2 * Copyright (C) 2009-2013 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file buffer_tree.c Buffer tree and buffer pool implementations. */
13 #include "buffer_tree.h"
17 /* whead = NULL means area full */
29 /** The number of references to this buffer. */
31 /* NULL means no buffer pool but a malloced buffer. */
32 struct btr_pool
*pool
;
33 /* Only relevant if pool is NULL. */
37 struct btr_buffer_reference
{
38 struct btr_buffer
*btrb
;
40 /* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
41 struct list_head node
;
47 struct btr_node
*parent
;
48 /* The position of this btr node in the buffer tree. */
49 struct list_head node
;
50 /* The children nodes of this btr node are linked together in a list. */
51 struct list_head children
;
52 /* Time of first data transfer. */
55 * The input queue is a list of references to btr buffers. Each item on
56 * the list represents an input buffer which has not been completely
57 * used by this btr node.
59 struct list_head input_queue
;
60 btr_command_handler execute
;
65 * Create a new buffer pool.
67 * \param name The name of the new buffer pool.
68 * \param area_size The size in bytes of the pool area.
70 * \return An opaque pointer to the newly created buffer pool. It must be
71 * passed to btr_pool_free() after it is no longer used to deallocate all
74 struct btr_pool
*btr_pool_new(const char *name
, size_t area_size
)
76 struct btr_pool
*btrp
;
78 PARA_INFO_LOG("%s, %zu bytes\n", name
, area_size
);
79 btrp
= para_malloc(sizeof(*btrp
));
80 btrp
->area_start
= para_malloc(area_size
);
81 btrp
->area_end
= btrp
->area_start
+ area_size
;
82 btrp
->rhead
= btrp
->area_start
;
83 btrp
->whead
= btrp
->area_start
;
84 btrp
->name
= para_strdup(name
);
89 * Deallocate resources used by a buffer pool.
91 * \param btrp A pointer obtained via btr_pool_new().
93 void btr_pool_free(struct btr_pool
*btrp
)
97 free(btrp
->area_start
);
103 * Return the size of the buffer pool area.
105 * \param btrp The buffer pool.
107 * \return The same value which was passed during creation time to
110 size_t btr_pool_size(struct btr_pool
*btrp
)
112 return btrp
->area_end
- btrp
->area_start
;
115 static size_t btr_pool_filled(struct btr_pool
*btrp
)
118 return btr_pool_size(btrp
);
119 if (btrp
->rhead
<= btrp
->whead
)
120 return btrp
->whead
- btrp
->rhead
;
121 return btr_pool_size(btrp
) - (btrp
->rhead
- btrp
->whead
);
125 * Get the number of unused bytes in the buffer pool.
127 * \param btrp The pool.
129 * \return The number of bytes that can currently be allocated.
131 * Note that in general the returned number of bytes is not available as a
132 * single contiguous buffer. Use btr_pool_available() to obtain the length of
133 * the largest contiguous buffer that can currently be allocated from the
136 size_t btr_pool_unused(struct btr_pool
*btrp
)
138 return btr_pool_size(btrp
) - btr_pool_filled(btrp
);
142 * Return maximal size available for one read. This is
143 * smaller than the value returned by btr_pool_unused().
145 static size_t btr_pool_available(struct btr_pool
*btrp
)
149 if (btrp
->rhead
<= btrp
->whead
)
150 return btrp
->area_end
- btrp
->whead
;
151 return btrp
->rhead
- btrp
->whead
;
155 * Obtain the current write head.
157 * \param btrp The buffer pool.
158 * \param result The write head is returned here.
160 * \return The maximal amount of bytes that may be written to the returned
163 size_t btr_pool_get_buffer(struct btr_pool
*btrp
, char **result
)
166 *result
= btrp
->whead
;
167 return btr_pool_available(btrp
);
171 * Get references to buffers pointing to free space of the buffer pool area.
173 * \param btrp The buffer pool.
174 * \param iov The scatter array.
176 * \return Zero if the buffer pool is full, one if the free space of the buffer
177 * pool area is available as a single contiguous buffer, two if the free space
178 * consists of two buffers. If this function returns the value n, then n
179 * elements of \a iov are initialized.
181 int btr_pool_get_buffers(struct btr_pool
*btrp
, struct iovec iov
[2])
186 sz
= btr_pool_get_buffer(btrp
, &buf
);
190 iov
[0].iov_base
= buf
;
191 unused
= btr_pool_unused(btrp
);
194 iov
[1].iov_len
= unused
- sz
;
195 iov
[1].iov_base
= btrp
->area_start
;
200 * Mark a part of the buffer pool area as allocated.
