-/*
- * Copyright (C) 2009-2011 Andre Noll <maan@systemlinux.org>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* Copyright (C) 2009 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
/** \file buffer_tree.c Buffer tree and buffer pool implementations. */
#include <regex.h>
-#include <stdbool.h>
#include "para.h"
#include "list.h"
int refcount;
/* NULL means no buffer pool but a malloced buffer. */
struct btr_pool *pool;
+ /* Only relevant if pool is NULL. */
+ bool dont_free;
};
struct btr_buffer_reference {
*
* \param bnd Specifies how to create the new node.
*
+ * \return A pointer to the newly allocated node.
+ *
* This function always succeeds (or calls exit()). The returned pointer must
* be freed using btr_free_node() after the node has been removed from the
* buffer tree via btr_remove_node().
bnd->child->parent = btrn;
goto out;
}
- PARA_EMERG_LOG("inserting internal nodes not yet supported.\n");
- exit(EXIT_FAILURE);
- assert(bnd->child->parent == bnd->parent);
+ list_add_tail(&btrn->node, &bnd->parent->children);
+ list_move(&bnd->child->node, &btrn->children);
+ bnd->child->parent = btrn;
+ PARA_INFO_LOG("added %s as internal node\n", bnd->name);
out:
return btrn;
}
{
if (btrb->pool)
btr_pool_deallocate(btrb->pool, btrb->size);
- else
+ else if (!btrb->dont_free)
free(btrb->buf);
}
{
struct btr_buffer *btrb;
- assert(size != 0);
+ if (size == 0)
+ return;
if (list_empty(&btrn->children)) {
free(buf);
return;
add_btrb_to_children(btrb, btrn, 0);
}
+/**
+ * Insert a buffer into the buffer tree, non-freeing variant.
+ *
+ * \param buf See \ref btr_add_output().
+ * \param size See \ref btr_add_output().
+ * \param btrn See \ref btr_add_output().
+ *
+ * This is similar to btr_add_output() but additionally sets the \p dont_free
+ * flag on \a buf. If the refcount for the buffer drops to zero, \a buf will
+ * not be deallocated if this flag is set.
+ *
+ * The \p dont_free bit also prevents the children of \a btrn from modifying
+ * the buffer contents inplace. Specifically, \ref btr_inplace_ok() returns
+ * false if there is any buffer in the input queue with the \p dont_free bit
+ * set.
+ */
+void btr_add_output_dont_free(const char *buf, size_t size, struct btr_node *btrn)
+{
+ struct btr_buffer *btrb;
+
+ if (size == 0)
+ return;
+ if (list_empty(&btrn->children))
+ return;
+ btrb = new_btrb((char *)buf, size);
+ btrb->dont_free = true;
+ add_btrb_to_children(btrb, btrn, 0);
+}
+
/**
* Feed data to child nodes of a buffer tree node.
*
char *buf;
size_t avail;
- assert(size != 0);
+ if (size == 0)
+ return;
if (list_empty(&btrn->children))
return;
avail = btr_pool_get_buffer(btrp, &buf);
}
/**
- * Find out whether a node is an orphan node.
+ * Find out whether a node is an orphan.
*
* \param btrn The buffer tree node.
*
* \return True if \a btrn has no parent.
*
- * This function will always return true for the root node. However in case
- * nodes have been removed from the tree, other nodes may become orphans too.
+ * This function returns true for the root node and false for any other node.
+ *
+ * After a (non-leaf) node was removed removed from the tree, the function
+ * returns true for all child nodes.
*/
bool btr_no_parent(struct btr_node *btrn)
{
*/
bool btr_inplace_ok(struct btr_node *btrn)
{
- if (!btrn->parent)
- return true;
- return list_is_singular(&btrn->parent->children);
+ struct btr_buffer_reference *br;
+ FOR_EACH_BUFFER_REF(br, btrn) {
+ struct btr_buffer *btrb = br->btrb;
+ if (btrb->refcount > 1)
+ return false;
+ if (btrb->dont_free == true)
+ return false;
+ }
+ return true;
}
static inline size_t br_available_bytes(struct btr_buffer_reference *br)
}
/**
- * Obtain the next buffer of the input queue of a buffer tree node.
+ * Obtain the next buffer of the input queue, omitting data.
*
* \param btrn The node whose input queue is to be queried.
- * \param bufp Result pointer.
+ * \param omit Number of bytes to be omitted.
+ * \param bufp Result pointer. It is OK to pass \p NULL here.
+ *
+ * If a buffer tree node needs more input data but can not consume the data it
+ * already has (because it might be needed again later) this function can be
+ * used instead of btr_next_buffer() to get a reference to the buffer obtained
+ * by skipping the given number of bytes. Skipped input bytes are not consumed.
+ *
+ * With a zero \a omit argument, this function is equivalent to \ref
+ * btr_next_buffer().
*
- * \return The number of bytes that can be read from buf. Zero if the input
- * buffer queue is empty. In this case the value of \a bufp is undefined.
