src/rt/rayfifo.c

#ifndef lint
static const char RCSid[] = "$Id: rayfifo.c,v 2.2 2009/12/12 19:01:00 greg Exp $";
#endif
/*
 *  rayfifo.c - parallelize ray queue that respects order
 *
 *  External symbols declared in ray.h
 */

#include "copyright.h"

/*
 *  These routines are essentially an adjunct to raypcalls.c, providing
 *  a convenient means to get first-in/first-out behavior from multiple
 *  processor cores.  The interface is quite simple, with two functions
 *  and a callback, which must be defined by the calling program.  The
 *  hand-off for finished rays is assigned to ray_fifo_out, which takes
 *  a single pointer to the finished ray and returns a non-negative
 *  integer.  If there is an exceptional condition where termination
 *  is desired, a negative value may be returned.
 *
 *  The ray_fifo_in() call takes a ray that has been initialized in
 *  the same manner as for the ray_trace() call, i.e., the origin,
 *  direction, and maximum length have been assigned. The ray number
 *  will be set according to the number of rays traced since the
 *  last call to ray_fifo_flush().  This final call completes all
 *  pending ray calculations and frees the FIFO buffer.  If any of
 *  the automatic calls to the ray_fifo_out callback return a
 *  negative value, processing stops and -1 is returned.
 *
 *  Note:  The ray passed to ray_fifo_in() may be overwritten
 *  arbitrarily, since it is passed to ray_pqueue().
 */

#include  "ray.h"
#include  <string.h>

int             (*ray_fifo_out)(RAY *r) = NULL; /* ray output callback */

static RAY      *r_fifo_buf = NULL;             /* circular FIFO out buffer */
static int      r_fifo_len = 0;                 /* allocated FIFO length */
static RNUMBER  r_fifo_start = 1;               /* first awaited ray */
static RNUMBER  r_fifo_end = 1;                 /* one past FIFO last */
static RNUMBER  r_fifo_next = 1;                /* next ray assignment */

#define r_fifo(rn)      (&r_fifo_buf[(rn)&(r_fifo_len-1)])


static void
ray_fifo_growbuf(void)  /* double buffer size (or set to minimum if NULL) */
{
        RAY     *old_buf = r_fifo_buf;
        int     old_len = r_fifo_len;
        int     i;

        if (r_fifo_buf == NULL)
                r_fifo_len = 1<<4;
        else
                r_fifo_len <<= 1;
                                                /* allocate new */
        r_fifo_buf = (RAY *)calloc(r_fifo_len, sizeof(RAY));
        if (r_fifo_buf == NULL)
                error(SYSTEM, "out of memory in ray_fifo_growbuf");
        if (old_buf == NULL)
                return;
                                                /* copy old & free */
        for (i = r_fifo_start; i < r_fifo_end; i++)
                *r_fifo(i) = old_buf[i&(old_len-1)];

        free(old_buf);
}


static int
ray_fifo_push(          /* send finished ray to output (or queue it) */
        RAY *r
)
{
        int     rv, nsent = 0;

        if (ray_fifo_out == NULL)
                error(INTERNAL, "ray_fifo_out is NULL");
        if ((r->rno < r_fifo_start) | (r->rno >= r_fifo_next))
                error(INTERNAL, "unexpected ray number in ray_fifo_push()");

        if (r->rno > r_fifo_start) {            /* insert into output queue */
                if (r->rno - r_fifo_start >= r_fifo_len)
                        ray_fifo_growbuf();     /* need more space */
                *r_fifo(r->rno) = *r;
                if (r->rno >= r_fifo_end)
                        r_fifo_end = r->rno + 1;
                return(0);
        }
                        /* r->rno == r_fifo_start, so transfer ray(s) */
        do {
                rv = (*ray_fifo_out)(r);
                r->rno = 0;                     /* flag this entry complete */
                if (rv < 0)
                        return(-1);
                nsent += rv;
                if (++r_fifo_start < r_fifo_end)
                        r = r_fifo(r_fifo_start);
                else if (r_fifo_start > r_fifo_end)
                        r_fifo_end = r_fifo_start;
        } while (r->rno == r_fifo_start);

        return(nsent);
}


int
ray_fifo_in(            /* add ray to FIFO */
        RAY     *r
)
{
        static int      incall = 0;             /* prevent recursion */
        int             rv, rval = 0;

        if (incall++)
                error(INTERNAL, "recursive call to ray_fifo_in()");

