server: Fix brown paper bag bug in generic_com_on().
[paraslash.git] / buffer_tree.c
1 /* Copyright (C) 2009 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
2
3 /** \file buffer_tree.c Buffer tree and buffer pool implementations. */
4 #include <regex.h>
5
6 #include "para.h"
7 #include "list.h"
8 #include "string.h"
9 #include "buffer_tree.h"
10 #include "error.h"
11 #include "sched.h"
12
13 /* whead = NULL means area full */
14 struct btr_pool {
15 char *name;
16 char *area_start;
17 char *area_end;
18 char *rhead;
19 char *whead;
20 };
21
22 struct btr_buffer {
23 char *buf;
24 size_t size;
25 /** The number of references to this buffer. */
26 int refcount;
27 /* NULL means no buffer pool but a malloced buffer. */
28 struct btr_pool *pool;
29 /* Only relevant if pool is NULL. */
30 bool dont_free;
31 };
32
33 struct btr_buffer_reference {
34 struct btr_buffer *btrb;
35 size_t consumed;
36 /* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
37 struct list_head node;
38 size_t wrap_count;
39 };
40
41 struct btr_node {
42 char *name;
43 struct btr_node *parent;
44 /* The position of this btr node in the buffer tree. */
45 struct list_head node;
46 /* The children nodes of this btr node are linked together in a list. */
47 struct list_head children;
48 /* Time of first data transfer. */
49 struct timeval start;
50 /**
51 * The input queue is a list of references to btr buffers. Each item on
52 * the list represents an input buffer which has not been completely
53 * used by this btr node.
54 */
55 struct list_head input_queue;
56 btr_command_handler execute;
57 void *context;
58 };
59
60 /**
61 * Create a new buffer pool.
62 *
63 * \param name The name of the new buffer pool.
64 * \param area_size The size in bytes of the pool area.
65 *
66 * \return An opaque pointer to the newly created buffer pool. It must be
67 * passed to btr_pool_free() after it is no longer used to deallocate all
68 * resources.
69 */
70 struct btr_pool *btr_pool_new(const char *name, size_t area_size)
71 {
72 struct btr_pool *btrp;
73
74 PARA_INFO_LOG("%s, %zu bytes\n", name, area_size);
75 btrp = para_malloc(sizeof(*btrp));
76 btrp->area_start = para_malloc(area_size);
77 btrp->area_end = btrp->area_start + area_size;
78 btrp->rhead = btrp->area_start;
79 btrp->whead = btrp->area_start;
80 btrp->name = para_strdup(name);
81 return btrp;
82 }
83
84 /**
85 * Deallocate resources used by a buffer pool.
86 *
87 * \param btrp A pointer obtained via btr_pool_new().
88 */
89 void btr_pool_free(struct btr_pool *btrp)
90 {
91 if (!btrp)
92 return;
93 free(btrp->area_start);
94 free(btrp->name);
95 free(btrp);
96 }
97
98 /**
99 * Return the size of the buffer pool area.
100 *
101 * \param btrp The buffer pool.
102 *
103 * \return The same value which was passed during creation time to
104 * btr_pool_new().
105 */
106 size_t btr_pool_size(struct btr_pool *btrp)
107 {
108 return btrp->area_end - btrp->area_start;
109 }
110
111 static size_t btr_pool_filled(struct btr_pool *btrp)
112 {
113 if (!btrp->whead)
114 return btr_pool_size(btrp);
115 if (btrp->rhead <= btrp->whead)
116 return btrp->whead - btrp->rhead;
117 return btr_pool_size(btrp) - (btrp->rhead - btrp->whead);
118 }
119
120 /**
121 * Get the number of unused bytes in the buffer pool.
122 *
123 * \param btrp The pool.
124 *
125 * \return The number of bytes that can currently be allocated.
126 *
127 * Note that in general the returned number of bytes is not available as a
128 * single contiguous buffer. Use btr_pool_available() to obtain the length of
129 * the largest contiguous buffer that can currently be allocated from the
130 * buffer pool.
131 */
132 size_t btr_pool_unused(struct btr_pool *btrp)
133 {
134 return btr_pool_size(btrp) - btr_pool_filled(btrp);
135 }
136
137 /*
138 * Return maximal size available for one read. This is
139 * smaller than the value returned by btr_pool_unused().
140 */
141 static size_t btr_pool_available(struct btr_pool *btrp)
142 {
143 if (!btrp->whead)
144 return 0;
145 if (btrp->rhead <= btrp->whead)
146 return btrp->area_end - btrp->whead;
147 return btrp->rhead - btrp->whead;
148 }
149
150 /**
151 * Obtain the current write head.
152 *
153 * \param btrp The buffer pool.
154 * \param result The write head is returned here.
155 *
156 * \return The maximal amount of bytes that may be written to the returned
157 * buffer.
