Merge branch 't/audiod_cleanups'
[paraslash.git] / buffer_tree.c
1 /*
2 * Copyright (C) 2009-2013 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
10 #include "para.h"
11 #include "list.h"
12 #include "string.h"
13 #include "buffer_tree.h"
14 #include "error.h"
15 #include "sched.h"
16
17 /* whead = NULL means area full */
18 struct btr_pool {
19 char *name;
20 char *area_start;
21 char *area_end;
22 char *rhead;
23 char *whead;
24 };
25
26 struct btr_buffer {
27 char *buf;
28 size_t size;
29 /** The number of references to this buffer. */
30 int refcount;
31 /* NULL means no buffer pool but a malloced buffer. */
32 struct btr_pool *pool;
33 /* Only relevant if pool is NULL. */
34 bool dont_free;
35 };
36
37 struct btr_buffer_reference {
38 struct btr_buffer *btrb;
39 size_t consumed;
40 /* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
41 struct list_head node;
42 size_t wrap_count;
43 };
44
45 struct btr_node {
46 char *name;
47 struct btr_node *parent;
48 /* The position of this btr node in the buffer tree. */
49 struct list_head node;
50 /* The children nodes of this btr node are linked together in a list. */
51 struct list_head children;
52 /* Time of first data transfer. */
53 struct timeval start;
54 /**
55 * The input queue is a list of references to btr buffers. Each item on
56 * the list represents an input buffer which has not been completely
57 * used by this btr node.
58 */
59 struct list_head input_queue;
60 btr_command_handler execute;
61 void *context;
62 };
63
64 /**
65 * Create a new buffer pool.
66 *
67 * \param name The name of the new buffer pool.
68 * \param area_size The size in bytes of the pool area.
69 *
70 * \return An opaque pointer to the newly created buffer pool. It must be
71 * passed to btr_pool_free() after it is no longer used to deallocate all
72 * resources.
73 */
74 struct btr_pool *btr_pool_new(const char *name, size_t area_size)
75 {
76 struct btr_pool *btrp;
77
78 PARA_INFO_LOG("%s, %zu bytes\n", name, area_size);
79 btrp = para_malloc(sizeof(*btrp));
80 btrp->area_start = para_malloc(area_size);
81 btrp->area_end = btrp->area_start + area_size;
82 btrp->rhead = btrp->area_start;
83 btrp->whead = btrp->area_start;
84 btrp->name = para_strdup(name);
85 return btrp;
86 }
87
88 /**
89 * Deallocate resources used by a buffer pool.
90 *
91 * \param btrp A pointer obtained via btr_pool_new().
92 */
93 void btr_pool_free(struct btr_pool *btrp)
94 {
95 if (!btrp)
96 return;
97 free(btrp->area_start);
98 free(btrp->name);
99 free(btrp);
100 }
101
102 /**
103 * Return the size of the buffer pool area.
104 *
105 * \param btrp The buffer pool.
106 *
107 * \return The same value which was passed during creation time to
108 * btr_pool_new().
109 */
110 size_t btr_pool_size(struct btr_pool *btrp)
111 {
112 return btrp->area_end - btrp->area_start;
113 }
114
115 static size_t btr_pool_filled(struct btr_pool *btrp)
116 {
117 if (!btrp->whead)
118 return btr_pool_size(btrp);
119 if (btrp->rhead <= btrp->whead)
120 return btrp->whead - btrp->rhead;
121 return btr_pool_size(btrp) - (btrp->rhead - btrp->whead);
122 }
123
124 /**
125 * Get the number of unused bytes in the buffer pool.
126 *
127 * \param btrp The pool.
128 *
129 * \return The number of bytes that can currently be allocated.
130 *
131 * Note that in general the returned number of bytes is not available as a
132 * single contiguous buffer. Use btr_pool_available() to obtain the length of
133 * the largest contiguous buffer that can currently be allocated from the
134 * buffer pool.
135 */
136 size_t btr_pool_unused(struct btr_pool *btrp)
137 {
138 return btr_pool_size(btrp) - btr_pool_filled(btrp);
139 }
140
141 /*
142 * Return maximal size available for one read. This is
143 * smaller than the value returned by btr_pool_unused().
144 */
145 static size_t btr_pool_available(struct btr_pool *btrp)
146 {
147 if (!btrp->whead)
148 return 0;
149 if (btrp->rhead <= btrp->whead)
150 return btrp->area_end - btrp->whead;
151 return btrp->rhead - btrp->whead;
152 }
153
154 /**
155 * Obtain the current write head.
156 *
157 * \param btrp The buffer pool.
158 * \param result The write head is returned here.
159 *
160 * \return The maximal amount of bytes that may be written to the returned
161 * buffer.
162 */
163 size_t btr_pool_get_buffer(struct btr_pool *btrp, char **result)
164 {
165 if (result)
166 *result = btrp->whead;
167 return btr_pool_available(btrp);
168 }
169
170 /**
171 * Get references to buffers pointing to free space of the buffer pool area.
172 *
173 * \param btrp The buffer pool.
174 * \param iov The scatter array.
