2 * Copyright (C) 2009-2011 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. */
14 #include "buffer_tree.h"
18 /* whead = NULL means area full */
30 /** The number of references to this buffer. */
32 /* NULL means no buffer pool but a malloced buffer. */
33 struct btr_pool
*pool
;
36 struct btr_buffer_reference
{
37 struct btr_buffer
*btrb
;
39 /* Each buffer reference belongs to the buffer queue list of some buffer tree node. */
40 struct list_head node
;
46 struct btr_node
*parent
;
47 /* The position of this btr node in the buffer tree. */
48 struct list_head node
;
49 /* The children nodes of this btr node are linked together in a list. */
50 struct list_head children
;
51 /* Time of first data transfer. */
54 * The input queue is a list of references to btr buffers. Each item on
55 * the list represents an input buffer which has not been completely
56 * used by this btr node.
58 struct list_head input_queue
;
59 btr_command_handler execute
;
64 * Create a new buffer pool.
66 * \param name The name of the new buffer pool.
67 * \param area_size The size in bytes of the pool area.
69 * \return An opaque pointer to the newly created buffer pool. It must be
70 * passed to btr_pool_free() after it is no longer used to deallocate all
73 struct btr_pool
*btr_pool_new(const char *name
, size_t area_size
)
75 struct btr_pool
*btrp
;
77 PARA_INFO_LOG("%s, %zu bytes\n", name
, area_size
);
78 btrp
= para_malloc(sizeof(*btrp
));
79 btrp
->area_start
= para_malloc(area_size
);
80 btrp
->area_end
= btrp
->area_start
+ area_size
;
81 btrp
->rhead
= btrp
->area_start
;
82 btrp
->whead
= btrp
->area_start
;
83 btrp
->name
= para_strdup(name
);
88 * Deallocate resources used by a buffer pool.
90 * \param btrp A pointer obtained via btr_pool_new().
92 void btr_pool_free(struct btr_pool
*btrp
)
96 free(btrp
->area_start
);
102 * Return the size of the buffer pool area.
104 * \param btrp The buffer pool.
106 * \return The same value which was passed during creation time to
109 size_t btr_pool_size(struct btr_pool
*btrp
)
111 return btrp
->area_end
- btrp
->area_start
;
114 static size_t btr_pool_filled(struct btr_pool
*btrp
)
117 return btr_pool_size(btrp
);
118 if (btrp
->rhead
<= btrp
->whead
)
119 return btrp
->whead
- btrp
->rhead
;
120 return btr_pool_size(btrp
) - (btrp
->rhead
- btrp
->whead
);
124 * Get the number of unused bytes in the buffer pool.
126 * \param btrp The pool.
128 * \return The number of bytes that can currently be allocated.
130 * Note that in general the returned number of bytes is not available as a
131 * single contiguous buffer. Use btr_pool_available() to obtain the length of
132 * the largest contiguous buffer that can currently be allocated from the
135 size_t btr_pool_unused(struct btr_pool
*btrp
)
137 return btr_pool_size(btrp
) - btr_pool_filled(btrp
);
141 * Return maximal size available for one read. This is
142 * smaller than the value returned by btr_pool_unused().
144 static size_t btr_pool_available(struct btr_pool
*btrp
)
148 if (btrp
->rhead
<= btrp
->whead
)
149 return btrp
->area_end
- btrp
->whead
;
150 return btrp
->rhead
- btrp
->whead
;
154 * Obtain the current write head.
156 * \param btrp The buffer pool.
157 * \param result The write head is returned here.
159 * \return The maximal amount of bytes that may be written to the returned
162 size_t btr_pool_get_buffer(struct btr_pool
*btrp
, char **result
)
165 *result
= btrp
->whead
;
166 return btr_pool_available(btrp
);
170 * Get references to buffers pointing to free space of the buffer pool area.
172 * \param btrp The buffer pool.
173 * \param iov The scatter array.
175 * \return Zero if the buffer pool is full, one if the free space of the buffer
176 * pool area is available as a single contiguous buffer, two if the free space
177 * consists of two buffers. If this function returns the value n, then n
178 * elements of \a iov are initialized.
180 int btr_pool_get_buffers(struct btr_pool
*btrp
, struct iovec iov
[2])
185 sz
= btr_pool_get_buffer(btrp
, &buf
);
189 iov
[0].iov_base
= buf
;
190 unused
= btr_pool_unused(btrp
);
193 iov
[1].iov_len
= unused
- sz
;
194 iov
[1].iov_base
= btrp
->area_start
;
199 * Mark a part of the buffer pool area as allocated.