158 */
159 size_t btr_pool_get_buffer(struct btr_pool *btrp, char **result)
160 {
161 if (result)
162 *result = btrp->whead;
163 return btr_pool_available(btrp);
164 }
165
166 /**
167 * Get references to buffers pointing to free space of the buffer pool area.
168 *
169 * \param btrp The buffer pool.
170 * \param iov The scatter array.
171 *
172 * \return Zero if the buffer pool is full, one if the free space of the buffer
173 * pool area is available as a single contiguous buffer, two if the free space
174 * consists of two buffers. If this function returns the value n, then n
175 * elements of \a iov are initialized.
176 */
177 int btr_pool_get_buffers(struct btr_pool *btrp, struct iovec iov[2])
178 {
179 size_t sz, unused;
180 char *buf;
181
182 sz = btr_pool_get_buffer(btrp, &buf);
183 if (sz == 0)
184 return 0;
185 iov[0].iov_len = sz;
186 iov[0].iov_base = buf;
187 unused = btr_pool_unused(btrp);
188 if (sz == unused)
189 return 1;
190 iov[1].iov_len = unused - sz;
191 iov[1].iov_base = btrp->area_start;
192 return 2;
193 }
194
195 /**
196 * Mark a part of the buffer pool area as allocated.
197 *
198 * \param btrp The buffer pool.
199 * \param size The amount of bytes to be allocated.
200 *
201 * This is usually called after the caller wrote to the buffer obtained by
202 * btr_pool_get_buffer().
203 */
204 static void btr_pool_allocate(struct btr_pool *btrp, size_t size)
205 {
206 char *end;
207
208 if (size == 0)
209 return;
210 assert(size <= btr_pool_available(btrp));
211 end = btrp->whead + size;
212 assert(end <= btrp->area_end);
213
214 if (end == btrp->area_end) {
215 PARA_DEBUG_LOG("%s: end of pool area reached\n", btrp->name);
216 end = btrp->area_start;
217 }
218 if (end == btrp->rhead) {
219 PARA_DEBUG_LOG("%s btrp buffer full\n", btrp->name);
220 end = NULL; /* buffer full */
221 }
222 btrp->whead = end;
223 }
224
225 static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
226 {
227 char *end = btrp->rhead + size;
228
229 if (size == 0)
230 return;
231 assert(end <= btrp->area_end);
232 assert(size <= btr_pool_filled(btrp));
233 if (end == btrp->area_end)
234 end = btrp->area_start;
235 if (!btrp->whead)
236 btrp->whead = btrp->rhead;
237 btrp->rhead = end;
238 if (btrp->rhead == btrp->whead)
239 btrp->rhead = btrp->whead = btrp->area_start;
240 }
241
242 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
243 &((_btrn)->children), node)
244 #define FOR_EACH_CHILD_SAFE(_tn, _tmp, _btrn) \
245 list_for_each_entry_safe((_tn), (_tmp), &((_btrn)->children), node)
246
247 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
248 list_for_each_entry((_br), &(_btrn)->input_queue, node)
249 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
250 list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
251
252 /**
253 * Create a new buffer tree node.
254 *
255 * \param bnd Specifies how to create the new node.
256 *
257 * \return A pointer to the newly allocated node.
258 *
259 * This function always succeeds (or calls exit()). The returned pointer must
260 * be freed using btr_free_node() after the node has been removed from the
261 * buffer tree via btr_remove_node().
262 */
263 struct btr_node *btr_new_node(struct btr_node_description *bnd)
264 {
265 struct btr_node *btrn = para_malloc(sizeof(*btrn));
266
267 btrn->name = para_strdup(bnd->name);
268 btrn->parent = bnd->parent;
269 btrn->execute = bnd->handler;
270 btrn->context = bnd->context;
271 btrn->start.tv_sec = 0;
272 btrn->start.tv_usec = 0;
273 INIT_LIST_HEAD(&btrn->children);
274 INIT_LIST_HEAD(&btrn->input_queue);
275 if (!bnd->child) {
276 if (bnd->parent) {
277 list_add_tail(&btrn->node, &bnd->parent->children);
278 PARA_INFO_LOG("new leaf node: %s (child of %s)\n",
279 bnd->name, bnd->parent->name);
280 } else
281 PARA_INFO_LOG("added %s as btr root\n", bnd->name);
282 goto out;
283 }
284 if (!bnd->parent) {
285 assert(!bnd->child->parent);
286 PARA_INFO_LOG("new root: %s (was %s)\n",
287 bnd->name, bnd->child->name);
288 btrn->parent = NULL;
289 list_add_tail(&bnd->child->node, &btrn->children);
290 /* link it in */
291 bnd->child->parent = btrn;
292 goto out;
293 }
294 list_add_tail(&btrn->node, &bnd->parent->children);
295 list_move(&bnd->child->node, &btrn->children);
296 bnd->child->parent = btrn;
297 PARA_INFO_LOG("added %s as internal node\n", bnd->name);
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 if (!btrb->dont_free)
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 if (size == 0)
386 return;
387 if (list_empty(&btrn->children)) {
388 free(buf);
389 return;
390 }
391 btrb = new_btrb(buf, size);
392 add_btrb_to_children(btrb, btrn, 0);
393 }
394
395 /**
396 * Insert a buffer into the buffer tree, non-freeing variant.