175 *
176 * \return Zero if the buffer pool is full, one if the free space of the buffer
177 * pool area is available as a single contiguous buffer, two if the free space
178 * consists of two buffers. If this function returns the value n, then n
179 * elements of \a iov are initialized.
180 */
181 int btr_pool_get_buffers(struct btr_pool *btrp, struct iovec iov[2])
182 {
183 size_t sz, unused;
184 char *buf;
185
186 sz = btr_pool_get_buffer(btrp, &buf);
187 if (sz == 0)
188 return 0;
189 iov[0].iov_len = sz;
190 iov[0].iov_base = buf;
191 unused = btr_pool_unused(btrp);
192 if (sz == unused)
193 return 1;
194 iov[1].iov_len = unused - sz;
195 iov[1].iov_base = btrp->area_start;
196 return 2;
197 }
198
199 /**
200 * Mark a part of the buffer pool area as allocated.
201 *
202 * \param btrp The buffer pool.
203 * \param size The amount of bytes to be allocated.
204 *
205 * This is usually called after the caller wrote to the buffer obtained by
206 * btr_pool_get_buffer().
207 */
208 static void btr_pool_allocate(struct btr_pool *btrp, size_t size)
209 {
210 char *end;
211
212 if (size == 0)
213 return;
214 assert(size <= btr_pool_available(btrp));
215 end = btrp->whead + size;
216 assert(end <= btrp->area_end);
217
218 if (end == btrp->area_end) {
219 PARA_DEBUG_LOG("%s: end of pool area reached\n", btrp->name);
220 end = btrp->area_start;
221 }
222 if (end == btrp->rhead) {
223 PARA_DEBUG_LOG("%s btrp buffer full\n", btrp->name);
224 end = NULL; /* buffer full */
225 }
226 btrp->whead = end;
227 }
228
229 static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
230 {
231 char *end = btrp->rhead + size;
232
233 if (size == 0)
234 return;
235 assert(end <= btrp->area_end);
236 assert(size <= btr_pool_filled(btrp));
237 if (end == btrp->area_end)
238 end = btrp->area_start;
239 if (!btrp->whead)
240 btrp->whead = btrp->rhead;
241 btrp->rhead = end;
242 if (btrp->rhead == btrp->whead)
243 btrp->rhead = btrp->whead = btrp->area_start;
244 }
245
246 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
247 &((_btrn)->children), node)
248 #define FOR_EACH_CHILD_SAFE(_tn, _tmp, _btrn) \
249 list_for_each_entry_safe((_tn), (_tmp), &((_btrn)->children), node)
250
251 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
252 list_for_each_entry((_br), &(_btrn)->input_queue, node)
253 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
254 list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
255
256 /**
257 * Create a new buffer tree node.
258 *
259 * \param bnd Specifies how to create the new node.
260 *
261 * \return A pointer to the newly allocated node.
262 *
263 * This function always succeeds (or calls exit()). The returned pointer must
264 * be freed using btr_free_node() after the node has been removed from the
265 * buffer tree via btr_remove_node().
266 */
267 struct btr_node *btr_new_node(struct btr_node_description *bnd)
268 {
269 struct btr_node *btrn = para_malloc(sizeof(*btrn));
270
271 btrn->name = para_strdup(bnd->name);
272 btrn->parent = bnd->parent;
273 btrn->execute = bnd->handler;
274 btrn->context = bnd->context;
275 btrn->start.tv_sec = 0;
276 btrn->start.tv_usec = 0;
277 INIT_LIST_HEAD(&btrn->children);
278 INIT_LIST_HEAD(&btrn->input_queue);
279 if (!bnd->child) {
280 if (bnd->parent) {
281 list_add_tail(&btrn->node, &bnd->parent->children);
282 PARA_INFO_LOG("new leaf node: %s (child of %s)\n",
283 bnd->name, bnd->parent->name);
284 } else
285 PARA_INFO_LOG("added %s as btr root\n", bnd->name);
286 goto out;
287 }
288 if (!bnd->parent) {
289 assert(!bnd->child->parent);
290 PARA_INFO_LOG("new root: %s (was %s)\n",
291 bnd->name, bnd->child->name);
292 btrn->parent = NULL;
293 list_add_tail(&bnd->child->node, &btrn->children);
294 /* link it in */
295 bnd->child->parent = btrn;
296 goto out;
297 }
298 list_add_tail(&btrn->node, &bnd->parent->children);
299 list_move(&bnd->child->node, &btrn->children);
300 bnd->child->parent = btrn;
301 PARA_INFO_LOG("added %s as internal node\n", bnd->name);
302 out:
303 return btrn;
304 }
305
306 /*
307 * Allocate a new btr buffer.
308 *
309 * The freshly allocated buffer will have a zero refcount and will
310 * not be associated with a btr pool.
311 */
312 static struct btr_buffer *new_btrb(char *buf, size_t size)
313 {
314 struct btr_buffer *btrb = para_calloc(sizeof(*btrb));
315
316 btrb->buf = buf;
317 btrb->size = size;
318 return btrb;
319 }
320
321 static void dealloc_buffer(struct btr_buffer *btrb)
322 {
323 if (btrb->pool)
324 btr_pool_deallocate(btrb->pool, btrb->size);
325 else if (!btrb->dont_free)
326 free(btrb->buf);
327 }
328
329 static struct btr_buffer_reference *get_first_input_br(struct btr_node *btrn)
330 {
331 if (list_empty(&btrn->input_queue))
332 return NULL;
333 return list_first_entry(&btrn->input_queue,
334 struct btr_buffer_reference, node);
335 }
336
337 /*
338 * Deallocate the reference, release the resources if refcount drops to zero.