201 * \param btrp The buffer pool.
202 * \param size The amount of bytes to be allocated.
204 * This is usually called after the caller wrote to the buffer obtained by
205 * btr_pool_get_buffer().
207 static void btr_pool_allocate(struct btr_pool
*btrp
, size_t size
)
213 assert(size
<= btr_pool_available(btrp
));
214 end
= btrp
->whead
+ size
;
215 assert(end
<= btrp
->area_end
);
217 if (end
== btrp
->area_end
) {
218 PARA_DEBUG_LOG("%s: end of pool area reached\n", btrp
->name
);
219 end
= btrp
->area_start
;
221 if (end
== btrp
->rhead
) {
222 PARA_DEBUG_LOG("%s btrp buffer full\n", btrp
->name
);
223 end
= NULL
; /* buffer full */
228 static void btr_pool_deallocate(struct btr_pool
*btrp
, size_t size
)
230 char *end
= btrp
->rhead
+ size
;
234 assert(end
<= btrp
->area_end
);
235 assert(size
<= btr_pool_filled(btrp
));
236 if (end
== btrp
->area_end
)
237 end
= btrp
->area_start
;
239 btrp
->whead
= btrp
->rhead
;
241 if (btrp
->rhead
== btrp
->whead
)
242 btrp
->rhead
= btrp
->whead
= btrp
->area_start
;
245 #define FOR_EACH_CHILD(_tn, _btrn) list_for_each_entry((_tn), \
246 &((_btrn)->children), node)
247 #define FOR_EACH_CHILD_SAFE(_tn, _tmp, _btrn) \
248 list_for_each_entry_safe((_tn), (_tmp), &((_btrn)->children), node)
250 #define FOR_EACH_BUFFER_REF(_br, _btrn) \
251 list_for_each_entry((_br), &(_btrn)->input_queue, node)
252 #define FOR_EACH_BUFFER_REF_SAFE(_br, _tmp, _btrn) \
253 list_for_each_entry_safe((_br), (_tmp), &(_btrn)->input_queue, node)
256 * Create a new buffer tree node.
258 * \param bnd Specifies how to create the new node.
260 * \return A pointer to the newly allocated node.
262 * This function always succeeds (or calls exit()). The returned pointer must
263 * be freed using btr_free_node() after the node has been removed from the
264 * buffer tree via btr_remove_node().
266 struct btr_node
*btr_new_node(struct btr_node_description
*bnd
)
268 struct btr_node
*btrn
= para_malloc(sizeof(*btrn
));
270 btrn
->name
= para_strdup(bnd
->name
);
271 btrn
->parent
= bnd
->parent
;
272 btrn
->execute
= bnd
->handler
;
273 btrn
->context
= bnd
->context
;
274 btrn
->start
.tv_sec
= 0;
275 btrn
->start
.tv_usec
= 0;
276 INIT_LIST_HEAD(&btrn
->children
);
277 INIT_LIST_HEAD(&btrn
->input_queue
);
280 list_add_tail(&btrn
->node
, &bnd
->parent
->children
);
281 PARA_INFO_LOG("new leaf node: %s (child of %s)\n",
282 bnd
->name
, bnd
->parent
->name
);
284 PARA_INFO_LOG("added %s as btr root\n", bnd
->name
);
288 assert(!bnd
->child
->parent
);
289 PARA_INFO_LOG("new root: %s (was %s)\n",
290 bnd
->name
, bnd
->child
->name
);
292 list_add_tail(&bnd
->child
->node
, &btrn
->children
);
294 bnd
->child
->parent
= btrn
;
297 PARA_EMERG_LOG("inserting internal nodes not yet supported.\n");
299 assert(bnd
->child
->parent
== bnd
->parent
);
305 * Allocate a new btr buffer.
307 * The freshly allocated buffer will have a zero refcount and will
308 * not be associated with a btr pool.
