1 /* Copyright (C) 2009 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
3 /** \file buffer_tree.c Buffer tree and buffer pool implementations. */
9 #include "buffer_tree.h"
13 /* whead = NULL means area full */
25 /** The number of references to this buffer. */
27 /* NULL means no buffer pool but a malloced buffer. */
28 struct btr_pool *pool;
29 /* Only relevant if pool is NULL. */
33 struct btr_buffer_reference {
34 struct btr_buffer *btrb;
36 /* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
37 struct list_head node;
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. */
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.
55 struct list_head input_queue;
56 btr_command_handler execute;
61 * Create a new buffer pool.
63 * \param name The name of the new buffer pool.
64 * \param area_size The size in bytes of the pool area.
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
70 struct btr_pool *btr_pool_new(const char *name, size_t area_size)
72 struct btr_pool *btrp;
74 PARA_INFO_LOG("%s, %zu bytes\n", name, area_size);
75 btrp = alloc(sizeof(*btrp));
76 btrp->area_start = alloc(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);
85 * Deallocate resources used by a buffer pool.
87 * \param btrp A pointer obtained via btr_pool_new().
89 void btr_pool_free(struct btr_pool *btrp)
93 free(btrp->area_start);
99 * Return the size of the buffer pool area.
101 * \param btrp The buffer pool.
103 * \return The same value which was passed during creation time to
106 size_t btr_pool_size(struct btr_pool *btrp)
108 return btrp->area_end - btrp->area_start;
111 static size_t btr_pool_filled(struct btr_pool *btrp)
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);
121 * Get the number of unused bytes in the buffer pool.
123 * \param btrp The pool.
125 * \return The number of bytes that can currently be allocated.
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
132 size_t btr_pool_unused(struct btr_pool *btrp)
134 return btr_pool_size(btrp) - btr_pool_filled(btrp);
138 * Return maximal size available for one read. This is
139 * smaller than the value returned by btr_pool_unused().
141 static size_t btr_pool_available(struct btr_pool *btrp)
145 if (btrp->rhead <= btrp->whead)
146 return btrp->area_end - btrp->whead;
147 return btrp->rhead - btrp->whead;
151 * Obtain the current write head.
153 * \param btrp The buffer pool.
154 * \param result The write head is returned here.
156 * \return The maximal amount of bytes that may be written to the returned
159 size_t btr_pool_get_buffer(struct btr_pool *btrp, char **result)
162 *result = btrp->whead;
163 return btr_pool_available(btrp);
167 * Get references to buffers pointing to free space of the buffer pool area.
169 * \param btrp The buffer pool.
170 * \param iov The scatter array.
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.
177 int btr_pool_get_buffers(struct btr_pool *btrp, struct iovec iov[2])
182 sz = btr_pool_get_buffer(btrp, &buf);
186 iov[0].iov_base = buf;
187 unused = btr_pool_unused(btrp);
190 iov[1].iov_len = unused - sz;
191 iov[1].iov_base = btrp->area_start;
196 * Mark a part of the buffer pool area as allocated.
198 * \param btrp The buffer pool.
199 * \param size The amount of bytes to be allocated.
201 * This is usually called after the caller wrote to the buffer obtained by
202 * btr_pool_get_buffer().
204 static void btr_pool_allocate(struct btr_pool *btrp, size_t size)
210 assert(size <= btr_pool_available(btrp));
211 end = btrp->whead + size;
212 assert(end <= btrp->area_end);
214 if (end == btrp->area_end) {
215 PARA_DEBUG_LOG("%s: end of pool area reached\n", btrp->name);
216 end = btrp->area_start;
218 if (end == btrp->rhead) {
219 PARA_DEBUG_LOG("%s btrp buffer full\n", btrp->name);
220 end = NULL; /* buffer full */
225 static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
227 char *end = btrp->rhead + size;
231 assert(end <= btrp->area_end);
232 assert(size <= btr_pool_filled(btrp));
233 if (end == btrp->area_end)
234 end = btrp->area_start;
236 btrp->whead = btrp->rhead;
238 if (btrp->rhead == btrp->whead)
239 btrp->rhead = btrp->whead = btrp->area_start;
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)
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)
253 * Create a new buffer tree node.
255 * \param bnd Specifies how to create the new node.
257 * \return A pointer to the newly allocated node.
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().