397 *
398 * \param buf See \ref btr_add_output().
399 * \param size See \ref btr_add_output().
400 * \param btrn See \ref btr_add_output().
401 *
402 * This is similar to btr_add_output() but additionally sets the \p dont_free
403 * flag on \a buf. If the refcount for the buffer drops to zero, \a buf will
404 * not be deallocated if this flag is set.
405 *
406 * The \p dont_free bit also prevents the children of \a btrn from modifying
407 * the buffer contents inplace. Specifically, \ref btr_inplace_ok() returns
408 * false if there is any buffer in the input queue with the \p dont_free bit
409 * set.
410 */
411 void btr_add_output_dont_free(const char *buf, size_t size, struct btr_node *btrn)
412 {
413 struct btr_buffer *btrb;
414
415 if (size == 0)
416 return;
417 if (list_empty(&btrn->children))
418 return;
419 btrb = new_btrb((char *)buf, size);
420 btrb->dont_free = true;
421 add_btrb_to_children(btrb, btrn, 0);
422 }
423
424 /**
425 * Feed data to child nodes of a buffer tree node.
426 *
427 * \param btrp The buffer pool.
428 * \param size The number of bytes to be allocated and fed to each child.
429 * \param btrn The node whose children are to be fed.
430 *
431 * This function allocates the amount of bytes from the buffer pool area,
432 * starting at the current value of the write head, and creates buffer
433 * references to the resulting part of the buffer pool area, one for each child
434 * of \a btrn. The references are then fed into the input queue of each child.
435 */
436 void btr_add_output_pool(struct btr_pool *btrp, size_t size,
437 struct btr_node *btrn)
438 {
439 struct btr_buffer *btrb;
440 char *buf;
441 size_t avail;
442
443 if (size == 0)
444 return;
445 if (list_empty(&btrn->children))
446 return;
447 avail = btr_pool_get_buffer(btrp, &buf);
448 assert(avail >= size);
449 btr_pool_allocate(btrp, size);
450 btrb = new_btrb(buf, size);
451 btrb->pool = btrp;
452 add_btrb_to_children(btrb, btrn, 0);
453 }
454
455 /**
456 * Copy data to write head of a buffer pool and feed it to all children nodes.
457 *
458 * \param src The source buffer.
459 * \param n The size of the source buffer in bytes.
460 * \param btrp The destination buffer pool.
461 * \param btrn Add the data as output of this node.
462 *
463 * This is expensive. The caller must make sure the data fits into the buffer
464 * pool area.
465 */
466 void btr_copy(const void *src, size_t n, struct btr_pool *btrp,
467 struct btr_node *btrn)
468 {
469 char *buf;
470 size_t sz, copy;
471
472 if (n == 0)
473 return;
474 assert(n <= btr_pool_unused(btrp));
475 sz = btr_pool_get_buffer(btrp, &buf);
476 copy = PARA_MIN(sz, n);
477 memcpy(buf, src, copy);
478 btr_add_output_pool(btrp, copy, btrn);
479 if (copy == n)
480 return;
481 sz = btr_pool_get_buffer(btrp, &buf);
482 assert(sz >= n - copy);
483 memcpy(buf, src + copy, n - copy);
484 btr_add_output_pool(btrp, n - copy, btrn);
485 }
486
487 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
488 {
489 add_btrb_to_children(br->btrb, btrn, br->consumed);
490 btr_drop_buffer_reference(br);
491 }
492
493 /**
494 * Feed all buffer references of the input queue through the output channel.
495 *
496 * \param btrn The node whose buffer references should be pushed down.
497 *
498 * This function is useful for filters that do not change the contents of the
499 * buffers at all, like the wav filter or the amp filter if no amplification
500 * was specified. This function is rather cheap.
501 *
502 * \sa \ref btr_pushdown_one().
503 */
504 void btr_pushdown(struct btr_node *btrn)
505 {
506 struct btr_buffer_reference *br, *tmp;
507
508 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
509 btr_pushdown_br(br, btrn);
510 }
511
512 /**
513 * Feed the next buffer of the input queue through the output channel.
514 *
515 * \param btrn The node whose first input queue buffer should be pushed down.
516 *
517 * This works like \ref btr_pushdown() but pushes down only one buffer
518 * reference.
519 */
520 void btr_pushdown_one(struct btr_node *btrn)
521 {
522 struct btr_buffer_reference *br;
523
524 if (list_empty(&btrn->input_queue))
525 return;
526 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
527 btr_pushdown_br(br, btrn);
528 }
529
530 /*
531 * Find out whether a node is a leaf node.
