7 #include "buffer_tree.h"
11 /* whead = NULL means area full */
23 /** The number of references to this buffer. */
25 /* NULL means no buffer pool but a malloced buffer. */
26 struct btr_pool *pool;
29 struct btr_buffer_reference {
30 struct btr_buffer *btrb;
32 /* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
33 struct list_head node;
39 struct btr_node *parent;
40 /* The position of this btr node in the buffer tree. */
41 struct list_head node;
42 /* The children nodes of this btr node are linked together in a list. */
43 struct list_head children;
44 /* Time of first data transfer. */
47 * The input queue is a list of references to btr buffers. Each item on
48 * the list represents an input buffer which has not been completely
49 * used by this btr node.
51 struct list_head input_queue;
52 btr_command_handler execute;
57 * Create a new buffer pool.
59 * \param name The name of the new buffer pool.
60 * \param area_size The size in bytes of the pool area.
62 * \return An opaque pointer to the newly created buffer pool. It must be
63 * passed to btr_pool_free() after it is no longer used to deallocate all
66 struct btr_pool *btr_pool_new(const char *name, size_t area_size)
68 struct btr_pool *btrp;
70 PARA_INFO_LOG("%s, %zu bytes\n", name, area_size);
71 btrp = para_malloc(sizeof(*btrp));
72 btrp->area_start = para_malloc(area_size);
73 btrp->area_end = btrp->area_start + area_size;
74 btrp->rhead = btrp->area_start;
75 btrp->whead = btrp->area_start;
76 btrp->name = para_strdup(name);
81 * Deallocate resources used by a buffer pool.
83 * \param btrp A pointer obtained via btr_pool_new().
85 void btr_pool_free(struct btr_pool *btrp)
89 free(btrp->area_start);
95 * Return the size of the buffer pool area.
97 * \param btrp The buffer pool.
99 * \return The same value which was passed during creation time to
102 size_t btr_pool_size(struct btr_pool *btrp)
104 return btrp->area_end - btrp->area_start;
107 static size_t btr_pool_filled(struct btr_pool *btrp)
110 return btr_pool_size(btrp);
111 if (btrp->rhead <= btrp->whead)
112 return btrp->whead - btrp->rhead;
113 return btr_pool_size(btrp) - (btrp->rhead - btrp->whead);
117 * Get the number of unused bytes in the buffer pool.
119 * \param btrp The pool.
121 * \return The number of bytes that can currently be allocated.
123 * Note that in general the returned number of bytes is not available as a
124 * single contiguous buffer. Use btr_pool_available() to obtain the length of
125 * the largest contiguous buffer that can currently be allocated from the
128 size_t btr_pool_unused(struct btr_pool *btrp)
130 return btr_pool_size(btrp) - btr_pool_filled(btrp);
134 * Return maximal size available for one read. This is
135 * smaller than the value returned by btr_pool_unused().
137 static size_t btr_pool_available(struct btr_pool *btrp)
141 if (btrp->rhead <= btrp->whead)
142 return btrp->area_end - btrp->whead;
143 return btrp->rhead - btrp->whead;
147 * Obtain the current write head.
149 * \param btrp The buffer pool.
150 * \param result The write head is returned here.
152 * \return The maximal amount of bytes that may be written to the returned
155 size_t btr_pool_get_buffer(struct btr_pool *btrp, char **result)
158 *result = btrp->whead;
159 return btr_pool_available(btrp);
163 * Get references to buffers pointing to free space of the buffer pool area.
165 * \param btrp The buffer pool.
166 * \param iov The scatter array.
168 * \return Zero if the buffer pool is full, one if the free space of the buffer
169 * pool area is available as a single contiguous buffer, two if the free space
170 * consists of two buffers. If this function returns the value n, then n
171 * elements of \a iov are initialized.
173 int btr_pool_get_buffers(struct btr_pool *btrp, struct iovec iov[2])
178 sz = btr_pool_get_buffer(btrp, &buf);
182 iov[0].iov_base = buf;
183 unused = btr_pool_unused(btrp);
186 iov[1].iov_len = unused - sz;
187 iov[1].iov_base = btrp->area_start;
192 * Mark a part of the buffer pool area as allocated.
