Add irc_dictionary code.

include/irc_dictionary.h

@@ -0,0 +1,155 @@
+/*
+ * charybdis: an advanced ircd.
+ * irc_dictionary.h: Dictionary-based storage.
+ *
+ * Copyright (c) 2007 William Pitcock <nenolod -at- sacredspiral.co.uk>
+ * Copyright (c) 2007 Jilles Tjoelker <jilles -at- stack.nl>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice is present in all copies.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __IRC_DICTIONARY_H__
+#define __IRC_DICTIONARY_H__
+
+struct Dictionary; /* defined in src/dictionary.c */
+
+typedef int (*DCF)(const char *a, const char *b);
+
+struct DictionaryElement
+{
+	struct DictionaryElement *left, *right, *prev, *next;
+	void *data;
+	char *key;
+	int position;
+};
+
+struct DictionaryIter
+{
+	struct DictionaryElement *cur, *next;
+};
+
+/*
+ * this is a convenience macro for inlining iteration of dictionaries.
+ */
+#define DICTIONARY_FOREACH(element, state, dict) for (irc_dictionary_foreach_start((dict), (state)); (element = irc_dictionary_foreach_cur((dict), (state))); irc_dictionary_foreach_next((dict), (state)))
+
+/*
+ * irc_dictionary_create() creates a new dictionary tree.
+ * compare_cb is the comparison function, typically strcmp, strcasecmp or
+ * irccasecmp.
+ */
+extern struct Dictionary *irc_dictionary_create(DCF compare_cb);
+
+/*
+ * irc_dictionary_create_named() creates a new dictionary tree which has a name.
+ * name is the name, compare_cb is the comparator.
+ */
+extern struct Dictionary *irc_dictionary_create_named(const char *name, DCF compare_cb);
+
+/*
+ * irc_dictionary_set_comparator_func() resets the comparator used for lookups and
+ * insertions in the DTree structure.
+ */
+extern void irc_dictionary_set_comparator_func(struct Dictionary *dict,
+	DCF compare_cb);
+
+/*
+ * irc_dictionary_get_comparator_func() returns the comparator used for lookups and
+ * insertions in the DTree structure.
+ */
+extern DCF irc_dictionary_get_comparator_func(struct Dictionary *dict);
+
+/*
+ * irc_dictionary_get_linear_index() returns the linear index of an object in the
+ * DTree structure.
+ */
+extern int irc_dictionary_get_linear_index(struct Dictionary *dict, const char *key);
+
+/*
+ * irc_dictionary_destroy() destroys all entries in a dtree, and also optionally calls
+ * a defined callback function to destroy any data attached to it.
+ */
+extern void irc_dictionary_destroy(struct Dictionary *dtree,
+	void (*destroy_cb)(struct DictionaryElement *delem, void *privdata),
+	void *privdata);
+
+/*
+ * irc_dictionary_foreach() iterates all entries in a dtree, and also optionally calls
+ * a defined callback function to use any data attached to it.
+ *
+ * To shortcircuit iteration, return non-zero from the callback function.
+ */
+extern void irc_dictionary_foreach(struct Dictionary *dtree,
+	int (*foreach_cb)(struct DictionaryElement *delem, void *privdata),
+	void *privdata);
+
+/*
+ * irc_dictionary_search() iterates all entries in a dtree, and also optionally calls
+ * a defined callback function to use any data attached to it.
+ *
+ * When the object is found, a non-NULL is returned from the callback, which results
+ * in that object being returned to the user.
+ */
+extern void *irc_dictionary_search(struct Dictionary *dtree,
+	void *(*foreach_cb)(struct DictionaryElement *delem, void *privdata),
+	void *privdata);
+
+/*
+ * irc_dictionary_foreach_start() begins an iteration over all items
+ * keeping state in the given struct. If there is only one iteration
+ * in progress at a time, it is permitted to remove the current element
+ * of the iteration (but not any other element).
+ */
+extern void irc_dictionary_foreach_start(struct Dictionary *dtree,
+	struct DictionaryIter *state);
+
+/*
+ * irc_dictionary_foreach_cur() returns the current element of the iteration,
+ * or NULL if there are no more elements.
+ */
+extern void *irc_dictionary_foreach_cur(struct Dictionary *dtree,
+	struct DictionaryIter *state);
+
+/*
+ * irc_dictionary_foreach_next() moves to the next element.
