configure: Check for broken snprintf().
[paraslash.git] / buffer_tree.c
1 #include <regex.h>
2 #include <stdbool.h>
3
4 #include "para.h"
5 #include "list.h"
6 #include "string.h"
7 #include "buffer_tree.h"
8 #include "error.h"
9 #include "sched.h"
10
11 /* whead = NULL means area full */
12 struct btr_pool {
13 char *name;
14 char *area_start;
15 char *area_end;
16 char *rhead;
17 char *whead;
18 };
19
20 struct btr_buffer {
21 char *buf;
22 size_t size;
23 /** The number of references to this buffer. */
24 int refcount;
25 /* NULL means no buffer pool but a malloced buffer. */
26 struct btr_pool *pool;
27 };
28
29 struct btr_buffer_reference {
30 struct btr_buffer *btrb;
31 size_t consumed;
32 /* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
33 struct list_head node;
34 size_t wrap_count;
35 };
36
37 struct btr_node {
38 char *name;
39 struct btr_node *parent;
40 /* The position of this btr node in the buffer tree. */
41 struct list_head node;
42 /* The children nodes of this btr node are linked together in a list. */
43 struct list_head children;
44 /* Time of first data transfer. */
45 struct timeval start;
46 /**
47 * The input queue is a list of references to btr buffers. Each item on
48 * the list represents an input buffer which has not been completely
49 * used by this btr node.
50 */
51 struct list_head input_queue;
52 btr_command_handler execute;
53 void *context;
54 };
55
56 /**
57 * Create a new buffer pool.
58 *
59 * \param name The name of the new buffer pool.
60 * \param area_size The size in bytes of the pool area.
61 *
62 * \return An opaque pointer to the newly created buffer pool. It must be
63 * passed to btr_pool_free() after it is no longer used to deallocate all
64 * resources.
65 */
66 struct btr_pool *btr_pool_new(const char *name, size_t area_size)
67 {
68 struct btr_pool *btrp;
69
70 PARA_INFO_LOG("%s, %zu bytes\n", name, area_size);
71 btrp = para_malloc(sizeof(*btrp));
72 btrp->area_start = para_malloc(area_size);
73 btrp->area_end = btrp->area_start + area_size;
74 btrp->rhead = btrp->area_start;
75 btrp->whead = btrp->area_start;
76 btrp->name = para_strdup(name);
77 return btrp;
78 }
79
80 /**
81 * Deallocate resources used by a buffer pool.
82 *
83 * \param btrp A pointer obtained via btr_pool_new().
84 */
85 void btr_pool_free(struct btr_pool *btrp)
86 {
87 if (!btrp)
88 return;
89 free(btrp->area_start);
90 free(btrp->name);
91 free(btrp);
92 }
93
94 /**
95 * Return the size of the buffer pool area.
96 *
97 * \param btrp The buffer pool.
98 *
99 * \return The same value which was passed during creation time to
100 * btr_pool_new().
101 */
102 size_t btr_pool_size(struct btr_pool *btrp)
103 {
104 return btrp->area_end - btrp->area_start;
105 }
106
107 static size_t btr_pool_filled(struct btr_pool *btrp)
108 {
109 if (!btrp->whead)
110 return btr_pool_size(btrp);
111 if (btrp->rhead <= btrp->whead)
112 return btrp->whead - btrp->rhead;
113 return btr_pool_size(btrp) - (btrp->rhead - btrp->whead);
114 }
115
116 /**
117 * Get the number of unused bytes in the buffer pool.
118 *
119 * \param btrp The pool.
120 *
121 * \return The number of bytes that can currently be allocated.
122 *
123 * Note that in general the returned number of bytes is not available as a
124 * single contiguous buffer. Use btr_pool_available() to obtain the length of
125 * the largest contiguous buffer that can currently be allocated from the
126 * buffer pool.
127 */
128 size_t btr_pool_unused(struct btr_pool *btrp)
129 {
130 return btr_pool_size(btrp) - btr_pool_filled(btrp);
131 }
132
133 /*
134 * Return maximal size available for one read. This is
135 * smaller than the value returned by btr_pool_unused().
136 */
137 static size_t btr_pool_available(struct btr_pool *btrp)
138 {
139 if (!btrp->whead)
140 return 0;
141 if (btrp->rhead <= btrp->whead)
142 return btrp->area_end - btrp->whead;
143 return btrp->rhead - btrp->whead;
144 }
145
146 /**
147 * Obtain the current write head.
148 *
149 * \param btrp The buffer pool.
