src/rt/raypcalls.c

#ifndef lint
static const char       RCSid[] = "$Id: raypcalls.c,v 2.13 2005/12/20 20:36:44 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 processors, 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 undrstand 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 then 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.
 *
 *  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.  A negative return value
 *  indicates that a rendering process died.  If this
 *  happens, ray_close(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 fatal error to call ra_psend() when
 *  ray_pnidle is zero.  The ray_presult() and/or ray_pqueue()
 *  functions may be called subsequently to read back the results.
 *
 *  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 want to bother cleaning up memory or not, you
 *  should at least call ray_pclose(0) to clean the child processes.
 *
 *  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_close(), 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 <stdio.h>
#include <sys/types.h>
#include <sys/wait.h> /* XXX platform */

#include  "rtprocess.h"
#include  "ray.h"
#include  "ambient.h"
#include  "selcall.h"

#ifndef RAYQLEN
#define RAYQLEN         12              /* # 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 {
        int     pid;                            /* child process id */
        int     fd_send;                        /* write to child here */
        int     fd_recv;                        /* read from child here */
        int     npending;                       /* # rays in process */
        unsigned long  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;            /* next send ray placement */
static int      r_recv_first;           /* position of first unreported ray */
static int      r_recv_next;            /* next receive ray placement */

#define sendq_full()    (r_send_next >= RAYQLEN)

static int ray_pflush(void);
static void ray_pchild(int fd_in, int fd_out);


extern 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 */

        preload_objs();                 /* preload auxiliary data */

                                        /* set shared memory boundary */
        shm_boundary = (char *)malloc(16);
        strcpy(shm_boundary, "SHM_BOUNDARY");

        r_send_next = 0;                /* set up queue */
        r_recv_first = r_recv_next = RAYQLEN;

        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 */
}


extern void
ray_psend(                      /* add a ray to our send queue */
        RAY     *r
)
{
        if (r == NULL)
                return;
                                        /* flush output if necessary */
        if (sendq_full() && ray_pflush() <= 0)
                error(INTERNAL, "ray_pflush failed in ray_psend");

        r_queue[r_send_next++] = *r;
}


extern 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;
                int     rval;
                mySend = *r;
                                        /* wait for a result */
                rval = ray_presult(r, 0);
                                        /* put new ray in queue */
                r_queue[r_send_next++] = mySend;
                return(rval);           /* done */
        }
                                        /* 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);
}


extern 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;
        register 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);
        }
        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);
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--; ) {
                register 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);
}


extern 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;
        register int    i;
                                        /* 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;
                        samplendx++;
                        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 */
}


extern 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 */
        fflush(NULL);                   /* clear pending output */
        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]);
                                        /* 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]);
                /*
                 * 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++;
        }
}


extern void
ray_pclose(             /* close one or more child processes */
        int     nsub
)
{
        static int      inclose = 0;
        RAY     res;
                                        /* check recursion */
        if (inclose)
                return;
        inclose++;
                                        /* check argument */
        if ((nsub <= 0) | (nsub > ray_pnprocs))
                nsub = ray_pnprocs;
                                        /* clear our ray queue */
        while (ray_presult(&res,0) > 0)
                ;
                                        /* clean up children */
        while (nsub--) {
                int     status;
                ray_pnprocs--;
                close(r_proc[ray_pnprocs].fd_recv);
                close(r_proc[ray_pnprocs].fd_send);
                if (waitpid(r_proc[ray_pnprocs].pid, &status, 0) < 0)
                        status = 127<<8;
                if (status) {
                        sprintf(errmsg,
                                "rendering process %d exited with code %d",
                                        r_proc[ray_pnprocs].pid, status>>8);
                        error(WARNING, errmsg);
                }
                ray_pnidle--;
        }
        inclose--;
}