+ */
+extern void irc_dictionary_foreach_next(struct Dictionary *dtree,
+	struct DictionaryIter *state);
+
+/*
+ * irc_dictionary_add() adds a key->value entry to the dictionary tree.
+ */
+extern struct DictionaryElement *irc_dictionary_add(struct Dictionary *dtree, char *key, void *data);
+
+/*
+ * irc_dictionary_find() returns a struct DictionaryElement container from a dtree for key 'key'.
+ */
+extern struct DictionaryElement *irc_dictionary_find(struct Dictionary *dtree, const char *key);
+
+/*
+ * irc_dictionary_find() returns data from a dtree for key 'key'.
+ */
+extern void *irc_dictionary_retrieve(struct Dictionary *dtree, const char *key);
+
+/*
+ * irc_dictionary_delete() deletes a key->value entry from the dictionary tree.
+ */
+extern void *irc_dictionary_delete(struct Dictionary *dtree, const char *key);
+
+void irc_dictionary_stats(struct Dictionary *dict, void (*cb)(const char *line, void *privdata), void *privdata);
+
+#endif

src/Makefile.in

@@ -66,6 +66,7 @@ SRCS =                          \
   hook.c                        \
   hostmask.c			\
   irc_string.c                  \
+  irc_dictionary.c		\
   ircd.c                        \
   ircd_signal.c                 \
   ircd_state.c			\

src/irc_dictionary.c

@@ -0,0 +1,902 @@
+/*
+ * charybdis: an advanced ircd
+ * irc_dictionary.c: Dictionary-based information storage.
+ *
+ * Copyright (c) 2007 William Pitcock <nenolod -at- sacredspiral.co.uk>
+ * Copyright (c) 2007 Jilles Tjoelker <jilles -at- stack.nl>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice is present in all copies.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "stdinc.h"
+#include "sprintf_irc.h"
+#include "tools.h"
+#include "irc_string.h"
+#include "client.h"
+#include "memory.h"
+#include "setup.h"
+#include "balloc.h"
+#include "irc_dictionary.h"
+
+static BlockHeap *elem_heap = NULL;
+
+struct Dictionary
+{
+	DCF compare_cb;
+	struct DictionaryElement *root, *head, *tail;
+	unsigned int count;
+	char *id;
+	unsigned int dirty:1;
+};
+
+/*
+ * irc_dictionary_create(DCF compare_cb)
+ *
+ * Dictionary object factory.
+ *
+ * Inputs:
+ *     - function to use for comparing two entries in the dtree
+ *
+ * Outputs:
+ *     - on success, a new dictionary object.
+ *
+ * Side Effects:
+ *     - if services runs out of memory and cannot allocate the object,
+ *       the program will abort.
+ */
+struct Dictionary *irc_dictionary_create(DCF compare_cb)
+{
+	struct Dictionary *dtree = (struct Dictionary *) MyMalloc(sizeof(struct Dictionary));
+
+	dtree->compare_cb = compare_cb;
+
+	if (!elem_heap)
+		elem_heap = BlockHeapCreate(sizeof(struct DictionaryElement), 1024);
+
+	return dtree;
+}
+
+/*
+ * irc_dictionary_create_named(const char *name, 
+ *     DCF compare_cb)
+ *
+ * Dictionary object factory.
+ *
+ * Inputs:
+ *     - dictionary name
+ *     - function to use for comparing two entries in the dtree
+ *
+ * Outputs:
+ *     - on success, a new dictionary object.
+ *
+ * Side Effects:
+ *     - if services runs out of memory and cannot allocate the object,
+ *       the program will abort.
+ */
+struct Dictionary *irc_dictionary_create_named(const char *name,
+	DCF compare_cb)
+{
+	struct Dictionary *dtree = (struct Dictionary *) MyMalloc(sizeof(struct Dictionary));
+
+	dtree->compare_cb = compare_cb;
+	DupString(dtree->id, name);
+
+	if (!elem_heap)
+		elem_heap = BlockHeapCreate(sizeof(struct DictionaryElement), 1024);
+
+	return dtree;
+}
+
+/*
+ * irc_dictionary_set_comparator_func(struct Dictionary *dict,
+ *     DCF compare_cb)
+ *
+ * Resets the comparator function used by the dictionary code for
+ * updating the DTree structure.
