Merge branch 'maint'
[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 * Get references to buffers pointing to free space of the buffer pool area.
164 *
165 * \param btrp The buffer pool.
166 * \param iov The scatter array.
167 *
168 * \return Zero if the buffer pool is full, one if the free space of the buffer
169 * pool area is available as a single contiguous buffer, two if the free space
170 * consists of two buffers. If this function returns the value n, then n
171 * elements of \a iov are initialized.
172 */
173 int btr_pool_get_buffers(struct btr_pool *btrp, struct iovec iov[2])
174 {
175 size_t sz, unused;
176 char *buf;
177
178 sz = btr_pool_get_buffer(btrp, &buf);
179 if (sz == 0)
180 return 0;
181 iov[0].iov_len = sz;
182 iov[0].iov_base = buf;
183 unused = btr_pool_unused(btrp);
184 if (sz == unused)
185 return 1;
186 iov[1].iov_len = unused - sz;
187 iov[1].iov_base = btrp->area_start;
188 return 2;
189 }
190
191 /**
192 * Mark a part of the buffer pool area as allocated.
193 *
194 * \param btrp The buffer pool.
195 * \param size The amount of bytes to be allocated.
196 *
197 * This is usually called after the caller wrote to the buffer obtained by
198 * btr_pool_get_buffer().
199 */
200 static void btr_pool_allocate(struct btr_pool *btrp, size_t size)
201 {
202 char *end;
203
204 if (size == 0)
205 return;
206 assert(size <= btr_pool_available(btrp));
207 end = btrp->whead + size;
208 assert(end <= btrp->area_end);
209
210 if (end == btrp->area_end) {
211 PARA_DEBUG_LOG("%s: end of pool area reached\n", btrp->name);
212 end = btrp->area_start;
213 }
214 if (end == btrp->rhead) {
215 PARA_DEBUG_LOG("%s btrp buffer full\n", btrp->name);
216 end = NULL; /* buffer full */
217 }
218 btrp->whead = end;
219 }
220
221 static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
222 {
223 char *end = btrp->rhead + size;
224
225 if (size == 0)
226 return;
227 assert(end <= btrp->area_end);
228 assert(size <= btr_pool_filled(btrp));
229 if (end == btrp->area_end)
230 end = btrp->area_start;
231 if (!btrp->whead)
232 btrp->whead = btrp->rhead;
233 btrp->rhead = end;
234 if (btrp->rhead == btrp->whead)
235 btrp->rhead = btrp->whead = btrp->area_start;
236 }
237
238 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
239 &((_btrn)->children), node)
240 #define FOR_EACH_CHILD_SAFE(_tn, _tmp, _btrn) \
241 list_for_each_entry_safe((_tn), (_tmp), &((_btrn)->children), node)
242
243 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
244 list_for_each_entry((_br), &(_btrn)->input_queue, node)
245 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
246 list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
247
248 /**
249 * Create a new buffer tree node.
250 *
251 * \param bnd Specifies how to create the new node.
252 *
253 * This function always succeeds (or calls exit()). The returned pointer must
254 * be freed using btr_free_node() after the node has been removed from the
255 * buffer tree via btr_remove_node().
256 */
257 struct btr_node *btr_new_node(struct btr_node_description *bnd)
258 {
259 struct btr_node *btrn = para_malloc(sizeof(*btrn));
260
261 btrn->name = para_strdup(bnd->name);
262 btrn->parent = bnd->parent;
263 btrn->execute = bnd->handler;
264 btrn->context = bnd->context;
265 btrn->start.tv_sec = 0;
266 btrn->start.tv_usec = 0;
267 INIT_LIST_HEAD(&btrn->children);
268 INIT_LIST_HEAD(&btrn->input_queue);
269 if (!bnd->child) {
270 if (bnd->parent) {
271 list_add_tail(&btrn->node, &bnd->parent->children);
272 PARA_INFO_LOG("new leaf node: %s (child of %s)\n",
273 bnd->name, bnd->parent->name);
274 } else
275 PARA_INFO_LOG("added %s as btr root\n", bnd->name);
276 goto out;
277 }
278 if (!bnd->parent) {
279 assert(!bnd->child->parent);
280 PARA_INFO_LOG("new root: %s (was %s)\n",
281 bnd->name, bnd->child->name);
282 btrn->parent = NULL;
283 list_add_tail(&bnd->child->node, &btrn->children);
284 /* link it in */
285 bnd->child->parent = btrn;
286 goto out;
287 }
288 PARA_EMERG_LOG("inserting internal nodes not yet supported.\n");
289 exit(EXIT_FAILURE);
290 assert(bnd->child->parent == bnd->parent);
291 out:
292 return btrn;
293 }
294
295 /*
296 * Allocate a new btr buffer.