202 * \param btrp The buffer pool.
203 * \param size The amount of bytes to be allocated.
205 * This is usually called after the caller wrote to the buffer obtained by
206 * btr_pool_get_buffer().
208 static void btr_pool_allocate(struct btr_pool
*btrp
, size_t size
)
214 assert(size
<= btr_pool_available(btrp
));
215 end
= btrp
->whead
+ size
;
216 assert(end
<= btrp
->area_end
);
218 if (end
== btrp
->area_end
) {
219 PARA_DEBUG_LOG("%s: end of pool area reached\n", btrp
->name
);
220 end
= btrp
->area_start
;
222 if (end
== btrp
->rhead
) {
223 PARA_DEBUG_LOG("%s btrp buffer full\n", btrp
->name
);
224 end
= NULL
; /* buffer full */
229 static void btr_pool_deallocate(struct btr_pool
*btrp
, size_t size
)
231 char *end
= btrp
->rhead
+ size
;
235 assert(end
<= btrp
->area_end
);
236 assert(size
<= btr_pool_filled(btrp
));
237 if (end
== btrp
->area_end
)
238 end
= btrp
->area_start
;
240 btrp
->whead
= btrp
->rhead
;
242 if (btrp
->rhead
== btrp
->whead
)
243 btrp
->rhead
= btrp
->whead
= btrp
->area_start
;
246 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
247 &((_btrn)->children), node)
248 #define FOR_EACH_CHILD_SAFE(_tn, _tmp, _btrn) \
249 list_for_each_entry_safe((_tn), (_tmp), &((_btrn)->children), node)
251 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
252 list_for_each_entry((_br), &(_btrn)->input_queue, node)
253 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
254 list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
257 * Create a new buffer tree node.
259 * \param bnd Specifies how to create the new node.
261 * \return A pointer to the newly allocated node.
263 * This function always succeeds (or calls exit()). The returned pointer must
264 * be freed using btr_free_node() after the node has been removed from the
265 * buffer tree via btr_remove_node().
267 struct btr_node
*btr_new_node(struct btr_node_description
*bnd
)
269 struct btr_node
*btrn
= para_malloc(sizeof(*btrn
));
271 btrn
->name
= para_strdup(bnd
->name
);
272 btrn
->parent
= bnd
->parent
;
273 btrn
->execute
= bnd
->handler
;
274 btrn
->context
= bnd
->context
;
275 btrn
->start
.tv_sec
= 0;
276 btrn
->start
.tv_usec
= 0;
277 INIT_LIST_HEAD(&btrn
->children
);
278 INIT_LIST_HEAD(&btrn
->input_queue
);
281 list_add_tail(&btrn
->node
, &bnd
->parent
->children
);
282 PARA_INFO_LOG("new leaf node: %s (child of %s)\n",
283 bnd
->name
, bnd
->parent
->name
);
285 PARA_INFO_LOG("added %s as btr root\n", bnd
->name
);
289 assert(!bnd
->child
->parent
);
290 PARA_INFO_LOG("new root: %s (was %s)\n",
291 bnd
->name
, bnd
->child
->name
);
293 list_add_tail(&bnd
->child
->node
, &btrn
->children
);
295 bnd
->child
->parent
= btrn
;
298 list_add_tail(&btrn
->node
, &bnd
->parent
->children
);
299 list_move(&bnd
->child
->node
, &btrn
->children
);
300 bnd
->child
->parent
= btrn
;
301 PARA_INFO_LOG("added %s as internal node\n", bnd
->name
);
307 * Allocate a new btr buffer.
309 * The freshly allocated buffer will have a zero refcount and will
310 * not be associated with a btr pool.
312 static struct btr_buffer
*new_btrb(char *buf
, size_t size
)
314 struct btr_buffer
*btrb
= para_calloc(sizeof(*btrb
));
321 static void dealloc_buffer(struct btr_buffer
*btrb
)
324 btr_pool_deallocate(btrb
->pool
, btrb
->size
);
325 else if (!btrb
->dont_free
)
329 static struct btr_buffer_reference
*get_first_input_br(struct btr_node
*btrn
)
331 if (list_empty(&btrn
->input_queue
))
333 return list_first_entry(&btrn
->input_queue
,
334 struct btr_buffer_reference
, node
);
338 * Deallocate the reference, release the resources if refcount drops to zero.