+ * \return Number of bytes in \a bufp. If there are less than or equal to \a
+ * omit many bytes available in the input queue of the buffer tree node pointed
+ * to by \a btrn, the function returns zero and the value of \a bufp is
+ * undefined.
*/
-size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
+size_t btr_next_buffer_omit(struct btr_node *btrn, size_t omit, char **bufp)
{
struct btr_buffer_reference *br;
+ size_t wrap_count, sz, rv = 0;
char *buf, *result = NULL;
- size_t sz, rv = 0;
- FOR_EACH_BUFFER_REF(br, btrn) {
+ br = get_first_input_br(btrn);
+ if (!br)
+ return 0;
+ wrap_count = br->wrap_count;
+ if (wrap_count > 0) { /* we have a wrap buffer */
sz = btr_get_buffer_by_reference(br, &buf);
- if (!result) {
- result = buf;
- rv = sz;
- if (!br->btrb->pool)
- break;
- continue;
+ if (sz > omit) { /* and it's big enough */
+ result = buf + omit;
+ rv = sz - omit;
+ /*
+ * Wrap buffers are allocated by malloc(), so the next
+ * buffer ref will not align nicely, so we return the
+ * tail of the wrap buffer.
+ */
+ goto out;
}
- if (!br->btrb->pool)
- break;
- if (result + rv != buf)
- break;
- rv += sz;
+ /*
+ * The next wrap_count bytes exist twice, in the wrap buffer
+ * and as a buffer reference in the buffer tree pool.
+ */
+ omit += wrap_count;
+ }
+ /*
+ * For buffer tree pools, the buffers in the list align, i.e. the next
+ * buffer in the list starts directly at the end of its predecessor. In
+ * this case we merge adjacent buffers and return one larger buffer
+ * instead.
+ */
+ FOR_EACH_BUFFER_REF(br, btrn) {
+ sz = btr_get_buffer_by_reference(br, &buf);
+ if (result) {
+ if (result + rv != buf)
+ goto out;
+ rv += sz;
+ } else if (sz > omit) {
+ result = buf + omit;
+ rv = sz - omit;
+ } else
+ omit -= sz;
}
+ if (!result)
+ return 0;
+out:
if (bufp)
*bufp = result;
return rv;
}
+/**
+ * Obtain the next buffer of the input queue of a buffer tree node.
+ *
+ * \param btrn The node whose input queue is to be queried.
+ * \param bufp Result pointer.
+ *
+ * \return The number of bytes that can be read from buf.
+ *
+ * The call of this function is is equivalent to calling \ref
+ * btr_next_buffer_omit() with an \a omit value of zero.
+ */
+size_t btr_next_buffer(struct btr_node *btrn, char **bufp)
+{
+ return btr_next_buffer_omit(btrn, 0, bufp);
+}
+
/**
* Deallocate the given number of bytes from the input queue.
*
return btr_consume(btrn, sz);
}
+/**
+ * Clear the input queue of a buffer tree node.
+ *
+ * \param btrn The node whose input queue should be cleared.
+ */
void btr_drain(struct btr_node *btrn)
{
struct btr_buffer_reference *br, *tmp;
btr_drop_buffer_reference(br);
}
-/**
- * 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)
+static void btr_free_node(struct btr_node *btrn)
{
- if (!btrn)
- return;
free(btrn->name);
free(btrn);
}
/**
* Remove a node from a buffer tree.
*
- * \param btrn The node to remove.
+ * \param btrnp Determines the node to remove.
*
- * This makes all child nodes of \a btrn orphans and removes \a btrn from the
- * list of children of its parent. Moreover, the input queue of \a btrn is
- * flushed if it is not empty.
+ * This orphans all children of the node given by \a btrnp and removes this
+ * node from the child list of its parent. Moreover, the input queue is flushed
+ * and the node pointer given by \a btrp is set to \p NULL.
*
* \sa \ref btr_splice_out_node.
*/
-void btr_remove_node(struct btr_node *btrn)
+void btr_remove_node(struct btr_node **btrnp)
{
struct btr_node *ch;
+ struct btr_node *btrn;
- if (!btrn)
+ if (!btrnp)
return;
- PARA_NOTICE_LOG("removing btr node %s from buffer tree\n", btrn->name);
+ btrn = *btrnp;
+ if (!btrn)
+ goto out;
+ PARA_INFO_LOG("removing btr node %s from buffer tree\n", btrn->name);
FOR_EACH_CHILD(ch, btrn)
ch->parent = NULL;
btr_drain(btrn);
if (btrn->parent)
list_del(&btrn->node);
+ btr_free_node(btrn);
+out:
+ *btrnp = NULL;
}
/**
/**
* Remove a node from the buffer tree, reconnecting parent and children.
*
- * \param btrn The node to splice out.
+ * \param btrnp The node to splice out.
*
* This function is used by buffer tree nodes that do not exist during the
* whole lifetime of the buffer tree. Unlike btr_remove_node(), calling
* but reconnects the buffer tree by making all child nodes of \a btrn children
* of the parent of \a btrn.