263 struct btr_node *btr_new_node(struct btr_node_description *bnd)
265 struct btr_node *btrn = alloc(sizeof(*btrn));
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);
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);
281 PARA_INFO_LOG("added %s as btr root\n", bnd->name);
285 assert(!bnd->child->parent);
286 PARA_INFO_LOG("new root: %s (was %s)\n",
287 bnd->name, bnd->child->name);
289 list_add_tail(&bnd->child->node, &btrn->children);
291 bnd->child->parent = btrn;
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);
303 * Allocate a new btr buffer.
305 * The freshly allocated buffer will have a zero refcount and will
306 * not be associated with a btr pool.
308 static struct btr_buffer *new_btrb(char *buf, size_t size)
310 struct btr_buffer *btrb = zalloc(sizeof(*btrb));
317 static void dealloc_buffer(struct btr_buffer *btrb)
320 btr_pool_deallocate(btrb->pool, btrb->size);
321 else if (!btrb->dont_free)
325 static struct btr_buffer_reference *get_first_input_br(struct btr_node *btrn)
327 if (list_empty(&btrn->input_queue))
329 return list_first_entry(&btrn->input_queue,
330 struct btr_buffer_reference, node);
333 static struct btr_buffer_reference *get_last_input_br(struct btr_node *btrn)
335 if (list_empty(&btrn->input_queue))
337 return list_last_entry(&btrn->input_queue,
338 struct btr_buffer_reference, node);
342 * Deallocate the reference, release the resources if refcount drops to zero.
344 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
346 struct btr_buffer *btrb = br->btrb;
351 if (btrb->refcount == 0) {
352 dealloc_buffer(btrb);
357 static bool may_merge_btrb(const struct btr_buffer *btrb,
358 const struct btr_buffer_reference *br)
362 if (br->consumed > 0)
364 if (br->btrb->buf + br->btrb->size != btrb->buf)
368 return br->btrb->size + btrb->size < btr_pool_size(br->btrb->pool) / 3;
371 static void add_btrb_to_children(struct btr_buffer *btrb,
372 struct btr_node *btrn, size_t consumed)
376 if (btrn->start.tv_sec == 0)
378 FOR_EACH_CHILD(ch, btrn) {
379 struct btr_buffer_reference *br = get_last_input_br(ch);
380 if (may_merge_btrb(btrb, br)) {
381 br->btrb->size += btrb->size;
384 br = zalloc(sizeof(*br));
386 br->consumed = consumed;
387 list_add_tail(&br->node, &ch->input_queue);
390 if (ch->start.tv_sec == 0)
396 * Insert a malloced buffer into the buffer tree.
398 * \param buf The buffer to insert.
399 * \param size The size of \a buf in bytes.
400 * \param btrn Position in the buffer tree to create the output.
402 * This creates references to \a buf and adds these references to each child of
403 * \a btrn. The buffer will be freed using standard free() once no buffer tree
404 * node is referencing it any more.
406 * Note that this function must not be used if \a buf was obtained from a
407 * buffer pool. Use btr_add_output_pool() in this case.
409 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
411 struct btr_buffer *btrb;
415 if (list_empty(&btrn->children)) {
419 btrb = new_btrb(buf, size);
420 add_btrb_to_children(btrb, btrn, 0);
424 * Insert a buffer into the buffer tree, non-freeing variant.
426 * \param buf See \ref btr_add_output().
427 * \param size See \ref btr_add_output().
428 * \param btrn See \ref btr_add_output().
430 * This is similar to btr_add_output() but additionally sets the \p dont_free
431 * flag on \a buf. If the refcount for the buffer drops to zero, \a buf will
432 * not be deallocated if this flag is set.
434 * The \p dont_free bit also prevents the children of \a btrn from modifying
435 * the buffer contents inplace. Specifically, \ref btr_inplace_ok() returns
436 * false if there is any buffer in the input queue with the \p dont_free bit
439 void btr_add_output_dont_free(const char *buf, size_t size, struct btr_node *btrn)
441 struct btr_buffer *btrb;
445 if (list_empty(&btrn->children))
447 btrb = new_btrb((char *)buf, size);
448 btrb->dont_free = true;
449 add_btrb_to_children(btrb, btrn, 0);
453 * Feed data to child nodes of a buffer tree node.
455 * \param btrp The buffer pool.
456 * \param size The number of bytes to be allocated and fed to each child.
457 * \param btrn The node whose children are to be fed.