297 *
298 * The freshly allocated buffer will have a zero refcount and will
299 * not be associated with a btr pool.
300 */
301 static struct btr_buffer *new_btrb(char *buf, size_t size)
302 {
303 struct btr_buffer *btrb = para_calloc(sizeof(*btrb));
304
305 btrb->buf = buf;
306 btrb->size = size;
307 return btrb;
308 }
309
310 static void dealloc_buffer(struct btr_buffer *btrb)
311 {
312 if (btrb->pool)
313 btr_pool_deallocate(btrb->pool, btrb->size);
314 else
315 free(btrb->buf);
316 }
317
318 static struct btr_buffer_reference *get_first_input_br(struct btr_node *btrn)
319 {
320 if (list_empty(&btrn->input_queue))
321 return NULL;
322 return list_first_entry(&btrn->input_queue,
323 struct btr_buffer_reference, node);
324 }
325
326 /*
327 * Deallocate the reference, release the resources if refcount drops to zero.
328 */
329 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
330 {
331 struct btr_buffer *btrb = br->btrb;
332
333 list_del(&br->node);
334 free(br);
335 btrb->refcount--;
336 if (btrb->refcount == 0) {
337 dealloc_buffer(btrb);
338 free(btrb);
339 }
340 }
341
342 static void add_btrb_to_children(struct btr_buffer *btrb,
343 struct btr_node *btrn, size_t consumed)
344 {
345 struct btr_node *ch;
346
347 if (btrn->start.tv_sec == 0)
348 btrn->start = *now;
349 FOR_EACH_CHILD(ch, btrn) {
350 struct btr_buffer_reference *br = para_calloc(sizeof(*br));
351 br->btrb = btrb;
352 br->consumed = consumed;
353 list_add_tail(&br->node, &ch->input_queue);
354 btrb->refcount++;
355 if (ch->start.tv_sec == 0)
356 ch->start = *now;
357 }
358 }
359
360 /**
361 * Insert a malloced buffer into the buffer tree.
362 *
363 * \param buf The buffer to insert.
364 * \param size The size of \a buf in bytes.
365 * \param btrn Position in the buffer tree to create the output.
366 *
367 * This creates references to \a buf and adds these references to each child of
368 * \a btrn. The buffer will be freed using standard free() once no buffer tree
369 * node is referencing it any more.
370 *
371 * Note that this function must not be used if \a buf was obtained from a
372 * buffer pool. Use btr_add_output_pool() in this case.
373 */
374 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
375 {
376 struct btr_buffer *btrb;
377
378 assert(size != 0);
379 if (list_empty(&btrn->children)) {
380 free(buf);
381 return;
382 }
383 btrb = new_btrb(buf, size);
384 add_btrb_to_children(btrb, btrn, 0);
385 }
386
387 /**
388 * Feed data to child nodes of a buffer tree node.
389 *
390 * \param btrp The buffer pool.
391 * \param size The number of bytes to be allocated and fed to each child.
392 * \param btrn The node whose children are to be fed.
393 *
394 * This function allocates the amount of bytes from the buffer pool area,
395 * starting at the current value of the write head, and creates buffer
396 * references to the resulting part of the buffer pool area, one for each child
397 * of \a btrn. The references are then fed into the input queue of each child.