310 static struct btr_buffer
*new_btrb(char *buf
, size_t size
)
312 struct btr_buffer
*btrb
= para_calloc(sizeof(*btrb
));
319 static void dealloc_buffer(struct btr_buffer
*btrb
)
322 btr_pool_deallocate(btrb
->pool
, btrb
->size
);
327 static struct btr_buffer_reference
*get_first_input_br(struct btr_node
*btrn
)
329 if (list_empty(&btrn
->input_queue
))
331 return list_first_entry(&btrn
->input_queue
,
332 struct btr_buffer_reference
, node
);
336 * Deallocate the reference, release the resources if refcount drops to zero.
338 static void btr_drop_buffer_reference(struct btr_buffer_reference
*br
)
340 struct btr_buffer
*btrb
= br
->btrb
;
345 if (btrb
->refcount
== 0) {
346 dealloc_buffer(btrb
);
351 static void add_btrb_to_children(struct btr_buffer
*btrb
,
352 struct btr_node
*btrn
, size_t consumed
)
356 if (btrn
->start
.tv_sec
== 0)
358 FOR_EACH_CHILD(ch
, btrn
) {
359 struct btr_buffer_reference
*br
= para_calloc(sizeof(*br
));
361 br
->consumed
= consumed
;
362 list_add_tail(&br
->node
, &ch
->input_queue
);
364 if (ch
->start
.tv_sec
== 0)
370 * Insert a malloced buffer into the buffer tree.
372 * \param buf The buffer to insert.
373 * \param size The size of \a buf in bytes.
374 * \param btrn Position in the buffer tree to create the output.
376 * This creates references to \a buf and adds these references to each child of
377 * \a btrn. The buffer will be freed using standard free() once no buffer tree
378 * node is referencing it any more.
380 * Note that this function must not be used if \a buf was obtained from a
381 * buffer pool. Use btr_add_output_pool() in this case.
383 void btr_add_output(char *buf
, size_t size
, struct btr_node
*btrn
)
385 struct btr_buffer
*btrb
;
388 if (list_empty(&btrn
->children
)) {
392 btrb
= new_btrb(buf
, size
);
393 add_btrb_to_children(btrb
, btrn
, 0);
397 * Feed data to child nodes of a buffer tree node.
399 * \param btrp The buffer pool.
400 * \param size The number of bytes to be allocated and fed to each child.
401 * \param btrn The node whose children are to be fed.
403 * This function allocates the amount of bytes from the buffer pool area,
404 * starting at the current value of the write head, and creates buffer
405 * references to the resulting part of the buffer pool area, one for each child
406 * of \a btrn. The references are then fed into the input queue of each child.
408 void btr_add_output_pool(struct btr_pool
*btrp
, size_t size
,
409 struct btr_node
*btrn
)
411 struct btr_buffer
*btrb
;
416 if (list_empty(&btrn
->children
))
418 avail
= btr_pool_get_buffer(btrp
, &buf
);
419 assert(avail
>= size
);
420 btr_pool_allocate(btrp
, size
);
421 btrb
= new_btrb(buf
, size
);
423 add_btrb_to_children(btrb
, btrn
, 0);
427 * Copy data to write head of a buffer pool and feed it to all children nodes.
429 * \param src The source buffer.
430 * \param n The size of the source buffer in bytes.
431 * \param btrp The destination buffer pool.
432 * \param btrn Add the data as output of this node.
434 * This is expensive. The caller must make sure the data fits into the buffer
437 void btr_copy(const void *src
, size_t n
, struct btr_pool
*btrp
,
438 struct btr_node
*btrn
)
445 assert(n
<= btr_pool_unused(btrp
));
446 sz
= btr_pool_get_buffer(btrp
, &buf
);
447 copy
= PARA_MIN(sz
, n
);
448 memcpy(buf
, src
, copy
);
449 btr_add_output_pool(btrp
, copy
, btrn
);
452 sz
= btr_pool_get_buffer(btrp
, &buf
);
453 assert(sz
>= n
- copy
);
454 memcpy(buf
, src
+ copy
, n
- copy
);
455 btr_add_output_pool(btrp
, n
- copy
, btrn
);
458 static void btr_pushdown_br(struct btr_buffer_reference
*br
, struct btr_node
*btrn
)
460 add_btrb_to_children(br
->btrb
, btrn
, br
->consumed
);
461 btr_drop_buffer_reference(br
);
465 * Feed all buffer references of the input queue through the output channel.
467 * \param btrn The node whose buffer references should be pushed down.
469 * This function is useful for filters that do not change the contents of the
470 * buffers at all, like the wav filter or the amp filter if no amplification
471 * was specified. This function is rather cheap.