340 static void btr_drop_buffer_reference(struct btr_buffer_reference
*br
)
342 struct btr_buffer
*btrb
= br
->btrb
;
347 if (btrb
->refcount
== 0) {
348 dealloc_buffer(btrb
);
353 static void add_btrb_to_children(struct btr_buffer
*btrb
,
354 struct btr_node
*btrn
, size_t consumed
)
358 if (btrn
->start
.tv_sec
== 0)
360 FOR_EACH_CHILD(ch
, btrn
) {
361 struct btr_buffer_reference
*br
= para_calloc(sizeof(*br
));
363 br
->consumed
= consumed
;
364 list_add_tail(&br
->node
, &ch
->input_queue
);
366 if (ch
->start
.tv_sec
== 0)
372 * Insert a malloced buffer into the buffer tree.
374 * \param buf The buffer to insert.
375 * \param size The size of \a buf in bytes.
376 * \param btrn Position in the buffer tree to create the output.
378 * This creates references to \a buf and adds these references to each child of
379 * \a btrn. The buffer will be freed using standard free() once no buffer tree
380 * node is referencing it any more.
382 * Note that this function must not be used if \a buf was obtained from a
383 * buffer pool. Use btr_add_output_pool() in this case.
385 void btr_add_output(char *buf
, size_t size
, struct btr_node
*btrn
)
387 struct btr_buffer
*btrb
;
391 if (list_empty(&btrn
->children
)) {
395 btrb
= new_btrb(buf
, size
);
396 add_btrb_to_children(btrb
, btrn
, 0);
400 * Insert a buffer into the buffer tree, non-freeing variant.
402 * \param buf See \ref btr_add_output().
403 * \param size See \ref btr_add_output().
404 * \param btrn See \ref btr_add_output().
406 * This is similar to btr_add_output() but additionally sets the \p dont_free
407 * flag on \a buf. If the refcount for the buffer drops to zero, \a buf will
408 * not be deallocated if this flag is set.
410 * The \p dont_free bit also prevents the children of \a btrn from modifying
411 * the buffer contents inplace. Specifically, \ref btr_inplace_ok() returns
412 * false if there is any buffer in the input queue with the \p dont_free bit
415 void btr_add_output_dont_free(const char *buf
, size_t size
, struct btr_node
*btrn
)
417 struct btr_buffer
*btrb
;
421 if (list_empty(&btrn
->children
))
423 btrb
= new_btrb((char *)buf
, size
);
424 btrb
->dont_free
= true;
425 add_btrb_to_children(btrb
, btrn
, 0);
429 * Feed data to child nodes of a buffer tree node.
431 * \param btrp The buffer pool.
432 * \param size The number of bytes to be allocated and fed to each child.
433 * \param btrn The node whose children are to be fed.
435 * This function allocates the amount of bytes from the buffer pool area,
436 * starting at the current value of the write head, and creates buffer
437 * references to the resulting part of the buffer pool area, one for each child
438 * of \a btrn. The references are then fed into the input queue of each child.
440 void btr_add_output_pool(struct btr_pool
*btrp
, size_t size
,
441 struct btr_node
*btrn
)
443 struct btr_buffer
*btrb
;
449 if (list_empty(&btrn
->children
))
451 avail
= btr_pool_get_buffer(btrp
, &buf
);
452 assert(avail
>= size
);
453 btr_pool_allocate(btrp
, size
);
454 btrb
= new_btrb(buf
, size
);
456 add_btrb_to_children(btrb
, btrn
, 0);
460 * Copy data to write head of a buffer pool and feed it to all children nodes.
462 * \param src The source buffer.
463 * \param n The size of the source buffer in bytes.
464 * \param btrp The destination buffer pool.
465 * \param btrn Add the data as output of this node.
467 * This is expensive. The caller must make sure the data fits into the buffer
470 void btr_copy(const void *src
, size_t n
, struct btr_pool
*btrp
,
471 struct btr_node
*btrn
)
478 assert(n
<= btr_pool_unused(btrp
));
479 sz
= btr_pool_get_buffer(btrp
, &buf
);
480 copy
= PARA_MIN(sz
, n
);
481 memcpy(buf
, src
, copy
);
482 btr_add_output_pool(btrp
, copy
, btrn
);
485 sz
= btr_pool_get_buffer(btrp
, &buf
);
486 assert(sz
>= n
- copy
);
487 memcpy(buf
, src
+ copy
, n
- copy
);
488 btr_add_output_pool(btrp
, n
- copy
, btrn
);
491 static void btr_pushdown_br(struct btr_buffer_reference
*br
, struct btr_node
*btrn
)
493 add_btrb_to_children(br
->btrb
, btrn
, br
->consumed
);
494 btr_drop_buffer_reference(br
);
498 * Feed all buffer references of the input queue through the output channel.
