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 = para_calloc(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);
334 * Deallocate the reference, release the resources if refcount drops to zero.
336 static void btr_drop_buffer_reference(struct btr_buffer_reference *br)
338 struct btr_buffer *btrb = br->btrb;
343 if (btrb->refcount == 0) {
344 dealloc_buffer(btrb);
349 static void add_btrb_to_children(struct btr_buffer *btrb,
350 struct btr_node *btrn, size_t consumed)
354 if (btrn->start.tv_sec == 0)
356 FOR_EACH_CHILD(ch, btrn) {
357 struct btr_buffer_reference *br = para_calloc(sizeof(*br));
359 br->consumed = consumed;
360 list_add_tail(&br->node, &ch->input_queue);
362 if (ch->start.tv_sec == 0)
368 * Insert a malloced buffer into the buffer tree.
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.
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.
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.
381 void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
383 struct btr_buffer *btrb;
387 if (list_empty(&btrn->children)) {
391 btrb = new_btrb(buf, size);
392 add_btrb_to_children(btrb, btrn, 0);
396 * Insert a buffer into the buffer tree, non-freeing variant.
398 * \param buf See \ref btr_add_output().
399 * \param size See \ref btr_add_output().
400 * \param btrn See \ref btr_add_output().
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.
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
411 void btr_add_output_dont_free(const char *buf, size_t size, struct btr_node *btrn)
413 struct btr_buffer *btrb;
417 if (list_empty(&btrn->children))
419 btrb = new_btrb((char *)buf, size);
420 btrb->dont_free = true;
421 add_btrb_to_children(btrb, btrn, 0);
425 * Feed data to child nodes of a buffer tree node.
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.
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.
436 void btr_add_output_pool(struct btr_pool *btrp, size_t size,
437 struct btr_node *btrn)
439 struct btr_buffer *btrb;
445 if (list_empty(&btrn->children))
447 avail = btr_pool_get_buffer(btrp, &buf);
448 assert(avail >= size);
449 btr_pool_allocate(btrp, size);
450 btrb = new_btrb(buf, size);
452 add_btrb_to_children(btrb, btrn, 0);
456 * Copy data to write head of a buffer pool and feed it to all children nodes.
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.
463 * This is expensive. The caller must make sure the data fits into the buffer
466 void btr_copy(const void *src, size_t n, struct btr_pool *btrp,
467 struct btr_node *btrn)
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);
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);
487 static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *btrn)
489 add_btrb_to_children(br->btrb, btrn, br->consumed);
490 btr_drop_buffer_reference(br);
494 * Feed all buffer references of the input queue through the output channel.
496 * \param btrn The node whose buffer references should be pushed down.
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.
502 * \sa \ref btr_pushdown_one().
504 void btr_pushdown(struct btr_node *btrn)
506 struct btr_buffer_reference *br, *tmp;
508 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
509 btr_pushdown_br(br, btrn);
513 * Feed the next buffer of the input queue through the output channel.
515 * \param btrn The node whose first input queue buffer should be pushed down.
517 * This works like \ref btr_pushdown() but pushes down only one buffer
520 void btr_pushdown_one(struct btr_node *btrn)
522 struct btr_buffer_reference *br;
524 if (list_empty(&btrn->input_queue))
526 br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node);
527 btr_pushdown_br(br, btrn);
531 * Find out whether a node is a leaf node.
533 * \param btrn The node to check.
535 * \return True if this node has no children. False otherwise.
537 static bool btr_no_children(struct btr_node *btrn)
539 return list_empty(&btrn->children);
543 * Find out whether a node is an orphan.
545 * \param btrn The buffer tree node.
547 * \return True if \a btrn has no parent.
549 * This function returns true for the root node and false for any other node.
551 * After a (non-leaf) node was removed removed from the tree, the function
552 * returns true for all child nodes.
554 bool btr_no_parent(struct btr_node *btrn)
556 return !btrn->parent;
560 * Find out whether it is OK to change an input buffer.
562 * \param btrn The buffer tree node to check.
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
572 * Since the buffer tree may change at any time, this function should be called
573 * during each post_select call.
575 * \return True if \a btrn has no siblings.
577 bool btr_inplace_ok(struct btr_node *btrn)
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)
584 if (btrb->dont_free == true)
590 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
592 return br->btrb->size - br->consumed;
595 static size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf)
598 *buf = br->btrb->buf + br->consumed;
599 return br_available_bytes(br);
603 * Obtain the next buffer of the input queue, omitting data.
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.
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.
614 * With a zero \a omit argument, this function is equivalent to \ref
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
622 size_t btr_next_buffer_omit(struct btr_node *btrn, size_t omit, char **bufp)
624 struct btr_buffer_reference *br;
625 size_t wrap_count, sz, rv = 0;
626 char *buf, *result = NULL;
628 br = get_first_input_br(btrn);
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 */
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.
645 * The next wrap_count bytes exist twice, in the wrap buffer
646 * and as a buffer reference in the buffer tree pool.