void
quit(ec)                        /* make sure exit is called */
int     ec;
{
        exit(ec);
}
Revision:	2.14
Committed:	Wed Dec 21 17:36:06 2005 UTC (18 years, 4 months ago) by greg
Content type:	text/plain
Branch:	MAIN
CVS Tags:	rad3R8
Changes since 2.13:	+9 -13 lines
Log Message:	Minor cosmetic changes
#	Content
1	#ifndef lint
2	static const char RCSid[] = "$Id: raypcalls.c,v 2.13 2005/12/20 20:36:44 greg Exp $";
3	#endif
4	/*
5	* raypcalls.c - interface for parallel rendering using Radiance
6	*
7	* External symbols declared in ray.h
8	*/
9
10	#include "copyright.h"
11
12	/*
13	* These calls are designed similarly to the ones in raycalls.c,
14	* but allow for multiple rendering processes on the same host
15	* machine. There is no sense in specifying more child processes
16	* than you have processors, but one child may help by allowing
17	* asynchronous ray computation in an interactive program, and
18	* will protect the caller from fatal rendering errors.
19	*
20	* You should first read and undrstand the header in raycalls.c,
21	* as some things are explained there that are not repated here.
22	*
23	* The first step is opening one or more rendering processes
24	* with a call to ray_pinit(oct, nproc). Before calling fork(),
25	* ray_pinit() loads the octree and data structures into the
26	* caller's memory, and ray_popen() synchronizes the ambient
27	* file, if any. Shared memory permits all sorts of queries
28	* that wouldn't be possible otherwise, without causing any real
29	* memory overhead, since all the static data are shared
30	* between processes. Rays are then traced using a simple
31	* queuing mechanism, explained below.
32	*
33	* The ray queue buffers RAYQLEN rays before sending to
34	* children, each of which may internally buffer RAYQLEN rays.
35	*
36	* Rays are queued and returned by a single
37	* ray_pqueue() call. A ray_pqueue() return
38	* value of 0 indicates that no rays are ready
39	* and the queue is not yet full. A return value of 1
40	* indicates that a ray was returned, though it is probably
41	* not the one you just requested. Rays may be identified by
42	* the rno member of the RAY struct, which is incremented
43	* by the rayorigin() call, or may be set explicitly by
44	* the caller. Below is an example call sequence:
45	*
46	* myRay.rorg = ( ray origin point )
47	* myRay.rdir = ( normalized ray direction )
48	* myRay.rmax = ( maximum length, or zero for no limit )
49	* rayorigin(&myRay, PRIMARY, NULL, NULL);
50	* myRay.rno = ( my personal ray identifier )
51	* if (ray_pqueue(&myRay) == 1)
52	* { do something with results }
53	*
54	* Note the differences between this and the simpler ray_trace()
55	* call. In particular, the call may or may not return a value
56	* in the passed ray structure. Also, you need to call rayorigin()
57	* yourself, which is normally called for you by ray_trace(). The
58	* benefit is that ray_pqueue() will trace rays faster in
59	* proportion to the number of CPUs you have available on your
60	* system. If the ray queue is full before the call, ray_pqueue()
61	* will block until a result is ready so it can queue this one.
62	* The global int ray_pnidle indicates the number of currently idle
63	* children. If you want to check for completed rays without blocking,
64	* or get the results from rays that have been queued without
65	* queuing any new ones, the ray_presult() call is for you:
66	*