500 * \param btrn The node whose buffer references should be pushed down.
502 * This function is useful for filters that do not change the contents of the
503 * buffers at all, like the wav filter or the amp filter if no amplification
504 * was specified. This function is rather cheap.
506 * \sa \ref btr_pushdown_one().
508 void btr_pushdown(struct btr_node
*btrn
)
510 struct btr_buffer_reference
*br
, *tmp
;
512 FOR_EACH_BUFFER_REF_SAFE(br
, tmp
, btrn
)
513 btr_pushdown_br(br
, btrn
);
517 * Feed the next buffer of the input queue through the output channel.
519 * \param btrn The node whose first input queue buffer should be pushed down.
521 * This works like \ref btr_pushdown() but pushes down only one buffer
524 void btr_pushdown_one(struct btr_node
*btrn
)
526 struct btr_buffer_reference
*br
;
528 if (list_empty(&btrn
->input_queue
))
530 br
= list_first_entry(&btrn
->input_queue
, struct btr_buffer_reference
, node
);
531 btr_pushdown_br(br
, btrn
);
535 * Find out whether a node is a leaf node.
537 * \param btrn The node to check.
539 * \return True if this node has no children. False otherwise.
541 static bool btr_no_children(struct btr_node
*btrn
)
543 return list_empty(&btrn
->children
);
547 * Find out whether a node is an orphan.
549 * \param btrn The buffer tree node.
551 * \return True if \a btrn has no parent.
553 * This function returns true for the root node and false for any other node.
555 * After a (non-leaf) node was removed removed from the tree, the function
556 * returns true for all child nodes.
558 bool btr_no_parent(struct btr_node
*btrn
)
560 return !btrn
->parent
;
564 * Find out whether it is OK to change an input buffer.
566 * \param btrn The buffer tree node to check.
568 * This is used by filters that produce exactly the same amount of output as
569 * there is input. The amp filter which multiplies each sample by some number
570 * is an example of such a filter. If there are no other nodes in the buffer
571 * tree that read the same input stream (i.e. if \a btrn has no siblings), a
572 * node may modify its input buffer directly and push down the modified buffer
573 * to its children, thereby avoiding to allocate a possibly large additional
576 * Since the buffer tree may change at any time, this function should be called
577 * during each post_select call.
579 * \return True if \a btrn has no siblings.
581 bool btr_inplace_ok(struct btr_node
*btrn
)
583 struct btr_buffer_reference
*br
;
584 FOR_EACH_BUFFER_REF(br
, btrn
) {
585 struct btr_buffer
*btrb
= br
->btrb
;
586 if (btrb
->refcount
> 1)
588 if (btrb
->dont_free
== true)
594 static inline size_t br_available_bytes(struct btr_buffer_reference
*br
)
596 return br
->btrb
->size
- br
->consumed
;
599 static size_t btr_get_buffer_by_reference(struct btr_buffer_reference
*br
, char **buf
)
602 *buf
= br
->btrb
->buf
+ br
->consumed
;
603 return br_available_bytes(br
);
607 * Obtain the next buffer of the input queue, omitting data.
609 * \param btrn The node whose input queue is to be queried.
610 * \param omit Number of bytes to be omitted.
611 * \param bufp Result pointer. It is OK to pass \p NULL here.
613 * If a buffer tree node needs more input data but can not consume the data it
614 * already has (because it might be needed again later) this function can be
615 * used instead of btr_next_buffer() to get a reference to the buffer obtained
616 * by skipping the given number of bytes. Skipped input bytes are not consumed.
618 * With a zero \a omit argument, this function is equivalent to \ref
621 * \return Number of bytes in \a bufp. If there are less than or equal to \a
622 * omit many bytes available in the input queue of the buffer tree node pointed
623 * to by \a btrn, the function returns zero and the value of \a bufp is
626 size_t btr_next_buffer_omit(struct btr_node
*btrn
, size_t omit
, char **bufp
)
628 struct btr_buffer_reference
*br
;
629 size_t wrap_count
, sz
, rv
= 0;
630 char *buf
, *result
= NULL
;
632 br
= get_first_input_br(btrn
);
635 wrap_count
= br
->wrap_count
;
636 if (wrap_count
> 0) { /* we have a wrap buffer */
637 sz
= btr_get_buffer_by_reference(br
, &buf
);
638 if (sz
> omit
) { /* and it's big enough */
642 * Wrap buffers are allocated by malloc(), so the next
643 * buffer ref will not align nicely, so we return the
644 * tail of the wrap buffer.
