X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=buffer_tree.c;h=0e460dd30247a70d418d191b1568de41240a93b8;hp=201fb0b0e21ac4556b12968b3e22cde23fd5c302;hb=ab273892c54e29087d2a6b0d52de8081be1b905f;hpb=7faa0f554231900fea2eb1dfc45fac3a18f94ea2 diff --git a/buffer_tree.c b/buffer_tree.c index 201fb0b0..0e460dd3 100644 --- a/buffer_tree.c +++ b/buffer_tree.c @@ -1,3 +1,10 @@ +/* + * Copyright (C) 2009-2011 Andre Noll + * + * Licensed under the GPL v2. For licencing details see COPYING. + */ + +/** \file buffer_tree.c Buffer tree and buffer pool implementations. */ #include #include @@ -104,7 +111,7 @@ size_t btr_pool_size(struct btr_pool *btrp) return btrp->area_end - btrp->area_start; } -size_t btr_pool_filled(struct btr_pool *btrp) +static size_t btr_pool_filled(struct btr_pool *btrp) { if (!btrp->whead) return btr_pool_size(btrp); @@ -134,7 +141,7 @@ size_t btr_pool_unused(struct btr_pool *btrp) * Return maximal size available for one read. This is * smaller than the value returned by btr_pool_unused(). */ -size_t btr_pool_available(struct btr_pool *btrp) +static size_t btr_pool_available(struct btr_pool *btrp) { if (!btrp->whead) return 0; @@ -159,6 +166,35 @@ size_t btr_pool_get_buffer(struct btr_pool *btrp, char **result) return btr_pool_available(btrp); } +/** + * Get references to buffers pointing to free space of the buffer pool area. + * + * \param btrp The buffer pool. + * \param iov The scatter array. + * + * \return Zero if the buffer pool is full, one if the free space of the buffer + * pool area is available as a single contiguous buffer, two if the free space + * consists of two buffers. If this function returns the value n, then n + * elements of \a iov are initialized. + */ +int btr_pool_get_buffers(struct btr_pool *btrp, struct iovec iov[2]) +{ + size_t sz, unused; + char *buf; + + sz = btr_pool_get_buffer(btrp, &buf); + if (sz == 0) + return 0; + iov[0].iov_len = sz; + iov[0].iov_base = buf; + unused = btr_pool_unused(btrp); + if (sz == unused) + return 1; + iov[1].iov_len = unused - sz; + iov[1].iov_base = btrp->area_start; + return 2; +} + /** * Mark a part of the buffer pool area as allocated. * @@ -431,6 +467,8 @@ static void btr_pushdown_br(struct btr_buffer_reference *br, struct btr_node *bt * This function is useful for filters that do not change the contents of the * buffers at all, like the wav filter or the amp filter if no amplification * was specified. This function is rather cheap. + * + * \sa \ref btr_pushdown_one(). */ void btr_pushdown(struct btr_node *btrn) { @@ -440,15 +478,22 @@ void btr_pushdown(struct btr_node *btrn) btr_pushdown_br(br, btrn); } -int btr_pushdown_one(struct btr_node *btrn) +/** + * Feed the next buffer of the input queue through the output channel. + * + * \param btrn The node whose first input queue buffer should be pushed down. + * + * This works like \ref btr_pushdown() but pushes down only one buffer + * reference. + */ +void btr_pushdown_one(struct btr_node *btrn) { struct btr_buffer_reference *br; if (list_empty(&btrn->input_queue)) - return 0; + return; br = list_first_entry(&btrn->input_queue, struct btr_buffer_reference, node); btr_pushdown_br(br, btrn); - return 1; } /* @@ -478,6 +523,24 @@ bool btr_no_parent(struct btr_node *btrn) return !btrn->parent; } +/** + * Find out whether it is OK to change an input buffer. + * + * \param btrn The buffer tree node to check. + * + * This is used by filters that produce exactly the same amount of output as + * there is input. The amp filter which multiplies each sample by some number + * is an example of such a filter. If there are no other nodes in the buffer + * tree that read the same input stream (i.e. if \a btrn has no siblings), a + * node may modify its input buffer directly and push down the modified buffer + * to its children, thereby avoiding to allocate a possibly large additional + * buffer. + * + * Since the