
rp->rox = NULL;
rp->slights = NULL;
}
/* return first ray received */
*r = r_queue[r_recv_first++];
return(1);
}
void
ray_pdone( /* reap children and free data */
int freall
)
{
ray_pclose(0); /* close child processes */
if (shm_boundary != NULL) { /* clear shared memory boundary */
free((void *)shm_boundary);
shm_boundary = NULL;
}
ray_done(freall); /* free rendering data */
}
static void
ray_pchild( /* process rays (never returns) */
int fd_in,
int fd_out
)
{
int n;
int i;
/* flag child process for quit() */
ray_pnprocs = -1;
/* read each ray request set */
while ((n = read(fd_in, (char *)r_queue, sizeof(r_queue))) > 0) {
int n2;
if (n < sizeof(RAY))
break;
/* get smuggled set length */
n2 = sizeof(RAY)*r_queue[0].crtype - n;
if (n2 < 0)
error(INTERNAL, "buffer over-read in ray_pchild()");
if (n2 > 0) { /* read the rest of the set */
i = readbuf(fd_in, (char *)r_queue + n, n2);
if (i != n2)
break;
n += n2;
}
n /= sizeof(RAY);
/* evaluate rays */
for (i = 0; i < n; i++) {
r_queue[i].crtype = r_queue[i].rtype;
r_queue[i].parent = NULL;
r_queue[i].clipset = NULL;
r_queue[i].slights = NULL;
r_queue[i].rlvl = 0;
samplendx += samplestep;
rayclear(&r_queue[i]);
rayvalue(&r_queue[i]);
}
/* write back our results */
i = writebuf(fd_out, (char *)r_queue, sizeof(RAY)*n);
if (i != sizeof(RAY)*n)
error(SYSTEM, "write error in ray_pchild()");
}
if (n)
error(SYSTEM, "read error in ray_pchild()");
ambsync();
quit(0); /* normal exit */
}
void
ray_popen( /* open the specified # processes */
int nadd
)
{
/* check if our table has room */
if (ray_pnprocs + nadd > MAX_NPROCS)
nadd = MAX_NPROCS - ray_pnprocs;
if (nadd <= 0)
return;
ambsync(); /* load any new ambient values */
if (shm_boundary == NULL) { /* first child process? */
preload_objs(); /* preload auxiliary data */
/* set shared memory boundary */
shm_boundary = (char *)malloc(16);
strcpy(shm_boundary, "SHM_BOUNDARY");
}
fflush(NULL); /* clear pending output */
samplestep = ray_pnprocs + nadd;
while (nadd--) { /* fork each new process */
int p0[2], p1[2];
if (pipe(p0) < 0 || pipe(p1) < 0)
error(SYSTEM, "cannot create pipe");
if ((r_proc[ray_pnprocs].pid = fork()) == 0) {
int pn; /* close others' descriptors */
for (pn = ray_pnprocs; pn--; ) {
close(r_proc[pn].fd_send);
close(r_proc[pn].fd_recv);
}
close(p0[0]); close(p1[1]);
close(0); /* don't share stdin */
/* following call never returns */
ray_pchild(p1[0], p0[1]);
}
if (r_proc[ray_pnprocs].pid < 0)
error(SYSTEM, "cannot fork child process");
close(p1[0]); close(p0[1]);
if (rand_samp) /* decorrelate random sequence */
srandom(random());
else
samplendx++;
/*
* Close write stream on exec to avoid multiprocessing deadlock.
* No use in read stream without it, so set flag there as well.
*/
fcntl(p1[1], F_SETFD, FD_CLOEXEC);
fcntl(p0[0], F_SETFD, FD_CLOEXEC);
r_proc[ray_pnprocs].fd_send = p1[1];
r_proc[ray_pnprocs].fd_recv = p0[0];
r_proc[ray_pnprocs].npending = 0;
ray_pnprocs++;
ray_pnidle++;
}
}
void
ray_pclose( /* close one or more child processes */
int nsub
)
{
static int inclose = 0;
RAY res;
int i, status = 0;
/* check recursion */
if (inclose)
return;
inclose++;
/* check no child / in child */
if (ray_pnprocs <= 0)
return;
/* check argument */
if ((nsub <= 0) | (nsub > ray_pnprocs))
nsub = ray_pnprocs;
/* clear our ray queue */
while (ray_presult(&res,0) > 0)
;
r_send_next = 0; /* hard reset in case of error */
r_recv_first = r_recv_next = RAYQLEN;
/* close send pipes */
for (i = ray_pnprocs-nsub; i < ray_pnprocs; i++)
close(r_proc[i].fd_send);
if (nsub == 1) { /* awaiting single process? */
if (waitpid(r_proc[ray_pnprocs-1].pid, &status, 0) < 0)
status = 127<<8;
close(r_proc[ray_pnprocs-1].fd_recv);
} else /* else unordered wait */
for (i = 0; i < nsub; ) {
int j, mystatus;
RT_PID pid = wait(&mystatus);
for (j = ray_pnprocs-nsub; j < ray_pnprocs; j++)
if (r_proc[j].pid == pid) {
if (mystatus)
status = mystatus;
close(r_proc[j].fd_recv);
++i;
}
}
ray_pnprocs -= nsub;
ray_pnidle -= nsub;
if (status) {
sprintf(errmsg, "rendering process exited with code %d", status>>8);
error(WARNING, errmsg);
}
inclose--;
}

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