649 * The next wrap_count bytes exist twice, in the wrap buffer
650 * and as a buffer reference in the buffer tree pool.
655 * For buffer tree pools, the buffers in the list align, i.e. the next
656 * buffer in the list starts directly at the end of its predecessor. In
657 * this case we merge adjacent buffers and return one larger buffer
660 FOR_EACH_BUFFER_REF(br
, btrn
) {
661 sz
= btr_get_buffer_by_reference(br
, &buf
);
663 if (result
+ rv
!= buf
)
666 } else if (sz
> omit
) {
681 * Obtain the next buffer of the input queue of a buffer tree node.
683 * \param btrn The node whose input queue is to be queried.
684 * \param bufp Result pointer.
686 * \return The number of bytes that can be read from buf.
688 * The call of this function is is equivalent to calling \ref
689 * btr_next_buffer_omit() with an \a omit value of zero.
691 size_t btr_next_buffer(struct btr_node
*btrn
, char **bufp
)
693 return btr_next_buffer_omit(btrn
, 0, bufp
);
697 * Deallocate the given number of bytes from the input queue.
699 * \param btrn The buffer tree node.
700 * \param numbytes The number of bytes to be deallocated.
702 * This function must be used to get rid of existing buffer references in the
703 * node's input queue. If no references to a buffer remain, the underlying
704 * buffers are either freed (in the non-buffer pool case) or the read head of
705 * the buffer pool is being advanced.
707 * Note that \a numbytes may be smaller than the buffer size. In this case the
708 * buffer is not deallocated and subsequent calls to btr_next_buffer() return
709 * the remaining part of the buffer.
711 void btr_consume(struct btr_node
*btrn
, size_t numbytes
)
713 struct btr_buffer_reference
*br
, *tmp
;
718 br
= get_first_input_br(btrn
);
721 if (br
->wrap_count
== 0) {
723 * No wrap buffer. Drop buffer references whose buffer
724 * has been fully used. */
725 FOR_EACH_BUFFER_REF_SAFE(br
, tmp
, btrn
) {
726 if (br
->consumed
+ numbytes
<= br
->btrb
->size
) {
727 br
->consumed
+= numbytes
;
728 if (br
->consumed
== br
->btrb
->size
)
729 btr_drop_buffer_reference(br
);
732 numbytes
-= br
->btrb
->size
- br
->consumed
;
733 btr_drop_buffer_reference(br
);
738 * We have a wrap buffer, consume from it. If in total, i.e. including
739 * previous calls to brt_consume(), less than wrap_count has been
740 * consumed, there's nothing more we can do.
742 * Otherwise we drop the wrap buffer and consume from subsequent
743 * buffers of the input queue the correct amount of bytes. This is the
744 * total number of bytes that have been consumed from the wrap buffer.
746 PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes
,
747 br_available_bytes(br
));
749 assert(numbytes
<= br_available_bytes(br
));
750 if (br
->consumed
+ numbytes
< br
->wrap_count
) {
751 br
->consumed
+= numbytes
;
754 PARA_DEBUG_LOG("dropping wrap buffer (%zu bytes)\n", br
->btrb
->size
);
755 /* get rid of the wrap buffer */
756 sz
= br
->consumed
+ numbytes
;
757 btr_drop_buffer_reference(br
);
758 return btr_consume(btrn
, sz
);
762 * Clear the input queue of a buffer tree node.
764 * \param btrn The node whose input queue should be cleared.
766 void btr_drain(struct btr_node
*btrn
)
768 struct btr_buffer_reference
*br
, *tmp
;
770 FOR_EACH_BUFFER_REF_SAFE(br
, tmp
, btrn
)
771 btr_drop_buffer_reference(br
);
775 * Remove a node from a buffer tree.
777 * \param btrnp Determines the node to remove.
779 * This orphans all children of the node given by \a btrnp and removes this
780 * node from the child list of its parent. Moreover, the input queue is flushed
781 * and the node pointer given by \a btrp is set to \p NULL.
783 * \sa \ref btr_splice_out_node.
785 void btr_remove_node(struct btr_node
**btrnp
)
788 struct btr_node
*btrn
;
795 PARA_INFO_LOG("removing btr node %s from buffer tree\n", btrn
->name
);
796 FOR_EACH_CHILD(ch
, btrn
)
800 list_del(&btrn
->node
);
808 * Return the amount of available input bytes of a buffer tree node.