194 * \param btrp The buffer pool.
195 * \param size The amount of bytes to be allocated.
197 * This is usually called after the caller wrote to the buffer obtained by
198 * btr_pool_get_buffer().
200 static void btr_pool_allocate(struct btr_pool *btrp, size_t size)
206 assert(size <= btr_pool_available(btrp));
207 end = btrp->whead + size;
208 assert(end <= btrp->area_end);
210 if (end == btrp->area_end) {
211 PARA_DEBUG_LOG("%s: end of pool area reached\n", btrp->name);
212 end = btrp->area_start;
214 if (end == btrp->rhead) {
215 PARA_DEBUG_LOG("%s btrp buffer full\n", btrp->name);
216 end = NULL; /* buffer full */
221 static void btr_pool_deallocate(struct btr_pool *btrp, size_t size)
223 char *end = btrp->rhead + size;
227 assert(end <= btrp->area_end);
228 assert(size <= btr_pool_filled(btrp));
229 if (end == btrp->area_end)
230 end = btrp->area_start;
232 btrp->whead = btrp->rhead;
234 if (btrp->rhead == btrp->whead)
235 btrp->rhead = btrp->whead = btrp->area_start;
238 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
239 &((_btrn)->children), node)
240 #define FOR_EACH_CHILD_SAFE(_tn, _tmp, _btrn) \
241 list_for_each_entry_safe((_tn), (_tmp), &((_btrn)->children), node)
243 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
244 list_for_each_entry((_br), &(_btrn)->input_queue, node)
245 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
246 list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
249 * Create a new buffer tree node.
251 * \param bnd Specifies how to create the new node.
253 * This function always succeeds (or calls exit()). The returned pointer must
254 * be freed using btr_free_node() after the node has been removed from the
255 * buffer tree via btr_remove_node().
257 struct btr_node *btr_new_node(struct btr_node_description *bnd)
259 struct btr_node *btrn = para_malloc(sizeof(*btrn));
261 btrn->name = para_strdup(bnd->name);
262 btrn->parent = bnd->parent;
263 btrn->execute = bnd->handler;
264 btrn->context = bnd->context;
265 btrn->start.tv_sec = 0;
266 btrn->start.tv_usec = 0;
267 INIT_LIST_HEAD(&btrn->children);
268 INIT_LIST_HEAD(&btrn->input_queue);
271 list_add_tail(&btrn->node, &bnd->parent->children);
272 PARA_INFO_LOG("new leaf node: %s (child of %s)\n",
273 bnd->name, bnd->parent->name);
275 PARA_INFO_LOG("added %s as btr root\n", bnd->name);
279 assert(!bnd->child->parent);
280 PARA_INFO_LOG("new root: %s (was %s)\n",
281 bnd->name, bnd->child->name);
283 list_add_tail(&bnd->child->node, &btrn->children);
285 bnd->child->parent = btrn;
288 PARA_EMERG_LOG("inserting internal nodes not yet supported.\n");
290 assert(bnd->child->parent == bnd->parent);
296 * Allocate a new btr buffer.
298 * The freshly allocated buffer will have a zero refcount and will
299 * not be associated with a btr pool.
301 static struct btr_buffer *new_btrb(char *buf, size_t size)
303 struct btr_buffer *btrb = para_calloc(sizeof(*btrb));
310 static void dealloc_buffer(struct btr_buffer *btrb)
313 btr_pool_deallocate(btrb->pool, btrb->size);
318 static struct btr_buffer_reference *get_first_input_br(struct btr_node *btrn)
320 if (list_empty(&btrn->input_queue))
322 return list_first_entry(&btrn->input_queue,
323 struct btr_buffer_reference, node);
327 * Deallocate the reference, release the resources if refcount drops to zero.