532 *
533 * \param btrn The node to check.
534 *
535 * \return True if this node has no children. False otherwise.
536 */
537 static bool btr_no_children(struct btr_node *btrn)
538 {
539 return list_empty(&btrn->children);
540 }
541
542 /**
543 * Find out whether a node is an orphan.
544 *
545 * \param btrn The buffer tree node.
546 *
547 * \return True if \a btrn has no parent.
548 *
549 * This function returns true for the root node and false for any other node.
550 *
551 * After a (non-leaf) node was removed removed from the tree, the function
552 * returns true for all child nodes.
553 */
554 bool btr_no_parent(struct btr_node *btrn)
555 {
556 return !btrn->parent;
557 }
558
559 /**
560 * Find out whether it is OK to change an input buffer.
561 *
562 * \param btrn The buffer tree node to check.
563 *
564 * This is used by filters that produce exactly the same amount of output as
565 * there is input. The amp filter which multiplies each sample by some number
566 * is an example of such a filter. If there are no other nodes in the buffer
567 * tree that read the same input stream (i.e. if \a btrn has no siblings), a
568 * node may modify its input buffer directly and push down the modified buffer
569 * to its children, thereby avoiding to allocate a possibly large additional
570 * buffer.
571 *
572 * Since the buffer tree may change at any time, this function should be called
573 * during each post_select call.
574 *
575 * \return True if \a btrn has no siblings.
576 */
577 bool btr_inplace_ok(struct btr_node *btrn)
578 {
579 struct btr_buffer_reference *br;
580 FOR_EACH_BUFFER_REF(br, btrn) {
581 struct btr_buffer *btrb = br->btrb;
582 if (btrb->refcount > 1)
583 return false;
584 if (btrb->dont_free == true)
585 return false;
586 }
587 return true;
588 }
589
590 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
591 {
592 return br->btrb->size - br->consumed;
593 }
594
595 static size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
596 {
597 if (buf)
598 *buf = br->btrb->buf + br->consumed;
599 return br_available_bytes(br);
600 }
601
602 /**
603 * Obtain the next buffer of the input queue, omitting data.
604 *
605 * \param btrn The node whose input queue is to be queried.
606 * \param omit Number of bytes to be omitted.
607 * \param bufp Result pointer. It is OK to pass \p NULL here.
608 *
609 * If a buffer tree node needs more input data but can not consume the data it
610 * already has (because it might be needed again later) this function can be
611 * used instead of btr_next_buffer() to get a reference to the buffer obtained
612 * by skipping the given number of bytes. Skipped input bytes are not consumed.
613 *
614 * With a zero \a omit argument, this function is equivalent to \ref
615 * btr_next_buffer().
616 *
617 * \return Number of bytes in \a bufp. If there are less than or equal to \a
618 * omit many bytes available in the input queue of the buffer tree node pointed
619 * to by \a btrn, the function returns zero and the value of \a bufp is
620 * undefined.
621 */
622 size_t btr_next_buffer_omit(struct btr_node *btrn, size_t omit, char **bufp)
623 {
624 struct btr_buffer_reference *br;
625 size_t wrap_count, sz, rv = 0;
626 char *buf, *result = NULL;
627
628 br = get_first_input_br(btrn);
629 if (!br)
630 return 0;
631 wrap_count = br->wrap_count;
632 if (wrap_count > 0) { /* we have a wrap buffer */
633 sz = btr_get_buffer_by_reference(br, &buf);
634 if (sz > omit) { /* and it's big enough */
635 result = buf + omit;
636 rv = sz - omit;
637 /*
638 * Wrap buffers are allocated by malloc(), so the next
639 * buffer ref will not align nicely, so we return the
640 * tail of the wrap buffer.
641 */
642 goto out;
643 }
644 /*
645 * The next wrap_count bytes exist twice, in the wrap buffer
646 * and as a buffer reference in the buffer tree pool.
647 */
648 omit += wrap_count;
649 }
650 /*
651 * For buffer tree pools, the buffers in the list align, i.e. the next
652 * buffer in the list starts directly at the end of its predecessor. In
653 * this case we merge adjacent buffers and return one larger buffer
654 * instead.
655 */
656 FOR_EACH_BUFFER_REF(br, btrn) {
657 sz = btr_get_buffer_by_reference(br, &buf);
658 if (result) {
659 if (result + rv != buf)
660 goto out;
661 rv += sz;
662 } else if (sz > omit) {
663 result = buf + omit;
664 rv = sz - omit;
665 } else
666 omit -= sz;
667 }
668 if (!result)
669 return 0;
670 out:
671 if (bufp)
672 *bufp = result;
673 return rv;
674 }
675
676 /**
677 * Obtain the next buffer of the input queue of a buffer tree node.
678 *
679 * \param btrn The node whose input queue is to be queried.
680 * \param bufp Result pointer.
681 *
682 * \return The number of bytes that can be read from buf.