67	* if (ray_presult(&myRay, 1) == 1)
68	* { do something with results }
69	*
70	* If the second argument is 1, the call won't block when
71	* results aren't ready, but will immediately return 0.
72	* If the second argument is 0, the call will block
73	* until a value is available, returning 0 only if the
74	* queue is completely empty. A negative return value
75	* indicates that a rendering process died. If this
76	* happens, ray_close(0) is automatically called to close
77	* all child processes, and ray_pnprocs is set to zero.
78	*
79	* If you just want to fill the ray queue without checking for
80	* results, check ray_pnidle and call ray_psend():
81	*
82	* while (ray_pnidle) {
83	* ( set up ray )
84	* ray_psend(&myRay);
85	* }
86	*
87	* Note that it is a fatal error to call ra_psend() when
88	* ray_pnidle is zero. The ray_presult() and/or ray_pqueue()
89	* functions may be called subsequently to read back the results.
90	*
91	* When you are done, you may call ray_pdone(1) to close
92	* all child processes and clean up memory used by Radiance.
93	* Any queued ray calculations will be awaited and discarded.
94	* As with ray_done(), ray_pdone(0) hangs onto data files
95	* and fonts that are likely to be used in subsequent renderings.
96	* Whether you want to bother cleaning up memory or not, you
97	* should at least call ray_pclose(0) to clean the child processes.
98	*
99	* Warning: You cannot affect any of the rendering processes
100	* by changing global parameter values onece ray_pinit() has
101	* been called. Changing global parameters will have no effect
102	* until the next call to ray_pinit(), which restarts everything.
103	* If you just want to reap children so that you can alter the
104	* rendering parameters without reloading the scene, use the
105	* ray_pclose(0) and ray_popen(nproc) calls to close
106	* then restart the child processes after the changes are made.
107	*
108	* Note: These routines are written to coordinate with the
109	* definitions in raycalls.c, and in fact depend on them.
110	* If you want to trace a ray and get a result synchronously,
111	* use the ray_trace() call to compute it in the parent process.
112	* This will not interfere with any subprocess calculations,
113	* but beware that a fatal error may end with a call to quit().
114	*
115	* Note: One of the advantages of using separate processes
116	* is that it gives the calling program some immunity from
117	* fatal rendering errors. As discussed in raycalls.c,
118	* Radiance tends to throw up its hands and exit at the
119	* first sign of trouble, calling quit() to return control
120	* to the top level. Although you can avoid exit() with
121	* your own longjmp() in quit(), the cleanup afterwards
122	* is always suspect. Through the use of subprocesses,
123	* we avoid this pitfall by closing the processes and
124	* returning a negative value from ray_pqueue() or
125	* ray_presult(). If you get a negative value from either
126	* of these calls, you can assume that the processes have
127	* been cleaned up with a call to ray_close(), though you
128	* will have to call ray_pdone() yourself if you want to
129	* free memory. Obviously, you cannot continue rendering
130	* without risking further errors, but otherwise your
131	* process should not be compromised.
132	*/
133
134	#include <stdio.h>
135	#include <sys/types.h>
136	#include <sys/wait.h> /* XXX platform */
137