339 */
340 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
341 {
342 struct btr_buffer *btrb = br->btrb;
343
344 list_del(&br->node);
345 free(br);
346 btrb->refcount--;
347 if (btrb->refcount == 0) {
348 dealloc_buffer(btrb);
349 free(btrb);
350 }
351 }
352
353 static void add_btrb_to_children(struct btr_buffer *btrb,
354 struct btr_node *btrn, size_t consumed)
355 {
356 struct btr_node *ch;
357
358 if (btrn->start.tv_sec == 0)
359 btrn->start = *now;
360 FOR_EACH_CHILD(ch, btrn) {
361 struct btr_buffer_reference *br = para_calloc(sizeof(*br));
362 br->btrb = btrb;
363 br->consumed = consumed;
364 list_add_tail(&br->node, &ch->input_queue);
365 btrb->refcount++;
366 if (ch->start.tv_sec == 0)
367 ch->start = *now;
368 }
369 }
370
371 /**
372 * Insert a malloced buffer into the buffer tree.
373 *
374 * \param buf The buffer to insert.
375 * \param size The size of \a buf in bytes.
376 * \param btrn Position in the buffer tree to create the output.
377 *
378 * This creates references to \a buf and adds these references to each child of
379 * \a btrn. The buffer will be freed using standard free() once no buffer tree
380 * node is referencing it any more.
381 *
382 * Note that this function must not be used if \a buf was obtained from a
383 * buffer pool. Use btr_add_output_pool() in this case.
384 */
385 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
386 {
387 struct btr_buffer *btrb;
388
389 if (size == 0)
390 return;
391 if (list_empty(&btrn->children)) {
392 free(buf);
393 return;
394 }
395 btrb = new_btrb(buf, size);
396 add_btrb_to_children(btrb, btrn, 0);
397 }
398
399 /**
400 * Insert a buffer into the buffer tree, non-freeing variant.
401 *
402 * \param buf See \ref btr_add_output().
403 * \param size See \ref btr_add_output().
404 * \param btrn See \ref btr_add_output().
405 *
406 * This is similar to btr_add_output() but additionally sets the \p dont_free
407 * flag on \a buf. If the refcount for the buffer drops to zero, \a buf will
408 * not be deallocated if this flag is set.
409 *
410 * The \p dont_free bit also prevents the children of \a btrn from modifying
411 * the buffer contents inplace. Specifically, \ref btr_inplace_ok() returns
412 * false if there is any buffer in the input queue with the \p dont_free bit
413 * set.
414 */
415 void btr_add_output_dont_free(const char *buf, size_t size, struct btr_node *btrn)
416 {
417 struct btr_buffer *btrb;
418
419 if (size == 0)
420 return;
421 if (list_empty(&btrn->children))
422 return;
423 btrb = new_btrb((char *)buf, size);
424 btrb->dont_free = true;
425 add_btrb_to_children(btrb, btrn, 0);
426 }
427
428 /**
429 * Feed data to child nodes of a buffer tree node.
430 *
431 * \param btrp The buffer pool.
432 * \param size The number of bytes to be allocated and fed to each child.
433 * \param btrn The node whose children are to be fed.
434 *
435 * This function allocates the amount of bytes from the buffer pool area,
436 * starting at the current value of the write head, and creates buffer
437 * references to the resulting part of the buffer pool area, one for each child
438 * of \a btrn. The references are then fed into the input queue of each child.
439 */
440 void btr_add_output_pool(struct btr_pool *btrp, size_t size,
441 struct btr_node *btrn)
442 {
443 struct btr_buffer *btrb;
444 char *buf;
445 size_t avail;
446
447 if (size == 0)
448 return;
449 if (list_empty(&btrn->children))
450 return;
451 avail = btr_pool_get_buffer(btrp, &buf);
452 assert(avail >= size);
453 btr_pool_allocate(btrp, size);
454 btrb = new_btrb(buf, size);
455 btrb->pool = btrp;
456 add_btrb_to_children(btrb, btrn, 0);
457 }
458
459 /**
460 * Copy data to write head of a buffer pool and feed it to all children nodes.
461 *
462 * \param src The source buffer.
463 * \param n The size of the source buffer in bytes.
464 * \param btrp The destination buffer pool.
465 * \param btrn Add the data as output of this node.
466 *
467 * This is expensive. The caller must make sure the data fits into the buffer
468 * pool area.