473 * \sa \ref btr_pushdown_one().
475 void btr_pushdown(struct btr_node
*btrn
)
477 struct btr_buffer_reference
*br
, *tmp
;
479 FOR_EACH_BUFFER_REF_SAFE(br
, tmp
, btrn
)
480 btr_pushdown_br(br
, btrn
);
484 * Feed the next buffer of the input queue through the output channel.
486 * \param btrn The node whose first input queue buffer should be pushed down.
488 * This works like \ref btr_pushdown() but pushes down only one buffer
491 void btr_pushdown_one(struct btr_node
*btrn
)
493 struct btr_buffer_reference
*br
;
495 if (list_empty(&btrn
->input_queue
))
497 br
= list_first_entry(&btrn
->input_queue
, struct btr_buffer_reference
, node
);
498 btr_pushdown_br(br
, btrn
);
502 * Find out whether a node is a leaf node.
504 * \param btrn The node to check.
506 * \return True if this node has no children. False otherwise.
508 static bool btr_no_children(struct btr_node
*btrn
)
510 return list_empty(&btrn
->children
);
514 * Find out whether a node is an orphan node.
516 * \param btrn The buffer tree node.
518 * \return True if \a btrn has no parent.
520 * This function will always return true for the root node. However in case
521 * nodes have been removed from the tree, other nodes may become orphans too.
523 bool btr_no_parent(struct btr_node
*btrn
)
525 return !btrn
->parent
;
529 * Find out whether it is OK to change an input buffer.
531 * \param btrn The buffer tree node to check.
533 * This is used by filters that produce exactly the same amount of output as
534 * there is input. The amp filter which multiplies each sample by some number
535 * is an example of such a filter. If there are no other nodes in the buffer
536 * tree that read the same input stream (i.e. if \a btrn has no siblings), a
537 * node may modify its input buffer directly and push down the modified buffer
538 * to its children, thereby avoiding to allocate a possibly large additional
541 * Since the buffer tree may change at any time, this function should be called
542 * during each post_select call.
544 * \return True if \a btrn has no siblings.
546 bool btr_inplace_ok(struct btr_node
*btrn
)
550 return list_is_singular(&btrn
->parent
->children
);
553 static inline size_t br_available_bytes(struct btr_buffer_reference
*br
)
555 return br
->btrb
->size
- br
->consumed
;
558 static size_t btr_get_buffer_by_reference(struct btr_buffer_reference
*br
, char **buf
)
561 *buf
= br
->btrb
->buf
+ br
->consumed
;
562 return br_available_bytes(br
);
566 * Obtain the next buffer of the input queue, omitting data.
568 * \param btrn The node whose input queue is to be queried.
569 * \param omit Number of bytes to be omitted.
570 * \param bufp Result pointer.
572 * If a buffer tree node needs more input data but can not consume the data it
573 * already has (because it might be needed again later) this function can be
574 * used instead of btr_next_buffer() to get a reference to the buffer obtained
575 * by skipping the given number of bytes. Skipped input bytes are not consumed.
577 * With a zero \a omit argument, this function is equivalent to \ref
580 * \return Number of bytes in \a bufp. If there are less than or equal to \a
581 * omit many bytes available in the input queue of the buffer tree node pointed
582 * to by \a btrn, the function returns zero and the value of \a bufp is
585 size_t btr_next_buffer_omit(struct btr_node
*btrn
, size_t omit
, char **bufp
)
587 struct btr_buffer_reference
*br
;
588 size_t wrap_count
, sz
, rv
= 0;
589 char *buf
, *result
= NULL
;
591 br
= get_first_input_br(btrn
);
594 wrap_count
= br
->wrap_count
;
595 if (wrap_count
> 0) { /* we have a wrap buffer */
596 sz
= btr_get_buffer_by_reference(br
, &buf
);
597 if (sz
> omit
) { /* and it's big enough */
601 * Wrap buffers are allocated by malloc(), so the next
602 * buffer ref will not align nicely, so we return the
603 * tail of the wrap buffer.
608 * The next wrap_count bytes exist twice, in the wrap buffer
609 * and as a buffer reference in the buffer tree pool.