150 * \param result The write head is returned here.
151 *
152 * \return The maximal amount of bytes that may be written to the returned
153 * buffer.
154 */
155 size_t btr_pool_get_buffer(struct btr_pool *btrp, char **result)
156 {
157 if (result)
158 *result = btrp->whead;
159 return btr_pool_available(btrp);
160 }
161
162 /**
163 * Mark a part of the buffer pool area as allocated.
164 *
165 * \param btrp The buffer pool.
166 * \param size The amount of bytes to be allocated.
167 *
168 * This is usually called after the caller wrote to the buffer obtained by
169 * btr_pool_get_buffer().
170 */
171 static void btr_pool_allocate(struct btr_pool *btrp, size_t size)
172 {
173 char *end;
174
175 if (size == 0)
176 return;
177 assert(size <= btr_pool_available(btrp));
178 end = btrp->whead + size;
179 assert(end <= btrp->area_end);
180
181 if (end == btrp->area_end) {
182 PARA_DEBUG_LOG("%s: end of pool area reached\n", btrp->name);
183 end = btrp->area_start;
184 }
185 if (end == btrp->rhead) {
186 PARA_DEBUG_LOG("%s btrp buffer full\n", btrp->name);
187 end = NULL; /* buffer full */
188 }
189 btrp->whead = end;
190 }
191
192 static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
193 {
194 char *end = btrp->rhead + size;
195
196 if (size == 0)
197 return;
198 assert(end <= btrp->area_end);
199 assert(size <= btr_pool_filled(btrp));
200 if (end == btrp->area_end)
201 end = btrp->area_start;
202 if (!btrp->whead)
203 btrp->whead = btrp->rhead;
204 btrp->rhead = end;
205 if (btrp->rhead == btrp->whead)
206 btrp->rhead = btrp->whead = btrp->area_start;
207 }
208
209 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
210 &((_btrn)->children), node)
211 #define FOR_EACH_CHILD_SAFE(_tn, _tmp, _btrn) \
212 list_for_each_entry_safe((_tn), (_tmp), &((_btrn)->children), node)
213
214 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
215 list_for_each_entry((_br), &(_btrn)->input_queue, node)
216 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
217 list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
218
219 /**
220 * Create a new buffer tree node.
221 *
222 * \param bnd Specifies how to create the new node.
223 *
224 * This function always succeeds (or calls exit()). The returned pointer must
225 * be freed using btr_free_node() after the node has been removed from the
226 * buffer tree via btr_remove_node().
227 */
228 struct btr_node *btr_new_node(struct btr_node_description *bnd)
229 {
230 struct btr_node *btrn = para_malloc(sizeof(*btrn));
231
232 btrn->name = para_strdup(bnd->name);
233 btrn->parent = bnd->parent;
234 btrn->execute = bnd->handler;
235 btrn->context = bnd->context;
236 btrn->start.tv_sec = 0;
237 btrn->start.tv_usec = 0;
238 INIT_LIST_HEAD(&btrn->children);
239 INIT_LIST_HEAD(&btrn->input_queue);
240 if (!bnd->child) {
241 if (bnd->parent) {
242 list_add_tail(&btrn->node, &bnd->parent->children);
243 PARA_INFO_LOG("new leaf node: %s (child of %s)\n",
244 bnd->name, bnd->parent->name);
245 } else
246 PARA_INFO_LOG("added %s as btr root\n", bnd->name);
247 goto out;
248 }
249 if (!bnd->parent) {
250 assert(!bnd->child->parent);
251 PARA_INFO_LOG("new root: %s (was %s)\n",
252 bnd->name, bnd->child->name);
253 btrn->parent = NULL;
254 list_add_tail(&bnd->child->node, &btrn->children);
255 /* link it in */
256 bnd->child->parent = btrn;
257 goto out;
258 }
259 PARA_EMERG_LOG("inserting internal nodes not yet supported.\n");
260 exit(EXIT_FAILURE);
261 assert(bnd->child->parent == bnd->parent);
262 out:
263 return btrn;
264 }
265
266 /*
267 * Allocate a new btr buffer.
268 *
269 * The freshly allocated buffer will have a zero refcount and will
270 * not be associated with a btr pool.