398 */
399 void btr_add_output_pool(struct btr_pool *btrp, size_t size,
400 struct btr_node *btrn)
401 {
402 struct btr_buffer *btrb;
403 char *buf;
404 size_t avail;
405
406 assert(size != 0);
407 if (list_empty(&btrn->children))
408 return;
409 avail = btr_pool_get_buffer(btrp, &buf);
410 assert(avail >= size);
411 btr_pool_allocate(btrp, size);
412 btrb = new_btrb(buf, size);
413 btrb->pool = btrp;
414 add_btrb_to_children(btrb, btrn, 0);
415 }
416
417 /**
418 * Copy data to write head of a buffer pool and feed it to all children nodes.
419 *
420 * \param src The source buffer.
421 * \param n The size of the source buffer in bytes.
422 * \param btrp The destination buffer pool.
423 * \param btrn Add the data as output of this node.
424 *
425 * This is expensive. The caller must make sure the data fits into the buffer
426 * pool area.
427 */
428 void btr_copy(const void *src, size_t n, struct btr_pool *btrp,
429 struct btr_node *btrn)
430 {
431 char *buf;
432 size_t sz, copy;
433
434 if (n == 0)
435 return;
436 assert(n <= btr_pool_unused(btrp));
437 sz = btr_pool_get_buffer(btrp, &buf);
438 copy = PARA_MIN(sz, n);
439 memcpy(buf, src, copy);
440 btr_add_output_pool(btrp, copy, btrn);
441 if (copy == n)
442 return;
443 sz = btr_pool_get_buffer(btrp, &buf);
444 assert(sz >= n - copy);
445 memcpy(buf, src + copy, n - copy);
446 btr_add_output_pool(btrp, n - copy, btrn);
447 }
448
449 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
450 {
451 add_btrb_to_children(br->btrb, btrn, br->consumed);
452 btr_drop_buffer_reference(br);
453 }
454
455 /**
456 * Feed all buffer references of the input queue through the output channel.
457 *
458 * \param btrn The node whose buffer references should be pushed down.
459 *
460 * This function is useful for filters that do not change the contents of the
461 * buffers at all, like the wav filter or the amp filter if no amplification
462 * was specified. This function is rather cheap.
463 *
464 * \sa \ref btr_pushdown_one().
465 */
466 void btr_pushdown(struct btr_node *btrn)
467 {
468 struct btr_buffer_reference *br, *tmp;
469
470 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
471 btr_pushdown_br(br, btrn);
472 }
473
474 /**
475 * Feed the next buffer of the input queue through the output channel.
476 *
477 * \param btrn The node whose first input queue buffer should be pushed down.
478 *
479 * This works like \ref btr_pushdown() but pushes down only one buffer
480 * reference.
481 */
482 void btr_pushdown_one(struct btr_node *btrn)
483 {
484 struct btr_buffer_reference *br;
485
486 if (list_empty(&btrn->input_queue))
487 return;
488 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
489 btr_pushdown_br(br, btrn);
490 }
491
492 /*
493 * Find out whether a node is a leaf node.
494 *
495 * \param btrn The node to check.
496 *
497 * \return True if this node has no children. False otherwise.
498 */
499 static bool btr_no_children(struct btr_node *btrn)
500 {
501 return list_empty(&btrn->children);
502 }
503
504 /**
505 * Find out whether a node is an orphan node.
506 *
507 * \param btrn The buffer tree node.
508 *
509 * \return True if \a btrn has no parent.
510 *
511 * This function will always return true for the root node. However in case
512 * nodes have been removed from the tree, other nodes may become orphans too.
513 */
514 bool btr_no_parent(struct btr_node *btrn)
515 {
516 return !btrn->parent;
517 }
518
519 /**
520 * Find out whether it is OK to change an input buffer.
521 *
522 * \param btrn The buffer tree node to check.
523 *
524 * This is used by filters that produce exactly the same amount of output as
525 * there is input. The amp filter which multiplies each sample by some number
526 * is an example of such a filter. If there are no other nodes in the buffer
527 * tree that read the same input stream (i.e. if \a btrn has no siblings), a
528 * node may modify its input buffer directly and push down the modified buffer
529 * to its children, thereby avoiding to allocate a possibly large additional
530 * buffer.