614 * For buffer tree pools, the buffers in the list align, i.e. the next
615 * buffer in the list starts directly at the end of its predecessor. In
616 * this case we merge adjacent buffers and return one larger buffer
619 FOR_EACH_BUFFER_REF(br
, btrn
) {
620 sz
= btr_get_buffer_by_reference(br
, &buf
);
622 if (result
+ rv
!= buf
)
625 } else if (sz
> omit
) {
640 * Obtain the next buffer of the input queue of a buffer tree node.
642 * \param btrn The node whose input queue is to be queried.
643 * \param bufp Result pointer.
645 * \return The number of bytes that can be read from buf.
647 * The call of this function is is equivalent to calling \ref
648 * btr_next_buffer_omit() with an \a omit value of zero.
650 size_t btr_next_buffer(struct btr_node
*btrn
, char **bufp
)
652 return btr_next_buffer_omit(btrn
, 0, bufp
);
656 * Deallocate the given number of bytes from the input queue.
658 * \param btrn The buffer tree node.
659 * \param numbytes The number of bytes to be deallocated.
661 * This function must be used to get rid of existing buffer references in the
662 * node's input queue. If no references to a buffer remain, the underlying
663 * buffers are either freed (in the non-buffer pool case) or the read head of
664 * the buffer pool is being advanced.
666 * Note that \a numbytes may be smaller than the buffer size. In this case the
667 * buffer is not deallocated and subsequent calls to btr_next_buffer() return
668 * the remaining part of the buffer.
670 void btr_consume(struct btr_node
*btrn
, size_t numbytes
)
672 struct btr_buffer_reference
*br
, *tmp
;
677 br
= get_first_input_br(btrn
);
680 if (br
->wrap_count
== 0) {
682 * No wrap buffer. Drop buffer references whose buffer
683 * has been fully used. */
684 FOR_EACH_BUFFER_REF_SAFE(br
, tmp
, btrn
) {
685 if (br
->consumed
+ numbytes
<= br
->btrb
->size
) {
686 br
->consumed
+= numbytes
;
687 if (br
->consumed
== br
->btrb
->size
)
688 btr_drop_buffer_reference(br
);
691 numbytes
-= br
->btrb
->size
- br
->consumed
;
692 btr_drop_buffer_reference(br
);
697 * We have a wrap buffer, consume from it. If in total, i.e. including
698 * previous calls to brt_consume(), less than wrap_count has been
699 * consumed, there's nothing more we can do.
701 * Otherwise we drop the wrap buffer and consume from subsequent
702 * buffers of the input queue the correct amount of bytes. This is the
703 * total number of bytes that have been consumed from the wrap buffer.
705 PARA_DEBUG_LOG("consuming %zu/%zu bytes from wrap buffer\n", numbytes
,
706 br_available_bytes(br
));
708 assert(numbytes
<= br_available_bytes(br
));
709 if (br
->consumed
+ numbytes
< br
->wrap_count
) {
710 br
->consumed
+= numbytes
;
713 PARA_DEBUG_LOG("dropping wrap buffer (%zu bytes)\n", br
->btrb
->size
);
714 /* get rid of the wrap buffer */
715 sz
= br
->consumed
+ numbytes
;
716 btr_drop_buffer_reference(br
);
717 return btr_consume(btrn
, sz
);
721 * Clear the input queue of a buffer tree node.
723 * \param btrn The node whose input queue should be cleared.
725 void btr_drain(struct btr_node
*btrn
)
727 struct btr_buffer_reference
*br
, *tmp
;
729 FOR_EACH_BUFFER_REF_SAFE(br
, tmp
, btrn
)
730 btr_drop_buffer_reference(br
);
734 * Free all resources allocated by btr_new_node().
736 * \param btrn Pointer to a btr node obtained by \ref btr_new_node().
738 * Like free(3), it is OK to call this with a \p NULL pointer argument.
740 void btr_free_node(struct btr_node
*btrn
)
749 * Remove a node from a buffer tree.
751 * \param btrn The node to remove.
753 * This makes all child nodes of \a btrn orphans and removes \a btrn from the
754 * list of children of its parent. Moreover, the input queue of \a btrn is
755 * flushed if it is not empty.
757 * \sa \ref btr_splice_out_node.
759 void btr_remove_node(struct btr_node
*btrn
)
765 PARA_NOTICE_LOG("removing btr node %s from buffer tree\n", btrn
->name
);
766 FOR_EACH_CHILD(ch
, btrn
)
770 list_del(&btrn
->node
);
774 * Return the amount of available input bytes of a buffer tree node.