810 * \param btrn The node whose input size should be computed.
812 * \return The total number of bytes available in the node's input
815 * This simply iterates over all buffer references in the input queue and
816 * returns the sum of the sizes of all references.
818 size_t btr_get_input_queue_size(struct btr_node
*btrn
)
820 struct btr_buffer_reference
*br
;
821 size_t size
= 0, wrap_consumed
= 0;
823 FOR_EACH_BUFFER_REF(br
, btrn
) {
824 if (br
->wrap_count
!= 0) {
825 wrap_consumed
= br
->consumed
;
828 size
+= br_available_bytes(br
);
830 assert(wrap_consumed
<= size
);
831 size
-= wrap_consumed
;
836 * Remove a node from the buffer tree, reconnecting parent and children.
838 * \param btrn The node to splice out.
840 * This function is used by buffer tree nodes that do not exist during the
841 * whole lifetime of the buffer tree. Unlike btr_remove_node(), calling
842 * btr_splice_out_node() does not split the tree into disconnected components
843 * but reconnects the buffer tree by making all child nodes of \a btrn children
844 * of the parent of \a btrn.
846 void btr_splice_out_node(struct btr_node
*btrn
)
848 struct btr_node
*ch
, *tmp
;
851 PARA_NOTICE_LOG("splicing out %s\n", btrn
->name
);
854 list_del(&btrn
->node
);
855 FOR_EACH_CHILD_SAFE(ch
, tmp
, btrn
) {
856 PARA_INFO_LOG("parent(%s): %s\n", ch
->name
,
857 btrn
->parent
? btrn
->parent
->name
: "NULL");
858 ch
->parent
= btrn
->parent
;
860 list_move(&ch
->node
, &btrn
->parent
->children
);
864 assert(list_empty(&btrn
->children
));
869 * Return number of queued output bytes of a buffer tree node.
871 * \param btrn The node whose output queue size should be computed.
873 * \return This function iterates over all children of the given node and
874 * returns the size of the largest input queue.
876 size_t btr_get_output_queue_size(struct btr_node
*btrn
)
881 FOR_EACH_CHILD(ch
, btrn
) {
882 size_t size
= btr_get_input_queue_size(ch
);
883 max_size
= PARA_MAX(max_size
, size
);
889 * Execute an inter-node command on the given node or on a parent node.
891 * \param btrn The node to start looking.
892 * \param command The command to execute.
893 * \param value_result Additional arguments and result value.
895 * This function traverses the buffer tree from \a btrn upwards and looks for
896 * the first node that understands \a command. On this node \a command is
897 * executed, and the result is stored in \a value_result.
899 * \return \p -ENOTSUP if no parent node of \a btrn understands \a command.
900 * Otherwise the return value of the command handler is returned.
902 * \sa \ref receiver::execute, filter::execute, writer::execute.
904 int btr_exec_up(struct btr_node
*btrn
, const char *command
, char **value_result
)
908 for (; btrn
; btrn
= btrn
->parent
) {
911 PARA_INFO_LOG("executing %s on %s\n", command
, btrn
->name
);
912 ret
= btrn
->execute(btrn
, command
, value_result
);
913 if (ret
== -ERRNO_TO_PARA_ERROR(ENOTSUP
))
917 if (value_result
&& *value_result
)
918 PARA_INFO_LOG("%s(%s): %s\n", command
, btrn
->name
,
922 return -ERRNO_TO_PARA_ERROR(ENOTSUP
);
926 * Obtain the context of a buffer node tree.
928 * \param btrn The node whose output queue size should be computed.
930 * \return A pointer to the \a context address specified at node creation time.
932 * \sa btr_new_node(), struct \ref btr_node_description.