683 *
684 * The call of this function is is equivalent to calling \ref
685 * btr_next_buffer_omit() with an \a omit value of zero.
686 */
687 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
688 {
689 return btr_next_buffer_omit(btrn, 0, bufp);
690 }
691
692 /**
693 * Deallocate the given number of bytes from the input queue.
694 *
695 * \param btrn The buffer tree node.
696 * \param numbytes The number of bytes to be deallocated.
697 *
698 * This function must be used to get rid of existing buffer references in the
699 * node's input queue. If no references to a buffer remain, the underlying
700 * buffers are either freed (in the non-buffer pool case) or the read head of
701 * the buffer pool is being advanced.
702 *
703 * Note that \a numbytes may be smaller than the buffer size. In this case the
704 * buffer is not deallocated and subsequent calls to btr_next_buffer() return
705 * the remaining part of the buffer.
706 */
707 void btr_consume(struct btr_node *btrn, size_t numbytes)
708 {
709 struct btr_buffer_reference *br, *tmp;
710 size_t sz;
711
712 if (numbytes == 0)
713 return;
714 br = get_first_input_br(btrn);
715 assert(br);
716
717 if (br->wrap_count == 0) {
718 /*
719 * No wrap buffer. Drop buffer references whose buffer
720 * has been fully used. */
721 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn) {
722 if (br->consumed + numbytes <= br->btrb->size) {
723 br->consumed += numbytes;
724 if (br->consumed == br->btrb->size)
725 btr_drop_buffer_reference(br);
726 return;
727 }
728 numbytes -= br->btrb->size - br->consumed;
729 btr_drop_buffer_reference(br);
730 }
731 assert(false);
732 }
733 /*
734 * We have a wrap buffer, consume from it. If in total, i.e. including
735 * previous calls to brt_consume(), less than wrap_count has been
736 * consumed, there's nothing more we can do.
737 *
738 * Otherwise we drop the wrap buffer and consume from subsequent
739 * buffers of the input queue the correct amount of bytes. This is the
740 * total number of bytes that have been consumed from the wrap buffer.
741 */
742 PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes,
743 br_available_bytes(br));
744
745 assert(numbytes <= br_available_bytes(br));
746 if (br->consumed + numbytes < br->wrap_count) {
747 br->consumed += numbytes;
748 return;
749 }
750 PARA_DEBUG_LOG("dropping wrap buffer (%zu bytes)\n", br->btrb->size);
751 /* get rid of the wrap buffer */
752 sz = br->consumed + numbytes;
753 btr_drop_buffer_reference(br);
754 return btr_consume(btrn, sz);
755 }
756
757 /**
758 * Clear the input queue of a buffer tree node.
759 *
760 * \param btrn The node whose input queue should be cleared.
761 */
762 void btr_drain(struct btr_node *btrn)
763 {
764 struct btr_buffer_reference *br, *tmp;
765
766 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
767 btr_drop_buffer_reference(br);
768 }
769
770 static void btr_free_node(struct btr_node *btrn)
771 {
772 free(btrn->name);
773 free(btrn);
774 }
775
776 /**
777 * Remove a node from a buffer tree.
778 *
779 * \param btrnp Determines the node to remove.
780 *
781 * This orphans all children of the node given by \a btrnp and removes this
782 * node from the child list of its parent. Moreover, the input queue is flushed
783 * and the node pointer given by \a btrp is set to \p NULL.
784 *
785 * \sa \ref btr_splice_out_node.
786 */
787 void btr_remove_node(struct btr_node **btrnp)
788 {
789 struct btr_node *ch;
790 struct btr_node *btrn;
791
792 if (!btrnp)
793 return;
794 btrn = *btrnp;
795 if (!btrn)
796 goto out;
797 PARA_INFO_LOG("removing btr node %s from buffer tree\n", btrn->name);
798 FOR_EACH_CHILD(ch, btrn)
799 ch->parent = NULL;
800 btr_drain(btrn);
801 if (btrn->parent)
802 list_del(&btrn->node);
803 btr_free_node(btrn);
804 out:
805 *btrnp = NULL;
806 }
807
808 /**
809 * Return the amount of available input bytes of a buffer tree node.
810 *
811 * \param btrn The node whose input size should be computed.
812 *
813 * \return The total number of bytes available in the node's input
814 * queue.
815 *
816 * This simply iterates over all buffer references in the input queue and
817 * returns the sum of the sizes of all references.
818 */
819 size_t btr_get_input_queue_size(struct btr_node *btrn)
820 {
821 struct btr_buffer_reference *br;
822 size_t size = 0, wrap_consumed = 0;
823
824 FOR_EACH_BUFFER_REF(br, btrn) {
825 if (br->wrap_count != 0) {
826 wrap_consumed = br->consumed;
827 continue;
828 }
829 size += br_available_bytes(br);
830 }
831 assert(wrap_consumed <= size);
832 size -= wrap_consumed;
833 return size;
834 }
835
836 /**
837 * Remove a node from the buffer tree, reconnecting parent and children.
