udp: initialize common structure only once
[paraslash.git] / buffer_tree.c
1 /*
2 * Copyright (C) 2009-2010 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file buffer_tree.c Buffer tree and buffer pool implementations. */
8 #include <regex.h>
9 #include <stdbool.h>
10
11 #include "para.h"
12 #include "list.h"
13 #include "string.h"
14 #include "buffer_tree.h"
15 #include "error.h"
16 #include "sched.h"
17
18 /* whead = NULL means area full */
19 struct btr_pool {
20 char *name;
21 char *area_start;
22 char *area_end;
23 char *rhead;
24 char *whead;
25 };
26
27 struct btr_buffer {
28 char *buf;
29 size_t size;
30 /** The number of references to this buffer. */
31 int refcount;
32 /* NULL means no buffer pool but a malloced buffer. */
33 struct btr_pool *pool;
34 };
35
36 struct btr_buffer_reference {
37 struct btr_buffer *btrb;
38 size_t consumed;
39 /* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
40 struct list_head node;
41 size_t wrap_count;
42 };
43
44 struct btr_node {
45 char *name;
46 struct btr_node *parent;
47 /* The position of this btr node in the buffer tree. */
48 struct list_head node;
49 /* The children nodes of this btr node are linked together in a list. */
50 struct list_head children;
51 /* Time of first data transfer. */
52 struct timeval start;
53 /**
54 * The input queue is a list of references to btr buffers. Each item on
55 * the list represents an input buffer which has not been completely
56 * used by this btr node.
57 */
58 struct list_head input_queue;
59 btr_command_handler execute;
60 void *context;
61 };
62
63 /**
64 * Create a new buffer pool.
65 *
66 * \param name The name of the new buffer pool.
67 * \param area_size The size in bytes of the pool area.
68 *
69 * \return An opaque pointer to the newly created buffer pool. It must be
70 * passed to btr_pool_free() after it is no longer used to deallocate all
71 * resources.
72 */
73 struct btr_pool *btr_pool_new(const char *name, size_t area_size)
74 {
75 struct btr_pool *btrp;
76
77 PARA_INFO_LOG("%s, %zu bytes\n", name, area_size);
78 btrp = para_malloc(sizeof(*btrp));
79 btrp->area_start = para_malloc(area_size);
80 btrp->area_end = btrp->area_start + area_size;
81 btrp->rhead = btrp->area_start;
82 btrp->whead = btrp->area_start;
83 btrp->name = para_strdup(name);
84 return btrp;
85 }
86
87 /**
88 * Deallocate resources used by a buffer pool.
89 *
90 * \param btrp A pointer obtained via btr_pool_new().
91 */
92 void btr_pool_free(struct btr_pool *btrp)
93 {
94 if (!btrp)
95 return;
96 free(btrp->area_start);
97 free(btrp->name);
98 free(btrp);
99 }
100
101 /**
102 * Return the size of the buffer pool area.
103 *
104 * \param btrp The buffer pool.
105 *
106 * \return The same value which was passed during creation time to
107 * btr_pool_new().
108 */
109 size_t btr_pool_size(struct btr_pool *btrp)
110 {
111 return btrp->area_end - btrp->area_start;
112 }
113
114 static size_t btr_pool_filled(struct btr_pool *btrp)
115 {
116 if (!btrp->whead)
117 return btr_pool_size(btrp);
118 if (btrp->rhead <= btrp->whead)
119 return btrp->whead - btrp->rhead;
120 return btr_pool_size(btrp) - (btrp->rhead - btrp->whead);
121 }
122
123 /**
124 * Get the number of unused bytes in the buffer pool.
125 *
126 * \param btrp The pool.
127 *
128 * \return The number of bytes that can currently be allocated.
129 *
130 * Note that in general the returned number of bytes is not available as a
131 * single contiguous buffer. Use btr_pool_available() to obtain the length of
132 * the largest contiguous buffer that can currently be allocated from the
133 * buffer pool.
134 */
135 size_t btr_pool_unused(struct btr_pool *btrp)
136 {
137 return btr_pool_size(btrp) - btr_pool_filled(btrp);
138 }
139
140 /*
141 * Return maximal size available for one read. This is
142 * smaller than the value returned by btr_pool_unused().
143 */
144 static size_t btr_pool_available(struct btr_pool *btrp)
145 {
146 if (!btrp->whead)
147 return 0;
148 if (btrp->rhead <= btrp->whead)
149 return btrp->area_end - btrp->whead;
150 return btrp->rhead - btrp->whead;
151 }
152
153 /**
154 * Obtain the current write head.
155 *
156 * \param btrp The buffer pool.