934 void *btr_context(struct btr_node
*btrn
)
936 return btrn
->context
;
939 static bool need_buffer_pool_merge(struct btr_node
*btrn
)
941 struct btr_buffer_reference
*br
= get_first_input_br(btrn
);
945 if (br
->wrap_count
!= 0)
952 static void merge_input_pool(struct btr_node
*btrn
, size_t dest_size
)
954 struct btr_buffer_reference
*br
, *wbr
= NULL
;
955 int num_refs
; /* including wrap buffer */
956 char *buf
, *buf1
= NULL
, *buf2
= NULL
;
957 size_t sz
, sz1
= 0, sz2
= 0, wb_consumed
= 0;
959 br
= get_first_input_br(btrn
);
960 if (!br
|| br_available_bytes(br
) >= dest_size
)
963 FOR_EACH_BUFFER_REF(br
, btrn
) {
965 sz
= btr_get_buffer_by_reference(br
, &buf
);
968 if (br
->wrap_count
!= 0) {
970 assert(num_refs
== 1);
974 wb_consumed
= br
->consumed
;
982 if (buf1
+ sz1
== buf
) {
991 assert(buf2
+ sz2
== buf
);
994 if (sz1
+ sz2
>= dest_size
+ wb_consumed
)
997 if (!buf2
) /* nothing to do */
999 assert(buf1
&& sz2
> 0);
1001 * If the second buffer is large, we only take the first part of it to
1002 * avoid having to memcpy() huge buffers.
1004 sz2
= PARA_MIN(sz2
, (size_t)(64 * 1024));
1006 /* Make a new wrap buffer combining buf1 and buf2. */
1008 buf
= para_malloc(sz
);
1009 PARA_DEBUG_LOG("merging input buffers: (%p:%zu, %p:%zu) -> %p:%zu\n",
1010 buf1
, sz1
, buf2
, sz2
, buf
, sz
);
1011 memcpy(buf
, buf1
, sz1
);
1012 memcpy(buf
+ sz1
, buf2
, sz2
);
1013 br
= para_calloc(sizeof(*br
));
1014 br
->btrb
= new_btrb(buf
, sz
);
1015 br
->btrb
->refcount
= 1;
1017 /* This is a wrap buffer */
1018 br
->wrap_count
= sz1
;
1019 para_list_add(&br
->node
, &btrn
->input_queue
);
1023 * We already have a wrap buffer, but it is too small. It might be
1026 if (wbr
->wrap_count
== sz1
&& wbr
->btrb
->size
>= sz1
+ sz2
) /* nothing we can do about it */
1028 sz
= sz1
+ sz2
- wbr
->btrb
->size
; /* amount of new data */
1029 PARA_DEBUG_LOG("increasing wrap buffer %zu -> %zu\n", wbr
->btrb
->size
,
1030 wbr
->btrb
->size
+ sz
);
1031 wbr
->btrb
->size
+= sz
;
1032 wbr
->btrb
->buf
= para_realloc(wbr
->btrb
->buf
, wbr
->btrb
->size
);
1033 /* copy the new data to the end of the reallocated buffer */
1035 memcpy(wbr
->btrb
->buf
+ wbr
->btrb
->size
- sz
, buf2
+ sz2
- sz
, sz
);
1039 * Merge the first two input buffers into one.
1041 * This is a quite expensive operation.
1043 * \return The number of buffers that have been available (zero, one or two).
1045 static int merge_input(struct btr_node
*btrn
)
1047 struct btr_buffer_reference
*brs
[2], *br
;
1048 char *bufs
[2], *buf
;
1052 if (list_empty(&btrn
->input_queue
))
1054 if (list_is_singular(&btrn
->input_queue
))
1057 /* get references to the first two buffers */
1058 FOR_EACH_BUFFER_REF(br
, btrn
) {
1060 szs
[i
] = btr_get_buffer_by_reference(brs
[i
], bufs
+ i
);
1066 /* make a new btrb that combines the two buffers and a br to it. */
1067 sz
= szs
[0] + szs
[1];
1068 buf
= para_malloc(sz
);
1069 PARA_DEBUG_LOG("%s: memory merging input buffers: (%zu, %zu) -> %zu\n",
1070 btrn
->name
, szs
[0], szs
[1], sz
);
1071 memcpy(buf
, bufs
[0], szs
[0]);
1072 memcpy(buf
+ szs
[0], bufs
[1], szs
[1]);
1074 br
= para_calloc(sizeof(*br
));
1075 br
->btrb
= new_btrb(buf
, sz
);
1076 br
->btrb
->refcount
= 1;
1078 /* replace the first two refs by the new one */
1079 btr_drop_buffer_reference(brs
[0]);
1080 btr_drop_buffer_reference(brs
[1]);
1081 para_list_add(&br
->node
, &btrn
->input_queue
);
1086 * Combine input queue buffers.
1088 * \param btrn The buffer tree node whose input should be merged.
1089 * \param dest_size Stop merging if a buffer of at least this size exists.
1091 * Used to combine as many buffers as needed into a single buffer whose size is
1092 * at least \a dest_size. This function is rather cheap in case the parent node
1093 * uses buffer pools and rather expensive otherwise.