271 */
272 static struct btr_buffer *new_btrb(char *buf, size_t size)
273 {
274 struct btr_buffer *btrb = para_calloc(sizeof(*btrb));
275
276 btrb->buf = buf;
277 btrb->size = size;
278 return btrb;
279 }
280
281 static void dealloc_buffer(struct btr_buffer *btrb)
282 {
283 if (btrb->pool)
284 btr_pool_deallocate(btrb->pool, btrb->size);
285 else
286 free(btrb->buf);
287 }
288
289 static struct btr_buffer_reference *get_first_input_br(struct btr_node *btrn)
290 {
291 if (list_empty(&btrn->input_queue))
292 return NULL;
293 return list_first_entry(&btrn->input_queue,
294 struct btr_buffer_reference, node);
295 }
296
297 /*
298 * Deallocate the reference, release the resources if refcount drops to zero.
299 */
300 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
301 {
302 struct btr_buffer *btrb = br->btrb;
303
304 list_del(&br->node);
305 free(br);
306 btrb->refcount--;
307 if (btrb->refcount == 0) {
308 dealloc_buffer(btrb);
309 free(btrb);
310 }
311 }
312
313 static void add_btrb_to_children(struct btr_buffer *btrb,
314 struct btr_node *btrn, size_t consumed)
315 {
316 struct btr_node *ch;
317
318 if (btrn->start.tv_sec == 0)
319 btrn->start = *now;
320 FOR_EACH_CHILD(ch, btrn) {
321 struct btr_buffer_reference *br = para_calloc(sizeof(*br));
322 br->btrb = btrb;
323 br->consumed = consumed;
324 list_add_tail(&br->node, &ch->input_queue);
325 btrb->refcount++;
326 if (ch->start.tv_sec == 0)
327 ch->start = *now;
328 }
329 }
330
331 /**
332 * Insert a malloced buffer into the buffer tree.
333 *
334 * \param buf The buffer to insert.
335 * \param size The size of \a buf in bytes.
336 * \param btrn Position in the buffer tree to create the output.
337 *
338 * This creates references to \a buf and adds these references to each child of
339 * \a btrn. The buffer will be freed using standard free() once no buffer tree
340 * node is referencing it any more.
341 *
342 * Note that this function must not be used if \a buf was obtained from a
343 * buffer pool. Use btr_add_output_pool() in this case.
344 */
345 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
346 {
347 struct btr_buffer *btrb;
348
349 assert(size != 0);
350 if (list_empty(&btrn->children)) {
351 free(buf);
352 return;
353 }
354 btrb = new_btrb(buf, size);
355 add_btrb_to_children(btrb, btrn, 0);
356 }
357
358 /**
359 * Feed data to child nodes of a buffer tree node.
360 *
361 * \param btrp The buffer pool.
362 * \param size The number of bytes to be allocated and fed to each child.
363 * \param btrn The node whose children are to be fed.
364 *
365 * This function allocates the amount of bytes from the buffer pool area,
366 * starting at the current value of the write head, and creates buffer
367 * references to the resulting part of the buffer pool area, one for each child
368 * of \a btrn. The references are then fed into the input queue of each child.
369 */
370 void btr_add_output_pool(struct btr_pool *btrp, size_t size,
371 struct btr_node *btrn)
372 {
373 struct btr_buffer *btrb;
374 char *buf;
375 size_t avail;
376
377 assert(size != 0);
378 if (list_empty(&btrn->children))
379 return;
380 avail = btr_pool_get_buffer(btrp, &buf);
381 assert(avail >= size);
382 btr_pool_allocate(btrp, size);
383 btrb = new_btrb(buf, size);
384 btrb->pool = btrp;
385 add_btrb_to_children(btrb, btrn, 0);
386 }
387
388 /**
389 * Copy data to write head of a buffer pool and feed it to all children nodes.
390 *
391 * \param src The source buffer.
392 * \param n The size of the source buffer in bytes.
393 * \param btrp The destination buffer pool.
394 * \param btrn Add the data as output of this node.
395 *
396 * This is expensive. The caller must make sure the data fits into the buffer
397 * pool area.
398 */
399 void btr_copy(const void *src, size_t n, struct btr_pool *btrp,
400 struct btr_node *btrn)
401 {
402 char *buf;
403 size_t sz, copy;
404
405 if (n == 0)
406 return;
407 assert(n <= btr_pool_unused(btrp));
408 sz = btr_pool_get_buffer(btrp, &buf);
409 copy = PARA_MIN(sz, n);
410 memcpy(buf, src, copy);
411 btr_add_output_pool(btrp, copy, btrn);
412 if (copy == n)
413 return;
414 sz = btr_pool_get_buffer(btrp, &buf);
415 assert(sz >= n - copy);
416 memcpy(buf, src + copy, n - copy);
417 btr_add_output_pool(btrp, n - copy, btrn);
418 }
419
420 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
421 {
422 add_btrb_to_children(br->btrb, btrn, br->consumed);
423 btr_drop_buffer_reference(br);
424 }
425
426 /**
427 * Feed all buffer references of the input queue through the output channel.