+ *
+ * Inputs:
+ *     - dictionary object
+ *     - new comparator function (passed as functor)
+ *
+ * Outputs:
+ *     - nothing
+ *
+ * Side Effects:
+ *     - the dictionary comparator function is reset.
+ */
+void irc_dictionary_set_comparator_func(struct Dictionary *dict,
+	DCF compare_cb)
+{
+	s_assert(dict != NULL);
+	s_assert(compare_cb != NULL);
+
+	dict->compare_cb = compare_cb;
+}
+
+/*
+ * irc_dictionary_get_comparator_func(struct Dictionary *dict)
+ *
+ * Returns the current comparator function used by the dictionary.
+ *
+ * Inputs:
+ *     - dictionary object
+ *
+ * Outputs:
+ *     - comparator function (returned as functor)
+ *
+ * Side Effects:
+ *     - none
+ */
+DCF
+irc_dictionary_get_comparator_func(struct Dictionary *dict)
+{
+	s_assert(dict != NULL);
+
+	return dict->compare_cb;
+}
+
+/*
+ * irc_dictionary_get_linear_index(struct Dictionary *dict,
+ *     const char *key)
+ *
+ * Gets a linear index number for key.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - pointer to data
+ *
+ * Outputs:
+ *     - position, from zero.
+ *
+ * Side Effects:
+ *     - rebuilds the linear index if the tree is marked as dirty.
+ */
+int
+irc_dictionary_get_linear_index(struct Dictionary *dict, const char *key)
+{
+	struct DictionaryElement *elem;
+
+	s_assert(dict != NULL);
+	s_assert(key != NULL);
+
+	elem = irc_dictionary_find(dict, key);
+	if (elem == NULL)
+		return -1;
+
+	if (!dict->dirty)
+		return elem->position;
+	else
+	{
+		struct DictionaryElement *delem;
+		int i;
+
+		for (delem = dict->head, i = 0; delem != NULL; delem = delem->next, i++)
+			delem->position = i;
+
+		dict->dirty = FALSE;
+	}
+
+	return elem->position;
+}
+
+/*
+ * irc_dictionary_retune(struct Dictionary *dict, const char *key)
+ *
+ * Retunes the tree, self-optimizing for the element which belongs to key.
+ *
+ * Tuning the tree structure is a very complex operation. Unlike
+ * 2-3-4 trees and BTree/BTree+ structures, this structure is a
+ * constantly evolving algorithm.
+ *
+ * Instead of maintaining a balanced tree, we constantly adapt the
+ * tree by nominating a new root nearby the most recently looked up
+ * or added data. We are constantly retuning ourselves instead of
+ * doing massive O(n) rebalance operations as seen in BTrees,
+ * and the level of data stored in a tree is dynamic, instead of being
+ * held to a restricted design like other trees.
+ *
+ * Moreover, we are different than a radix/patricia tree, because we
+ * don't statically allocate positions. Radix trees have the advantage
+ * of not requiring tuning or balancing operations while having the
+ * disadvantage of requiring a large amount of memory to store
+ * large trees. Our efficiency as far as speed goes is not as
+ * fast as a radix tree; but is close to it.
+ *
+ * The retuning algorithm uses the comparison callback that is
+ * passed in the initialization of the tree container. If the
+ * comparator returns a value which is less than zero, we push the
+ * losing node out of the way, causing it to later be reparented
+ * with another node. The winning child of this comparison is always
+ * the right-most node.
+ *
+ * Once we have reached the key which has been targeted, or have reached
+ * a deadend, we nominate the nearest node as the new root of the tree.
+ * If an exact match has been found, the new root becomes the node which
+ * represents key.
+ *
+ * This results in a tree which can self-optimize for both critical
+ * conditions: nodes which are distant and similar and trees which
+ * have ordered lookups.
+ *
+ * Inputs:
+ *     - node to begin search from
+ *
+ * Outputs:
+ *     - none
+ *
+ * Side Effects:
+ *     - a new root node is nominated.
+ */
+void
+irc_dictionary_retune(struct Dictionary *dict, const char *key)
+{
+	struct DictionaryElement n, *tn, *left, *right, *node;
+	int ret;
+
+	s_assert(dict != NULL);
+
+	if (dict->root == NULL)
+		return;
+
+	/*
+	 * we initialize n with known values, since it's on stack
+	 * memory. otherwise the dict would become corrupted.