459 * This function allocates the amount of bytes from the buffer pool area,
460 * starting at the current value of the write head, and creates buffer
461 * references to the resulting part of the buffer pool area, one for each child
462 * of \a btrn. The references are then fed into the input queue of each child.
464 void btr_add_output_pool(struct btr_pool *btrp, size_t size,
465 struct btr_node *btrn)
467 struct btr_buffer *btrb;
473 if (list_empty(&btrn->children))
475 avail = btr_pool_get_buffer(btrp, &buf);
476 assert(avail >= size);
477 btr_pool_allocate(btrp, size);
478 btrb = new_btrb(buf, size);
480 add_btrb_to_children(btrb, btrn, 0);
484 * Copy data to write head of a buffer pool and feed it to all children nodes.
486 * \param src The source buffer.
487 * \param n The size of the source buffer in bytes.
488 * \param btrp The destination buffer pool.
489 * \param btrn Add the data as output of this node.
491 * This is expensive. The caller must make sure the data fits into the buffer
494 void btr_copy(const void *src, size_t n, struct btr_pool *btrp,
495 struct btr_node *btrn)
502 assert(n <= btr_pool_unused(btrp));
503 sz = btr_pool_get_buffer(btrp, &buf);
504 copy = PARA_MIN(sz, n);
505 memcpy(buf, src, copy);
506 btr_add_output_pool(btrp, copy, btrn);
509 sz = btr_pool_get_buffer(btrp, &buf);
510 assert(sz >= n - copy);
511 memcpy(buf, src + copy, n - copy);
512 btr_add_output_pool(btrp, n - copy, btrn);
515 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
517 add_btrb_to_children(br->btrb, btrn, br->consumed);
518 btr_drop_buffer_reference(br);
522 * Feed all buffer references of the input queue through the output channel.
524 * \param btrn The node whose buffer references should be pushed down.
526 * This function is useful for filters that do not change the contents of the
527 * buffers at all, like the wav filter or the amp filter if no amplification
528 * was specified. This function is rather cheap.
530 * \sa \ref btr_pushdown_one().
532 void btr_pushdown(struct btr_node *btrn)
534 struct btr_buffer_reference *br, *tmp;
536 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
537 btr_pushdown_br(br, btrn);
541 * Feed the next buffer of the input queue through the output channel.
543 * \param btrn The node whose first input queue buffer should be pushed down.
545 * This works like \ref btr_pushdown() but pushes down only one buffer
548 void btr_pushdown_one(struct btr_node *btrn)
550 struct btr_buffer_reference *br;
552 if (list_empty(&btrn->input_queue))
554 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
555 btr_pushdown_br(br, btrn);
559 * Find out whether a node is a leaf node.
561 * \param btrn The node to check.
563 * \return True if this node has no children. False otherwise.
565 static bool btr_no_children(struct btr_node *btrn)
567 return list_empty(&btrn->children);
571 * Find out whether a node is an orphan.
573 * \param btrn The buffer tree node.
575 * \return True if \a btrn has no parent.
577 * This function returns true for the root node and false for any other node.
579 * After a (non-leaf) node was removed removed from the tree, the function
580 * returns true for all child nodes.
582 bool btr_no_parent(struct btr_node *btrn)
584 return !btrn->parent;
588 * Find out whether it is OK to change an input buffer.
590 * \param btrn The buffer tree node to check.
592 * This is used by filters that produce exactly the same amount of output as
593 * there is input. The amp filter which multiplies each sample by some number
594 * is an example of such a filter. If there are no other nodes in the buffer
595 * tree that read the same input stream (i.e. if \a btrn has no siblings), a
596 * node may modify its input buffer directly and push down the modified buffer
597 * to its children, thereby avoiding to allocate a possibly large additional
600 * Since the buffer tree may change at any time, this function should be called
601 * during each post_monitor call.
603 * \return True if \a btrn has no siblings.
605 bool btr_inplace_ok(struct btr_node *btrn)
607 struct btr_buffer_reference *br;
608 FOR_EACH_BUFFER_REF(br, btrn) {
609 struct btr_buffer *btrb = br->btrb;
610 if (btrb->refcount > 1)
612 if (btrb->dont_free == true)
618 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
620 return br->btrb->size - br->consumed;
623 static size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
626 *buf = br->btrb->buf + br->consumed;
627 return br_available_bytes(br);
631 * Obtain the next buffer of the input queue, omitting data.