157 * \param result The write head is returned here.
158 *
159 * \return The maximal amount of bytes that may be written to the returned
160 * buffer.
161 */
162 size_t btr_pool_get_buffer(struct btr_pool *btrp, char **result)
163 {
164 if (result)
165 *result = btrp->whead;
166 return btr_pool_available(btrp);
167 }
168
169 /**
170 * Get references to buffers pointing to free space of the buffer pool area.
171 *
172 * \param btrp The buffer pool.
173 * \param iov The scatter array.
174 *
175 * \return Zero if the buffer pool is full, one if the free space of the buffer
176 * pool area is available as a single contiguous buffer, two if the free space
177 * consists of two buffers. If this function returns the value n, then n
178 * elements of \a iov are initialized.
179 */
180 int btr_pool_get_buffers(struct btr_pool *btrp, struct iovec iov[2])
181 {
182 size_t sz, unused;
183 char *buf;
184
185 sz = btr_pool_get_buffer(btrp, &buf);
186 if (sz == 0)
187 return 0;
188 iov[0].iov_len = sz;
189 iov[0].iov_base = buf;
190 unused = btr_pool_unused(btrp);
191 if (sz == unused)
192 return 1;
193 iov[1].iov_len = unused - sz;
194 iov[1].iov_base = btrp->area_start;
195 return 2;
196 }
197
198 /**
199 * Mark a part of the buffer pool area as allocated.
200 *
201 * \param btrp The buffer pool.
202 * \param size The amount of bytes to be allocated.
203 *
204 * This is usually called after the caller wrote to the buffer obtained by
205 * btr_pool_get_buffer().
206 */
207 static void btr_pool_allocate(struct btr_pool *btrp, size_t size)
208 {
209 char *end;
210
211 if (size == 0)
212 return;
213 assert(size <= btr_pool_available(btrp));
214 end = btrp->whead + size;
215 assert(end <= btrp->area_end);
216
217 if (end == btrp->area_end) {
218 PARA_DEBUG_LOG("%s: end of pool area reached\n", btrp->name);
219 end = btrp->area_start;
220 }
221 if (end == btrp->rhead) {
222 PARA_DEBUG_LOG("%s btrp buffer full\n", btrp->name);
223 end = NULL; /* buffer full */
224 }
225 btrp->whead = end;
226 }
227
228 static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
229 {
230 char *end = btrp->rhead + size;
231
232 if (size == 0)
233 return;
234 assert(end <= btrp->area_end);
235 assert(size <= btr_pool_filled(btrp));
236 if (end == btrp->area_end)
237 end = btrp->area_start;
238 if (!btrp->whead)
239 btrp->whead = btrp->rhead;
240 btrp->rhead = end;
241 if (btrp->rhead == btrp->whead)
242 btrp->rhead = btrp->whead = btrp->area_start;
243 }
244
245 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
246 &((_btrn)->children), node)
247 #define FOR_EACH_CHILD_SAFE(_tn, _tmp, _btrn) \
248 list_for_each_entry_safe((_tn), (_tmp), &((_btrn)->children), node)
249
250 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
251 list_for_each_entry((_br), &(_btrn)->input_queue, node)
252 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
253 list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
254
255 /**
256 * Create a new buffer tree node.
257 *
258 * \param bnd Specifies how to create the new node.
259 *
260 * This function always succeeds (or calls exit()). The returned pointer must
261 * be freed using btr_free_node() after the node has been removed from the
262 * buffer tree via btr_remove_node().
263 */
264 struct btr_node *btr_new_node(struct btr_node_description *bnd)
265 {
266 struct btr_node *btrn = para_malloc(sizeof(*btrn));
267
268 btrn->name = para_strdup(bnd->name);
269 btrn->parent = bnd->parent;
270 btrn->execute = bnd->handler;
271 btrn->context = bnd->context;
272 btrn->start.tv_sec = 0;
273 btrn->start.tv_usec = 0;
274 INIT_LIST_HEAD(&btrn->children);
275 INIT_LIST_HEAD(&btrn->input_queue);
276 if (!bnd->child) {
277 if (bnd->parent) {
278 list_add_tail(&btrn->node, &bnd->parent->children);
279 PARA_INFO_LOG("new leaf node: %s (child of %s)\n",
280 bnd->name, bnd->parent->name);
281 } else
282 PARA_INFO_LOG("added %s as btr root\n", bnd->name);
283 goto out;
284 }
285 if (!bnd->parent) {
286 assert(!bnd->child->parent);
287 PARA_INFO_LOG("new root: %s (was %s)\n",
288 bnd->name, bnd->child->name);
289 btrn->parent = NULL;
290 list_add_tail(&bnd->child->node, &btrn->children);
291 /* link it in */
292 bnd->child->parent = btrn;
293 goto out;
294 }
295 PARA_EMERG_LOG("inserting internal nodes not yet supported.\n");
296 exit(EXIT_FAILURE);
297 assert(bnd->child->parent == bnd->parent);
298 out:
299 return btrn;
300 }
301
302 /*
303 * Allocate a new btr buffer.