138	#include "rtprocess.h"
139	#include "ray.h"
140	#include "ambient.h"
141	#include "selcall.h"
142
143	#ifndef RAYQLEN
144	#define RAYQLEN 12 /* # rays to send at once */
145	#endif
146
147	#ifndef MAX_RPROCS
148	#if (FD_SETSIZE/2-4 < 64)
149	#define MAX_NPROCS (FD_SETSIZE/2-4)
150	#else
151	#define MAX_NPROCS 64 /* max. # rendering processes */
152	#endif
153	#endif
154
155	extern char shm_boundary; / boundary of shared memory */
156
157	int ray_pnprocs = 0; /* number of child processes */
158	int ray_pnidle = 0; /* number of idle children */
159
160	static struct child_proc {
161	int pid; /* child process id */
162	int fd_send; /* write to child here */
163	int fd_recv; /* read from child here */
164	int npending; /* # rays in process */
165	unsigned long rno[RAYQLEN]; /* working on these rays */
166	} r_proc[MAX_NPROCS]; /* our child processes */
167
168	static RAY r_queue[2RAYQLEN]; / ray i/o buffer */
169	static int r_send_next; /* next send ray placement */
170	static int r_recv_first; /* position of first unreported ray */
171	static int r_recv_next; /* next receive ray placement */
172
173	#define sendq_full() (r_send_next >= RAYQLEN)
174
175	static int ray_pflush(void);
176	static void ray_pchild(int fd_in, int fd_out);
177
178
179	extern void
180	ray_pinit( /* initialize ray-tracing processes */
181	char *otnm,
182	int nproc
183	)
184	{
185	if (nobjects > 0) /* close old calculation */
186	ray_pdone(0);
187
188	ray_init(otnm); /* load the shared scene */
189
190	preload_objs(); /* preload auxiliary data */
191
192	/* set shared memory boundary */
193	shm_boundary = (char *)malloc(16);
194	strcpy(shm_boundary, "SHM_BOUNDARY");
195
196	r_send_next = 0; /* set up queue */
197	r_recv_first = r_recv_next = RAYQLEN;
198
199	ray_popen(nproc); /* fork children */
200	}
201
202
203	static int
204	ray_pflush(void) /* send queued rays to idle children */
205	{
206	int nc, n, nw, i, sfirst;
207
208	if ((ray_pnidle <= 0) \| (r_send_next <= 0))
209	return(0); /* nothing we can send */
210
211	sfirst = 0; /* divvy up labor */
212	nc = ray_pnidle;
213	for (i = ray_pnprocs; nc && i--; ) {
214	if (r_proc[i].npending > 0)
215	continue; /* child looks busy */
216	n = (r_send_next - sfirst)/nc--;
217	if (!n)
218	continue;
219	/* smuggle set size in crtype */
220	r_queue[sfirst].crtype = n;
221	nw = writebuf(r_proc[i].fd_send, (char *)&r_queue[sfirst],
222	sizeof(RAY)*n);
223	if (nw != sizeof(RAY)*n)
224	return(-1); /* write error */
225	r_proc[i].npending = n;
226	while (n--) /* record ray IDs */
227	r_proc[i].rno[n] = r_queue[sfirst+n].rno;
228	sfirst += r_proc[i].npending;
229	ray_pnidle--; /* now she's busy */
230	}
231	if (sfirst != r_send_next)
232	error(CONSISTENCY, "code screwup in ray_pflush");
233	r_send_next = 0;
234	return(sfirst); /* return total # sent */
235	}
236
237
238	extern void
239	ray_psend( /* add a ray to our send queue */
240	RAY *r
241	)
242	{
243	if (r == NULL)
244	return;
245	/* flush output if necessary */
246	if (sendq_full() && ray_pflush() <= 0)
247	error(INTERNAL, "ray_pflush failed in ray_psend");
248
249	r_queue[r_send_next++] = *r;
250	}
251
252
253	extern int
254	ray_pqueue( /* queue a ray for computation */
255	RAY *r
256	)
257	{
258	if (r == NULL)
259	return(0);
260	/* check for full send queue */
261	if (sendq_full()) {
262	RAY mySend;
263	int rval;
264	mySend = *r;
265	/* wait for a result */
266	rval = ray_presult(r, 0);