329 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
331 struct btr_buffer *btrb = br->btrb;
336 if (btrb->refcount == 0) {
337 dealloc_buffer(btrb);
342 static void add_btrb_to_children(struct btr_buffer *btrb,
343 struct btr_node *btrn, size_t consumed)
347 if (btrn->start.tv_sec == 0)
349 FOR_EACH_CHILD(ch, btrn) {
350 struct btr_buffer_reference *br = para_calloc(sizeof(*br));
352 br->consumed = consumed;
353 list_add_tail(&br->node, &ch->input_queue);
355 if (ch->start.tv_sec == 0)
361 * Insert a malloced buffer into the buffer tree.
363 * \param buf The buffer to insert.
364 * \param size The size of \a buf in bytes.
365 * \param btrn Position in the buffer tree to create the output.
367 * This creates references to \a buf and adds these references to each child of
368 * \a btrn. The buffer will be freed using standard free() once no buffer tree
369 * node is referencing it any more.
371 * Note that this function must not be used if \a buf was obtained from a
372 * buffer pool. Use btr_add_output_pool() in this case.
374 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
376 struct btr_buffer *btrb;
379 if (list_empty(&btrn->children)) {
383 btrb = new_btrb(buf, size);
384 add_btrb_to_children(btrb, btrn, 0);
388 * Feed data to child nodes of a buffer tree node.
390 * \param btrp The buffer pool.
391 * \param size The number of bytes to be allocated and fed to each child.
392 * \param btrn The node whose children are to be fed.
394 * This function allocates the amount of bytes from the buffer pool area,
395 * starting at the current value of the write head, and creates buffer
396 * references to the resulting part of the buffer pool area, one for each child
397 * of \a btrn. The references are then fed into the input queue of each child.
399 void btr_add_output_pool(struct btr_pool *btrp, size_t size,
400 struct btr_node *btrn)
402 struct btr_buffer *btrb;
407 if (list_empty(&btrn->children))
409 avail = btr_pool_get_buffer(btrp, &buf);
410 assert(avail >= size);
411 btr_pool_allocate(btrp, size);
412 btrb = new_btrb(buf, size);
414 add_btrb_to_children(btrb, btrn, 0);
418 * Copy data to write head of a buffer pool and feed it to all children nodes.
420 * \param src The source buffer.
421 * \param n The size of the source buffer in bytes.
422 * \param btrp The destination buffer pool.
423 * \param btrn Add the data as output of this node.
425 * This is expensive. The caller must make sure the data fits into the buffer
428 void btr_copy(const void *src, size_t n, struct btr_pool *btrp,
429 struct btr_node *btrn)
436 assert(n <= btr_pool_unused(btrp));
437 sz = btr_pool_get_buffer(btrp, &buf);
438 copy = PARA_MIN(sz, n);
439 memcpy(buf, src, copy);
440 btr_add_output_pool(btrp, copy, btrn);
443 sz = btr_pool_get_buffer(btrp, &buf);
444 assert(sz >= n - copy);
445 memcpy(buf, src + copy, n - copy);
446 btr_add_output_pool(btrp, n - copy, btrn);
449 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
451 add_btrb_to_children(br->btrb, btrn, br->consumed);
452 btr_drop_buffer_reference(br);
456 * Feed all buffer references of the input queue through the output channel.
458 * \param btrn The node whose buffer references should be pushed down.
460 * This function is useful for filters that do not change the contents of the
461 * buffers at all, like the wav filter or the amp filter if no amplification
462 * was specified. This function is rather cheap.
464 * \sa \ref btr_pushdown_one().
466 void btr_pushdown(struct btr_node *btrn)
468 struct btr_buffer_reference *br, *tmp;
470 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
471 btr_pushdown_br(br, btrn);
475 * Feed the next buffer of the input queue through the output channel.
477 * \param btrn The node whose first input queue buffer should be pushed down.
479 * This works like \ref btr_pushdown() but pushes down only one buffer
482 void btr_pushdown_one(struct btr_node *btrn)
484 struct btr_buffer_reference *br;
486 if (list_empty(&btrn->input_queue))
488 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
489 btr_pushdown_br(br, btrn);
493 * Find out whether a node is a leaf node.
495 * \param btrn The node to check.
497 * \return True if this node has no children. False otherwise.