304 *
305 * The freshly allocated buffer will have a zero refcount and will
306 * not be associated with a btr pool.
307 */
308 static struct btr_buffer *new_btrb(char *buf, size_t size)
309 {
310 struct btr_buffer *btrb = para_calloc(sizeof(*btrb));
311
312 btrb->buf = buf;
313 btrb->size = size;
314 return btrb;
315 }
316
317 static void dealloc_buffer(struct btr_buffer *btrb)
318 {
319 if (btrb->pool)
320 btr_pool_deallocate(btrb->pool, btrb->size);
321 else
322 free(btrb->buf);
323 }
324
325 static struct btr_buffer_reference *get_first_input_br(struct btr_node *btrn)
326 {
327 if (list_empty(&btrn->input_queue))
328 return NULL;
329 return list_first_entry(&btrn->input_queue,
330 struct btr_buffer_reference, node);
331 }
332
333 /*
334 * Deallocate the reference, release the resources if refcount drops to zero.
335 */
336 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
337 {
338 struct btr_buffer *btrb = br->btrb;
339
340 list_del(&br->node);
341 free(br);
342 btrb->refcount--;
343 if (btrb->refcount == 0) {
344 dealloc_buffer(btrb);
345 free(btrb);
346 }
347 }
348
349 static void add_btrb_to_children(struct btr_buffer *btrb,
350 struct btr_node *btrn, size_t consumed)
351 {
352 struct btr_node *ch;
353
354 if (btrn->start.tv_sec == 0)
355 btrn->start = *now;
356 FOR_EACH_CHILD(ch, btrn) {
357 struct btr_buffer_reference *br = para_calloc(sizeof(*br));
358 br->btrb = btrb;
359 br->consumed = consumed;
360 list_add_tail(&br->node, &ch->input_queue);
361 btrb->refcount++;
362 if (ch->start.tv_sec == 0)
363 ch->start = *now;
364 }
365 }
366
367 /**
368 * Insert a malloced buffer into the buffer tree.
369 *
370 * \param buf The buffer to insert.
371 * \param size The size of \a buf in bytes.
372 * \param btrn Position in the buffer tree to create the output.
373 *
374 * This creates references to \a buf and adds these references to each child of
375 * \a btrn. The buffer will be freed using standard free() once no buffer tree
376 * node is referencing it any more.
377 *
378 * Note that this function must not be used if \a buf was obtained from a
379 * buffer pool. Use btr_add_output_pool() in this case.
380 */
381 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
382 {
383 struct btr_buffer *btrb;
384
385 assert(size != 0);
386 if (list_empty(&btrn->children)) {
387 free(buf);
388 return;
389 }
390 btrb = new_btrb(buf, size);
391 add_btrb_to_children(btrb, btrn, 0);
392 }
393
394 /**
395 * Feed data to child nodes of a buffer tree node.
396 *
397 * \param btrp The buffer pool.
398 * \param size The number of bytes to be allocated and fed to each child.
399 * \param btrn The node whose children are to be fed.
400 *
401 * This function allocates the amount of bytes from the buffer pool area,
402 * starting at the current value of the write head, and creates buffer
403 * references to the resulting part of the buffer pool area, one for each child
404 * of \a btrn. The references are then fed into the input queue of each child.
405 */
406 void btr_add_output_pool(struct btr_pool *btrp, size_t size,
407 struct btr_node *btrn)
408 {
409 struct btr_buffer *btrb;
410 char *buf;
411 size_t avail;
412
413 assert(size != 0);
414 if (list_empty(&btrn->children))
415 return;
416 avail = btr_pool_get_buffer(btrp, &buf);
417 assert(avail >= size);
418 btr_pool_allocate(btrp, size);
419 btrb = new_btrb(buf, size);
420 btrb->pool = btrp;
421 add_btrb_to_children(btrb, btrn, 0);
422 }
423
424 /**
425 * Copy data to write head of a buffer pool and feed it to all children nodes.
426 *
427 * \param src The source buffer.
428 * \param n The size of the source buffer in bytes.
429 * \param btrp The destination buffer pool.
430 * \param btrn Add the data as output of this node.
431 *
432 * This is expensive. The caller must make sure the data fits into the buffer
433 * pool area.