469 */
470 void btr_copy(const void *src, size_t n, struct btr_pool *btrp,
471 struct btr_node *btrn)
472 {
473 char *buf;
474 size_t sz, copy;
475
476 if (n == 0)
477 return;
478 assert(n <= btr_pool_unused(btrp));
479 sz = btr_pool_get_buffer(btrp, &buf);
480 copy = PARA_MIN(sz, n);
481 memcpy(buf, src, copy);
482 btr_add_output_pool(btrp, copy, btrn);
483 if (copy == n)
484 return;
485 sz = btr_pool_get_buffer(btrp, &buf);
486 assert(sz >= n - copy);
487 memcpy(buf, src + copy, n - copy);
488 btr_add_output_pool(btrp, n - copy, btrn);
489 }
490
491 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
492 {
493 add_btrb_to_children(br->btrb, btrn, br->consumed);
494 btr_drop_buffer_reference(br);
495 }
496
497 /**
498 * Feed all buffer references of the input queue through the output channel.
499 *
500 * \param btrn The node whose buffer references should be pushed down.
501 *
502 * This function is useful for filters that do not change the contents of the
503 * buffers at all, like the wav filter or the amp filter if no amplification
504 * was specified. This function is rather cheap.
505 *
506 * \sa \ref btr_pushdown_one().
507 */
508 void btr_pushdown(struct btr_node *btrn)
509 {
510 struct btr_buffer_reference *br, *tmp;
511
512 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
513 btr_pushdown_br(br, btrn);
514 }
515
516 /**
517 * Feed the next buffer of the input queue through the output channel.
518 *
519 * \param btrn The node whose first input queue buffer should be pushed down.
520 *
521 * This works like \ref btr_pushdown() but pushes down only one buffer
522 * reference.
523 */
524 void btr_pushdown_one(struct btr_node *btrn)
525 {
526 struct btr_buffer_reference *br;
527
528 if (list_empty(&btrn->input_queue))
529 return;
530 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
531 btr_pushdown_br(br, btrn);
532 }
533
534 /*
535 * Find out whether a node is a leaf node.
536 *
537 * \param btrn The node to check.
538 *
539 * \return True if this node has no children. False otherwise.
540 */
541 static bool btr_no_children(struct btr_node *btrn)
542 {
543 return list_empty(&btrn->children);
544 }
545
546 /**
547 * Find out whether a node is an orphan.
548 *
549 * \param btrn The buffer tree node.
550 *
551 * \return True if \a btrn has no parent.
552 *
553 * This function returns true for the root node and false for any other node.
554 *
555 * After a (non-leaf) node was removed removed from the tree, the function
556 * returns true for all child nodes.
557 */
558 bool btr_no_parent(struct btr_node *btrn)
559 {
560 return !btrn->parent;
561 }
562
563 /**
564 * Find out whether it is OK to change an input buffer.
565 *
566 * \param btrn The buffer tree node to check.
567 *
568 * This is used by filters that produce exactly the same amount of output as
569 * there is input. The amp filter which multiplies each sample by some number
570 * is an example of such a filter. If there are no other nodes in the buffer
571 * tree that read the same input stream (i.e. if \a btrn has no siblings), a
572 * node may modify its input buffer directly and push down the modified buffer
573 * to its children, thereby avoiding to allocate a possibly large additional
574 * buffer.
575 *
576 * Since the buffer tree may change at any time, this function should be called
577 * during each post_select call.
578 *
579 * \return True if \a btrn has no siblings.
580 */
581 bool btr_inplace_ok(struct btr_node *btrn)
582 {
583 struct btr_buffer_reference *br;
584 FOR_EACH_BUFFER_REF(br, btrn) {
585 struct btr_buffer *btrb = br->btrb;
586 if (btrb->refcount > 1)
587 return false;
588 if (btrb->dont_free == true)
589 return false;
590 }
591 return true;
592 }
593
594 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
595 {
596 return br->btrb->size - br->consumed;
597 }
598
599 static size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
600 {
601 if (buf)
602 *buf = br->btrb->buf + br->consumed;
603 return br_available_bytes(br);
604 }
605
606 /**
607 * Obtain the next buffer of the input queue, omitting data.
608 *
609 * \param btrn The node whose input queue is to be queried.
610 * \param omit Number of bytes to be omitted.
611 * \param bufp Result pointer. It is OK to pass \p NULL here.
612 *
613 * If a buffer tree node needs more input data but can not consume the data it
614 * already has (because it might be needed again later) this function can be
615 * used instead of btr_next_buffer() to get a reference to the buffer obtained
616 * by skipping the given number of bytes. Skipped input bytes are not consumed.
617 *
618 * With a zero \a omit argument, this function is equivalent to \ref
619 * btr_next_buffer().
620 *
621 * \return Number of bytes in \a bufp. If there are less than or equal to \a
622 * omit many bytes available in the input queue of the buffer tree node pointed
623 * to by \a btrn, the function returns zero and the value of \a bufp is
624 * undefined.
625 */
626 size_t btr_next_buffer_omit(struct btr_node *btrn, size_t omit, char **bufp)
627 {
628 struct btr_buffer_reference *br;
629 size_t wrap_count, sz, rv = 0;
630 char *buf, *result = NULL;
631
632 br = get_first_input_br(btrn);
633 if (!br)
634 return 0;
635 wrap_count = br->wrap_count;
636 if (wrap_count > 0) { /* we have a wrap buffer */
637 sz = btr_get_buffer_by_reference(br, &buf);
638 if (sz > omit) { /* and it's big enough */
639 result = buf + omit;
640 rv = sz - omit;
641 /*
642 * Wrap buffers are allocated by malloc(), so the next
643 * buffer ref will not align nicely, so we return the
644 * tail of the wrap buffer.