531 *
532 * Since the buffer tree may change at any time, this function should be called
533 * during each post_select call.
534 *
535 * \return True if \a btrn has no siblings.
536 */
537 bool btr_inplace_ok(struct btr_node *btrn)
538 {
539 if (!btrn->parent)
540 return true;
541 return list_is_singular(&btrn->parent->children);
542 }
543
544 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
545 {
546 return br->btrb->size - br->consumed;
547 }
548
549 static size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
550 {
551 if (buf)
552 *buf = br->btrb->buf + br->consumed;
553 return br_available_bytes(br);
554 }
555
556 /**
557 * Obtain the next buffer of the input queue of a buffer tree node.
558 *
559 * \param btrn The node whose input queue is to be queried.
560 * \param bufp Result pointer.
561 *
562 * \return The number of bytes that can be read from buf. Zero if the input
563 * buffer queue is empty. In this case the value of \a bufp is undefined.
564 */
565 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
566 {
567 struct btr_buffer_reference *br;
568 char *buf, *result = NULL;
569 size_t sz, rv = 0;
570
571 FOR_EACH_BUFFER_REF(br, btrn) {
572 sz = btr_get_buffer_by_reference(br, &buf);
573 if (!result) {
574 result = buf;
575 rv = sz;
576 if (!br->btrb->pool)
577 break;
578 continue;
579 }
580 if (!br->btrb->pool)
581 break;
582 if (result + rv != buf)
583 break;
584 rv += sz;
585 }
586 if (bufp)
587 *bufp = result;
588 return rv;
589 }
590
591 /**
592 * Deallocate the given number of bytes from the input queue.
593 *
594 * \param btrn The buffer tree node.
595 * \param numbytes The number of bytes to be deallocated.
596 *
597 * This function must be used to get rid of existing buffer references in the
598 * node's input queue. If no references to a buffer remain, the underlying
599 * buffers are either freed (in the non-buffer tree case) or the read head of
600 * the buffer pool is being advanced.
601 *
602 * Note that \a numbytes may be smaller than the buffer size. In this case the
603 * buffer is not deallocated and subsequent calls to btr_next_buffer() return
604 * the remaining part of the buffer.
605 */
606 void btr_consume(struct btr_node *btrn, size_t numbytes)
607 {
608 struct btr_buffer_reference *br, *tmp;
609 size_t sz;
610
611 if (numbytes == 0)
612 return;
613 br = get_first_input_br(btrn);
614 assert(br);
615
616 if (br->wrap_count == 0) {
617 /*
618 * No wrap buffer. Drop buffer references whose buffer
619 * has been fully used. */
620 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn) {
621 if (br->consumed + numbytes <= br->btrb->size) {
622 br->consumed += numbytes;
623 if (br->consumed == br->btrb->size)
624 btr_drop_buffer_reference(br);
625 return;
626 }
627 numbytes -= br->btrb->size - br->consumed;
628 btr_drop_buffer_reference(br);
629 }
630 assert(true);
631 }
632 /*
633 * We have a wrap buffer, consume from it. If in total, i.e. including
634 * previous calls to brt_consume(), less than wrap_count has been
635 * consumed, there's nothing more we can do.
636 *
637 * Otherwise we drop the wrap buffer and consume from subsequent
638 * buffers of the input queue the correct amount of bytes. This is the
639 * total number of bytes that have been consumed from the wrap buffer.
640 */
641 PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes,
642 br_available_bytes(br));
643
644 assert(numbytes <= br_available_bytes(br));
645 if (br->consumed + numbytes < br->wrap_count) {
646 br->consumed += numbytes;
647 return;
648 }
649 PARA_DEBUG_LOG("dropping wrap buffer (%zu bytes)\n", br->btrb->size);
650 /* get rid of the wrap buffer */
651 sz = br->consumed + numbytes;
652 btr_drop_buffer_reference(br);
653 return btr_consume(btrn, sz);
654 }
655
656 static void flush_input_queue(struct btr_node *btrn)
657 {
658 struct btr_buffer_reference *br, *tmp;
659 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
660 btr_drop_buffer_reference(br);
661 }
662
663 /**
664 * Free all resources allocated by btr_new_node().