428 *
429 * \param btrn The node whose buffer references should be pushed down.
430 *
431 * This function is useful for filters that do not change the contents of the
432 * buffers at all, like the wav filter or the amp filter if no amplification
433 * was specified. This function is rather cheap.
434 *
435 * \sa \ref btr_pushdown_one().
436 */
437 void btr_pushdown(struct btr_node *btrn)
438 {
439 struct btr_buffer_reference *br, *tmp;
440
441 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
442 btr_pushdown_br(br, btrn);
443 }
444
445 /**
446 * Feed the next buffer of the input queue through the output channel.
447 *
448 * \param btrn The node whose first input queue buffer should be pushed down.
449 *
450 * This works like \ref btr_pushdown() but pushes down only one buffer
451 * reference.
452 */
453 void btr_pushdown_one(struct btr_node *btrn)
454 {
455 struct btr_buffer_reference *br;
456
457 if (list_empty(&btrn->input_queue))
458 return;
459 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
460 btr_pushdown_br(br, btrn);
461 }
462
463 /*
464 * Find out whether a node is a leaf node.
465 *
466 * \param btrn The node to check.
467 *
468 * \return True if this node has no children. False otherwise.
469 */
470 static bool btr_no_children(struct btr_node *btrn)
471 {
472 return list_empty(&btrn->children);
473 }
474
475 /**
476 * Find out whether a node is an orphan node.
477 *
478 * \param btrn The buffer tree node.
479 *
480 * \return True if \a btrn has no parent.
481 *
482 * This function will always return true for the root node. However in case
483 * nodes have been removed from the tree, other nodes may become orphans too.
484 */
485 bool btr_no_parent(struct btr_node *btrn)
486 {
487 return !btrn->parent;
488 }
489
490 /**
491 * Find out whether it is OK to change an input buffer.
492 *
493 * \param btrn The buffer tree node to check.
494 *
495 * This is used by filters that produce exactly the same amount of output as
496 * there is input. The amp filter which multiplies each sample by some number
497 * is an example of such a filter. If there are no other nodes in the buffer
498 * tree that read the same input stream (i.e. if \a btrn has no siblings), a
499 * node may modify its input buffer directly and push down the modified buffer
500 * to its children, thereby avoiding to allocate a possibly large additional
501 * buffer.
502 *
503 * Since the buffer tree may change at any time, this function should be called
504 * during each post_select call.
505 *
506 * \return True if \a btrn has no siblings.
507 */
508 bool btr_inplace_ok(struct btr_node *btrn)
509 {
510 if (!btrn->parent)
511 return true;
512 return list_is_singular(&btrn->parent->children);
513 }
514
515 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
516 {
517 return br->btrb->size - br->consumed;
518 }
519
520 static size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
521 {
522 if (buf)
523 *buf = br->btrb->buf + br->consumed;
524 return br_available_bytes(br);
525 }
526
527 /**
528 * Obtain the next buffer of the input queue of a buffer tree node.
529 *
530 * \param btrn The node whose input queue is to be queried.
531 * \param bufp Result pointer.
532 *
533 * \return The number of bytes that can be read from buf. Zero if the input
534 * buffer queue is empty. In this case the value of \a bufp is undefined.
535 */
536 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
537 {
538 struct btr_buffer_reference *br;
539 char *buf, *result = NULL;
540 size_t sz, rv = 0;
541
542 FOR_EACH_BUFFER_REF(br, btrn) {
543 sz = btr_get_buffer_by_reference(br, &buf);
544 if (!result) {
545 result = buf;
546 rv = sz;
547 if (!br->btrb->pool)
548 break;
549 continue;
550 }
551 if (!br->btrb->pool)
552 break;
553 if (result + rv != buf)
554 break;
555 rv += sz;
556 }
557 if (bufp)
558 *bufp = result;
559 return rv;
560 }
561
562 /**
563 * Deallocate the given number of bytes from the input queue.
564 *
565 * \param btrn The buffer tree node.
566 * \param numbytes The number of bytes to be deallocated.
567 *
568 * This function must be used to get rid of existing buffer references in the
569 * node's input queue. If no references to a buffer remain, the underlying
570 * buffers are either freed (in the non-buffer tree case) or the read head of
571 * the buffer pool is being advanced.