645 */
646 goto out;
647 }
648 /*
649 * The next wrap_count bytes exist twice, in the wrap buffer
650 * and as a buffer reference in the buffer tree pool.
651 */
652 omit += wrap_count;
653 }
654 /*
655 * For buffer tree pools, the buffers in the list align, i.e. the next
656 * buffer in the list starts directly at the end of its predecessor. In
657 * this case we merge adjacent buffers and return one larger buffer
658 * instead.
659 */
660 FOR_EACH_BUFFER_REF(br, btrn) {
661 sz = btr_get_buffer_by_reference(br, &buf);
662 if (result) {
663 if (result + rv != buf)
664 goto out;
665 rv += sz;
666 } else if (sz > omit) {
667 result = buf + omit;
668 rv = sz - omit;
669 } else
670 omit -= sz;
671 }
672 if (!result)
673 return 0;
674 out:
675 if (bufp)
676 *bufp = result;
677 return rv;
678 }
679
680 /**
681 * Obtain the next buffer of the input queue of a buffer tree node.
682 *
683 * \param btrn The node whose input queue is to be queried.
684 * \param bufp Result pointer.
685 *
686 * \return The number of bytes that can be read from buf.
687 *
688 * The call of this function is is equivalent to calling \ref
689 * btr_next_buffer_omit() with an \a omit value of zero.
690 */
691 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
692 {
693 return btr_next_buffer_omit(btrn, 0, bufp);
694 }
695
696 /**
697 * Deallocate the given number of bytes from the input queue.
698 *
699 * \param btrn The buffer tree node.
700 * \param numbytes The number of bytes to be deallocated.
701 *
702 * This function must be used to get rid of existing buffer references in the
703 * node's input queue. If no references to a buffer remain, the underlying
704 * buffers are either freed (in the non-buffer pool case) or the read head of
705 * the buffer pool is being advanced.
706 *
707 * Note that \a numbytes may be smaller than the buffer size. In this case the
708 * buffer is not deallocated and subsequent calls to btr_next_buffer() return
709 * the remaining part of the buffer.
710 */
711 void btr_consume(struct btr_node *btrn, size_t numbytes)
712 {
713 struct btr_buffer_reference *br, *tmp;
714 size_t sz;
715
716 if (numbytes == 0)
717 return;
718 br = get_first_input_br(btrn);
719 assert(br);
720
721 if (br->wrap_count == 0) {
722 /*
723 * No wrap buffer. Drop buffer references whose buffer
724 * has been fully used. */
725 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn) {
726 if (br->consumed + numbytes <= br->btrb->size) {
727 br->consumed += numbytes;
728 if (br->consumed == br->btrb->size)
729 btr_drop_buffer_reference(br);
730 return;
731 }
732 numbytes -= br->btrb->size - br->consumed;
733 btr_drop_buffer_reference(br);
734 }
735 assert(false);
736 }
737 /*
738 * We have a wrap buffer, consume from it. If in total, i.e. including
739 * previous calls to brt_consume(), less than wrap_count has been
740 * consumed, there's nothing more we can do.
741 *
742 * Otherwise we drop the wrap buffer and consume from subsequent
743 * buffers of the input queue the correct amount of bytes. This is the
744 * total number of bytes that have been consumed from the wrap buffer.
745 */
746 PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes,
747 br_available_bytes(br));
748
749 assert(numbytes <= br_available_bytes(br));
750 if (br->consumed + numbytes < br->wrap_count) {
751 br->consumed += numbytes;
752 return;
753 }
754 PARA_DEBUG_LOG("dropping wrap buffer (%zu bytes)\n", br->btrb->size);
755 /* get rid of the wrap buffer */
756 sz = br->consumed + numbytes;
757 btr_drop_buffer_reference(br);
758 return btr_consume(btrn, sz);
759 }
760
761 /**
762 * Clear the input queue of a buffer tree node.
763 *
764 * \param btrn The node whose input queue should be cleared.
765 */
766 void btr_drain(struct btr_node *btrn)
767 {
768 struct btr_buffer_reference *br, *tmp;
769
770 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
771 btr_drop_buffer_reference(br);
772 }
773
774 /**
775 * Remove a node from a buffer tree.
776 *
777 * \param btrnp Determines the node to remove.
778 *
779 * This orphans all children of the node given by \a btrnp and removes this
780 * node from the child list of its parent. Moreover, the input queue is flushed
781 * and the node pointer given by \a btrp is set to \p NULL.
782 *
783 * \sa \ref btr_splice_out_node.
784 */
785 void btr_remove_node(struct btr_node **btrnp)
786 {
787 struct btr_node *ch;
788 struct btr_node *btrn;
789
790 if (!btrnp)
791 return;
792 btrn = *btrnp;
793 if (!btrn)
794 goto out;
795 PARA_INFO_LOG("removing btr node %s from buffer tree\n", btrn->name);
796 FOR_EACH_CHILD(ch, btrn)
797 ch->parent = NULL;
798 btr_drain(btrn);
799 if (btrn->parent)
800 list_del(&btrn->node);
801 free(btrn->name);
802 free(btrn);
803 out:
804 *btrnp = NULL;
805 }
806
807 /**
808 * Return the amount of available input bytes of a buffer tree node.