776 * \param btrn The node whose input size should be computed.
778 * \return The total number of bytes available in the node's input
781 * This simply iterates over all buffer references in the input queue and
782 * returns the sum of the sizes of all references.
784 size_t btr_get_input_queue_size(struct btr_node
*btrn
)
786 struct btr_buffer_reference
*br
;
787 size_t size
= 0, wrap_consumed
= 0;
789 FOR_EACH_BUFFER_REF(br
, btrn
) {
790 if (br
->wrap_count
!= 0) {
791 wrap_consumed
= br
->consumed
;
794 size
+= br_available_bytes(br
);
796 assert(wrap_consumed
<= size
);
797 size
-= wrap_consumed
;
802 * Remove a node from the buffer tree, reconnecting parent and children.
804 * \param btrn The node to splice out.
806 * This function is used by buffer tree nodes that do not exist during the
807 * whole lifetime of the buffer tree. Unlike btr_remove_node(), calling
808 * btr_splice_out_node() does not split the tree into disconnected components
809 * but reconnects the buffer tree by making all child nodes of \a btrn children
810 * of the parent of \a btrn.
812 void btr_splice_out_node(struct btr_node
*btrn
)
814 struct btr_node
*ch
, *tmp
;
817 PARA_NOTICE_LOG("splicing out %s\n", btrn
->name
);
820 list_del(&btrn
->node
);
821 FOR_EACH_CHILD_SAFE(ch
, tmp
, btrn
) {
822 PARA_INFO_LOG("parent(%s): %s\n", ch
->name
,
823 btrn
->parent
? btrn
->parent
->name
: "NULL");
824 ch
->parent
= btrn
->parent
;
826 list_move(&ch
->node
, &btrn
->parent
->children
);
828 assert(list_empty(&btrn
->children
));
832 * Return number of queued output bytes of a buffer tree node.
834 * \param btrn The node whose output queue size should be computed.
836 * \return This function iterates over all children of the given node and
837 * returns the size of the largest input queue.
839 size_t btr_get_output_queue_size(struct btr_node
*btrn
)
844 FOR_EACH_CHILD(ch
, btrn
) {
845 size_t size
= btr_get_input_queue_size(ch
);
846 max_size
= PARA_MAX(max_size
, size
);
852 * Execute a inter-node command on a parent node.
854 * \param btrn The node to start looking.
855 * \param command The command to execute.
856 * \param value_result Additional arguments and result value.
858 * This function traverses the buffer tree upwards and looks for parent nodes
859 * of \a btrn that understands \a command. On the first such node the command
860 * is executed, and the result is stored in \a value_result.
862 * \return \p -ENOTSUP if no parent node of \a btrn understands \a command.
863 * Otherwise the return value of the command handler is returned.
865 int btr_exec_up(struct btr_node
*btrn
, const char *command
, char **value_result
)
869 for (; btrn
; btrn
= btrn
->parent
) {
870 struct btr_node
*parent
= btrn
->parent
;
872 return -ERRNO_TO_PARA_ERROR(ENOTSUP
);
873 if (!parent
->execute
)
875 PARA_INFO_LOG("parent: %s, cmd: %s\n", parent
->name
, command
);
876 ret
= parent
->execute(parent
, command
, value_result
);
877 if (ret
== -ERRNO_TO_PARA_ERROR(ENOTSUP
))
881 if (value_result
&& *value_result
)
882 PARA_NOTICE_LOG("%s(%s): %s\n", command
, parent
->name
,
886 return -ERRNO_TO_PARA_ERROR(ENOTSUP
);
890 * Obtain the context of a buffer node tree.
892 * \param btrn The node whose output queue size should be computed.
894 * \return A pointer to the \a context address specified at node creation time.
896 * \sa btr_new_node(), struct \ref btr_node_description.