572 *
573 * Note that \a numbytes may be smaller than the buffer size. In this case the
574 * buffer is not deallocated and subsequent calls to btr_next_buffer() return
575 * the remaining part of the buffer.
576 */
577 void btr_consume(struct btr_node *btrn, size_t numbytes)
578 {
579 struct btr_buffer_reference *br, *tmp;
580 size_t sz;
581
582 if (numbytes == 0)
583 return;
584 br = get_first_input_br(btrn);
585 assert(br);
586
587 if (br->wrap_count == 0) {
588 /*
589 * No wrap buffer. Drop buffer references whose buffer
590 * has been fully used. */
591 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn) {
592 if (br->consumed + numbytes <= br->btrb->size) {
593 br->consumed += numbytes;
594 if (br->consumed == br->btrb->size)
595 btr_drop_buffer_reference(br);
596 return;
597 }
598 numbytes -= br->btrb->size - br->consumed;
599 btr_drop_buffer_reference(br);
600 }
601 assert(true);
602 }
603 /*
604 * We have a wrap buffer, consume from it. If in total, i.e. including
605 * previous calls to brt_consume(), less than wrap_count has been
606 * consumed, there's nothing more we can do.
607 *
608 * Otherwise we drop the wrap buffer and consume from subsequent
609 * buffers of the input queue the correct amount of bytes. This is the
610 * total number of bytes that have been consumed from the wrap buffer.
611 */
612 PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes,
613 br_available_bytes(br));
614
615 assert(numbytes <= br_available_bytes(br));
616 if (br->consumed + numbytes < br->wrap_count) {
617 br->consumed += numbytes;
618 return;
619 }
620 PARA_DEBUG_LOG("dropping wrap buffer (%zu bytes)\n", br->btrb->size);
621 /* get rid of the wrap buffer */
622 sz = br->consumed + numbytes;
623 btr_drop_buffer_reference(br);
624 return btr_consume(btrn, sz);
625 }
626
627 static void flush_input_queue(struct btr_node *btrn)
628 {
629 struct btr_buffer_reference *br, *tmp;
630 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
631 btr_drop_buffer_reference(br);
632 }
633
634 /**
635 * Free all resources allocated by btr_new_node().
636 *
637 * Like free(3), it is OK to call this with a \p NULL pointer argument.
638 */
639 void btr_free_node(struct btr_node *btrn)
640 {
641 if (!btrn)
642 return;
643 free(btrn->name);
644 free(btrn);
645 }
646
647 /**
648 * Remove a node from a buffer tree.
649 *
650 * \param btrn The node to remove.
651 *
652 * This makes all child nodes of \a btrn orphans and removes \a btrn from the
653 * list of children of its parent. Moreover, the input queue of \a btrn is
654 * flushed if it is not empty.
655 *
656 * \sa \ref btr_splice_out_node.
657 */
658 void btr_remove_node(struct btr_node *btrn)
659 {
660 struct btr_node *ch;
661
662 if (!btrn)
663 return;
664 PARA_NOTICE_LOG("removing btr node %s from buffer tree\n", btrn->name);
665 FOR_EACH_CHILD(ch, btrn)
666 ch->parent = NULL;
667 flush_input_queue(btrn);
668 if (btrn->parent)
669 list_del(&btrn->node);
670 }
671
672 /**
673 * Return the amount of available input bytes of a buffer tree node.
674 *
675 * \param btrn The node whose input size should be computed.
676 *
677 * \return The total number of bytes available in the node's input
678 * queue.
679 *
680 * This simply iterates over all buffer references in the input queue and
681 * returns the sum of the sizes of all references.
682 */
683 size_t btr_get_input_queue_size(struct btr_node *btrn)
684 {
685 struct btr_buffer_reference *br;
686 size_t size = 0, wrap_consumed = 0;
687
688 FOR_EACH_BUFFER_REF(br, btrn) {
689 if (br->wrap_count != 0) {
690 wrap_consumed = br->consumed;
691 continue;
692 }
693 size += br_available_bytes(br);
694 }
695 assert(wrap_consumed <= size);
696 size -= wrap_consumed;
697 return size;
698 }
699
700 /**
701 * Remove a node from the buffer tree, reconnecting parent and children.
702 *
703 * \param btrn The node to splice out.
704 *
705 * This function is used by buffer tree nodes that do not exist during the
706 * whole lifetime of the buffer tree. Unlike btr_remove_node(), calling
707 * btr_splice_out_node() does not split the tree into disconnected components
708 * but reconnects the buffer tree by making all child nodes of \a btrn children
709 * of the parent of \a btrn.