499 static bool btr_no_children(struct btr_node *btrn)
501 return list_empty(&btrn->children);
505 * Find out whether a node is an orphan node.
507 * \param btrn The buffer tree node.
509 * \return True if \a btrn has no parent.
511 * This function will always return true for the root node. However in case
512 * nodes have been removed from the tree, other nodes may become orphans too.
514 bool btr_no_parent(struct btr_node *btrn)
516 return !btrn->parent;
520 * Find out whether it is OK to change an input buffer.
522 * \param btrn The buffer tree node to check.
524 * This is used by filters that produce exactly the same amount of output as
525 * there is input. The amp filter which multiplies each sample by some number
526 * is an example of such a filter. If there are no other nodes in the buffer
527 * tree that read the same input stream (i.e. if \a btrn has no siblings), a
528 * node may modify its input buffer directly and push down the modified buffer
529 * to its children, thereby avoiding to allocate a possibly large additional
532 * Since the buffer tree may change at any time, this function should be called
533 * during each post_select call.
535 * \return True if \a btrn has no siblings.
537 bool btr_inplace_ok(struct btr_node *btrn)
541 return list_is_singular(&btrn->parent->children);
544 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
546 return br->btrb->size - br->consumed;
549 static size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
552 *buf = br->btrb->buf + br->consumed;
553 return br_available_bytes(br);
557 * Obtain the next buffer of the input queue of a buffer tree node.
559 * \param btrn The node whose input queue is to be queried.
560 * \param bufp Result pointer.
562 * \return The number of bytes that can be read from buf. Zero if the input
563 * buffer queue is empty. In this case the value of \a bufp is undefined.
565 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
567 struct btr_buffer_reference *br;
568 char *buf, *result = NULL;
571 FOR_EACH_BUFFER_REF(br, btrn) {
572 sz = btr_get_buffer_by_reference(br, &buf);
582 if (result + rv != buf)
592 * Deallocate the given number of bytes from the input queue.
594 * \param btrn The buffer tree node.
595 * \param numbytes The number of bytes to be deallocated.
597 * This function must be used to get rid of existing buffer references in the
598 * node's input queue. If no references to a buffer remain, the underlying
599 * buffers are either freed (in the non-buffer tree case) or the read head of
600 * the buffer pool is being advanced.
602 * Note that \a numbytes may be smaller than the buffer size. In this case the
603 * buffer is not deallocated and subsequent calls to btr_next_buffer() return
604 * the remaining part of the buffer.
606 void btr_consume(struct btr_node *btrn, size_t numbytes)
608 struct btr_buffer_reference *br, *tmp;
613 br = get_first_input_br(btrn);
616 if (br->wrap_count == 0) {
618 * No wrap buffer. Drop buffer references whose buffer
619 * has been fully used. */
620 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn) {
621 if (br->consumed + numbytes <= br->btrb->size) {
622 br->consumed += numbytes;
623 if (br->consumed == br->btrb->size)
624 btr_drop_buffer_reference(br);
627 numbytes -= br->btrb->size - br->consumed;
628 btr_drop_buffer_reference(br);
633 * We have a wrap buffer, consume from it. If in total, i.e. including
634 * previous calls to brt_consume(), less than wrap_count has been
635 * consumed, there's nothing more we can do.
637 * Otherwise we drop the wrap buffer and consume from subsequent
638 * buffers of the input queue the correct amount of bytes. This is the
639 * total number of bytes that have been consumed from the wrap buffer.
641 PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes,
642 br_available_bytes(br));
644 assert(numbytes <= br_available_bytes(br));
645 if (br->consumed + numbytes < br->wrap_count) {
646 br->consumed += numbytes;
649 PARA_DEBUG_LOG("dropping wrap buffer (%zu bytes)\n", br->btrb->size);
650 /* get rid of the wrap buffer */
651 sz = br->consumed + numbytes;
652 btr_drop_buffer_reference(br);
653 return btr_consume(btrn, sz);
656 static void flush_input_queue(struct btr_node *btrn)
658 struct btr_buffer_reference *br, *tmp;
659 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
660 btr_drop_buffer_reference(br);
664 * Free all resources allocated by btr_new_node().
