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#ifndef lint |
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static const char RCSid[] = "$Id: rayfifo.c,v 2.5 2018/04/26 18:09:55 greg Exp $"; |
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#endif |
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/* |
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* rayfifo.c - parallelize ray queue that respects order |
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* |
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* External symbols declared in ray.h |
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*/ |
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|
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#include "copyright.h" |
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|
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/* |
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* These routines are essentially an adjunct to raypcalls.c, providing |
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* a convenient means to get first-in/first-out behavior from multiple |
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* processor cores. The interface is quite simple, with two functions |
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* and a callback, which must be defined by the calling program. The |
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* hand-off for finished rays is assigned to ray_fifo_out, which takes |
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* a single pointer to the finished ray and returns a non-negative |
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* integer. If there is an exceptional condition where termination |
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* is desired, a negative value may be returned. |
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* |
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* The ray_fifo_in() call takes a ray that has been initialized in |
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* the same manner as for the ray_pqueue() call, i.e., rayorigin() |
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* has been called and the origin, direction and maximum distance |
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* have all been assigned. However, the ray number will be reset |
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* by ray_fifo_in() according to the number of rays traced since the |
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* last call to ray_fifo_flush(). This final call completes all |
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* pending ray calculations and frees the FIFO buffer. If any of |
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* the automatic calls to the ray_fifo_out callback return a |
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* negative value, processing stops and -1 is returned. |
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* |
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* Note: The ray passed to ray_fifo_in() may be overwritten |
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* arbitrarily, since it is passed to ray_pqueue(). |
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*/ |
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|
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#include "ray.h" |
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#include <string.h> |
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|
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#ifndef MAXFIFO |
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#define MAXFIFO 4096 /* clear FIFO past this */ |
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#endif |
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|
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int (*ray_fifo_out)(RAY *r) = NULL; /* ray output callback */ |
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|
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static RAY *r_fifo_buf = NULL; /* circular FIFO out buffer */ |
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static int r_fifo_len = 0; /* allocated FIFO length */ |
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static RNUMBER r_fifo_start = 1; /* first awaited ray */ |
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static RNUMBER r_fifo_end = 1; /* one past FIFO last */ |
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static RNUMBER r_fifo_next = 1; /* next ray assignment */ |
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|
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#define r_fifo(rn) (&r_fifo_buf[(rn)&(r_fifo_len-1)]) |
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|
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|
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static void |
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ray_fifo_growbuf(void) /* double buffer size (or set to minimum if NULL) */ |
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{ |
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RAY *old_buf = r_fifo_buf; |
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int old_len = r_fifo_len; |
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int i; |
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|
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if (r_fifo_buf == NULL) |
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r_fifo_len = 1<<5; /* must be power of two */ |
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else |
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r_fifo_len <<= 1; |
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/* allocate new */ |
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r_fifo_buf = (RAY *)calloc(r_fifo_len, sizeof(RAY)); |
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if (r_fifo_buf == NULL) |
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error(SYSTEM, "out of memory in ray_fifo_growbuf"); |
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if (old_buf == NULL) |
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return; |
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/* copy old & free */ |
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for (i = r_fifo_start; i < r_fifo_end; i++) |
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*r_fifo(i) = old_buf[i&(old_len-1)]; |
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|
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free(old_buf); |
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} |
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|
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|
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static int |
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ray_fifo_push( /* send finished ray to output (or queue it) */ |
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RAY *r |
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) |
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{ |
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int rv, nsent = 0; |
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|
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if (ray_fifo_out == NULL) |
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error(INTERNAL, "ray_fifo_out is NULL"); |
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if ((r->rno < r_fifo_start) | (r->rno >= r_fifo_next)) |
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error(INTERNAL, "unexpected ray number in ray_fifo_push()"); |
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|
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if (r->rno > r_fifo_start) { /* insert into output queue */ |
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while (r->rno - r_fifo_start >= r_fifo_len) |
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ray_fifo_growbuf(); /* need more space */ |
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*r_fifo(r->rno) = *r; |
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if (r->rno >= r_fifo_end) |
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r_fifo_end = r->rno + 1; |
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return(0); |
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} |
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/* r->rno == r_fifo_start, so transfer ray(s) */ |
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do { |
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rv = (*ray_fifo_out)(r); |
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r->rno = 0; /* flag this entry complete */ |
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if (rv < 0) |
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return(-1); |
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nsent += rv; |
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if (++r_fifo_start < r_fifo_end) |
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r = r_fifo(r_fifo_start); |
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else if (r_fifo_start > r_fifo_end) |
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r_fifo_end = r_fifo_start; |
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} while (r->rno == r_fifo_start); |
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|
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return(nsent); |
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} |
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|
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|
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int |
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ray_fifo_in( /* add ray to FIFO */ |
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RAY *r |
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) |
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{ |
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static int incall = 0; /* prevent recursion */ |
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int rv, rval = 0; |
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|
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if (incall++) |
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error(INTERNAL, "recursive call to ray_fifo_in()"); |
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|
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/* need to reset our FIFO? */ |
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if ((r_fifo_start >= 1L<<30) | (r_fifo_len > MAXFIFO)) { |
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if ((rv = ray_fifo_flush()) < 0) |
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{--incall; return(-1);} |
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rval += rv; |
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} |
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/* queue ray */ |
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r->rno = r_fifo_next++; |
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if ((rv = ray_pqueue(r)) < 0) |
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{--incall; return(-1);} |
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|
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if (!rv) /* no result this time? */ |
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{--incall; return(rval);} |
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|
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do { /* else send/queue result */ |
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if ((rv = ray_fifo_push(r)) < 0) |
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{--incall; return(-1);} |
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rval += rv; |
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|
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} while (ray_presult(r, -1) > 0); /* empty in-core queue */ |
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|
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--incall; return(rval); |
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} |
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|
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|
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int |
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ray_fifo_flush(void) /* flush everything and release buffer */ |
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{ |
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RAY myRay; |
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int rv, rval = 0; |
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/* clear parallel queue */ |
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while ((rv = ray_presult(&myRay, 0)) > 0 && |
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(rv = ray_fifo_push(&myRay)) >= 0) |
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rval += rv; |
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|
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if (rv < 0) /* check for exception */ |
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return(-1); |
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|
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if (r_fifo_start != r_fifo_end) |
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error(INTERNAL, "could not empty queue in ray_fifo_flush()"); |
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|
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if (r_fifo_buf != NULL) { |
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free(r_fifo_buf); |
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r_fifo_buf = NULL; r_fifo_len = 0; |
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} |
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r_fifo_next = r_fifo_end = r_fifo_start = 1; |
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|
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return(rval); |
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} |