267	/* put new ray in queue */
268	r_queue[r_send_next++] = mySend;
269	return(rval); /* done */
270	}
271	/* else add ray to send queue */
272	r_queue[r_send_next++] = *r;
273	/* check for returned ray... */
274	if (r_recv_first >= r_recv_next)
275	return(0);
276	/* ...one is sitting in queue */
277	*r = r_queue[r_recv_first++];
278	return(1);
279	}
280
281
282	extern int
283	ray_presult( /* check for a completed ray */
284	RAY *r,
285	int poll
286	)
287	{
288	static struct timeval tpoll; /* zero timeval struct */
289	static fd_set readset, errset;
290	int n, ok;
291	register int pn;
292
293	if (r == NULL)
294	return(0);
295	/* check queued results first */
296	if (r_recv_first < r_recv_next) {
297	*r = r_queue[r_recv_first++];
298	return(1);
299	}
300	n = ray_pnprocs - ray_pnidle; /* pending before flush? */
301
302	if (ray_pflush() < 0) /* send new rays to process */
303	return(-1);
304	/* reset receive queue */
305	r_recv_first = r_recv_next = RAYQLEN;
306
307	if (!poll) /* count newly sent unless polling */
308	n = ray_pnprocs - ray_pnidle;
309	if (n <= 0) /* return if nothing to await */
310	return(0);
311	getready: /* any children waiting for us? */
312	for (pn = ray_pnprocs; pn--; )
313	if (FD_ISSET(r_proc[pn].fd_recv, &readset) \|\|
314	FD_ISSET(r_proc[pn].fd_recv, &errset))
315	break;
316	/* call select if we must */
317	if (pn < 0) {
318	FD_ZERO(&readset); FD_ZERO(&errset); n = 0;
319	for (pn = ray_pnprocs; pn--; ) {
320	if (r_proc[pn].npending > 0)
321	FD_SET(r_proc[pn].fd_recv, &readset);
322	FD_SET(r_proc[pn].fd_recv, &errset);
323	if (r_proc[pn].fd_recv >= n)
324	n = r_proc[pn].fd_recv + 1;
325	}
326	/* find out who is ready */
327	while ((n = select(n, &readset, (fd_set *)NULL, &errset,
328	poll ? &tpoll : (struct timeval *)NULL)) < 0)
329	if (errno != EINTR) {
330	error(WARNING,
331	"select call failed in ray_presult");
332	ray_pclose(0);
333	return(-1);
334	}
335	if (n > 0) /* go back and get it */
336	goto getready;
337	return(0); /* else poll came up empty */
338	}
339	if (r_recv_next + r_proc[pn].npending > sizeof(r_queue)/sizeof(RAY))
340	error(CONSISTENCY, "buffer shortage in ray_presult()");
341
342	/* read rendered ray data */
343	n = readbuf(r_proc[pn].fd_recv, (char *)&r_queue[r_recv_next],
344	sizeof(RAY)*r_proc[pn].npending);
345	if (n > 0) {
346	r_recv_next += n/sizeof(RAY);
347	ok = (n == sizeof(RAY)*r_proc[pn].npending);
348	} else
349	ok = 0;
350	/* reset child's status */
351	FD_CLR(r_proc[pn].fd_recv, &readset);
352	if (n <= 0)
353	FD_CLR(r_proc[pn].fd_recv, &errset);
354	r_proc[pn].npending = 0;
355	ray_pnidle++;
356	/* check for rendering errors */
357	if (!ok) {
358	ray_pclose(0); /* process died -- clean up */
359	return(-1);
360	}
361	/* preen returned rays */
362	for (n = r_recv_next - r_recv_first; n--; ) {
363	register RAY *rp = &r_queue[r_recv_first + n];
364	rp->rno = r_proc[pn].rno[n];
365	rp->parent = NULL;
366	rp->newcset = rp->clipset = NULL;
367	rp->rox = NULL;
368	rp->slights = NULL;
369	}
370	/* return first ray received */
371	*r = r_queue[r_recv_first++];
372	return(1);
373	}
374
375
376	extern void
377	ray_pdone( /* reap children and free data */
378	int freall
379	)
380	{
381	ray_pclose(0); /* close child processes */
382
383	if (shm_boundary != NULL) { /* clear shared memory boundary */
384	free((void *)shm_boundary);
385	shm_boundary = NULL;
386	}
387	ray_done(freall); /* free rendering data */