633 * \param btrn The node whose input queue is to be queried.
634 * \param omit Number of bytes to be omitted.
635 * \param bufp Result pointer. It is OK to pass \p NULL here.
637 * If a buffer tree node needs more input data but can not consume the data it
638 * already has (because it might be needed again later) this function can be
639 * used instead of btr_next_buffer() to get a reference to the buffer obtained
640 * by skipping the given number of bytes. Skipped input bytes are not consumed.
642 * With a zero \a omit argument, this function is equivalent to \ref
645 * \return Number of bytes in \a bufp. If there are less than or equal to \a
646 * omit many bytes available in the input queue of the buffer tree node pointed
647 * to by \a btrn, the function returns zero and the value of \a bufp is
650 size_t btr_next_buffer_omit(struct btr_node *btrn, size_t omit, char **bufp)
652 struct btr_buffer_reference *br;
653 size_t wrap_count, sz, rv = 0;
654 char *buf, *result = NULL;
656 br = get_first_input_br(btrn);
659 wrap_count = br->wrap_count;
660 if (wrap_count > 0) { /* we have a wrap buffer */
661 sz = btr_get_buffer_by_reference(br, &buf);
662 if (sz > omit) { /* and it's big enough */
666 * Wrap buffers are allocated by malloc(), so the next
667 * buffer ref will not align nicely, so we return the
668 * tail of the wrap buffer.
673 * The next wrap_count bytes exist twice, in the wrap buffer
674 * and as a buffer reference in the buffer tree pool.
679 * For buffer tree pools, the buffers in the list align, i.e. the next
680 * buffer in the list starts directly at the end of its predecessor. In
681 * this case we merge adjacent buffers and return one larger buffer
684 FOR_EACH_BUFFER_REF(br, btrn) {
685 sz = btr_get_buffer_by_reference(br, &buf);
687 if (result + rv != buf)
690 } else if (sz > omit) {
705 * Obtain the next buffer of the input queue of a buffer tree node.
707 * \param btrn The node whose input queue is to be queried.
708 * \param bufp Result pointer.
710 * \return The number of bytes that can be read from buf.
712 * The call of this function is is equivalent to calling \ref
713 * btr_next_buffer_omit() with an \a omit value of zero.
715 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
717 return btr_next_buffer_omit(btrn, 0, bufp);
721 * Deallocate the given number of bytes from the input queue.
723 * \param btrn The buffer tree node.
724 * \param numbytes The number of bytes to be deallocated.
726 * This function must be used to get rid of existing buffer references in the
727 * node's input queue. If no references to a buffer remain, the underlying
728 * buffers are either freed (in the non-buffer pool case) or the read head of
729 * the buffer pool is being advanced.
731 * Note that \a numbytes may be smaller than the buffer size. In this case the
732 * buffer is not deallocated and subsequent calls to btr_next_buffer() return
733 * the remaining part of the buffer.
735 void btr_consume(struct btr_node *btrn, size_t numbytes)
737 struct btr_buffer_reference *br, *tmp;
742 br = get_first_input_br(btrn);
745 if (br->wrap_count == 0) {
747 * No wrap buffer. Drop buffer references whose buffer
748 * has been fully used. */
749 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn) {
750 if (br->consumed + numbytes <= br->btrb->size) {
751 br->consumed += numbytes;
752 if (br->consumed == br->btrb->size)
753 btr_drop_buffer_reference(br);
756 numbytes -= br->btrb->size - br->consumed;
757 btr_drop_buffer_reference(br);
762 * We have a wrap buffer, consume from it. If in total, i.e. including
763 * previous calls to brt_consume(), less than wrap_count has been
764 * consumed, there's nothing more we can do.
766 * Otherwise we drop the wrap buffer and consume from subsequent
767 * buffers of the input queue the correct amount of bytes. This is the
768 * total number of bytes that have been consumed from the wrap buffer.
770 PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes,
771 br_available_bytes(br));
773 assert(numbytes <= br_available_bytes(br));
774 if (br->consumed + numbytes < br->wrap_count) {
775 br->consumed += numbytes;
778 PARA_DEBUG_LOG("dropping wrap buffer (%zu bytes)\n", br->btrb->size);
779 /* get rid of the wrap buffer */
780 sz = br->consumed + numbytes;
781 btr_drop_buffer_reference(br);
782 return btr_consume(btrn, sz);
786 * Clear the input queue of a buffer tree node.