898 void *btr_context(struct btr_node
*btrn
)
900 return btrn
->context
;
903 static bool need_buffer_pool_merge(struct btr_node
*btrn
)
905 struct btr_buffer_reference
*br
= get_first_input_br(btrn
);
909 if (br
->wrap_count
!= 0)
916 static void merge_input_pool(struct btr_node
*btrn
, size_t dest_size
)
918 struct btr_buffer_reference
*br
, *wbr
= NULL
;
919 int num_refs
; /* including wrap buffer */
920 char *buf
, *buf1
= NULL
, *buf2
= NULL
;
921 size_t sz
, sz1
= 0, sz2
= 0, wb_consumed
= 0;
923 br
= get_first_input_br(btrn
);
924 if (!br
|| br_available_bytes(br
) >= dest_size
)
927 FOR_EACH_BUFFER_REF(br
, btrn
) {
929 sz
= btr_get_buffer_by_reference(br
, &buf
);
932 if (br
->wrap_count
!= 0) {
934 assert(num_refs
== 1);
938 wb_consumed
= br
->consumed
;
946 if (buf1
+ sz1
== buf
) {
955 assert(buf2
+ sz2
== buf
);
958 if (sz1
+ sz2
>= dest_size
+ wb_consumed
)
961 if (!buf2
) /* nothing to do */
963 assert(buf1
&& sz2
> 0);
965 * If the second buffer is large, we only take the first part of it to
966 * avoid having to memcpy() huge buffers.
968 sz2
= PARA_MIN(sz2
, (size_t)(64 * 1024));
970 /* Make a new wrap buffer combining buf1 and buf2. */
972 buf
= para_malloc(sz
);
973 PARA_DEBUG_LOG("merging input buffers: (%p:%zu, %p:%zu) -> %p:%zu\n",
974 buf1
, sz1
, buf2
, sz2
, buf
, sz
);
975 memcpy(buf
, buf1
, sz1
);
976 memcpy(buf
+ sz1
, buf2
, sz2
);
977 br
= para_calloc(sizeof(*br
));
978 br
->btrb
= new_btrb(buf
, sz
);
979 br
->btrb
->refcount
= 1;
981 /* This is a wrap buffer */
982 br
->wrap_count
= sz1
;
983 para_list_add(&br
->node
, &btrn
->input_queue
);
987 * We already have a wrap buffer, but it is too small. It might be
990 if (wbr
->wrap_count
== sz1
&& wbr
->btrb
->size
>= sz1
+ sz2
) /* nothing we can do about it */
992 sz
= sz1
+ sz2
- wbr
->btrb
->size
; /* amount of new data */
993 PARA_DEBUG_LOG("increasing wrap buffer %zu -> %zu\n", wbr
->btrb
->size
,
994 wbr
->btrb
->size
+ sz
);
995 wbr
->btrb
->size
+= sz
;
996 wbr
->btrb
->buf
= para_realloc(wbr
->btrb
->buf
, wbr
->btrb
->size
);
997 /* copy the new data to the end of the reallocated buffer */
999 memcpy(wbr
->btrb
->buf
+ wbr
->btrb
->size
- sz
, buf2
+ sz2
- sz
, sz
);
1003 * Merge the first two input buffers into one.
1005 * This is a quite expensive operation.
1007 * \return The number of buffers that have been available (zero, one or two).
1009 static int merge_input(struct btr_node
*btrn
)
1011 struct btr_buffer_reference
*brs
[2], *br
;
1012 char *bufs
[2], *buf
;
1016 if (list_empty(&btrn
->input_queue
))
1018 if (list_is_singular(&btrn
->input_queue
))
1021 /* get references to the first two buffers */
1022 FOR_EACH_BUFFER_REF(br
, btrn
) {
1024 szs
[i
] = btr_get_buffer_by_reference(brs
[i
], bufs
+ i
);
1030 /* make a new btrb that combines the two buffers and a br to it. */
1031 sz
= szs
[0] + szs
[1];
1032 buf
= para_malloc(sz
);
1033 PARA_DEBUG_LOG("%s: memory merging input buffers: (%zu, %zu) -> %zu\n",
1034 btrn
->name
, szs
[0], szs
[1], sz
);
1035 memcpy(buf
, bufs
[0], szs
[0]);
1036 memcpy(buf
+ szs
[0], bufs
[1], szs
[1]);
1038 br
= para_calloc(sizeof(*br
));
1039 br
->btrb
= new_btrb(buf
, sz
);
1040 br
->btrb
->refcount
= 1;
1042 /* replace the first two refs by the new one */
1043 btr_drop_buffer_reference(brs
[0]);
1044 btr_drop_buffer_reference(brs
[1]);
1045 para_list_add(&br
->node
, &btrn
->input_queue
);
1050 * Combine input queue buffers.
1052 * \param btrn The buffer tree node whose input should be merged.
1053 * \param dest_size Stop merging if a buffer of at least this size exists.