*/
-void btr_splice_out_node(struct btr_node *btrn)
+void btr_splice_out_node(struct btr_node **btrnp)
{
- struct btr_node *ch, *tmp;
+ struct btr_node *btrn = *btrnp, *ch, *tmp;
assert(btrn);
PARA_NOTICE_LOG("splicing out %s\n", btrn->name);
ch->parent = btrn->parent;
if (btrn->parent)
list_move(&ch->node, &btrn->parent->children);
+ else
+ list_del(&ch->node);
}
assert(list_empty(&btrn->children));
+ btr_free_node(btrn);
+ *btrnp = NULL;
}
/**
*
* \param btrn The node whose output queue size should be computed.
*
- * This function iterates over all children of the given node and returns the
- * size of the largest input queue.
+ * \return This function iterates over all children of the given node and
+ * returns the size of the largest input queue.
*/
size_t btr_get_output_queue_size(struct btr_node *btrn)
{
}
/**
- * Execute a inter-node command on a parent node.
+ * Execute an inter-node command on the given node or on a parent node.
*
* \param btrn The node to start looking.
* \param command The command to execute.
* \param value_result Additional arguments and result value.
*
- * This function traverses the buffer tree upwards and looks for parent nodes
- * of \a btrn that understands \a command. On the first such node the command
- * is executed, and the result is stored in \a value_result.
+ * This function traverses the buffer tree from \a btrn upwards and looks for
+ * the first node that understands \a command. On this node \a command is
+ * executed, and the result is stored in \a value_result.
*
* \return \p -ENOTSUP if no parent node of \a btrn understands \a command.
* Otherwise the return value of the command handler is returned.
+ *
+ * \sa \ref receiver::execute, \ref filter::execute, \ref writer::execute.
*/
int btr_exec_up(struct btr_node *btrn, const char *command, char **value_result)
{
int ret;
for (; btrn; btrn = btrn->parent) {
- struct btr_node *parent = btrn->parent;
- if (!parent)
- return -ERRNO_TO_PARA_ERROR(ENOTSUP);
- if (!parent->execute)
+ if (!btrn->execute)
continue;
- PARA_INFO_LOG("parent: %s, cmd: %s\n", parent->name, command);
- ret = parent->execute(parent, command, value_result);
+ PARA_INFO_LOG("executing %s on %s\n", command, btrn->name);
+ ret = btrn->execute(btrn, command, value_result);
if (ret == -ERRNO_TO_PARA_ERROR(ENOTSUP))
continue;
if (ret < 0)
return ret;
if (value_result && *value_result)
- PARA_NOTICE_LOG("%s(%s): %s\n", command, parent->name,
+ PARA_INFO_LOG("%s(%s): %s\n", command, btrn->name,
*value_result);
return 1;
}
/**
* Obtain the context of a buffer node tree.
*
- * The returned pointer equals the context pointer used at creation time of the
- * node.
+ * \param btrn The node whose output queue size should be computed.
+ *
+ * \return A pointer to the \a context address specified at node creation time.
*
- * \sa btr_new_node(), struct \ref btr_node_description.
+ * \sa \ref btr_new_node(), struct \ref btr_node_description.
*/
void *btr_context(struct btr_node *btrn)
{
size_t iqs;
assert(btrn);
- if (type != BTR_NT_LEAF) {
- if (btr_no_children(btrn))
- return -E_BTR_NO_CHILD;
- if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
- return 0;
- }
- if (type != BTR_NT_ROOT) {
- if (btr_eof(btrn))
- return -E_BTR_EOF;
- iqs = btr_get_input_queue_size(btrn);
- if (iqs == 0) /* we have a parent, because not eof */
- return 0;
- if (iqs < min_iqs && !btr_no_parent(btrn))
- return 0;
- }
+ if (type != BTR_NT_LEAF && btr_no_children(btrn))
+ return -E_BTR_NO_CHILD;
+ if (type != BTR_NT_ROOT && btr_eof(btrn))
+ return -E_BTR_EOF;
+
+ if (btr_get_output_queue_size(btrn) > BTRN_MAX_PENDING)
+ return 0;
+ if (type == BTR_NT_ROOT)
+ return 1;
+ iqs = btr_get_input_queue_size(btrn);
+ if (iqs == 0) /* we have a parent, because not eof */
+ return 0;
+ if (iqs < min_iqs && !btr_no_parent(btrn))
+ return 0;
return 1;
}
{
*tv = btrn->start;
}
+
+/**
+ * Get the parent node of a buffer tree node.
+ *
+ * \param btrn The node whose parent should be returned.
+ *
+ * \a btrn must not be \p NULL.
+ *
+ * \return The parent of \a btrn, or \p NULL if \a btrn is the
+ * root node of the buffer tree.
+ */
+struct btr_node *btr_parent(struct btr_node *btrn)
+{
+ return btrn->parent;
+}
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