        if (r_fifo_start >= 1L<<30) {           /* reset our counters */
                if ((rv = ray_fifo_flush()) < 0)
                        {--incall; return(-1);}
                rval += rv;
        }
                                                /* queue ray */
        rayorigin(r, PRIMARY, NULL, NULL);
        r->rno = r_fifo_next++;
        if ((rv = ray_pqueue(r)) < 0)
                {--incall; return(-1);}

        if (!rv)                                /* no result this time? */
                {--incall; return(rval);}
        
        do {                                    /* else send/queue result */
                if ((rv = ray_fifo_push(r)) < 0)
                        {--incall; return(-1);}
                rval += rv;

        } while (ray_presult(r, -1) > 0);       /* empty in-core queue */

        --incall; return(rval);
}


int
ray_fifo_flush(void)    /* flush everything and release buffer */
{
        RAY     myRay;
        int     rv, rval = 0;
                                                /* clear parallel queue */
        while ((rv = ray_presult(&myRay, 0)) > 0 &&
                        (rv = ray_fifo_push(&myRay)) >= 0)
                rval += rv;

        if (rv < 0)                             /* check for exception */
                return(-1);

        if (r_fifo_start != r_fifo_end)
                error(INTERNAL, "could not empty queue in ray_fifo_flush()");

        if (r_fifo_buf != NULL) {
                free(r_fifo_buf);
                r_fifo_buf = NULL; r_fifo_len = 0;
        }
        r_fifo_next = r_fifo_end = r_fifo_start = 1;