665 *
666 * Like free(3), it is OK to call this with a \p NULL pointer argument.
667 */
668 void btr_free_node(struct btr_node *btrn)
669 {
670 if (!btrn)
671 return;
672 free(btrn->name);
673 free(btrn);
674 }
675
676 /**
677 * Remove a node from a buffer tree.
678 *
679 * \param btrn The node to remove.
680 *
681 * This makes all child nodes of \a btrn orphans and removes \a btrn from the
682 * list of children of its parent. Moreover, the input queue of \a btrn is
683 * flushed if it is not empty.
684 *
685 * \sa \ref btr_splice_out_node.
686 */
687 void btr_remove_node(struct btr_node *btrn)
688 {
689 struct btr_node *ch;
690
691 if (!btrn)
692 return;
693 PARA_NOTICE_LOG("removing btr node %s from buffer tree\n", btrn->name);
694 FOR_EACH_CHILD(ch, btrn)
695 ch->parent = NULL;
696 flush_input_queue(btrn);
697 if (btrn->parent)
698 list_del(&btrn->node);
699 }
700
701 /**
702 * Return the amount of available input bytes of a buffer tree node.
703 *
704 * \param btrn The node whose input size should be computed.
705 *
706 * \return The total number of bytes available in the node's input
707 * queue.
708 *
709 * This simply iterates over all buffer references in the input queue and
710 * returns the sum of the sizes of all references.
711 */
712 size_t btr_get_input_queue_size(struct btr_node *btrn)
713 {
714 struct btr_buffer_reference *br;
715 size_t size = 0, wrap_consumed = 0;
716
717 FOR_EACH_BUFFER_REF(br, btrn) {
718 if (br->wrap_count != 0) {
719 wrap_consumed = br->consumed;
720 continue;
721 }
722 size += br_available_bytes(br);
723 }
724 assert(wrap_consumed <= size);
725 size -= wrap_consumed;
726 return size;
727 }
728
729 /**
730 * Remove a node from the buffer tree, reconnecting parent and children.
731 *
732 * \param btrn The node to splice out.
733 *
734 * This function is used by buffer tree nodes that do not exist during the
735 * whole lifetime of the buffer tree. Unlike btr_remove_node(), calling
736 * btr_splice_out_node() does not split the tree into disconnected components
737 * but reconnects the buffer tree by making all child nodes of \a btrn children
738 * of the parent of \a btrn.
739 */
740 void btr_splice_out_node(struct btr_node *btrn)
741 {
742 struct btr_node *ch, *tmp;
743
744 assert(btrn);
745 PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
746 btr_pushdown(btrn);
747 if (btrn->parent)
748 list_del(&btrn->node);
749 FOR_EACH_CHILD_SAFE(ch, tmp, btrn) {
750 PARA_INFO_LOG("parent(%s): %s\n", ch->name,
751 btrn->parent? btrn->parent->name : "NULL");
752 ch->parent = btrn->parent;
753 if (btrn->parent)
754 list_move(&ch->node, &btrn->parent->children);
755 }
756 assert(list_empty(&btrn->children));
757 }
758
759 /**
760 * Return number of queued output bytes of a buffer tree node.
761 *
762 * \param btrn The node whose output queue size should be computed.
763 *
764 * This function iterates over all children of the given node and returns the
765 * size of the largest input queue.
766 */
767 size_t btr_get_output_queue_size(struct btr_node *btrn)
768 {
769 size_t max_size = 0;
770 struct btr_node *ch;
771
772 FOR_EACH_CHILD(ch, btrn) {
773 size_t size = btr_get_input_queue_size(ch);
774 max_size = PARA_MAX(max_size, size);
775 }
776 return max_size;
777 }
778
779 int btr_exec(struct btr_node *btrn, const char *command, char **value_result)
780 {
781 if (!btrn)
782 return -ERRNO_TO_PARA_ERROR(EINVAL);
783 if (!btrn->execute)
784 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
785 return btrn->execute(btrn, command, value_result);
786 }
787
788 /**
789 * Execute a inter-node command on a parent node.