434 */
435 void btr_copy(const void *src, size_t n, struct btr_pool *btrp,
436 struct btr_node *btrn)
437 {
438 char *buf;
439 size_t sz, copy;
440
441 if (n == 0)
442 return;
443 assert(n <= btr_pool_unused(btrp));
444 sz = btr_pool_get_buffer(btrp, &buf);
445 copy = PARA_MIN(sz, n);
446 memcpy(buf, src, copy);
447 btr_add_output_pool(btrp, copy, btrn);
448 if (copy == n)
449 return;
450 sz = btr_pool_get_buffer(btrp, &buf);
451 assert(sz >= n - copy);
452 memcpy(buf, src + copy, n - copy);
453 btr_add_output_pool(btrp, n - copy, btrn);
454 }
455
456 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
457 {
458 add_btrb_to_children(br->btrb, btrn, br->consumed);
459 btr_drop_buffer_reference(br);
460 }
461
462 /**
463 * Feed all buffer references of the input queue through the output channel.
464 *
465 * \param btrn The node whose buffer references should be pushed down.
466 *
467 * This function is useful for filters that do not change the contents of the
468 * buffers at all, like the wav filter or the amp filter if no amplification
469 * was specified. This function is rather cheap.
470 *
471 * \sa \ref btr_pushdown_one().
472 */
473 void btr_pushdown(struct btr_node *btrn)
474 {
475 struct btr_buffer_reference *br, *tmp;
476
477 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
478 btr_pushdown_br(br, btrn);
479 }
480
481 /**
482 * Feed the next buffer of the input queue through the output channel.
483 *
484 * \param btrn The node whose first input queue buffer should be pushed down.
485 *
486 * This works like \ref btr_pushdown() but pushes down only one buffer
487 * reference.
488 */
489 void btr_pushdown_one(struct btr_node *btrn)
490 {
491 struct btr_buffer_reference *br;
492
493 if (list_empty(&btrn->input_queue))
494 return;
495 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
496 btr_pushdown_br(br, btrn);
497 }
498
499 /*
500 * Find out whether a node is a leaf node.
501 *
502 * \param btrn The node to check.
503 *
504 * \return True if this node has no children. False otherwise.
505 */
506 static bool btr_no_children(struct btr_node *btrn)
507 {
508 return list_empty(&btrn->children);
509 }
510
511 /**
512 * Find out whether a node is an orphan node.
513 *
514 * \param btrn The buffer tree node.
515 *
516 * \return True if \a btrn has no parent.
517 *
518 * This function will always return true for the root node. However in case
519 * nodes have been removed from the tree, other nodes may become orphans too.
520 */
521 bool btr_no_parent(struct btr_node *btrn)
522 {
523 return !btrn->parent;
524 }
525
526 /**
527 * Find out whether it is OK to change an input buffer.
528 *
529 * \param btrn The buffer tree node to check.
530 *
531 * This is used by filters that produce exactly the same amount of output as
532 * there is input. The amp filter which multiplies each sample by some number
533 * is an example of such a filter. If there are no other nodes in the buffer
534 * tree that read the same input stream (i.e. if \a btrn has no siblings), a
535 * node may modify its input buffer directly and push down the modified buffer
536 * to its children, thereby avoiding to allocate a possibly large additional
537 * buffer.
538 *
539 * Since the buffer tree may change at any time, this function should be called
540 * during each post_select call.
541 *
542 * \return True if \a btrn has no siblings.
543 */
544 bool btr_inplace_ok(struct btr_node *btrn)
545 {
546 if (!btrn->parent)
547 return true;
548 return list_is_singular(&btrn->parent->children);
549 }
550
551 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
552 {
553 return br->btrb->size - br->consumed;
554 }
555
556 static size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
557 {
558 if (buf)
559 *buf = br->btrb->buf + br->consumed;
560 return br_available_bytes(br);
561 }
562
563 /**
564 * Obtain the next buffer of the input queue of a buffer tree node.
565 *
566 * \param btrn The node whose input queue is to be queried.
567 * \param bufp Result pointer.
568 *
569 * \return The number of bytes that can be read from buf. Zero if the input
570 * buffer queue is empty. In this case the value of \a bufp is undefined.
571 */
572 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
573 {
574 struct btr_buffer_reference *br;
575 char *buf, *result = NULL;
576 size_t sz, rv = 0;
577
578 FOR_EACH_BUFFER_REF(br, btrn) {
579 sz = btr_get_buffer_by_reference(br, &buf);
580 if (!result) {
581 result = buf;
582 rv = sz;
583 if (!br->btrb->pool)
584 break;
585 continue;
586 }
587 if (!br->btrb->pool)
588 break;
589 if (result + rv != buf)
590 break;
591 rv += sz;
592 }
593 if (bufp)
594 *bufp = result;
595 return rv;
596 }
597
598 /**
599 * Deallocate the given number of bytes from the input queue.