388	}
389
390
391	static void
392	ray_pchild( /* process rays (never returns) */
393	int fd_in,
394	int fd_out
395	)
396	{
397	int n;
398	register int i;
399	/* read each ray request set */
400	while ((n = read(fd_in, (char *)r_queue, sizeof(r_queue))) > 0) {
401	int n2;
402	if (n < sizeof(RAY))
403	break;
404	/* get smuggled set length */
405	n2 = sizeof(RAY)*r_queue[0].crtype - n;
406	if (n2 < 0)
407	error(INTERNAL, "buffer over-read in ray_pchild");
408	if (n2 > 0) { /* read the rest of the set */
409	i = readbuf(fd_in, (char *)r_queue + n, n2);
410	if (i != n2)
411	break;
412	n += n2;
413	}
414	n /= sizeof(RAY);
415	/* evaluate rays */
416	for (i = 0; i < n; i++) {
417	r_queue[i].crtype = r_queue[i].rtype;
418	r_queue[i].parent = NULL;
419	r_queue[i].clipset = NULL;
420	r_queue[i].slights = NULL;
421	samplendx++;
422	rayclear(&r_queue[i]);
423	rayvalue(&r_queue[i]);
424	}
425	/* write back our results */
426	i = writebuf(fd_out, (char )r_queue, sizeof(RAY)n);
427	if (i != sizeof(RAY)*n)
428	error(SYSTEM, "write error in ray_pchild");
429	}
430	if (n)
431	error(SYSTEM, "read error in ray_pchild");
432	ambsync();
433	quit(0); /* normal exit */
434	}
435
436
437	extern void
438	ray_popen( /* open the specified # processes */
439	int nadd
440	)
441	{
442	/* check if our table has room */
443	if (ray_pnprocs + nadd > MAX_NPROCS)
444	nadd = MAX_NPROCS - ray_pnprocs;
445	if (nadd <= 0)
446	return;
447	ambsync(); /* load any new ambient values */
448	fflush(NULL); /* clear pending output */
449	while (nadd--) { /* fork each new process */
450	int p0[2], p1[2];
451	if (pipe(p0) < 0 \|\| pipe(p1) < 0)
452	error(SYSTEM, "cannot create pipe");
453	if ((r_proc[ray_pnprocs].pid = fork()) == 0) {
454	int pn; /* close others' descriptors */
455	for (pn = ray_pnprocs; pn--; ) {
456	close(r_proc[pn].fd_send);
457	close(r_proc[pn].fd_recv);
458	}
459	close(p0[0]); close(p1[1]);
460	/* following call never returns */
461	ray_pchild(p1[0], p0[1]);
462	}
463	if (r_proc[ray_pnprocs].pid < 0)
464	error(SYSTEM, "cannot fork child process");
465	close(p1[0]); close(p0[1]);
466	/*
467	* Close write stream on exec to avoid multiprocessing deadlock.
468	* No use in read stream without it, so set flag there as well.
469	*/
470	fcntl(p1[1], F_SETFD, FD_CLOEXEC);
471	fcntl(p0[0], F_SETFD, FD_CLOEXEC);
472	r_proc[ray_pnprocs].fd_send = p1[1];
473	r_proc[ray_pnprocs].fd_recv = p0[0];
474	r_proc[ray_pnprocs].npending = 0;
475	ray_pnprocs++;
476	ray_pnidle++;
477	}
478	}
479
480
481	extern void
482	ray_pclose( /* close one or more child processes */
483	int nsub
484	)
485	{
486	static int inclose = 0;
487	RAY res;
488	/* check recursion */
489	if (inclose)
490	return;
491	inclose++;
492	/* check argument */
493	if ((nsub <= 0) \| (nsub > ray_pnprocs))
494	nsub = ray_pnprocs;
495	/* clear our ray queue */
496	while (ray_presult(&res,0) > 0)
497	;
498	/* clean up children */
499	while (nsub--) {
500	int status;
501	ray_pnprocs--;
502	close(r_proc[ray_pnprocs].fd_recv);
503	close(r_proc[ray_pnprocs].fd_send);
504	if (waitpid(r_proc[ray_pnprocs].pid, &status, 0) < 0)
505	status = 127<<8;
506	if (status) {
507	sprintf(errmsg,
508	"rendering process %d exited with code %d",
509	r_proc[ray_pnprocs].pid, status>>8);
510	error(WARNING, errmsg);
511	}
512	ray_pnidle--;
513	}
514	inclose--;
515	}
516
517
518	void
519	quit(ec) /* make sure exit is called */
520	int ec;
521	{
522	exit(ec);
523	}