1055 * Used to combine as many buffers as needed into a single buffer whose size is
1056 * at least \a dest_size. This function is rather cheap in case the parent node
1057 * uses buffer pools and rather expensive otherwise.
1059 * Note that if less than \a dest_size bytes are available in total, this
1060 * function does nothing and subsequent calls to btr_next_buffer() will still
1061 * return a buffer size less than \a dest_size.
1063 void btr_merge(struct btr_node
*btrn
, size_t dest_size
)
1065 if (need_buffer_pool_merge(btrn
))
1066 return merge_input_pool(btrn
, dest_size
);
1069 size_t len
= btr_next_buffer(btrn
, &buf
);
1070 if (len
>= dest_size
)
1072 PARA_DEBUG_LOG("input size = %zu < %zu = dest\n", len
, dest_size
);
1073 if (merge_input(btrn
) < 2)
1078 static bool btr_eof(struct btr_node
*btrn
)
1081 size_t len
= btr_next_buffer(btrn
, &buf
);
1083 return (len
== 0 && btr_no_parent(btrn
));
1086 static void log_tree_recursively(struct btr_node
*btrn
, int loglevel
, int depth
)
1088 struct btr_node
*ch
;
1089 const char spaces
[] = " ", *space
= spaces
+ 16 - depth
;
1093 para_log(loglevel
, "%s%s\n", space
, btrn
->name
);
1094 FOR_EACH_CHILD(ch
, btrn
)
1095 log_tree_recursively(ch
, loglevel
, depth
+ 1);
1099 * Write the current buffer (sub-)tree to the log.
1101 * \param btrn Start logging at this node.
1102 * \param loglevel Set severity with which the tree should be logged.
1104 void btr_log_tree(struct btr_node
*btrn
, int loglevel
)
1106 return log_tree_recursively(btrn
, loglevel
, 0);
1110 * Find the node with the given name in the buffer tree.
1112 * \param name The name of the node to search.
1113 * \param root Where to start the search.
1115 * \return A pointer to the node with the given name on success. If \a name is
1116 * \p NULL, the function returns \a root. If there is no node with the given
1117 * name, \p NULL is returned.
1119 struct btr_node
*btr_search_node(const char *name
, struct btr_node
*root
)
1121 struct btr_node
*ch
;
1125 if (!strcmp(root
->name
, name
))
1127 FOR_EACH_CHILD(ch
, root
) {
1128 struct btr_node
*result
= btr_search_node(name
, ch
);
1135 /** 640K ought to be enough for everybody ;) */
1136 #define BTRN_MAX_PENDING (96 * 1024)
1139 * Return the current state of a buffer tree node.
1141 * \param btrn The node whose state should be queried.
1142 * \param min_iqs The minimal input queue size.
1143 * \param type The supposed type of \a btrn.
1145 * Most users of the buffer tree subsystem call this function from both
1146 * their pre_select and the post_select methods.
1148 * \return Negative if an error condition was detected, zero if there
1149 * is nothing to do and positive otherwise.
1153 * - If a non-root node has no parent and an empty input queue, the function
1154 * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p
1155 * -E_BTR_NO_CHILD is returned.
1157 * - If less than \a min_iqs many bytes are available in the input queue and no
1158 * EOF condition was detected, the function returns zero.
1160 * - If there's plenty of data left in the input queue of the children of \a
1161 * btrn, the function also returns zero in order to bound the memory usage of
1164 int btr_node_status(struct btr_node
*btrn
, size_t min_iqs
,
1165 enum btr_node_type type
)
1170 if (type
!= BTR_NT_LEAF
) {
1171 if (btr_no_children(btrn
))
1172 return -E_BTR_NO_CHILD
;
1173 if (btr_get_output_queue_size(btrn
) > BTRN_MAX_PENDING
)
1176 if (type
!= BTR_NT_ROOT
) {
1179 iqs
= btr_get_input_queue_size(btrn
);
1180 if (iqs
== 0) /* we have a parent, because not eof */
1182 if (iqs
< min_iqs
&& !btr_no_parent(btrn
))
1189 * Get the time of the first I/O for a buffer tree node.
1191 * \param btrn The node whose I/O time should be obtained.
1192 * \param tv Result pointer.
1194 * Mainly useful for the time display of para_audiod.
1196 void btr_get_node_start(struct btr_node
*btrn
, struct timeval
*tv
)