790 *
791 * \param btrn The node to start looking.
792 * \param command The command to execute.
793 * \param value_result Additional arguments and result value.
794 *
795 * This function traverses the buffer tree upwards and looks for parent nodes
796 * of \a btrn that understands \a command. On the first such node the command
797 * is executed, and the result is stored in \a value_result.
798 *
799 * \return \p -ENOTSUP if no parent node of \a btrn understands \a command.
800 * Otherwise the return value of the command handler is returned.
801 */
802 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
803 {
804 int ret;
805
806 for (; btrn; btrn = btrn->parent) {
807 struct btr_node *parent = btrn->parent;
808 if (!parent)
809 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
810 if (!parent->execute)
811 continue;
812 PARA_INFO_LOG("parent: %s, cmd: %s\n", parent->name, command);
813 ret = parent->execute(parent, command, value_result);
814 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
815 continue;
816 if (ret < 0)
817 return ret;
818 if (value_result && *value_result)
819 PARA_NOTICE_LOG("%s(%s): %s\n", command, parent->name,
820 *value_result);
821 return 1;
822 }
823 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
824 }
825
826 /**
827 * Obtain the context of a buffer node tree.
828 *
829 * The returned pointer equals the context pointer used at creation time of the
830 * node.
831 *
832 * \sa btr_new_node(), struct \ref btr_node_description.
833 */
834 void *btr_context(struct btr_node *btrn)
835 {
836 return btrn->context;
837 }
838
839 static bool need_buffer_pool_merge(struct btr_node *btrn)
840 {
841 struct btr_buffer_reference *br = get_first_input_br(btrn);
842
843 if (!br)
844 return false;
845 if (br->wrap_count != 0)
846 return true;
847 if (br->btrb->pool)
848 return true;
849 return false;
850 }
851
852 static void merge_input_pool(struct btr_node *btrn, size_t dest_size)
853 {
854 struct btr_buffer_reference *br, *wbr = NULL;
855 int num_refs; /* including wrap buffer */
856 char *buf, *buf1 = NULL, *buf2 = NULL;
857 size_t sz, sz1 = 0, sz2 = 0, wb_consumed = 0;
858
859 br = get_first_input_br(btrn);
860 if (!br || br_available_bytes(br) >= dest_size)
861 return;
862 num_refs = 0;
863 FOR_EACH_BUFFER_REF(br, btrn) {
864 num_refs++;
865 sz = btr_get_buffer_by_reference(br, &buf);
866 if (sz == 0)
867 break;
868 if (br->wrap_count != 0) {
869 assert(!wbr);
870 assert(num_refs == 1);
871 wbr = br;
872 if (sz >= dest_size)
873 return;
874 wb_consumed = br->consumed;
875 continue;
876 }
877 if (!buf1) {
878 buf1 = buf;
879 sz1 = sz;
880 goto next;
881 }
882 if (buf1 + sz1 == buf) {
883 sz1 += sz;
884 goto next;
885 }
886 if (!buf2) {
887 buf2 = buf;
888 sz2 = sz;
889 goto next;
890 }
891 assert(buf2 + sz2 == buf);
892 sz2 += sz;
893 next:
894 if (sz1 + sz2 >= dest_size + wb_consumed)
895 break;
896 }
897 if (!buf2) /* nothing to do */
898 return;
899 assert(buf1 && sz2 > 0);
900 /*
901 * If the second buffer is large, we only take the first part of it to
902 * avoid having to memcpy() huge buffers.