666 * Like free(3), it is OK to call this with a \p NULL pointer argument.
668 void btr_free_node(struct btr_node *btrn)
677 * Remove a node from a buffer tree.
679 * \param btrn The node to remove.
681 * This makes all child nodes of \a btrn orphans and removes \a btrn from the
682 * list of children of its parent. Moreover, the input queue of \a btrn is
683 * flushed if it is not empty.
685 * \sa \ref btr_splice_out_node.
687 void btr_remove_node(struct btr_node *btrn)
693 PARA_NOTICE_LOG("removing btr node %s from buffer tree\n", btrn->name);
694 FOR_EACH_CHILD(ch, btrn)
696 flush_input_queue(btrn);
698 list_del(&btrn->node);
702 * Return the amount of available input bytes of a buffer tree node.
704 * \param btrn The node whose input size should be computed.
706 * \return The total number of bytes available in the node's input
709 * This simply iterates over all buffer references in the input queue and
710 * returns the sum of the sizes of all references.
712 size_t btr_get_input_queue_size(struct btr_node *btrn)
714 struct btr_buffer_reference *br;
715 size_t size = 0, wrap_consumed = 0;
717 FOR_EACH_BUFFER_REF(br, btrn) {
718 if (br->wrap_count != 0) {
719 wrap_consumed = br->consumed;
722 size += br_available_bytes(br);
724 assert(wrap_consumed <= size);
725 size -= wrap_consumed;
730 * Remove a node from the buffer tree, reconnecting parent and children.
732 * \param btrn The node to splice out.
734 * This function is used by buffer tree nodes that do not exist during the
735 * whole lifetime of the buffer tree. Unlike btr_remove_node(), calling
736 * btr_splice_out_node() does not split the tree into disconnected components
737 * but reconnects the buffer tree by making all child nodes of \a btrn children
738 * of the parent of \a btrn.
740 void btr_splice_out_node(struct btr_node *btrn)
742 struct btr_node *ch, *tmp;
745 PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
748 list_del(&btrn->node);
749 FOR_EACH_CHILD_SAFE(ch, tmp, btrn) {
750 PARA_INFO_LOG("parent(%s): %s\n", ch->name,
751 btrn->parent? btrn->parent->name : "NULL");
752 ch->parent = btrn->parent;
754 list_move(&ch->node, &btrn->parent->children);
756 assert(list_empty(&btrn->children));
760 * Return number of queued output bytes of a buffer tree node.
762 * \param btrn The node whose output queue size should be computed.
764 * This function iterates over all children of the given node and returns the
765 * size of the largest input queue.
767 size_t btr_get_output_queue_size(struct btr_node *btrn)
772 FOR_EACH_CHILD(ch, btrn) {
773 size_t size = btr_get_input_queue_size(ch);
774 max_size = PARA_MAX(max_size, size);
779 int btr_exec(struct btr_node *btrn, const char *command, char **value_result)
782 return -ERRNO_TO_PARA_ERROR(EINVAL);
784 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
785 return btrn->execute(btrn, command, value_result);
789 * Execute a inter-node command on a parent node.
791 * \param btrn The node to start looking.
792 * \param command The command to execute.
793 * \param value_result Additional arguments and result value.
795 * This function traverses the buffer tree upwards and looks for parent nodes
796 * of \a btrn that understands \a command. On the first such node the command
797 * is executed, and the result is stored in \a value_result.
799 * \return \p -ENOTSUP if no parent node of \a btrn understands \a command.
800 * Otherwise the return value of the command handler is returned.
802 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
806 for (; btrn; btrn = btrn->parent) {
807 struct btr_node *parent = btrn->parent;
809 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
810 if (!parent->execute)
812 PARA_INFO_LOG("parent: %s, cmd: %s\n", parent->name, command);
813 ret = parent->execute(parent, command, value_result);
814 if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
818 if (value_result && *value_result)
819 PARA_NOTICE_LOG("%s(%s): %s\n", command, parent->name,
823 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
827 * Obtain the context of a buffer node tree.