1095 * Note that if less than \a dest_size bytes are available in total, this
1096 * function does nothing and subsequent calls to btr_next_buffer() will still
1097 * return a buffer size less than \a dest_size.
1099 void btr_merge(struct btr_node
*btrn
, size_t dest_size
)
1101 if (need_buffer_pool_merge(btrn
))
1102 return merge_input_pool(btrn
, dest_size
);
1105 size_t len
= btr_next_buffer(btrn
, &buf
);
1106 if (len
>= dest_size
)
1108 PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len
, dest_size
);
1109 if (merge_input(btrn
) < 2)
1114 static bool btr_eof(struct btr_node
*btrn
)
1117 size_t len
= btr_next_buffer(btrn
, &buf
);
1119 return (len
== 0 && btr_no_parent(btrn
));
1122 static void log_tree_recursively(struct btr_node
*btrn
, int loglevel
, int depth
)
1124 struct btr_node
*ch
;
1125 const char spaces
[] = " ", *space
= spaces
+ 16 - depth
;
1129 para_log(loglevel
, "%s%s\n", space
, btrn
->name
);
1130 FOR_EACH_CHILD(ch
, btrn
)
1131 log_tree_recursively(ch
, loglevel
, depth
+ 1);
1135 * Write the current buffer (sub-)tree to the log.
1137 * \param btrn Start logging at this node.
1138 * \param loglevel Set severity with which the tree should be logged.
1140 void btr_log_tree(struct btr_node
*btrn
, int loglevel
)
1142 return log_tree_recursively(btrn
, loglevel
, 0);
1146 * Find the node with the given name in the buffer tree.
1148 * \param name The name of the node to search.
1149 * \param root Where to start the search.
1151 * \return A pointer to the node with the given name on success. If \a name is
1152 * \p NULL, the function returns \a root. If there is no node with the given
1153 * name, \p NULL is returned.
1155 struct btr_node
*btr_search_node(const char *name
, struct btr_node
*root
)
1157 struct btr_node
*ch
;
1161 if (!strcmp(root
->name
, name
))
1163 FOR_EACH_CHILD(ch
, root
) {
1164 struct btr_node
*result
= btr_search_node(name
, ch
);
1171 /** 640K ought to be enough for everybody ;) */
1172 #define BTRN_MAX_PENDING (96 * 1024)
1175 * Return the current state of a buffer tree node.
1177 * \param btrn The node whose state should be queried.
1178 * \param min_iqs The minimal input queue size.
1179 * \param type The supposed type of \a btrn.
1181 * Most users of the buffer tree subsystem call this function from both
1182 * their pre_select and the post_select methods.
1184 * \return Negative if an error condition was detected, zero if there
1185 * is nothing to do and positive otherwise.
1189 * - If a non-root node has no parent and an empty input queue, the function
1190 * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p
1191 * -E_BTR_NO_CHILD is returned.
1193 * - If less than \a min_iqs many bytes are available in the input queue and no
1194 * EOF condition was detected, the function returns zero.
1196 * - If there's plenty of data left in the input queue of the children of \a
1197 * btrn, the function also returns zero in order to bound the memory usage of
1200 int btr_node_status(struct btr_node
*btrn
, size_t min_iqs
,
1201 enum btr_node_type type
)
1206 if (type
!= BTR_NT_LEAF
) {
1207 if (btr_no_children(btrn
))
1208 return -E_BTR_NO_CHILD
;
1209 if (btr_get_output_queue_size(btrn
) > BTRN_MAX_PENDING
)
1212 if (type
!= BTR_NT_ROOT
) {
1215 iqs
= btr_get_input_queue_size(btrn
);
1216 if (iqs
== 0) /* we have a parent, because not eof */
1218 if (iqs
< min_iqs
&& !btr_no_parent(btrn
))
1225 * Get the time of the first I/O for a buffer tree node.
1227 * \param btrn The node whose I/O time should be obtained.
1228 * \param tv Result pointer.
1230 * Mainly useful for the time display of para_audiod.
1232 void btr_get_node_start(struct btr_node
*btrn
, struct timeval
*tv
)
1238 * Get the parent node of a buffer tree node.
1240 * \param btrn The node whose parent should be returned.
1242 * \a btrn must not be \p NULL.
1244 * \return The parent of \a btrn, or \p NULL if \a btrn is the
1245 * root node of the buffer tree.
1247 struct btr_node
*btr_parent(struct btr_node
*btrn
)
1249 return btrn
->parent
;