788 * \param btrn The node whose input queue should be cleared.
790 void btr_drain(struct btr_node *btrn)
792 struct btr_buffer_reference *br, *tmp;
794 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
795 btr_drop_buffer_reference(br);
798 static void btr_free_node(struct btr_node *btrn)
805 * Remove a node from a buffer tree.
807 * \param btrnp Determines the node to remove.
809 * This orphans all children of the node given by \a btrnp and removes this
810 * node from the child list of its parent. Moreover, the input queue is flushed
811 * and the node pointer given by \a btrp is set to \p NULL.
813 * \sa \ref btr_splice_out_node.
815 void btr_remove_node(struct btr_node **btrnp)
818 struct btr_node *btrn;
825 PARA_INFO_LOG("removing btr node %s from buffer tree\n", btrn->name);
826 FOR_EACH_CHILD(ch, btrn)
830 list_del(&btrn->node);
837 * Return the amount of available input bytes of a buffer tree node.
839 * \param btrn The node whose input size should be computed.
841 * \return The total number of bytes available in the node's input
844 * This simply iterates over all buffer references in the input queue and
845 * returns the sum of the sizes of all references.
847 size_t btr_get_input_queue_size(struct btr_node *btrn)
849 struct btr_buffer_reference *br;
850 size_t size = 0, wrap_consumed = 0;
852 FOR_EACH_BUFFER_REF(br, btrn) {
853 if (br->wrap_count != 0) {
854 wrap_consumed = br->consumed;
857 size += br_available_bytes(br);
859 assert(wrap_consumed <= size);
860 size -= wrap_consumed;
864 static bool min_iqs_available(size_t min_iqs, struct btr_node *btrn)
866 struct btr_buffer_reference *br;
867 size_t have = 0, wrap_consumed = 0;
869 FOR_EACH_BUFFER_REF(br, btrn) {
870 if (br->wrap_count != 0) {
871 wrap_consumed = br->consumed;
874 have += br_available_bytes(br);
875 if (have > wrap_consumed + min_iqs)
881 * Remove a node from the buffer tree, reconnecting parent and children.
883 * \param btrnp The node to splice out.
885 * This function is used by buffer tree nodes that do not exist during the
886 * whole lifetime of the buffer tree. Unlike btr_remove_node(), calling
887 * btr_splice_out_node() does not split the tree into disconnected components
888 * but reconnects the buffer tree by making all child nodes of \a btrn children
889 * of the parent of \a btrn.
891 void btr_splice_out_node(struct btr_node **btrnp)
893 struct btr_node *btrn = *btrnp, *ch, *tmp;
896 PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
899 list_del(&btrn->node);
900 FOR_EACH_CHILD_SAFE(ch, tmp, btrn) {
901 PARA_INFO_LOG("parent(%s): %s\n", ch->name,
902 btrn->parent? btrn->parent->name : "NULL");
903 ch->parent = btrn->parent;
905 list_move(&ch->node, &btrn->parent->children);
909 assert(list_empty(&btrn->children));
915 * Return number of queued output bytes of a buffer tree node.
917 * \param btrn The node whose output queue size should be computed.
919 * \return This function iterates over all children of the given node and
920 * returns the size of the largest input queue.
922 size_t btr_get_output_queue_size(struct btr_node *btrn)
927 FOR_EACH_CHILD(ch, btrn) {
928 size_t size = btr_get_input_queue_size(ch);
929 max_size = PARA_MAX(max_size, size);
935 * Execute an inter-node command on the given node or on a parent node.
937 * \param btrn The node to start looking.
938 * \param command The command to execute.
939 * \param value_result Additional arguments and result value.
941 * This function traverses the buffer tree from \a btrn upwards and looks for
942 * the first node that understands \a command. On this node \a command is
943 * executed, and the result is stored in \a value_result.
945 * \return \p -ENOTSUP if no parent node of \a btrn understands \a command.
946 * Otherwise the return value of the command handler is returned.
948 * \sa \ref receiver::execute, \ref filter::execute, \ref writer::execute.
950 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
954 for (; btrn; btrn = btrn->parent) {
957 PARA_INFO_LOG("executing %s on %s\n", command, btrn->name);
958 ret = btrn->execute(btrn, command, value_result);
959 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
963 if (value_result && *value_result)
964 PARA_INFO_LOG("%s(%s): %s\n", command, btrn->name,
968 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
972 * Obtain the context of a buffer node tree.