809 *
810 * \param btrn The node whose input size should be computed.
811 *
812 * \return The total number of bytes available in the node's input
813 * queue.
814 *
815 * This simply iterates over all buffer references in the input queue and
816 * returns the sum of the sizes of all references.
817 */
818 size_t btr_get_input_queue_size(struct btr_node *btrn)
819 {
820 struct btr_buffer_reference *br;
821 size_t size = 0, wrap_consumed = 0;
822
823 FOR_EACH_BUFFER_REF(br, btrn) {
824 if (br->wrap_count != 0) {
825 wrap_consumed = br->consumed;
826 continue;
827 }
828 size += br_available_bytes(br);
829 }
830 assert(wrap_consumed <= size);
831 size -= wrap_consumed;
832 return size;
833 }
834
835 /**
836 * Remove a node from the buffer tree, reconnecting parent and children.
837 *
838 * \param btrn The node to splice out.
839 *
840 * This function is used by buffer tree nodes that do not exist during the
841 * whole lifetime of the buffer tree. Unlike btr_remove_node(), calling
842 * btr_splice_out_node() does not split the tree into disconnected components
843 * but reconnects the buffer tree by making all child nodes of \a btrn children
844 * of the parent of \a btrn.
845 */
846 void btr_splice_out_node(struct btr_node *btrn)
847 {
848 struct btr_node *ch, *tmp;
849
850 assert(btrn);
851 PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
852 btr_pushdown(btrn);
853 if (btrn->parent)
854 list_del(&btrn->node);
855 FOR_EACH_CHILD_SAFE(ch, tmp, btrn) {
856 PARA_INFO_LOG("parent(%s): %s\n", ch->name,
857 btrn->parent? btrn->parent->name : "NULL");
858 ch->parent = btrn->parent;
859 if (btrn->parent)
860 list_move(&ch->node, &btrn->parent->children);
861 else
862 list_del(&ch->node);
863 }
864 assert(list_empty(&btrn->children));
865 btrn->parent = NULL;
866 }
867
868 /**
869 * Return number of queued output bytes of a buffer tree node.
870 *
871 * \param btrn The node whose output queue size should be computed.
872 *
873 * \return This function iterates over all children of the given node and
874 * returns the size of the largest input queue.
875 */
876 size_t btr_get_output_queue_size(struct btr_node *btrn)
877 {
878 size_t max_size = 0;
879 struct btr_node *ch;
880
881 FOR_EACH_CHILD(ch, btrn) {
882 size_t size = btr_get_input_queue_size(ch);
883 max_size = PARA_MAX(max_size, size);
884 }
885 return max_size;
886 }
887
888 /**
889 * Execute an inter-node command on the given node or on a parent node.
890 *
891 * \param btrn The node to start looking.
892 * \param command The command to execute.
893 * \param value_result Additional arguments and result value.
894 *
895 * This function traverses the buffer tree from \a btrn upwards and looks for
896 * the first node that understands \a command. On this node \a command is
897 * executed, and the result is stored in \a value_result.
898 *
899 * \return \p -ENOTSUP if no parent node of \a btrn understands \a command.
900 * Otherwise the return value of the command handler is returned.
901 *
902 * \sa \ref receiver::execute, filter::execute, writer::execute.
903 */
904 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
905 {
906 int ret;
907
908 for (; btrn; btrn = btrn->parent) {
909 if (!btrn->execute)
910 continue;
911 PARA_INFO_LOG("executing %s on %s\n", command, btrn->name);
912 ret = btrn->execute(btrn, command, value_result);
913 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
914 continue;
915 if (ret < 0)
916 return ret;
917 if (value_result && *value_result)
918 PARA_INFO_LOG("%s(%s): %s\n", command, btrn->name,
919 *value_result);
920 return 1;
921 }
922 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
923 }
924
925 /**
926 * Obtain the context of a buffer node tree.
927 *
928 * \param btrn The node whose output queue size should be computed.
929 *
930 * \return A pointer to the \a context address specified at node creation time.
931 *
932 * \sa btr_new_node(), struct \ref btr_node_description.