829 * The returned pointer equals the context pointer used at creation time of the
832 * \sa btr_new_node(), struct \ref btr_node_description.
834 void *btr_context(struct btr_node *btrn)
836 return btrn->context;
839 static bool need_buffer_pool_merge(struct btr_node *btrn)
841 struct btr_buffer_reference *br = get_first_input_br(btrn);
845 if (br->wrap_count != 0)
852 static void merge_input_pool(struct btr_node *btrn, size_t dest_size)
854 struct btr_buffer_reference *br, *wbr = NULL;
855 int num_refs; /* including wrap buffer */
856 char *buf, *buf1 = NULL, *buf2 = NULL;
857 size_t sz, sz1 = 0, sz2 = 0, wsz;
859 br = get_first_input_br(btrn);
860 if (!br || br_available_bytes(br) >= dest_size)
863 FOR_EACH_BUFFER_REF(br, btrn) {
865 sz = btr_get_buffer_by_reference(br, &buf);
868 if (br->wrap_count != 0) {
870 assert(num_refs == 1);
881 if (buf1 + sz1 == buf) {
890 assert(buf2 + sz2 == buf);
893 if (sz1 + sz2 >= dest_size)
896 if (!buf2) /* nothing to do */
898 assert(buf1 && sz2 > 0);
900 * If the second buffer is large, we only take the first part of it to
901 * avoid having to memcpy() huge buffers.
903 sz2 = PARA_MIN(sz2, (size_t)(64 * 1024));
905 /* Make a new wrap buffer combining buf1 and buf2. */
907 buf = para_malloc(sz);
908 PARA_DEBUG_LOG("merging input buffers: (%p:%zu, %p:%zu) -> %p:%zu\n",
909 buf1, sz1, buf2, sz2, buf, sz);
910 memcpy(buf, buf1, sz1);
911 memcpy(buf + sz1, buf2, sz2);
912 br = para_calloc(sizeof(*br));
913 br->btrb = new_btrb(buf, sz);
914 br->btrb->refcount = 1;
916 /* This is a wrap buffer */
917 br->wrap_count = sz1;
918 para_list_add(&br->node, &btrn->input_queue);
922 * We already have a wrap buffer, but it is too small. It might be
925 wsz = br_available_bytes(wbr);
926 if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
928 sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */
929 PARA_DEBUG_LOG("increasing wrap buffer %zu -> %zu\n", wbr->btrb->size,
930 wbr->btrb->size + sz);
931 wbr->btrb->size += sz;
932 wbr->btrb->buf = para_realloc(wbr->btrb->buf, wbr->btrb->size);
933 /* copy the new data to the end of the reallocated buffer */
935 memcpy(wbr->btrb->buf + wbr->btrb->size - sz, buf2 + sz2 - sz, sz);
939 * Merge the first two input buffers into one.
941 * This is a quite expensive operation.
943 * \return The number of buffers that have been available (zero, one or two).
945 static int merge_input(struct btr_node *btrn)
947 struct btr_buffer_reference *brs[2], *br;
952 if (list_empty(&btrn->input_queue))
954 if (list_is_singular(&btrn->input_queue))
957 /* get references to the first two buffers */
958 FOR_EACH_BUFFER_REF(br, btrn) {
960 szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
966 /* make a new btrb that combines the two buffers and a br to it. */
967 sz = szs[0] + szs[1];
968 buf = para_malloc(sz);
969 PARA_DEBUG_LOG("%s: memory merging input buffers: (%zu, %zu) -> %zu\n",
970 btrn->name, szs[0], szs[1], sz);
971 memcpy(buf, bufs[0], szs[0]);
972 memcpy(buf + szs[0], bufs[1], szs[1]);
974 br = para_calloc(sizeof(*br));
975 br->btrb = new_btrb(buf, sz);
976 br->btrb->refcount = 1;
978 /* replace the first two refs by the new one */
979 btr_drop_buffer_reference(brs[0]);
980 btr_drop_buffer_reference(brs[1]);
981 para_list_add(&br->node, &btrn->input_queue);
986 * Combine input queue buffers.