600 *
601 * \param btrn The buffer tree node.
602 * \param numbytes The number of bytes to be deallocated.
603 *
604 * This function must be used to get rid of existing buffer references in the
605 * node's input queue. If no references to a buffer remain, the underlying
606 * buffers are either freed (in the non-buffer tree case) or the read head of
607 * the buffer pool is being advanced.
608 *
609 * Note that \a numbytes may be smaller than the buffer size. In this case the
610 * buffer is not deallocated and subsequent calls to btr_next_buffer() return
611 * the remaining part of the buffer.
612 */
613 void btr_consume(struct btr_node *btrn, size_t numbytes)
614 {
615 struct btr_buffer_reference *br, *tmp;
616 size_t sz;
617
618 if (numbytes == 0)
619 return;
620 br = get_first_input_br(btrn);
621 assert(br);
622
623 if (br->wrap_count == 0) {
624 /*
625 * No wrap buffer. Drop buffer references whose buffer
626 * has been fully used. */
627 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn) {
628 if (br->consumed + numbytes <= br->btrb->size) {
629 br->consumed += numbytes;
630 if (br->consumed == br->btrb->size)
631 btr_drop_buffer_reference(br);
632 return;
633 }
634 numbytes -= br->btrb->size - br->consumed;
635 btr_drop_buffer_reference(br);
636 }
637 assert(true);
638 }
639 /*
640 * We have a wrap buffer, consume from it. If in total, i.e. including
641 * previous calls to brt_consume(), less than wrap_count has been
642 * consumed, there's nothing more we can do.
643 *
644 * Otherwise we drop the wrap buffer and consume from subsequent
645 * buffers of the input queue the correct amount of bytes. This is the
646 * total number of bytes that have been consumed from the wrap buffer.
647 */
648 PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes,
649 br_available_bytes(br));
650
651 assert(numbytes <= br_available_bytes(br));
652 if (br->consumed + numbytes < br->wrap_count) {
653 br->consumed += numbytes;
654 return;
655 }
656 PARA_DEBUG_LOG("dropping wrap buffer (%zu bytes)\n", br->btrb->size);
657 /* get rid of the wrap buffer */
658 sz = br->consumed + numbytes;
659 btr_drop_buffer_reference(br);
660 return btr_consume(btrn, sz);
661 }
662
663 static void flush_input_queue(struct btr_node *btrn)
664 {
665 struct btr_buffer_reference *br, *tmp;
666 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
667 btr_drop_buffer_reference(br);
668 }
669
670 /**
671 * Free all resources allocated by btr_new_node().
672 *
673 * Like free(3), it is OK to call this with a \p NULL pointer argument.
674 */
675 void btr_free_node(struct btr_node *btrn)
676 {
677 if (!btrn)
678 return;
679 free(btrn->name);
680 free(btrn);
681 }
682
683 /**
684 * Remove a node from a buffer tree.
685 *
686 * \param btrn The node to remove.
687 *
688 * This makes all child nodes of \a btrn orphans and removes \a btrn from the
689 * list of children of its parent. Moreover, the input queue of \a btrn is
690 * flushed if it is not empty.
691 *
692 * \sa \ref btr_splice_out_node.
693 */
694 void btr_remove_node(struct btr_node *btrn)
695 {
696 struct btr_node *ch;
697
698 if (!btrn)
699 return;
700 PARA_NOTICE_LOG("removing btr node %s from buffer tree\n", btrn->name);
701 FOR_EACH_CHILD(ch, btrn)
702 ch->parent = NULL;
703 flush_input_queue(btrn);
704 if (btrn->parent)
705 list_del(&btrn->node);
706 }
707
708 /**
709 * Return the amount of available input bytes of a buffer tree node.
710 *
711 * \param btrn The node whose input size should be computed.
712 *
713 * \return The total number of bytes available in the node's input
714 * queue.
715 *
716 * This simply iterates over all buffer references in the input queue and
717 * returns the sum of the sizes of all references.
718 */
719 size_t btr_get_input_queue_size(struct btr_node *btrn)
720 {
721 struct btr_buffer_reference *br;
722 size_t size = 0, wrap_consumed = 0;
723
724 FOR_EACH_BUFFER_REF(br, btrn) {
725 if (br->wrap_count != 0) {
726 wrap_consumed = br->consumed;
727 continue;
728 }
729 size += br_available_bytes(br);
730 }
731 assert(wrap_consumed <= size);
732 size -= wrap_consumed;
733 return size;
734 }
735
736 /**
737 * Remove a node from the buffer tree, reconnecting parent and children.