933 */
934 void *btr_context(struct btr_node *btrn)
935 {
936 return btrn->context;
937 }
938
939 static bool need_buffer_pool_merge(struct btr_node *btrn)
940 {
941 struct btr_buffer_reference *br = get_first_input_br(btrn);
942
943 if (!br)
944 return false;
945 if (br->wrap_count != 0)
946 return true;
947 if (br->btrb->pool)
948 return true;
949 return false;
950 }
951
952 static void merge_input_pool(struct btr_node *btrn, size_t dest_size)
953 {
954 struct btr_buffer_reference *br, *wbr = NULL;
955 int num_refs; /* including wrap buffer */
956 char *buf, *buf1 = NULL, *buf2 = NULL;
957 size_t sz, sz1 = 0, sz2 = 0, wb_consumed = 0;
958
959 br = get_first_input_br(btrn);
960 if (!br || br_available_bytes(br) >= dest_size)
961 return;
962 num_refs = 0;
963 FOR_EACH_BUFFER_REF(br, btrn) {
964 num_refs++;
965 sz = btr_get_buffer_by_reference(br, &buf);
966 if (sz == 0)
967 break;
968 if (br->wrap_count != 0) {
969 assert(!wbr);
970 assert(num_refs == 1);
971 wbr = br;
972 if (sz >= dest_size)
973 return;
974 wb_consumed = br->consumed;
975 continue;
976 }
977 if (!buf1) {
978 buf1 = buf;
979 sz1 = sz;
980 goto next;
981 }
982 if (buf1 + sz1 == buf) {
983 sz1 += sz;
984 goto next;
985 }
986 if (!buf2) {
987 buf2 = buf;
988 sz2 = sz;
989 goto next;
990 }
991 assert(buf2 + sz2 == buf);
992 sz2 += sz;
993 next:
994 if (sz1 + sz2 >= dest_size + wb_consumed)
995 break;
996 }
997 if (!buf2) /* nothing to do */
998 return;
999 assert(buf1 && sz2 > 0);
1000 /*
1001 * If the second buffer is large, we only take the first part of it to
1002 * avoid having to memcpy() huge buffers.
1003 */
1004 sz2 = PARA_MIN(sz2, (size_t)(64 * 1024));
1005 if (!wbr) {
1006 /* Make a new wrap buffer combining buf1 and buf2. */
1007 sz = sz1 + sz2;
1008 buf = para_malloc(sz);
1009 PARA_DEBUG_LOG("merging input buffers: (%p:%zu, %p:%zu) -> %p:%zu\n",
1010 buf1, sz1, buf2, sz2, buf, sz);
1011 memcpy(buf, buf1, sz1);
1012 memcpy(buf + sz1, buf2, sz2);
1013 br = para_calloc(sizeof(*br));
1014 br->btrb = new_btrb(buf, sz);
1015 br->btrb->refcount = 1;
1016 br->consumed = 0;
1017 /* This is a wrap buffer */
1018 br->wrap_count = sz1;
1019 para_list_add(&br->node, &btrn->input_queue);
1020 return;
1021 }
1022 /*
1023 * We already have a wrap buffer, but it is too small. It might be
1024 * partially used.
1025 */
1026 if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
1027 return;
1028 sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */
1029 PARA_DEBUG_LOG("increasing wrap buffer %zu -> %zu\n", wbr->btrb->size,
1030 wbr->btrb->size + sz);
1031 wbr->btrb->size += sz;
1032 wbr->btrb->buf = para_realloc(wbr->btrb->buf, wbr->btrb->size);
1033 /* copy the new data to the end of the reallocated buffer */
1034 assert(sz2 >= sz);
1035 memcpy(wbr->btrb->buf + wbr->btrb->size - sz, buf2 + sz2 - sz, sz);
1036 }
1037
1038 /**
1039 * Merge the first two input buffers into one.
1040 *
1041 * This is a quite expensive operation.
1042 *
1043 * \return The number of buffers that have been available (zero, one or two).
1044 */
1045 static int merge_input(struct btr_node *btrn)
1046 {
1047 struct btr_buffer_reference *brs[2], *br;
1048 char *bufs[2], *buf;
1049 size_t szs[2], sz;
1050 int i;
1051
1052 if (list_empty(&btrn->input_queue))
1053 return 0;
1054 if (list_is_singular(&btrn->input_queue))
1055 return 1;
1056 i = 0;
1057 /* get references to the first two buffers */
1058 FOR_EACH_BUFFER_REF(br, btrn) {
1059 brs[i] = br;
1060 szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
1061 i++;
1062 if (i == 2)
1063 break;
1064 }
1065 assert(i == 2);
1066 /* make a new btrb that combines the two buffers and a br to it. */
1067 sz = szs[0] + szs[1];
1068 buf = para_malloc(sz);
1069 PARA_DEBUG_LOG("%s: memory merging input buffers: (%zu, %zu) -> %zu\n",
1070 btrn->name, szs[0], szs[1], sz);
1071 memcpy(buf, bufs[0], szs[0]);
1072 memcpy(buf + szs[0], bufs[1], szs[1]);
1073
1074 br = para_calloc(sizeof(*br));
1075 br->btrb = new_btrb(buf, sz);
1076 br->btrb->refcount = 1;
1077
1078 /* replace the first two refs by the new one */
1079 btr_drop_buffer_reference(brs[0]);
1080 btr_drop_buffer_reference(brs[1]);
1081 para_list_add(&br->node, &btrn->input_queue);
1082 return 2;
1083 }
1084
1085 /**
1086 * Combine input queue buffers.
1087 *
1088 * \param btrn The buffer tree node whose input should be merged.
1089 * \param dest_size Stop merging if a buffer of at least this size exists.
1090 *
1091 * Used to combine as many buffers as needed into a single buffer whose size is
1092 * at least \a dest_size. This function is rather cheap in case the parent node
1093 * uses buffer pools and rather expensive otherwise.
1094 *
1095 * Note that if less than \a dest_size bytes are available in total, this
1096 * function does nothing and subsequent calls to btr_next_buffer() will still
1097 * return a buffer size less than \a dest_size.