974 * \param btrn The node whose output queue size should be computed.
976 * \return A pointer to the \a context address specified at node creation time.
978 * \sa \ref btr_new_node(), struct \ref btr_node_description.
980 void *btr_context(struct btr_node *btrn)
982 return btrn->context;
985 static bool need_buffer_pool_merge(struct btr_node *btrn)
987 struct btr_buffer_reference *br = get_first_input_br(btrn);
991 if (br->wrap_count != 0)
998 static void merge_input_pool(struct btr_node *btrn, size_t dest_size)
1000 struct btr_buffer_reference *br, *wbr = NULL;
1001 int num_refs; /* including wrap buffer */
1002 char *buf, *buf1 = NULL, *buf2 = NULL;
1003 size_t sz, sz1 = 0, sz2 = 0, wb_consumed = 0;
1005 br = get_first_input_br(btrn);
1006 if (!br || br_available_bytes(br) >= dest_size)
1009 FOR_EACH_BUFFER_REF(br, btrn) {
1011 sz = btr_get_buffer_by_reference(br, &buf);
1014 if (br->wrap_count != 0) {
1016 assert(num_refs == 1);
1018 if (sz >= dest_size)
1020 wb_consumed = br->consumed;
1028 if (buf1 + sz1 == buf) {
1037 assert(buf2 + sz2 == buf);
1040 if (sz1 + sz2 >= dest_size + wb_consumed)
1043 if (!buf2) /* nothing to do */
1045 assert(buf1 && sz2 > 0);
1047 * If the second buffer is large, we only take the first part of it to
1048 * avoid having to memcpy() huge buffers.
1050 sz2 = PARA_MIN(sz2, (size_t)(64 * 1024));
1052 /* Make a new wrap buffer combining buf1 and buf2. */
1055 PARA_DEBUG_LOG("merging input buffers: (%p:%zu, %p:%zu) -> %p:%zu\n",
1056 buf1, sz1, buf2, sz2, buf, sz);
1057 memcpy(buf, buf1, sz1);
1058 memcpy(buf + sz1, buf2, sz2);
1059 br = zalloc(sizeof(*br));
1060 br->btrb = new_btrb(buf, sz);
1061 br->btrb->refcount = 1;
1063 /* This is a wrap buffer */
1064 br->wrap_count = sz1;
1065 para_list_add(&br->node, &btrn->input_queue);
1069 * We already have a wrap buffer, but it is too small. It might be
1072 if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
1074 sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */
1075 PARA_DEBUG_LOG("increasing wrap buffer %zu -> %zu\n", wbr->btrb->size,
1076 wbr->btrb->size + sz);
1077 wbr->btrb->size += sz;
1078 wbr->btrb->buf = para_realloc(wbr->btrb->buf, wbr->btrb->size);
1079 /* copy the new data to the end of the reallocated buffer */
1081 memcpy(wbr->btrb->buf + wbr->btrb->size - sz, buf2 + sz2 - sz, sz);
1085 * Merge the first two input buffers into one.
1087 * This is a quite expensive operation.
1089 * \return The number of buffers that have been available (zero, one or two).
1091 static int merge_input(struct btr_node *btrn)
1093 struct btr_buffer_reference *brs[2], *br;
1094 char *bufs[2], *buf;
1098 if (list_empty(&btrn->input_queue))
1100 if (list_is_singular(&btrn->input_queue))
1103 /* get references to the first two buffers */
1104 FOR_EACH_BUFFER_REF(br, btrn) {
1106 szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
1112 /* make a new btrb that combines the two buffers and a br to it. */
1113 sz = szs[0] + szs[1];
1115 PARA_DEBUG_LOG("%s: memory merging input buffers: (%zu, %zu) -> %zu\n",
1116 btrn->name, szs[0], szs[1], sz);
1117 memcpy(buf, bufs[0], szs[0]);
1118 memcpy(buf + szs[0], bufs[1], szs[1]);
1120 br = zalloc(sizeof(*br));
1121 br->btrb = new_btrb(buf, sz);
1122 br->btrb->refcount = 1;
1124 /* replace the first two refs by the new one */
1125 btr_drop_buffer_reference(brs[0]);
1126 btr_drop_buffer_reference(brs[1]);
1127 para_list_add(&br->node, &btrn->input_queue);
1132 * Combine input queue buffers.