738 *
739 * \param btrn The node to splice out.
740 *
741 * This function is used by buffer tree nodes that do not exist during the
742 * whole lifetime of the buffer tree. Unlike btr_remove_node(), calling
743 * btr_splice_out_node() does not split the tree into disconnected components
744 * but reconnects the buffer tree by making all child nodes of \a btrn children
745 * of the parent of \a btrn.
746 */
747 void btr_splice_out_node(struct btr_node *btrn)
748 {
749 struct btr_node *ch, *tmp;
750
751 assert(btrn);
752 PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
753 btr_pushdown(btrn);
754 if (btrn->parent)
755 list_del(&btrn->node);
756 FOR_EACH_CHILD_SAFE(ch, tmp, btrn) {
757 PARA_INFO_LOG("parent(%s): %s\n", ch->name,
758 btrn->parent? btrn->parent->name : "NULL");
759 ch->parent = btrn->parent;
760 if (btrn->parent)
761 list_move(&ch->node, &btrn->parent->children);
762 }
763 assert(list_empty(&btrn->children));
764 }
765
766 /**
767 * Return number of queued output bytes of a buffer tree node.
768 *
769 * \param btrn The node whose output queue size should be computed.
770 *
771 * This function iterates over all children of the given node and returns the
772 * size of the largest input queue.
773 */
774 size_t btr_get_output_queue_size(struct btr_node *btrn)
775 {
776 size_t max_size = 0;
777 struct btr_node *ch;
778
779 FOR_EACH_CHILD(ch, btrn) {
780 size_t size = btr_get_input_queue_size(ch);
781 max_size = PARA_MAX(max_size, size);
782 }
783 return max_size;
784 }
785
786 /**
787 * Execute a inter-node command on a parent node.
788 *
789 * \param btrn The node to start looking.
790 * \param command The command to execute.
791 * \param value_result Additional arguments and result value.
792 *
793 * This function traverses the buffer tree upwards and looks for parent nodes
794 * of \a btrn that understands \a command. On the first such node the command
795 * is executed, and the result is stored in \a value_result.
796 *
797 * \return \p -ENOTSUP if no parent node of \a btrn understands \a command.
798 * Otherwise the return value of the command handler is returned.
799 */
800 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
801 {
802 int ret;
803
804 for (; btrn; btrn = btrn->parent) {
805 struct btr_node *parent = btrn->parent;
806 if (!parent)
807 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
808 if (!parent->execute)
809 continue;
810 PARA_INFO_LOG("parent: %s, cmd: %s\n", parent->name, command);
811 ret = parent->execute(parent, command, value_result);
812 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
813 continue;
814 if (ret < 0)
815 return ret;
816 if (value_result && *value_result)
817 PARA_NOTICE_LOG("%s(%s): %s\n", command, parent->name,
818 *value_result);
819 return 1;
820 }
821 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
822 }
823
824 /**
825 * Obtain the context of a buffer node tree.
826 *
827 * The returned pointer equals the context pointer used at creation time of the
828 * node.
829 *
830 * \sa btr_new_node(), struct \ref btr_node_description.
831 */
832 void *btr_context(struct btr_node *btrn)
833 {
834 return btrn->context;
835 }
836
837 static bool need_buffer_pool_merge(struct btr_node *btrn)
838 {
839 struct btr_buffer_reference *br = get_first_input_br(btrn);
840
841 if (!br)
842 return false;
843 if (br->wrap_count != 0)
844 return true;
845 if (br->btrb->pool)
846 return true;
847 return false;
848 }
849
850 static void merge_input_pool(struct btr_node *btrn, size_t dest_size)
851 {
852 struct btr_buffer_reference *br, *wbr = NULL;
853 int num_refs; /* including wrap buffer */
854 char *buf, *buf1 = NULL, *buf2 = NULL;
855 size_t sz, sz1 = 0, sz2 = 0, wb_consumed = 0;
856
857 br = get_first_input_br(btrn);
858 if (!br || br_available_bytes(br) >= dest_size)
859 return;
860 num_refs = 0;
861 FOR_EACH_BUFFER_REF(br, btrn) {
862 num_refs++;
863 sz = btr_get_buffer_by_reference(br, &buf);
864 if (sz == 0)
865 break;
866 if (br->wrap_count != 0) {
867 assert(!wbr);
868 assert(num_refs == 1);
869 wbr = br;
870 if (sz >= dest_size)
871 return;
872 wb_consumed = br->consumed;
873 continue;
874 }
875 if (!buf1) {
876 buf1 = buf;
877 sz1 = sz;
878 goto next;
879 }
880 if (buf1 + sz1 == buf) {
881 sz1 += sz;
882 goto next;
883 }
884 if (!buf2) {
885 buf2 = buf;
886 sz2 = sz;
887 goto next;
888 }
889 assert(buf2 + sz2 == buf);
890 sz2 += sz;
891 next:
892 if (sz1 + sz2 >= dest_size + wb_consumed)
893 break;
894 }
895 if (!buf2) /* nothing to do */
896 return;
897 assert(buf1 && sz2 > 0);
898 /*
899 * If the second buffer is large, we only take the first part of it to
900 * avoid having to memcpy() huge buffers.