838 *
839 * \param btrnp The node to splice out.
840 *
841 * This function is used by buffer tree nodes that do not exist during the
842 * whole lifetime of the buffer tree. Unlike btr_remove_node(), calling
843 * btr_splice_out_node() does not split the tree into disconnected components
844 * but reconnects the buffer tree by making all child nodes of \a btrn children
845 * of the parent of \a btrn.
846 */
847 void btr_splice_out_node(struct btr_node **btrnp)
848 {
849 struct btr_node *btrn = *btrnp, *ch, *tmp;
850
851 assert(btrn);
852 PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
853 btr_pushdown(btrn);
854 if (btrn->parent)
855 list_del(&btrn->node);
856 FOR_EACH_CHILD_SAFE(ch, tmp, btrn) {
857 PARA_INFO_LOG("parent(%s): %s\n", ch->name,
858 btrn->parent? btrn->parent->name : "NULL");
859 ch->parent = btrn->parent;
860 if (btrn->parent)
861 list_move(&ch->node, &btrn->parent->children);
862 else
863 list_del(&ch->node);
864 }
865 assert(list_empty(&btrn->children));
866 btr_free_node(btrn);
867 *btrnp = NULL;
868 }
869
870 /**
871 * Return number of queued output bytes of a buffer tree node.
872 *
873 * \param btrn The node whose output queue size should be computed.
874 *
875 * \return This function iterates over all children of the given node and
876 * returns the size of the largest input queue.
877 */
878 size_t btr_get_output_queue_size(struct btr_node *btrn)
879 {
880 size_t max_size = 0;
881 struct btr_node *ch;
882
883 FOR_EACH_CHILD(ch, btrn) {
884 size_t size = btr_get_input_queue_size(ch);
885 max_size = PARA_MAX(max_size, size);
886 }
887 return max_size;
888 }
889
890 /**
891 * Execute an inter-node command on the given node or on a parent node.
892 *
893 * \param btrn The node to start looking.
894 * \param command The command to execute.
895 * \param value_result Additional arguments and result value.
896 *
897 * This function traverses the buffer tree from \a btrn upwards and looks for
898 * the first node that understands \a command. On this node \a command is
899 * executed, and the result is stored in \a value_result.
900 *
901 * \return \p -ENOTSUP if no parent node of \a btrn understands \a command.
902 * Otherwise the return value of the command handler is returned.
903 *
904 * \sa \ref receiver::execute, \ref filter::execute, \ref writer::execute.
905 */
906 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
907 {
908 int ret;
909
910 for (; btrn; btrn = btrn->parent) {
911 if (!btrn->execute)
912 continue;
913 PARA_INFO_LOG("executing %s on %s\n", command, btrn->name);
914 ret = btrn->execute(btrn, command, value_result);
915 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
916 continue;
917 if (ret < 0)
918 return ret;
919 if (value_result && *value_result)
920 PARA_INFO_LOG("%s(%s): %s\n", command, btrn->name,
921 *value_result);
922 return 1;
923 }
924 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
925 }
926
927 /**
928 * Obtain the context of a buffer node tree.
929 *
930 * \param btrn The node whose output queue size should be computed.
931 *
932 * \return A pointer to the \a context address specified at node creation time.
933 *
934 * \sa \ref btr_new_node(), struct \ref btr_node_description.
935 */
936 void *btr_context(struct btr_node *btrn)
937 {
938 return btrn->context;
939 }
940
941 static bool need_buffer_pool_merge(struct btr_node *btrn)
942 {
943 struct btr_buffer_reference *br = get_first_input_br(btrn);
944
945 if (!br)
946 return false;
947 if (br->wrap_count != 0)
948 return true;
949 if (br->btrb->pool)
950 return true;
951 return false;
952 }
953
954 static void merge_input_pool(struct btr_node *btrn, size_t dest_size)
955 {
956 struct btr_buffer_reference *br, *wbr = NULL;
957 int num_refs; /* including wrap buffer */
958 char *buf, *buf1 = NULL, *buf2 = NULL;
959 size_t sz, sz1 = 0, sz2 = 0, wb_consumed = 0;
960
961 br = get_first_input_br(btrn);
962 if (!br || br_available_bytes(br) >= dest_size)
963 return;
964 num_refs = 0;
965 FOR_EACH_BUFFER_REF(br, btrn) {
966 num_refs++;
967 sz = btr_get_buffer_by_reference(br, &buf);
968 if (sz == 0)
969 break;
970 if (br->wrap_count != 0) {
971 assert(!wbr);
972 assert(num_refs == 1);
973 wbr = br;
974 if (sz >= dest_size)
975 return;
976 wb_consumed = br->consumed;
977 continue;
978 }
979 if (!buf1) {
980 buf1 = buf;
981 sz1 = sz;
982 goto next;
983 }
984 if (buf1 + sz1 == buf) {
985 sz1 += sz;
986 goto next;
987 }
988 if (!buf2) {
989 buf2 = buf;
990 sz2 = sz;
991 goto next;
992 }
993 assert(buf2 + sz2 == buf);
994 sz2 += sz;
995 next:
996 if (sz1 + sz2 >= dest_size + wb_consumed)
997 break;
998 }
999 if (!buf2) /* nothing to do */
1000 return;
1001 assert(buf1 && sz2 > 0);
1002 /*
1003 * If the second buffer is large, we only take the first part of it to
1004 * avoid having to memcpy() huge buffers.