        return(rval);
}
Revision:	2.3
Committed:	Sat Dec 12 23:08:13 2009 UTC (14 years, 4 months ago) by greg
Content type:	text/plain
Branch:	MAIN
Changes since 2.2:	+32 -21 lines
Log Message:	Bug fixes and performance improvements to rtrace -n option
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	greg	2.3	static const char RCSid[] = "$Id: rayfifo.c,v 2.2 2009/12/12 19:01:00 greg Exp $";
3	greg	2.1	#endif
4			/*
5			* rayfifo.c - parallelize ray queue that respects order
6			*
7			* External symbols declared in ray.h
8			*/
9
10			#include "copyright.h"
11
12			/*
13			* These routines are essentially an adjunct to raypcalls.c, providing
14			* a convenient means to get first-in/first-out behavior from multiple
15			* processor cores. The interface is quite simple, with two functions
16			* and a callback, which must be defined by the calling program. The
17			* hand-off for finished rays is assigned to ray_fifo_out, which takes
18			* a single pointer to the finished ray and returns a non-negative
19			* integer. If there is an exceptional condition where termination
20			* is desired, a negative value may be returned.
21			*
22			* The ray_fifo_in() call takes a ray that has been initialized in
23			* the same manner as for the ray_trace() call, i.e., the origin,
24			* direction, and maximum length have been assigned. The ray number
25			* will be set according to the number of rays traced since the
26			* last call to ray_fifo_flush(). This final call completes all
27			* pending ray calculations and frees the FIFO buffer. If any of
28			* the automatic calls to the ray_fifo_out callback return a
29			* negative value, processing stops and -1 is returned.
30	greg	2.2	*
31			* Note: The ray passed to ray_fifo_in() may be overwritten
32			* arbitrarily, since it is passed to ray_pqueue().
33	greg	2.1	*/
34
35			#include "ray.h"
36			#include <string.h>
37
38			int (ray_fifo_out)(RAY r) = NULL; /* ray output callback */
39
40			static RAY r_fifo_buf = NULL; / circular FIFO out buffer */
41			static int r_fifo_len = 0; /* allocated FIFO length */
42			static RNUMBER r_fifo_start = 1; /* first awaited ray */
43			static RNUMBER r_fifo_end = 1; /* one past FIFO last */
44	greg	2.3	static RNUMBER r_fifo_next = 1; /* next ray assignment */
45	greg	2.1
46			#define r_fifo(rn) (&r_fifo_buf[(rn)&(r_fifo_len-1)])
47
48
49			static void
50			ray_fifo_growbuf(void) /* double buffer size (or set to minimum if NULL) */
51			{
52			RAY *old_buf = r_fifo_buf;
53			int old_len = r_fifo_len;
54			int i;
55
56			if (r_fifo_buf == NULL)
57			r_fifo_len = 1<<4;
58			else
59			r_fifo_len <<= 1;
60			/* allocate new */
61			r_fifo_buf = (RAY *)calloc(r_fifo_len, sizeof(RAY));
62			if (r_fifo_buf == NULL)
63			error(SYSTEM, "out of memory in ray_fifo_growbuf");
64			if (old_buf == NULL)
65			return;
66			/* copy old & free */
67			for (i = r_fifo_start; i < r_fifo_end; i++)
68			*r_fifo(i) = old_buf[i&(old_len-1)];
69
70			free(old_buf);
71			}
72
73
74			static int
75			ray_fifo_push( /* send finished ray to output (or queue it) */
76			RAY *r
77			)
78			{
79			int rv, nsent = 0;
80
81			if (ray_fifo_out == NULL)
82			error(INTERNAL, "ray_fifo_out is NULL");
83	greg	2.3	if ((r->rno < r_fifo_start) \| (r->rno >= r_fifo_next))
84			error(INTERNAL, "unexpected ray number in ray_fifo_push()");
85	greg	2.2
86	greg	2.1	if (r->rno > r_fifo_start) { /* insert into output queue */
87	greg	2.3	if (r->rno - r_fifo_start >= r_fifo_len)
88			ray_fifo_growbuf(); /* need more space */
89	greg	2.1	r_fifo(r->rno) = r;
90	greg	2.3	if (r->rno >= r_fifo_end)
91			r_fifo_end = r->rno + 1;
92	greg	2.1	return(0);
93			}
94			/* r->rno == r_fifo_start, so transfer ray(s) */
95			do {
96	greg	2.3	rv = (*ray_fifo_out)(r);
97			r->rno = 0; /* flag this entry complete */
98			if (rv < 0)
99	greg	2.1	return(-1);
100			nsent += rv;
101			if (++r_fifo_start < r_fifo_end)
102			r = r_fifo(r_fifo_start);
103	greg	2.3	else if (r_fifo_start > r_fifo_end)
104			r_fifo_end = r_fifo_start;
105	greg	2.1	} while (r->rno == r_fifo_start);
106
107			return(nsent);
108			}
109
110
111			int
112			ray_fifo_in( /* add ray to FIFO */
113			RAY *r
114			)
115			{
116	greg	2.3	static int incall = 0; /* prevent recursion */
117			int rv, rval = 0;
118
119			if (incall++)
120			error(INTERNAL, "recursive call to ray_fifo_in()");
121	greg	2.1
122	greg	2.3	if (r_fifo_start >= 1L<<30) { /* reset our counters */
123	greg	2.1	if ((rv = ray_fifo_flush()) < 0)
124	greg	2.3	{--incall; return(-1);}
125	greg	2.1	rval += rv;
126			}
127			/* queue ray */
128			rayorigin(r, PRIMARY, NULL, NULL);
129	greg	2.3	r->rno = r_fifo_next++;
130	greg	2.1	if ((rv = ray_pqueue(r)) < 0)
131	greg	2.3	{--incall; return(-1);}
132	greg	2.1
133			if (!rv) /* no result this time? */
134	greg	2.3	{--incall; return(rval);}
135	greg	2.2
136			do { /* else send/queue result */
137			if ((rv = ray_fifo_push(r)) < 0)
138	greg	2.3	{--incall; return(-1);}
139	greg	2.2	rval += rv;
140
141			} while (ray_presult(r, -1) > 0); /* empty in-core queue */
142
143	greg	2.3	--incall; return(rval);
144	greg	2.1	}
145
146
147			int
148			ray_fifo_flush(void) /* flush everything and release buffer */
149			{
150			RAY myRay;
151			int rv, rval = 0;
152			/* clear parallel queue */
153			while ((rv = ray_presult(&myRay, 0)) > 0 &&
154			(rv = ray_fifo_push(&myRay)) >= 0)
155			rval += rv;
156
157	greg	2.3	if (rv < 0) /* check for exception */
158	greg	2.1	return(-1);
159
160			if (r_fifo_start != r_fifo_end)
161	greg	2.3	error(INTERNAL, "could not empty queue in ray_fifo_flush()");
162	greg	2.1
163	greg	2.3	if (r_fifo_buf != NULL) {
164			free(r_fifo_buf);
165			r_fifo_buf = NULL; r_fifo_len = 0;
166			}
167			r_fifo_next = r_fifo_end = r_fifo_start = 1;
168	greg	2.1
169			return(rval);
170			}