903 */
904 sz2 = PARA_MIN(sz2, (size_t)(64 * 1024));
905 if (!wbr) {
906 /* Make a new wrap buffer combining buf1 and buf2. */
907 sz = sz1 + sz2;
908 buf = para_malloc(sz);
909 PARA_DEBUG_LOG("merging input buffers: (%p:%zu, %p:%zu) -> %p:%zu\n",
910 buf1, sz1, buf2, sz2, buf, sz);
911 memcpy(buf, buf1, sz1);
912 memcpy(buf + sz1, buf2, sz2);
913 br = para_calloc(sizeof(*br));
914 br->btrb = new_btrb(buf, sz);
915 br->btrb->refcount = 1;
916 br->consumed = 0;
917 /* This is a wrap buffer */
918 br->wrap_count = sz1;
919 para_list_add(&br->node, &btrn->input_queue);
920 return;
921 }
922 /*
923 * We already have a wrap buffer, but it is too small. It might be
924 * partially used.
925 */
926 if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
927 return;
928 sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */
929 PARA_DEBUG_LOG("increasing wrap buffer %zu -> %zu\n", wbr->btrb->size,
930 wbr->btrb->size + sz);
931 wbr->btrb->size += sz;
932 wbr->btrb->buf = para_realloc(wbr->btrb->buf, wbr->btrb->size);
933 /* copy the new data to the end of the reallocated buffer */
934 assert(sz2 >= sz);
935 memcpy(wbr->btrb->buf + wbr->btrb->size - sz, buf2 + sz2 - sz, sz);
936 }
937
938 /**
939 * Merge the first two input buffers into one.
940 *
941 * This is a quite expensive operation.
942 *
943 * \return The number of buffers that have been available (zero, one or two).
944 */
945 static int merge_input(struct btr_node *btrn)
946 {
947 struct btr_buffer_reference *brs[2], *br;
948 char *bufs[2], *buf;
949 size_t szs[2], sz;
950 int i;
951
952 if (list_empty(&btrn->input_queue))
953 return 0;
954 if (list_is_singular(&btrn->input_queue))
955 return 1;
956 i = 0;
957 /* get references to the first two buffers */
958 FOR_EACH_BUFFER_REF(br, btrn) {
959 brs[i] = br;
960 szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
961 i++;
962 if (i == 2)
963 break;
964 }
965 assert(i == 2);
966 /* make a new btrb that combines the two buffers and a br to it. */
967 sz = szs[0] + szs[1];
968 buf = para_malloc(sz);
969 PARA_DEBUG_LOG("%s: memory merging input buffers: (%zu, %zu) -> %zu\n",
970 btrn->name, szs[0], szs[1], sz);
971 memcpy(buf, bufs[0], szs[0]);
972 memcpy(buf + szs[0], bufs[1], szs[1]);
973
974 br = para_calloc(sizeof(*br));
975 br->btrb = new_btrb(buf, sz);
976 br->btrb->refcount = 1;
977
978 /* replace the first two refs by the new one */
979 btr_drop_buffer_reference(brs[0]);
980 btr_drop_buffer_reference(brs[1]);
981 para_list_add(&br->node, &btrn->input_queue);
982 return 2;
983 }
984
985 /**
986 * Combine input queue buffers.
987 *
988 * \param btrn The buffer tree node whose input should be merged.
989 * \param dest_size Stop merging if a buffer of at least this size exists.
990 *
991 * Used to combine as many buffers as needed into a single buffer whose size is
992 * at least \a dest_size. This function is rather cheap in case the parent node
993 * uses buffer pools and rather expensive otherwise.
994 *
995 * Note that if less than \a dest_size bytes are available in total, this
996 * function does nothing and subsequent calls to btr_next_buffer() will still
997 * return a buffer size less than \a dest_size.
998 */
999 void btr_merge(struct btr_node *btrn, size_t dest_size)
1000 {
1001 if (need_buffer_pool_merge(btrn))
1002 return merge_input_pool(btrn, dest_size);
1003 for (;;) {
1004 char *buf;
1005 size_t len = btr_next_buffer(btrn, &buf);
1006 if (len >= dest_size)
1007 return;
1008 PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len, dest_size);
1009 if (merge_input(btrn) < 2)
1010 return;
1011 }
1012 }
1013
1014 static bool btr_eof(struct btr_node *btrn)
1015 {
1016 char *buf;
1017 size_t len = btr_next_buffer(btrn, &buf);
1018
1019 return (len == 0 && btr_no_parent(btrn));
1020 }
1021
1022 static void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
1023 {
1024 struct btr_node *ch;
1025 const char spaces[] = " ", *space = spaces + 16 - depth;
1026
1027 if (depth > 16)
1028 return;
1029 para_log(loglevel, "%s%s\n", space, btrn->name);
1030 FOR_EACH_CHILD(ch, btrn)
1031 log_tree_recursively(ch, loglevel, depth + 1);
1032 }
1033
1034 /**
1035 * Write the current buffer (sub-)tree to the log.