988 * \param btrn The buffer tree node whose input should be merged.
989 * \param dest_size Stop merging if a buffer of at least this size exists.
991 * Used to combine as many buffers as needed into a single buffer whose size is
992 * at least \a dest_size. This function is rather cheap in case the parent node
993 * uses buffer pools and rather expensive otherwise.
995 * Note that if less than \a dest_size bytes are available in total, this
996 * function does nothing and subsequent calls to btr_next_buffer() will still
997 * return a buffer size less than \a dest_size.
999 void btr_merge(struct btr_node *btrn, size_t dest_size)
1001 if (need_buffer_pool_merge(btrn))
1002 return merge_input_pool(btrn, dest_size);
1005 size_t len = btr_next_buffer(btrn, &buf);
1006 if (len >= dest_size)
1008 PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len, dest_size);
1009 if (merge_input(btrn) < 2)
1014 static bool btr_eof(struct btr_node *btrn)
1017 size_t len = btr_next_buffer(btrn, &buf);
1019 return (len == 0 && btr_no_parent(btrn));
1022 static void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
1024 struct btr_node *ch;
1025 const char spaces[] = " ", *space = spaces + 16 - depth;
1029 para_log(loglevel, "%s%s\n", space, btrn->name);
1030 FOR_EACH_CHILD(ch, btrn)
1031 log_tree_recursively(ch, loglevel, depth + 1);
1035 * Write the current buffer (sub-)tree to the log.
1037 * \param btrn Start logging at this node.
1038 * \param loglevel Set severity with which the tree should be logged.
1040 void btr_log_tree(struct btr_node *btrn, int loglevel)
1042 return log_tree_recursively(btrn, loglevel, 0);
1046 * Find the node with the given name in the buffer tree.
1048 * \param name The name of the node to search.
1049 * \param root Where to start the search.
1051 * \return A pointer to the node with the given name on success. If \a name is
1052 * \p NULL, the function returns \a root. If there is no node with the given
1053 * name, \p NULL is returned.
1055 struct btr_node *btr_search_node(const char *name, struct btr_node *root)
1057 struct btr_node *ch;
1061 if (!strcmp(root->name, name))
1063 FOR_EACH_CHILD(ch, root) {
1064 struct btr_node *result = btr_search_node(name, ch);
1071 /** 640K ought to be enough for everybody ;) */
1072 #define BTRN_MAX_PENDING (640 * 1024)
1075 * Return the current state of a buffer tree node.
1077 * \param btrn The node whose state should be queried.
1078 * \param min_iqs The minimal input queue size.
1079 * \param type The supposed type of \a btrn.
1081 * Most users of the buffer tree subsystem call this function from both
1082 * their pre_select and the post_select methods.
1084 * \return Negative if an error condition was detected, zero if there
1085 * is nothing to do and positive otherwise.
1089 * - If a non-root node has no parent and an empty input queue, the function
1090 * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p
1091 * -E_BTR_NO_CHILD is returned.
1093 * - If less than \a min_iqs many bytes are available in the input queue and no
1094 * EOF condition was detected, the function returns zero.
1096 * - If there's plenty of data left in the input queue of the children of \a
1097 * btrn, the function also returns zero in order to bound the memory usage of
1100 int btr_node_status(struct btr_node *btrn, size_t min_iqs,
1101 enum btr_node_type type)
1106 if (type != BTR_NT_LEAF) {
1107 if (btr_no_children(btrn))
1108 return -E_BTR_NO_CHILD;
1109 if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
1112 if (type != BTR_NT_ROOT) {
1115 iqs = btr_get_input_queue_size(btrn);
1116 if (iqs == 0) /* we have a parent, because not eof */
1118 if (iqs < min_iqs && !btr_no_parent(btrn))
1125 * Get the time of the first I/O for a buffer tree node.
1127 * \param btrn The node whose I/O time should be obtained.
1128 * \param tv Result pointer.
1130 * Mainly useful for the time display of para_audiod.
1132 void btr_get_node_start(struct btr_node *btrn, struct timeval *tv)