710 */
711 void btr_splice_out_node(struct btr_node *btrn)
712 {
713 struct btr_node *ch, *tmp;
714
715 assert(btrn);
716 PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
717 btr_pushdown(btrn);
718 if (btrn->parent)
719 list_del(&btrn->node);
720 FOR_EACH_CHILD_SAFE(ch, tmp, btrn) {
721 PARA_INFO_LOG("parent(%s): %s\n", ch->name,
722 btrn->parent? btrn->parent->name : "NULL");
723 ch->parent = btrn->parent;
724 if (btrn->parent)
725 list_move(&ch->node, &btrn->parent->children);
726 }
727 assert(list_empty(&btrn->children));
728 }
729
730 /*
731 * Return the size of the largest input queue.
732 *
733 * Iterates over all children of the given node.
734 */
735 static size_t btr_bytes_pending(struct btr_node *btrn)
736 {
737 size_t max_size = 0;
738 struct btr_node *ch;
739
740 FOR_EACH_CHILD(ch, btrn) {
741 size_t size = btr_get_input_queue_size(ch);
742 max_size = PARA_MAX(max_size, size);
743 }
744 return max_size;
745 }
746
747 int btr_exec(struct btr_node *btrn, const char *command, char **value_result)
748 {
749 if (!btrn)
750 return -ERRNO_TO_PARA_ERROR(EINVAL);
751 if (!btrn->execute)
752 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
753 return btrn->execute(btrn, command, value_result);
754 }
755
756 /**
757 * Execute a inter-node command on a parent node.
758 *
759 * \param btrn The node to start looking.
760 * \param command The command to execute.
761 * \param value_result Additional arguments and result value.
762 *
763 * This function traverses the buffer tree upwards and looks for parent nodes
764 * of \a btrn that understands \a command. On the first such node the command
765 * is executed, and the result is stored in \a value_result.
766 *
767 * \return \p -ENOTSUP if no parent node of \a btrn understands \a command.
768 * Otherwise the return value of the command handler is returned.
769 */
770 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
771 {
772 int ret;
773
774 for (; btrn; btrn = btrn->parent) {
775 struct btr_node *parent = btrn->parent;
776 if (!parent)
777 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
778 if (!parent->execute)
779 continue;
780 PARA_INFO_LOG("parent: %s, cmd: %s\n", parent->name, command);
781 ret = parent->execute(parent, command, value_result);
782 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
783 continue;
784 if (ret < 0)
785 return ret;
786 if (value_result && *value_result)
787 PARA_NOTICE_LOG("%s(%s): %s\n", command, parent->name,
788 *value_result);
789 return 1;
790 }
791 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
792 }
793
794 /**
795 * Obtain the context of a buffer node tree.
796 *
797 * The returned pointer equals the context pointer used at creation time of the
798 * node.
799 *
800 * \sa btr_new_node(), struct \ref btr_node_description.
801 */
802 void *btr_context(struct btr_node *btrn)
803 {
804 return btrn->context;
805 }
806
807 static bool need_buffer_pool_merge(struct btr_node *btrn)
808 {
809 struct btr_buffer_reference *br = get_first_input_br(btrn);
810
811 if (!br)
812 return false;
813 if (br->wrap_count != 0)
814 return true;
815 if (br->btrb->pool)
816 return true;
817 return false;
818 }
819
820 static void merge_input_pool(struct btr_node *btrn, size_t dest_size)
821 {
822 struct btr_buffer_reference *br, *wbr = NULL;
823 int num_refs; /* including wrap buffer */
824 char *buf, *buf1 = NULL, *buf2 = NULL;
825 size_t sz, sz1 = 0, sz2 = 0, wsz;
826
827 br = get_first_input_br(btrn);
828 if (!br || br_available_bytes(br) >= dest_size)
829 return;
830 num_refs = 0;
831 FOR_EACH_BUFFER_REF(br, btrn) {
832 num_refs++;
833 sz = btr_get_buffer_by_reference(br, &buf);
834 if (sz == 0)
835 break;
836 if (br->wrap_count != 0) {
837 assert(!wbr);
838 assert(num_refs == 1);
839 wbr = br;
840 if (sz >= dest_size)
841 return;
842 continue;
843 }
844 if (!buf1) {
845 buf1 = buf;
846 sz1 = sz;
847 goto next;
848 }
849 if (buf1 + sz1 == buf) {
850 sz1 += sz;
851 goto next;
852 }
853 if (!buf2) {
854 buf2 = buf;
855 sz2 = sz;
856 goto next;
857 }
858 assert(buf2 + sz2 == buf);
859 sz2 += sz;
860 next:
861 if (sz1 + sz2 >= dest_size)
862 break;
863 }
864 if (!buf2) /* nothing to do */
865 return;
866 assert(buf1 && sz2 > 0);
867 /*
868 * If the second buffer is large, we only take the first part of it to
869 * avoid having to memcpy() huge buffers.