901 */
902 sz2 = PARA_MIN(sz2, (size_t)(64 * 1024));
903 if (!wbr) {
904 /* Make a new wrap buffer combining buf1 and buf2. */
905 sz = sz1 + sz2;
906 buf = para_malloc(sz);
907 PARA_DEBUG_LOG("merging input buffers: (%p:%zu, %p:%zu) -> %p:%zu\n",
908 buf1, sz1, buf2, sz2, buf, sz);
909 memcpy(buf, buf1, sz1);
910 memcpy(buf + sz1, buf2, sz2);
911 br = para_calloc(sizeof(*br));
912 br->btrb = new_btrb(buf, sz);
913 br->btrb->refcount = 1;
914 br->consumed = 0;
915 /* This is a wrap buffer */
916 br->wrap_count = sz1;
917 para_list_add(&br->node, &btrn->input_queue);
918 return;
919 }
920 /*
921 * We already have a wrap buffer, but it is too small. It might be
922 * partially used.
923 */
924 if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
925 return;
926 sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */
927 PARA_DEBUG_LOG("increasing wrap buffer %zu -> %zu\n", wbr->btrb->size,
928 wbr->btrb->size + sz);
929 wbr->btrb->size += sz;
930 wbr->btrb->buf = para_realloc(wbr->btrb->buf, wbr->btrb->size);
931 /* copy the new data to the end of the reallocated buffer */
932 assert(sz2 >= sz);
933 memcpy(wbr->btrb->buf + wbr->btrb->size - sz, buf2 + sz2 - sz, sz);
934 }
935
936 /**
937 * Merge the first two input buffers into one.
938 *
939 * This is a quite expensive operation.
940 *
941 * \return The number of buffers that have been available (zero, one or two).
942 */
943 static int merge_input(struct btr_node *btrn)
944 {
945 struct btr_buffer_reference *brs[2], *br;
946 char *bufs[2], *buf;
947 size_t szs[2], sz;
948 int i;
949
950 if (list_empty(&btrn->input_queue))
951 return 0;
952 if (list_is_singular(&btrn->input_queue))
953 return 1;
954 i = 0;
955 /* get references to the first two buffers */
956 FOR_EACH_BUFFER_REF(br, btrn) {
957 brs[i] = br;
958 szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
959 i++;
960 if (i == 2)
961 break;
962 }
963 assert(i == 2);
964 /* make a new btrb that combines the two buffers and a br to it. */
965 sz = szs[0] + szs[1];
966 buf = para_malloc(sz);
967 PARA_DEBUG_LOG("%s: memory merging input buffers: (%zu, %zu) -> %zu\n",
968 btrn->name, szs[0], szs[1], sz);
969 memcpy(buf, bufs[0], szs[0]);
970 memcpy(buf + szs[0], bufs[1], szs[1]);
971
972 br = para_calloc(sizeof(*br));
973 br->btrb = new_btrb(buf, sz);
974 br->btrb->refcount = 1;
975
976 /* replace the first two refs by the new one */
977 btr_drop_buffer_reference(brs[0]);
978 btr_drop_buffer_reference(brs[1]);
979 para_list_add(&br->node, &btrn->input_queue);
980 return 2;
981 }
982
983 /**
984 * Combine input queue buffers.
985 *
986 * \param btrn The buffer tree node whose input should be merged.
987 * \param dest_size Stop merging if a buffer of at least this size exists.
988 *
989 * Used to combine as many buffers as needed into a single buffer whose size is
990 * at least \a dest_size. This function is rather cheap in case the parent node
991 * uses buffer pools and rather expensive otherwise.
992 *
993 * Note that if less than \a dest_size bytes are available in total, this
994 * function does nothing and subsequent calls to btr_next_buffer() will still
995 * return a buffer size less than \a dest_size.