1005 */
1006 sz2 = PARA_MIN(sz2, (size_t)(64 * 1024));
1007 if (!wbr) {
1008 /* Make a new wrap buffer combining buf1 and buf2. */
1009 sz = sz1 + sz2;
1010 buf = para_malloc(sz);
1011 PARA_DEBUG_LOG("merging input buffers: (%p:%zu, %p:%zu) -> %p:%zu\n",
1012 buf1, sz1, buf2, sz2, buf, sz);
1013 memcpy(buf, buf1, sz1);
1014 memcpy(buf + sz1, buf2, sz2);
1015 br = para_calloc(sizeof(*br));
1016 br->btrb = new_btrb(buf, sz);
1017 br->btrb->refcount = 1;
1018 br->consumed = 0;
1019 /* This is a wrap buffer */
1020 br->wrap_count = sz1;
1021 para_list_add(&br->node, &btrn->input_queue);
1022 return;
1023 }
1024 /*
1025 * We already have a wrap buffer, but it is too small. It might be
1026 * partially used.
1027 */
1028 if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
1029 return;
1030 sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */
1031 PARA_DEBUG_LOG("increasing wrap buffer %zu -> %zu\n", wbr->btrb->size,
1032 wbr->btrb->size + sz);
1033 wbr->btrb->size += sz;
1034 wbr->btrb->buf = para_realloc(wbr->btrb->buf, wbr->btrb->size);
1035 /* copy the new data to the end of the reallocated buffer */
1036 assert(sz2 >= sz);
1037 memcpy(wbr->btrb->buf + wbr->btrb->size - sz, buf2 + sz2 - sz, sz);
1038 }
1039
1040 /**
1041 * Merge the first two input buffers into one.
1042 *
1043 * This is a quite expensive operation.
1044 *
1045 * \return The number of buffers that have been available (zero, one or two).
1046 */
1047 static int merge_input(struct btr_node *btrn)
1048 {
1049 struct btr_buffer_reference *brs[2], *br;
1050 char *bufs[2], *buf;
1051 size_t szs[2], sz;
1052 int i;
1053
1054 if (list_empty(&btrn->input_queue))
1055 return 0;
1056 if (list_is_singular(&btrn->input_queue))
1057 return 1;
1058 i = 0;
1059 /* get references to the first two buffers */
1060 FOR_EACH_BUFFER_REF(br, btrn) {
1061 brs[i] = br;
1062 szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
1063 i++;
1064 if (i == 2)
1065 break;
1066 }
1067 assert(i == 2);
1068 /* make a new btrb that combines the two buffers and a br to it. */
1069 sz = szs[0] + szs[1];
1070 buf = para_malloc(sz);
1071 PARA_DEBUG_LOG("%s: memory merging input buffers: (%zu, %zu) -> %zu\n",
1072 btrn->name, szs[0], szs[1], sz);
1073 memcpy(buf, bufs[0], szs[0]);
1074 memcpy(buf + szs[0], bufs[1], szs[1]);
1075
1076 br = para_calloc(sizeof(*br));
1077 br->btrb = new_btrb(buf, sz);
1078 br->btrb->refcount = 1;
1079
1080 /* replace the first two refs by the new one */
1081 btr_drop_buffer_reference(brs[0]);
1082 btr_drop_buffer_reference(brs[1]);
1083 para_list_add(&br->node, &btrn->input_queue);
1084 return 2;
1085 }
1086
1087 /**
1088 * Combine input queue buffers.
1089 *
1090 * \param btrn The buffer tree node whose input should be merged.
1091 * \param dest_size Stop merging if a buffer of at least this size exists.
1092 *
1093 * Used to combine as many buffers as needed into a single buffer whose size is
1094 * at least \a dest_size. This function is rather cheap in case the parent node
1095 * uses buffer pools and rather expensive otherwise.
1096 *
1097 * Note that if less than \a dest_size bytes are available in total, this
1098 * function does nothing and subsequent calls to btr_next_buffer() will still
1099 * return a buffer size less than \a dest_size.