1134 * \param btrn The buffer tree node whose input should be merged.
1135 * \param dest_size Stop merging if a buffer of at least this size exists.
1137 * Used to combine as many buffers as needed into a single buffer whose size is
1138 * at least \a dest_size. This function is rather cheap in case the parent node
1139 * uses buffer pools and rather expensive otherwise.
1141 * Note that if less than \a dest_size bytes are available in total, this
1142 * function does nothing and subsequent calls to btr_next_buffer() will still
1143 * return a buffer size less than \a dest_size.
1145 void btr_merge(struct btr_node *btrn, size_t dest_size)
1147 if (need_buffer_pool_merge(btrn))
1148 return merge_input_pool(btrn, dest_size);
1151 size_t len = btr_next_buffer(btrn, &buf);
1152 if (len >= dest_size)
1154 PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len, dest_size);
1155 if (merge_input(btrn) < 2)
1160 static bool btr_eof(struct btr_node *btrn)
1163 size_t len = btr_next_buffer(btrn, &buf);
1165 return (len == 0 && btr_no_parent(btrn));
1168 static void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
1170 struct btr_node *ch;
1171 const char spaces[] = " ", *space = spaces + 16 - depth;
1175 para_log(loglevel, "%s%s\n", space, btrn->name);
1176 FOR_EACH_CHILD(ch, btrn)
1177 log_tree_recursively(ch, loglevel, depth + 1);
1181 * Write the current buffer (sub-)tree to the log.
1183 * \param btrn Start logging at this node.
1184 * \param loglevel Set severity with which the tree should be logged.
1186 void btr_log_tree(struct btr_node *btrn, int loglevel)
1188 return log_tree_recursively(btrn, loglevel, 0);
1192 * Find the node with the given name in the buffer tree.
1194 * \param name The name of the node to search.
1195 * \param root Where to start the search.
1197 * \return A pointer to the node with the given name on success. If \a name is
1198 * \p NULL, the function returns \a root. If there is no node with the given
1199 * name, \p NULL is returned.
1201 struct btr_node *btr_search_node(const char *name, struct btr_node *root)
1203 struct btr_node *ch;
1207 if (!strcmp(root->name, name))
1209 FOR_EACH_CHILD(ch, root) {
1210 struct btr_node *result = btr_search_node(name, ch);
1217 /** 640K ought to be enough for everybody ;) */
1218 #define BTRN_MAX_PENDING (96 * 1024)
1221 * Return the current state of a buffer tree node.
1223 * \param btrn The node whose state should be queried.
1224 * \param min_iqs The minimal input queue size.
1225 * \param type The supposed type of \a btrn.
1227 * Most users of the buffer tree subsystem call this function from both
1228 * their ->pre_monitor() and ->post_monitor() methods.
1230 * \return Negative if an error condition was detected, zero if there
1231 * is nothing to do and positive otherwise.
1235 * - If a non-root node has no parent and an empty input queue, the function
1236 * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p
1237 * -E_BTR_NO_CHILD is returned.
1239 * - If less than \a min_iqs many bytes are available in the input queue and no
1240 * EOF condition was detected, the function returns zero.
1242 * - If there's plenty of data left in the input queue of the children of \a
1243 * btrn, the function also returns zero in order to bound the memory usage of
1246 int btr_node_status(struct btr_node *btrn, size_t min_iqs,
1247 enum btr_node_type type)
1249 if (type != BTR_NT_LEAF && btr_no_children(btrn))
1250 return -E_BTR_NO_CHILD;
1251 if (type != BTR_NT_ROOT && btr_eof(btrn))
1254 if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
1256 if (type == BTR_NT_ROOT)
1258 if (min_iqs_available(min_iqs, btrn))
1260 return btr_no_parent(btrn);
1264 * Get the time of the first I/O for a buffer tree node.
1266 * \param btrn The node whose I/O time should be obtained.
1267 * \param tv Result pointer.
1269 * Mainly useful for the time display of para_audiod.
1271 void btr_get_node_start(struct btr_node *btrn, struct timeval *tv)
1277 * Get the parent node of a buffer tree node.
1279 * \param btrn The node whose parent should be returned.
1281 * \a btrn must not be \p NULL.
1283 * \return The parent of \a btrn, or \p NULL if \a btrn is the
1284 * root node of the buffer tree.
1286 struct btr_node *btr_parent(struct btr_node *btrn)
1288 return btrn->parent;