870 */
871 sz2 = PARA_MIN(sz2, (size_t)(64 * 1024));
872 if (!wbr) {
873 /* Make a new wrap buffer combining buf1 and buf2. */
874 sz = sz1 + sz2;
875 buf = para_malloc(sz);
876 PARA_DEBUG_LOG("merging input buffers: (%p:%zu, %p:%zu) -> %p:%zu\n",
877 buf1, sz1, buf2, sz2, buf, sz);
878 memcpy(buf, buf1, sz1);
879 memcpy(buf + sz1, buf2, sz2);
880 br = para_calloc(sizeof(*br));
881 br->btrb = new_btrb(buf, sz);
882 br->btrb->refcount = 1;
883 br->consumed = 0;
884 /* This is a wrap buffer */
885 br->wrap_count = sz1;
886 para_list_add(&br->node, &btrn->input_queue);
887 return;
888 }
889 /*
890 * We already have a wrap buffer, but it is too small. It might be
891 * partially used.
892 */
893 wsz = br_available_bytes(wbr);
894 if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
895 return;
896 sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */
897 PARA_DEBUG_LOG("increasing wrap buffer %zu -> %zu\n", wbr->btrb->size,
898 wbr->btrb->size + sz);
899 wbr->btrb->size += sz;
900 wbr->btrb->buf = para_realloc(wbr->btrb->buf, wbr->btrb->size);
901 /* copy the new data to the end of the reallocated buffer */
902 assert(sz2 >= sz);
903 memcpy(wbr->btrb->buf + wbr->btrb->size - sz, buf2 + sz2 - sz, sz);
904 }
905
906 /**
907 * Merge the first two input buffers into one.
908 *
909 * This is a quite expensive operation.
910 *
911 * \return The number of buffers that have been available (zero, one or two).
912 */
913 static int merge_input(struct btr_node *btrn)
914 {
915 struct btr_buffer_reference *brs[2], *br;
916 char *bufs[2], *buf;
917 size_t szs[2], sz;
918 int i;
919
920 if (list_empty(&btrn->input_queue))
921 return 0;
922 if (list_is_singular(&btrn->input_queue))
923 return 1;
924 i = 0;
925 /* get references to the first two buffers */
926 FOR_EACH_BUFFER_REF(br, btrn) {
927 brs[i] = br;
928 szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
929 i++;
930 if (i == 2)
931 break;
932 }
933 assert(i == 2);
934 /* make a new btrb that combines the two buffers and a br to it. */
935 sz = szs[0] + szs[1];
936 buf = para_malloc(sz);
937 PARA_DEBUG_LOG("%s: memory merging input buffers: (%zu, %zu) -> %zu\n",
938 btrn->name, szs[0], szs[1], sz);
939 memcpy(buf, bufs[0], szs[0]);
940 memcpy(buf + szs[0], bufs[1], szs[1]);
941
942 br = para_calloc(sizeof(*br));
943 br->btrb = new_btrb(buf, sz);
944 br->btrb->refcount = 1;
945
946 /* replace the first two refs by the new one */
947 btr_drop_buffer_reference(brs[0]);
948 btr_drop_buffer_reference(brs[1]);
949 para_list_add(&br->node, &btrn->input_queue);
950 return 2;
951 }
952
953 /**
954 * Combine input queue buffers.
955 *
956 * \param btrn The buffer tree node whose input should be merged.
957 * \param dest_size Stop merging if a buffer of at least this size exists.
958 *
959 * Used to combine as many buffers as needed into a single buffer whose size is
960 * at least \a dest_size. This function is rather cheap in case the parent node
961 * uses buffer pools and rather expensive otherwise.
962 *
963 * Note that if less than \a dest_size bytes are available in total, this
964 * function does nothing and subsequent calls to btr_next_buffer() will still
965 * return a buffer size less than \a dest_size.