1036 *
1037 * \param btrn Start logging at this node.
1038 * \param loglevel Set severity with which the tree should be logged.
1039 */
1040 void btr_log_tree(struct btr_node *btrn, int loglevel)
1041 {
1042 return log_tree_recursively(btrn, loglevel, 0);
1043 }
1044
1045 /**
1046 * Find the node with the given name in the buffer tree.
1047 *
1048 * \param name The name of the node to search.
1049 * \param root Where to start the search.
1050 *
1051 * \return A pointer to the node with the given name on success. If \a name is
1052 * \p NULL, the function returns \a root. If there is no node with the given
1053 * name, \p NULL is returned.
1054 */
1055 struct btr_node *btr_search_node(const char *name, struct btr_node *root)
1056 {
1057 struct btr_node *ch;
1058
1059 if (!name)
1060 return root;
1061 if (!strcmp(root->name, name))
1062 return root;
1063 FOR_EACH_CHILD(ch, root) {
1064 struct btr_node *result = btr_search_node(name, ch);
1065 if (result)
1066 return result;
1067 }
1068 return NULL;
1069 }
1070
1071 /** 640K ought to be enough for everybody ;) */
1072 #define BTRN_MAX_PENDING (640 * 1024)
1073
1074 /**
1075 * Return the current state of a buffer tree node.
1076 *
1077 * \param btrn The node whose state should be queried.
1078 * \param min_iqs The minimal input queue size.
1079 * \param type The supposed type of \a btrn.
1080 *
1081 * Most users of the buffer tree subsystem call this function from both
1082 * their pre_select and the post_select methods.
1083 *
1084 * \return Negative if an error condition was detected, zero if there
1085 * is nothing to do and positive otherwise.
1086 *
1087 * Examples:
1088 *
1089 * - If a non-root node has no parent and an empty input queue, the function
1090 * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p
1091 * -E_BTR_NO_CHILD is returned.
1092 *
1093 * - If less than \a min_iqs many bytes are available in the input queue and no
1094 * EOF condition was detected, the function returns zero.
1095 *
1096 * - If there's plenty of data left in the input queue of the children of \a
1097 * btrn, the function also returns zero in order to bound the memory usage of
1098 * the buffer tree.
1099 */
1100 int btr_node_status(struct btr_node *btrn, size_t min_iqs,
1101 enum btr_node_type type)
1102 {
1103 size_t iqs;
1104
1105 assert(btrn);
1106 if (type != BTR_NT_LEAF) {
1107 if (btr_no_children(btrn))
1108 return -E_BTR_NO_CHILD;
1109 if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
1110 return 0;
1111 }
1112 if (type != BTR_NT_ROOT) {
1113 if (btr_eof(btrn))
1114 return -E_BTR_EOF;
1115 iqs = btr_get_input_queue_size(btrn);
1116 if (iqs == 0) /* we have a parent, because not eof */
1117 return 0;
1118 if (iqs < min_iqs && !btr_no_parent(btrn))
1119 return 0;
1120 }
1121 return 1;
1122 }
1123
1124 /**
1125 * Get the time of the first I/O for a buffer tree node.
1126 *
1127 * \param btrn The node whose I/O time should be obtained.
1128 * \param tv Result pointer.
1129 *
1130 * Mainly useful for the time display of para_audiod.
1131 */
1132 void btr_get_node_start(struct btr_node *btrn, struct timeval *tv)
1133 {
1134 *tv = btrn->start;
1135 }