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
656 FOR_EACH_BUFFER_REF(br, btrn) {
657 sz = btr_get_buffer_by_reference(br, &buf);
659 if (result + rv != buf)
662 } else if (sz > omit) {
677 * Obtain the next buffer of the input queue of a buffer tree node.
679 * \param btrn The node whose input queue is to be queried.
680 * \param bufp Result pointer.
682 * \return The number of bytes that can be read from buf.
684 * The call of this function is is equivalent to calling \ref
685 * btr_next_buffer_omit() with an \a omit value of zero.
687 size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
689 return btr_next_buffer_omit(btrn, 0, bufp);
693 * Deallocate the given number of bytes from the input queue.
695 * \param btrn The buffer tree node.
696 * \param numbytes The number of bytes to be deallocated.
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.
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.
707 void btr_consume(struct btr_node *btrn, size_t numbytes)
709 struct btr_buffer_reference *br, *tmp;
714 br = get_first_input_br(btrn);
717 if (br->wrap_count == 0) {
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);
728 numbytes -= br->btrb->size - br->consumed;
729 btr_drop_buffer_reference(br);
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.
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.
742 PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes,
743 br_available_bytes(br));
745 assert(numbytes <= br_available_bytes(br));
746 if (br->consumed + numbytes < br->wrap_count) {
747 br->consumed += numbytes;
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);
758 * Clear the input queue of a buffer tree node.
760 * \param btrn The node whose input queue should be cleared.
762 void btr_drain(struct btr_node *btrn)
764 struct btr_buffer_reference *br, *tmp;
766 FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn)
767 btr_drop_buffer_reference(br);
770 static void btr_free_node(struct btr_node *btrn)
777 * Remove a node from a buffer tree.
779 * \param btrnp Determines the node to remove.
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.
785 * \sa \ref btr_splice_out_node.
787 void btr_remove_node(struct btr_node **btrnp)
790 struct btr_node *btrn;
797 PARA_INFO_LOG("removing btr node %s from buffer tree\n", btrn->name);
798 FOR_EACH_CHILD(ch, btrn)
802 list_del(&btrn->node);
809 * Return the amount of available input bytes of a buffer tree node.
811 * \param btrn The node whose input size should be computed.
813 * \return The total number of bytes available in the node's input
816 * This simply iterates over all buffer references in the input queue and
817 * returns the sum of the sizes of all references.
819 size_t btr_get_input_queue_size(struct btr_node *btrn)
821 struct btr_buffer_reference *br;
822 size_t size = 0, wrap_consumed = 0;
824 FOR_EACH_BUFFER_REF(br, btrn) {
825 if (br->wrap_count != 0) {
826 wrap_consumed = br->consumed;
829 size += br_available_bytes(br);
831 assert(wrap_consumed <= size);
832 size -= wrap_consumed;
837 * Remove a node from the buffer tree, reconnecting parent and children.
839 * \param btrnp The node to splice out.
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.
847 void btr_splice_out_node(struct btr_node **btrnp)
849 struct btr_node *btrn = *btrnp, *ch, *tmp;
852 PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
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;
861 list_move(&ch->node, &btrn->parent->children);
865 assert(list_empty(&btrn->children));
871 * Return number of queued output bytes of a buffer tree node.
873 * \param btrn The node whose output queue size should be computed.
875 * \return This function iterates over all children of the given node and
876 * returns the size of the largest input queue.
878 size_t btr_get_output_queue_size(struct btr_node *btrn)
883 FOR_EACH_CHILD(ch, btrn) {
884 size_t size = btr_get_input_queue_size(ch);
885 max_size = PARA_MAX(max_size, size);
891 * Execute an inter-node command on the given node or on a parent node.
893 * \param btrn The node to start looking.
894 * \param command The command to execute.
895 * \param value_result Additional arguments and result value.
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.
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.
904 * \sa \ref receiver::execute, \ref filter::execute, \ref writer::execute.
906 int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
910 for (; btrn; btrn = btrn->parent) {
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))
919 if (value_result && *value_result)
920 PARA_INFO_LOG("%s(%s): %s\n", command, btrn->name,
924 return -ERRNO_TO_PARA_ERROR(ENOTSUP);
928 * Obtain the context of a buffer node tree.
930 * \param btrn The node whose output queue size should be computed.
932 * \return A pointer to the \a context address specified at node creation time.
934 * \sa \ref btr_new_node(), struct \ref btr_node_description.
936 void *btr_context(struct btr_node *btrn)
938 return btrn->context;
941 static bool need_buffer_pool_merge(struct btr_node *btrn)
943 struct btr_buffer_reference *br = get_first_input_br(btrn);
947 if (br->wrap_count != 0)
954 static void merge_input_pool(struct btr_node *btrn, size_t dest_size)
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;
961 br = get_first_input_br(btrn);
962 if (!br || br_available_bytes(br) >= dest_size)
965 FOR_EACH_BUFFER_REF(br, btrn) {
967 sz = btr_get_buffer_by_reference(br, &buf);
970 if (br->wrap_count != 0) {
972 assert(num_refs == 1);
976 wb_consumed = br->consumed;
984 if (buf1 + sz1 == buf) {
993 assert(buf2 + sz2 == buf);
996 if (sz1 + sz2 >= dest_size + wb_consumed)
999 if (!buf2) /* nothing to do */
1001 assert(buf1 && sz2 > 0);
1003 * If the second buffer is large, we only take the first part of it to
1004 * avoid having to memcpy() huge buffers.