1098 */
1099 void btr_merge(struct btr_node *btrn, size_t dest_size)
1100 {
1101 if (need_buffer_pool_merge(btrn))
1102 return merge_input_pool(btrn, dest_size);
1103 for (;;) {
1104 char *buf;
1105 size_t len = btr_next_buffer(btrn, &buf);
1106 if (len >= dest_size)
1107 return;
1108 PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len, dest_size);
1109 if (merge_input(btrn) < 2)
1110 return;
1111 }
1112 }
1113
1114 static bool btr_eof(struct btr_node *btrn)
1115 {
1116 char *buf;
1117 size_t len = btr_next_buffer(btrn, &buf);
1118
1119 return (len == 0 && btr_no_parent(btrn));
1120 }
1121
1122 static void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
1123 {
1124 struct btr_node *ch;
1125 const char spaces[] = " ", *space = spaces + 16 - depth;
1126
1127 if (depth > 16)
1128 return;
1129 para_log(loglevel, "%s%s\n", space, btrn->name);
1130 FOR_EACH_CHILD(ch, btrn)
1131 log_tree_recursively(ch, loglevel, depth + 1);
1132 }
1133
1134 /**
1135 * Write the current buffer (sub-)tree to the log.
1136 *
1137 * \param btrn Start logging at this node.
1138 * \param loglevel Set severity with which the tree should be logged.
1139 */
1140 void btr_log_tree(struct btr_node *btrn, int loglevel)
1141 {
1142 return log_tree_recursively(btrn, loglevel, 0);
1143 }
1144
1145 /**
1146 * Find the node with the given name in the buffer tree.
1147 *
1148 * \param name The name of the node to search.
1149 * \param root Where to start the search.
1150 *
1151 * \return A pointer to the node with the given name on success. If \a name is
1152 * \p NULL, the function returns \a root. If there is no node with the given
1153 * name, \p NULL is returned.
1154 */
1155 struct btr_node *btr_search_node(const char *name, struct btr_node *root)
1156 {
1157 struct btr_node *ch;
1158
1159 if (!name)
1160 return root;
1161 if (!strcmp(root->name, name))
1162 return root;
1163 FOR_EACH_CHILD(ch, root) {
1164 struct btr_node *result = btr_search_node(name, ch);
1165 if (result)
1166 return result;
1167 }
1168 return NULL;
1169 }
1170
1171 /** 640K ought to be enough for everybody ;) */
1172 #define BTRN_MAX_PENDING (96 * 1024)
1173
1174 /**
1175 * Return the current state of a buffer tree node.
1176 *
1177 * \param btrn The node whose state should be queried.
1178 * \param min_iqs The minimal input queue size.
1179 * \param type The supposed type of \a btrn.
1180 *
1181 * Most users of the buffer tree subsystem call this function from both
1182 * their pre_select and the post_select methods.
1183 *
1184 * \return Negative if an error condition was detected, zero if there
1185 * is nothing to do and positive otherwise.
1186 *
1187 * Examples:
1188 *
1189 * - If a non-root node has no parent and an empty input queue, the function
1190 * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p
1191 * -E_BTR_NO_CHILD is returned.
1192 *
1193 * - If less than \a min_iqs many bytes are available in the input queue and no
1194 * EOF condition was detected, the function returns zero.
1195 *
1196 * - If there's plenty of data left in the input queue of the children of \a
1197 * btrn, the function also returns zero in order to bound the memory usage of
1198 * the buffer tree.
1199 */
1200 int btr_node_status(struct btr_node *btrn, size_t min_iqs,
1201 enum btr_node_type type)
1202 {
1203 size_t iqs;
1204
1205 assert(btrn);
1206 if (type != BTR_NT_LEAF) {
1207 if (btr_no_children(btrn))
1208 return -E_BTR_NO_CHILD;
1209 if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
1210 return 0;
1211 }
1212 if (type != BTR_NT_ROOT) {
1213 if (btr_eof(btrn))
1214 return -E_BTR_EOF;
1215 iqs = btr_get_input_queue_size(btrn);
1216 if (iqs == 0) /* we have a parent, because not eof */
1217 return 0;
1218 if (iqs < min_iqs && !btr_no_parent(btrn))
1219 return 0;
1220 }
1221 return 1;
1222 }
1223
1224 /**
1225 * Get the time of the first I/O for a buffer tree node.
1226 *
1227 * \param btrn The node whose I/O time should be obtained.
1228 * \param tv Result pointer.
1229 *
1230 * Mainly useful for the time display of para_audiod.
1231 */
1232 void btr_get_node_start(struct btr_node *btrn, struct timeval *tv)
1233 {
1234 *tv = btrn->start;
1235 }
1236
1237 /**
1238 * Get the parent node of a buffer tree node.
1239 *
1240 * \param btrn The node whose parent should be returned.
1241 *
1242 * \a btrn must not be \p NULL.
1243 *
1244 * \return The parent of \a btrn, or \p NULL if \a btrn is the
1245 * root node of the buffer tree.
1246 */
1247 struct btr_node *btr_parent(struct btr_node *btrn)
1248 {
1249 return btrn->parent;
1250 }