1100 */
1101 void btr_merge(struct btr_node *btrn, size_t dest_size)
1102 {
1103 if (need_buffer_pool_merge(btrn))
1104 return merge_input_pool(btrn, dest_size);
1105 for (;;) {
1106 char *buf;
1107 size_t len = btr_next_buffer(btrn, &buf);
1108 if (len >= dest_size)
1109 return;
1110 PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len, dest_size);
1111 if (merge_input(btrn) < 2)
1112 return;
1113 }
1114 }
1115
1116 static bool btr_eof(struct btr_node *btrn)
1117 {
1118 char *buf;
1119 size_t len = btr_next_buffer(btrn, &buf);
1120
1121 return (len == 0 && btr_no_parent(btrn));
1122 }
1123
1124 static void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
1125 {
1126 struct btr_node *ch;
1127 const char spaces[] = " ", *space = spaces + 16 - depth;
1128
1129 if (depth > 16)
1130 return;
1131 para_log(loglevel, "%s%s\n", space, btrn->name);
1132 FOR_EACH_CHILD(ch, btrn)
1133 log_tree_recursively(ch, loglevel, depth + 1);
1134 }
1135
1136 /**
1137 * Write the current buffer (sub-)tree to the log.
1138 *
1139 * \param btrn Start logging at this node.
1140 * \param loglevel Set severity with which the tree should be logged.
1141 */
1142 void btr_log_tree(struct btr_node *btrn, int loglevel)
1143 {
1144 return log_tree_recursively(btrn, loglevel, 0);
1145 }
1146
1147 /**
1148 * Find the node with the given name in the buffer tree.
1149 *
1150 * \param name The name of the node to search.
1151 * \param root Where to start the search.
1152 *
1153 * \return A pointer to the node with the given name on success. If \a name is
1154 * \p NULL, the function returns \a root. If there is no node with the given
1155 * name, \p NULL is returned.
1156 */
1157 struct btr_node *btr_search_node(const char *name, struct btr_node *root)
1158 {
1159 struct btr_node *ch;
1160
1161 if (!name)
1162 return root;
1163 if (!strcmp(root->name, name))
1164 return root;
1165 FOR_EACH_CHILD(ch, root) {
1166 struct btr_node *result = btr_search_node(name, ch);
1167 if (result)
1168 return result;
1169 }
1170 return NULL;
1171 }
1172
1173 /** 640K ought to be enough for everybody ;) */
1174 #define BTRN_MAX_PENDING (96 * 1024)
1175
1176 /**
1177 * Return the current state of a buffer tree node.
1178 *
1179 * \param btrn The node whose state should be queried.
1180 * \param min_iqs The minimal input queue size.
1181 * \param type The supposed type of \a btrn.
1182 *
1183 * Most users of the buffer tree subsystem call this function from both
1184 * their pre_select and the post_select methods.
1185 *
1186 * \return Negative if an error condition was detected, zero if there
1187 * is nothing to do and positive otherwise.
1188 *
1189 * Examples:
1190 *
1191 * - If a non-root node has no parent and an empty input queue, the function
1192 * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p
1193 * -E_BTR_NO_CHILD is returned.
1194 *
1195 * - If less than \a min_iqs many bytes are available in the input queue and no
1196 * EOF condition was detected, the function returns zero.
1197 *
1198 * - If there's plenty of data left in the input queue of the children of \a
1199 * btrn, the function also returns zero in order to bound the memory usage of
1200 * the buffer tree.
1201 */
1202 int btr_node_status(struct btr_node *btrn, size_t min_iqs,
1203 enum btr_node_type type)
1204 {
1205 size_t iqs;
1206
1207 assert(btrn);
1208 if (type != BTR_NT_LEAF && btr_no_children(btrn))
1209 return -E_BTR_NO_CHILD;
1210 if (type != BTR_NT_ROOT && btr_eof(btrn))
1211 return -E_BTR_EOF;
1212
1213 if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
1214 return 0;
1215 if (type == BTR_NT_ROOT)
1216 return 1;
1217 iqs = btr_get_input_queue_size(btrn);
1218 if (iqs == 0) /* we have a parent, because not eof */
1219 return 0;
1220 if (iqs < min_iqs && !btr_no_parent(btrn))
1221 return 0;
1222 return 1;
1223 }
1224
1225 /**
1226 * Get the time of the first I/O for a buffer tree node.
1227 *
1228 * \param btrn The node whose I/O time should be obtained.
1229 * \param tv Result pointer.
1230 *
1231 * Mainly useful for the time display of para_audiod.
1232 */
1233 void btr_get_node_start(struct btr_node *btrn, struct timeval *tv)
1234 {
1235 *tv = btrn->start;
1236 }
1237
1238 /**
1239 * Get the parent node of a buffer tree node.
1240 *
1241 * \param btrn The node whose parent should be returned.
1242 *
1243 * \a btrn must not be \p NULL.
1244 *
1245 * \return The parent of \a btrn, or \p NULL if \a btrn is the
1246 * root node of the buffer tree.
1247 */
1248 struct btr_node *btr_parent(struct btr_node *btrn)
1249 {
1250 return btrn->parent;
1251 }