1006 sz2 = PARA_MIN(sz2, (size_t)(64 * 1024));
1008 /* Make a new wrap buffer combining buf1 and buf2. */
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;
1019 /* This is a wrap buffer */
1020 br->wrap_count = sz1;
1021 para_list_add(&br->node, &btrn->input_queue);
1025 * We already have a wrap buffer, but it is too small. It might be
1028 if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */
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 */
1037 memcpy(wbr->btrb->buf + wbr->btrb->size - sz, buf2 + sz2 - sz, sz);
1041 * Merge the first two input buffers into one.
1043 * This is a quite expensive operation.
1045 * \return The number of buffers that have been available (zero, one or two).
1047 static int merge_input(struct btr_node *btrn)
1049 struct btr_buffer_reference *brs[2], *br;
1050 char *bufs[2], *buf;
1054 if (list_empty(&btrn->input_queue))
1056 if (list_is_singular(&btrn->input_queue))
1059 /* get references to the first two buffers */
1060 FOR_EACH_BUFFER_REF(br, btrn) {
1062 szs[i] = btr_get_buffer_by_reference(brs[i], bufs + i);
1068 /* make a new btrb that combines the two buffers and a br to it. */
1069 sz = szs[0] + szs[1];
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]);
1076 br = para_calloc(sizeof(*br));
1077 br->btrb = new_btrb(buf, sz);
1078 br->btrb->refcount = 1;
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);
1088 * Combine input queue buffers.
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.
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.
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.
1101 void btr_merge(struct btr_node *btrn, size_t dest_size)
1103 if (need_buffer_pool_merge(btrn))
1104 return merge_input_pool(btrn, dest_size);
1107 size_t len = btr_next_buffer(btrn, &buf);
1108 if (len >= dest_size)
1110 PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len, dest_size);
1111 if (merge_input(btrn) < 2)
1116 static bool btr_eof(struct btr_node *btrn)
1119 size_t len = btr_next_buffer(btrn, &buf);
1121 return (len == 0 && btr_no_parent(btrn));
1124 static void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth)
1126 struct btr_node *ch;
1127 const char spaces[] = " ", *space = spaces + 16 - depth;
1131 para_log(loglevel, "%s%s\n", space, btrn->name);
1132 FOR_EACH_CHILD(ch, btrn)
1133 log_tree_recursively(ch, loglevel, depth + 1);
1137 * Write the current buffer (sub-)tree to the log.
1139 * \param btrn Start logging at this node.
1140 * \param loglevel Set severity with which the tree should be logged.
1142 void btr_log_tree(struct btr_node *btrn, int loglevel)
1144 return log_tree_recursively(btrn, loglevel, 0);
1148 * Find the node with the given name in the buffer tree.
1150 * \param name The name of the node to search.
1151 * \param root Where to start the search.
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.
1157 struct btr_node *btr_search_node(const char *name, struct btr_node *root)
1159 struct btr_node *ch;
1163 if (!strcmp(root->name, name))
1165 FOR_EACH_CHILD(ch, root) {
1166 struct btr_node *result = btr_search_node(name, ch);
1173 /** 640K ought to be enough for everybody ;) */
1174 #define BTRN_MAX_PENDING (96 * 1024)
1177 * Return the current state of a buffer tree node.
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.
1183 * Most users of the buffer tree subsystem call this function from both
1184 * their pre_select and the post_select methods.
1186 * \return Negative if an error condition was detected, zero if there
1187 * is nothing to do and positive otherwise.
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.
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.
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
1202 int btr_node_status(struct btr_node *btrn, size_t min_iqs,
1203 enum btr_node_type type)
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))
1213 if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
1215 if (type == BTR_NT_ROOT)
1217 iqs = btr_get_input_queue_size(btrn);
1218 if (iqs == 0) /* we have a parent, because not eof */
1220 if (iqs < min_iqs && !btr_no_parent(btrn))
1226 * Get the time of the first I/O for a buffer tree node.
1228 * \param btrn The node whose I/O time should be obtained.
1229 * \param tv Result pointer.
1231 * Mainly useful for the time display of para_audiod.
1233 void btr_get_node_start(struct btr_node *btrn, struct timeval *tv)
1239 * Get the parent node of a buffer tree node.
1241 * \param btrn The node whose parent should be returned.
1243 * \a btrn must not be \p NULL.
1245 * \return The parent of \a btrn, or \p NULL if \a btrn is the
1246 * root node of the buffer tree.
1248 struct btr_node *btr_parent(struct btr_node *btrn)
1250 return btrn->parent;