966 */
967 void btr_merge(struct btr_node *btrn, size_t dest_size)
968 {
969 if (need_buffer_pool_merge(btrn))
970 return merge_input_pool(btrn, dest_size);
971 for (;;) {
972 char *buf;
973 size_t len = btr_next_buffer(btrn, &buf);
974 if (len >= dest_size)
975 return;
976 PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len, dest_size);
977 if (merge_input(btrn) < 2)
978 return;
979 }
980 }
981
982 static bool btr_eof(struct btr_node *btrn)
983 {
984 char *buf;
985 size_t len = btr_next_buffer(btrn, &buf);
986
987 return (len == 0 && btr_no_parent(btrn));
988 }
989
990 static void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
991 {
992 struct btr_node *ch;
993 const char spaces[] = " ", *space = spaces + 16 - depth;
994
995 if (depth > 16)
996 return;
997 para_log(loglevel, "%s%s\n", space, btrn->name);
998 FOR_EACH_CHILD(ch, btrn)
999 log_tree_recursively(ch, loglevel, depth + 1);
1000 }
1001
1002 /**
1003 * Write the current buffer (sub-)tree to the log.
1004 *
1005 * \param btrn Start logging at this node.
1006 * \param loglevel Set severity with which the tree should be logged.
1007 */
1008 void btr_log_tree(struct btr_node *btrn, int loglevel)
1009 {
1010 return log_tree_recursively(btrn, loglevel, 0);
1011 }
1012
1013 /**
1014 * Find the node with the given name in the buffer tree.
1015 *
1016 * \param name The name of the node to search.
1017 * \param root Where to start the search.
1018 *
1019 * \return A pointer to the node with the given name on success. If \a name is
1020 * \p NULL, the function returns \a root. If there is no node with the given
1021 * name, \p NULL is returned.
1022 */
1023 struct btr_node *btr_search_node(const char *name, struct btr_node *root)
1024 {
1025 struct btr_node *ch;
1026
1027 if (!name)
1028 return root;
1029 if (!strcmp(root->name, name))
1030 return root;
1031 FOR_EACH_CHILD(ch, root) {
1032 struct btr_node *result = btr_search_node(name, ch);
1033 if (result)
1034 return result;
1035 }
1036 return NULL;
1037 }
1038
1039 /** 640K ought to be enough for everybody ;) */
1040 #define BTRN_MAX_PENDING (640 * 1024)
1041
1042 /**
1043 * Return the current state of a buffer tree node.
1044 *
1045 * \param btrn The node whose state should be queried.
1046 * \param min_iqs The minimal input queue size.
1047 * \param type The supposed type of \a btrn.
1048 *
1049 * Most users of the buffer tree subsystem call this function from both
1050 * their pre_select and the post_select methods.
1051 *
1052 * \return Negative if an error condition was detected, zero if there
1053 * is nothing to do and positive otherwise.
1054 *
1055 * Examples:
1056 *
1057 * - If a non-root node has no parent and an empty input queue, the function
1058 * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p
1059 * -E_BTR_NO_CHILD is returned.
1060 *
1061 * - If less than \a min_iqs many bytes are available in the input queue and no
1062 * EOF condition was detected, the function returns zero.
1063 *
1064 * - If there's plenty of data left in the input queue of the children of \a
1065 * btrn, the function also returns zero in order to bound the memory usage of
1066 * the buffer tree.
1067 */
1068 int btr_node_status(struct btr_node *btrn, size_t min_iqs,
1069 enum btr_node_type type)
1070 {
1071 size_t iqs;
1072
1073 assert(btrn);
1074 if (type != BTR_NT_LEAF) {
1075 if (btr_no_children(btrn))
1076 return -E_BTR_NO_CHILD;
1077 if (btr_bytes_pending(btrn) > BTRN_MAX_PENDING)
1078 return 0;
1079 }
1080 if (type != BTR_NT_ROOT) {
1081 if (btr_eof(btrn))
1082 return -E_BTR_EOF;
1083 iqs = btr_get_input_queue_size(btrn);
1084 if (iqs == 0) /* we have a parent, because not eof */
1085 return 0;
1086 if (iqs < min_iqs && !btr_no_parent(btrn))
1087 return 0;
1088 }
1089 return 1;
1090 }
1091
1092 /**
1093 * Get the time of the first I/O for a buffer tree node.
1094 *
1095 * \param btrn The node whose I/O time should be obtained.
1096 * \param tv Result pointer.
1097 *
1098 * Mainly useful for the time display of para_audiod.
1099 */
1100 void btr_get_node_start(struct btr_node *btrn, struct timeval *tv)
1101 {
1102 *tv = btrn->start;
1103 }