996 */
997 void btr_merge(struct btr_node *btrn, size_t dest_size)
998 {
999 if (need_buffer_pool_merge(btrn))
1000 return merge_input_pool(btrn, dest_size);
1001 for (;;) {
1002 char *buf;
1003 size_t len = btr_next_buffer(btrn, &buf);
1004 if (len >= dest_size)
1005 return;
1006 PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len, dest_size);
1007 if (merge_input(btrn) < 2)
1008 return;
1009 }
1010 }
1011
1012 static bool btr_eof(struct btr_node *btrn)
1013 {
1014 char *buf;
1015 size_t len = btr_next_buffer(btrn, &buf);
1016
1017 return (len == 0 && btr_no_parent(btrn));
1018 }
1019
1020 static void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
1021 {
1022 struct btr_node *ch;
1023 const char spaces[] = " ", *space = spaces + 16 - depth;
1024
1025 if (depth > 16)
1026 return;
1027 para_log(loglevel, "%s%s\n", space, btrn->name);
1028 FOR_EACH_CHILD(ch, btrn)
1029 log_tree_recursively(ch, loglevel, depth + 1);
1030 }
1031
1032 /**
1033 * Write the current buffer (sub-)tree to the log.
1034 *
1035 * \param btrn Start logging at this node.
1036 * \param loglevel Set severity with which the tree should be logged.
1037 */
1038 void btr_log_tree(struct btr_node *btrn, int loglevel)
1039 {
1040 return log_tree_recursively(btrn, loglevel, 0);
1041 }
1042
1043 /**
1044 * Find the node with the given name in the buffer tree.
1045 *
1046 * \param name The name of the node to search.
1047 * \param root Where to start the search.
1048 *
1049 * \return A pointer to the node with the given name on success. If \a name is
1050 * \p NULL, the function returns \a root. If there is no node with the given
1051 * name, \p NULL is returned.
1052 */
1053 struct btr_node *btr_search_node(const char *name, struct btr_node *root)
1054 {
1055 struct btr_node *ch;
1056
1057 if (!name)
1058 return root;
1059 if (!strcmp(root->name, name))
1060 return root;
1061 FOR_EACH_CHILD(ch, root) {
1062 struct btr_node *result = btr_search_node(name, ch);
1063 if (result)
1064 return result;
1065 }
1066 return NULL;
1067 }
1068
1069 /** 640K ought to be enough for everybody ;) */
1070 #define BTRN_MAX_PENDING (640 * 1024)
1071
1072 /**
1073 * Return the current state of a buffer tree node.
1074 *
1075 * \param btrn The node whose state should be queried.
1076 * \param min_iqs The minimal input queue size.
1077 * \param type The supposed type of \a btrn.
1078 *
1079 * Most users of the buffer tree subsystem call this function from both
1080 * their pre_select and the post_select methods.
1081 *
1082 * \return Negative if an error condition was detected, zero if there
1083 * is nothing to do and positive otherwise.
1084 *
1085 * Examples:
1086 *
1087 * - If a non-root node has no parent and an empty input queue, the function
1088 * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p
1089 * -E_BTR_NO_CHILD is returned.
1090 *
1091 * - If less than \a min_iqs many bytes are available in the input queue and no
1092 * EOF condition was detected, the function returns zero.
1093 *
1094 * - If there's plenty of data left in the input queue of the children of \a
1095 * btrn, the function also returns zero in order to bound the memory usage of
1096 * the buffer tree.
1097 */
1098 int btr_node_status(struct btr_node *btrn, size_t min_iqs,
1099 enum btr_node_type type)
1100 {
1101 size_t iqs;
1102
1103 assert(btrn);
1104 if (type != BTR_NT_LEAF) {
1105 if (btr_no_children(btrn))
1106 return -E_BTR_NO_CHILD;
1107 if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
1108 return 0;
1109 }
1110 if (type != BTR_NT_ROOT) {
1111 if (btr_eof(btrn))
1112 return -E_BTR_EOF;
1113 iqs = btr_get_input_queue_size(btrn);
1114 if (iqs == 0) /* we have a parent, because not eof */
1115 return 0;
1116 if (iqs < min_iqs && !btr_no_parent(btrn))
1117 return 0;
1118 }
1119 return 1;
1120 }
1121
1122 /**
1123 * Get the time of the first I/O for a buffer tree node.
1124 *
1125 * \param btrn The node whose I/O time should be obtained.
1126 * \param tv Result pointer.
1127 *
1128 * Mainly useful for the time display of para_audiod.
1129 */
1130 void btr_get_node_start(struct btr_node *btrn, struct timeval *tv)
1131 {
1132 *tv = btrn->start;
1133 }