buffer tree may change at any time, this function should be called + * during each post_select call. + * + * \return True if \a btrn has no siblings. + */ bool btr_inplace_ok(struct btr_node *btrn) { if (!btrn->parent) @@ -490,7 +553,7 @@ static inline size_t br_available_bytes(struct btr_buffer_reference *br) return br->btrb->size - br->consumed; } -size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf) +static size_t btr_get_buffer_by_reference(struct btr_buffer_reference *br, char **buf) { if (buf) *buf = br->btrb->buf + br->consumed; @@ -540,7 +603,7 @@ size_t btr_next_buffer(struct btr_node *btrn, char **bufp) * * This function must be used to get rid of existing buffer references in the * node's input queue. If no references to a buffer remain, the underlying - * buffers are either freed (in the non-buffer tree case) or the read head of + * buffers are either freed (in the non-buffer pool case) or the read head of * the buffer pool is being advanced. * * Note that \a numbytes may be smaller than the buffer size. In this case the @@ -571,7 +634,7 @@ void btr_consume(struct btr_node *btrn, size_t numbytes) numbytes -= br->btrb->size - br->consumed; btr_drop_buffer_reference(br); } - assert(true); + assert(false); } /* * We have a wrap buffer, consume from it. If in total, i.e. including @@ -597,9 +660,10 @@ void btr_consume(struct btr_node *btrn, size_t numbytes) return btr_consume(btrn, sz); } -static void flush_input_queue(struct btr_node *btrn) +void btr_drain(struct btr_node *btrn) { struct btr_buffer_reference *br, *tmp; + FOR_EACH_BUFFER_REF_SAFE(br, tmp, btrn) btr_drop_buffer_reference(br); } @@ -607,6 +671,8 @@ static void flush_input_queue(struct btr_node *btrn) /** * Free all resources allocated by btr_new_node(). * + * \param btrn Pointer to a btr node obtained by \ref btr_new_node(). + * * Like free(3), it is OK to call this with a \p NULL pointer argument. */ void btr_free_node(struct btr_node *btrn) @@ -637,7 +703,7 @@ void btr_remove_node(struct btr_node *btrn) PARA_NOTICE_LOG("removing btr node %s from buffer tree\n", btrn->name); FOR_EACH_CHILD(ch, btrn) ch->parent = NULL; - flush_input_queue(btrn); + btr_drain(btrn); if (btrn->parent) list_del(&btrn->node); } @@ -701,11 +767,14 @@ void btr_splice_out_node(struct btr_node *btrn) } /** - * Return the size of the largest input queue. + * Return number of queued output bytes of a buffer tree node. + * + * \param btrn The node whose output queue size should be computed. * - * Iterates over all children of the given node. + * This function iterates over all children of the given node and returns the + * size of the largest input queue. */ -static size_t btr_bytes_pending(struct btr_node *btrn) +size_t btr_get_output_queue_size(struct btr_node *btrn) { size_t max_size = 0; struct btr_node *ch; @@ -717,15 +786,6 @@ static size_t btr_bytes_pending(struct btr_node *btrn) return max_size; } -int btr_exec(struct btr_node *btrn, const char *command, char **value_result) -{ - if (!btrn) - return -ERRNO_TO_PARA_ERROR(EINVAL); - if (!btrn->execute) - return -ERRNO_TO_PARA_ERROR(ENOTSUP); - return btrn->execute(btrn, command, value_result); -} - /** * Execute a inter-node command on a parent node. * @@ -795,7 +855,7 @@ static void merge_input_pool(struct btr_node *btrn, size_t dest_size) struct btr_buffer_reference *br, *wbr = NULL; int num_refs; /* including wrap buffer */ char *buf, *buf1 = NULL, *buf2 = NULL; - size_t sz, sz1 = 0, sz2 = 0, wsz; + size_t sz, sz1 = 0, sz2 = 0, wb_consumed = 0; br = get_first_input_br(btrn); if (!br || br_available_bytes(br) >= dest_size) @@ -812,6 +872,7 @@ static void merge_input_pool(struct btr_node *btrn, size_t dest_size) wbr = br; if (sz >= dest_size) return; + wb_consumed = br->consumed; continue; } if (!buf1) { @@ -831,7 +892,7 @@ static void merge_input_pool(struct btr_node *btrn, size_t dest_size) assert(buf2 + sz2 == buf); sz2 += sz; next: - if (sz1 + sz2 >= dest_size) + if (sz1 + sz2 >= dest_size + wb_consumed) break; } if (!buf2) /* nothing to do */ @@ -863,7 +924,6 @@ next: * We already have a wrap buffer, but it is too small. It might be * partially used. */ - wsz = br_available_bytes(wbr); if (wbr->wrap_count == sz1 && wbr->btrb->size >= sz1 + sz2) /* nothing we can do about it */ return; sz = sz1 + sz2 - wbr->btrb->size; /* amount of new data */ @@ -952,7 +1012,7 @@ void btr_merge(struct btr_node *btrn, size_t dest_size) } } -bool btr_eof(struct btr_node *btrn) +static bool btr_eof(struct btr_node *btrn) { char *buf; size_t len = btr_next_buffer(btrn, &buf); @@ -960,7 +1020,7 @@ bool btr_eof(struct btr_node *btrn) return (len == 0 && btr_no_parent(btrn)); } -void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth) +static void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth) { struct btr_node *ch; const char spaces[] = " ", *space = spaces + 16 - depth; @@ -972,13 +1032,26 @@ void log_tree_recursively(struct btr_node *btrn, int loglevel, int depth) log_tree_recursively(ch, loglevel, depth + 1); } +/** + * Write the current buffer (sub-)tree to the log. + * + * \param btrn Start logging at this node. + * \param loglevel Set severity with which the tree should be logged. + */ void btr_log_tree(struct btr_node *btrn, int loglevel) { return log_tree_recursively(btrn, loglevel, 0); } -/* - * \return \a root if \a name is \p NULL. +/** + * Find the node with the given name in the buffer tree. + * + * \param name The name of the node to search. + * \param root Where to start the search. + * + * \return A pointer to the node with the given name on success. If \a name is + * \p NULL, the function returns \a root. If there is no node with the given + * name, \p NULL is returned. */ struct btr_node *btr_search_node(const char *name, struct btr_node *root) { @@ -997,8 +1070,34 @@ struct btr_node *btr_search_node(const char *name, struct btr_node *root) } /** 640K ought to be enough for everybody ;) */ -#define BTRN_MAX_PENDING (640 * 1024) +#define BTRN_MAX_PENDING (96 * 1024) +/** + * Return the current state of a buffer tree node. + * + * \param btrn The node whose state should be queried. + * \param min_iqs The minimal input queue size. + * \param type The supposed type of \a btrn. + * + * Most users of the buffer tree subsystem call this function from both + * their pre_select and the post_select methods. + * + * \return Negative if an error condition was detected, zero if there + * is nothing to do and positive otherwise. + * + * Examples: + * + * - If a non-root node has no parent and an empty input queue, the function + * returns \p -E_BTR_EOF. Similarly, if a non-leaf node has no children, \p + * -E_BTR_NO_CHILD is returned. + * + * - If less than \a min_iqs many bytes are available in the input queue and no + * EOF condition was detected, the function returns zero. + * + * - If there's plenty of data left in the input queue of the children of \a + * btrn, the function also returns zero in order to bound the memory usage of + * the buffer tree. + */ int btr_node_status(struct btr_node *btrn, size_t min_iqs, enum btr_node_type type) { @@ -1008,7 +1107,7 @@ int btr_node_status(struct btr_node *btrn, size_t min_iqs, if (type != BTR_NT_LEAF) { if (btr_no_children(btrn)) return -E_BTR_NO_CHILD; - if (btr_bytes_pending(btrn) > BTRN_MAX_PENDING) + if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING) return 0; } if (type != BTR_NT_ROOT) { @@ -1023,6 +1122,14 @@ int btr_node_status(struct btr_node *btrn, size_t min_iqs, return 1; } +/** + * Get the time of the first I/O for a buffer tree node. + * + * \param btrn The node whose I/O time should be obtained. + * \param tv Result pointer. + * + * Mainly useful for the time display of para_audiod. + */ void btr_get_node_start(struct btr_node *btrn, struct timeval *tv) { *tv = btrn->start;