+	 *
+ 	 * n is used for temporary storage while the tree is retuned.
+	 *    -nenolod
+	 */
+	n.left = n.right = NULL;
+	left = right = &n;
+
+	/* this for(;;) loop is the main workhorse of the rebalancing */
+	for (node = dict->root; ; )
+	{
+		if ((ret = dict->compare_cb(key, node->key)) == 0)
+			break;
+
+		if (ret < 0)
+		{
+			if (node->left == NULL)
+				break;
+
+			if ((ret = dict->compare_cb(key, node->left->key)) < 0)
+			{
+				tn = node->left;
+				node->left = tn->right;
+				tn->right = node;
+				node = tn;
+
+				if (node->left == NULL)
+					break;
+			}
+
+			right->left = node;
+			right = node;
+			node = node->left;
+		}
+		else
+		{
+			if (node->right == NULL)
+				break;
+
+			if ((ret = dict->compare_cb(key, node->right->key)) > 0)
+			{
+				tn = node->right;
+				node->right = tn->left;
+				tn->left = node;
+				node = tn;
+
+				if (node->right == NULL)
+					break;
+			}
+
+			left->right = node;
+			left = node;
+			node = node->right;
+		}
+	}
+
+	left->right = node->left;
+	right->left = node->right;
+
+	node->left = n.right;
+	node->right = n.left;
+
+	dict->root = node;
+}
+
+/*
+ * irc_dictionary_link(struct Dictionary *dict,
+ *     struct DictionaryElement *delem)
+ *
+ * Links a dictionary tree element to the dictionary.
+ *
+ * When we add new nodes to the tree, it becomes the
+ * next nominated root. This is perhaps not a wise
+ * optimization because of automatic retuning, but
+ * it keeps the code simple.
+ *
+ * Inputs:
+ *     - dictionary tree
+ *     - dictionary tree element
+ *
+ * Outputs:
+ *     - nothing
+ *
+ * Side Effects:
+ *     - a node is linked to the dictionary tree
+ */
+void
+irc_dictionary_link(struct Dictionary *dict,
+	struct DictionaryElement *delem)
+{
+	s_assert(dict != NULL);
+	s_assert(delem != NULL);
+
+	dict->dirty = TRUE;
+
+	dict->count++;
+
+	if (dict->root == NULL)
+	{
+		delem->left = delem->right = NULL;
+		delem->next = delem->prev = NULL;
+		dict->head = dict->tail = dict->root = delem;
+	}
+	else
+	{
+		int ret;
+
+		irc_dictionary_retune(dict, delem->key);
+
+		if ((ret = dict->compare_cb(delem->key, dict->root->key)) < 0)
+		{
+			delem->left = dict->root->left;
+			delem->right = dict->root;
+			dict->root->left = NULL;
+
+			if (dict->root->prev)
+				dict->root->prev->next = delem;
+			else
+				dict->head = delem;
+
+			delem->prev = dict->root->prev;
+			delem->next = dict->root;
+			dict->root->prev = delem;
+			dict->root = delem;
+		}
+		else if (ret > 0)
+		{
+			delem->right = dict->root->right;
+			delem->left = dict->root;
+			dict->root->right = NULL;
+
+			if (dict->root->next)
+				dict->root->next->prev = delem;
+			else
+				dict->tail = delem;
+
+			delem->next = dict->root->next;
+			delem->prev = dict->root;
+			dict->root->next = delem;
+			dict->root = delem;
+		}
+		else
+		{
+			dict->root->key = delem->key;
+			dict->root->data = delem->data;
+			dict->count--;
+
+			BlockHeapFree(elem_heap, delem);
+		}
+	}
+}
+
+/*
+ * irc_dictionary_unlink_root(struct Dictionary *dict)
+ *
+ * Unlinks the root dictionary tree element from the dictionary.
+ *
+ * Inputs:
+ *     - dictionary tree
+ *
+ * Outputs:
+ *     - nothing
+ *
+ * Side Effects:
+ *     - the root node is unlinked from the dictionary tree
+ */
+void
+irc_dictionary_unlink_root(struct Dictionary *dict)
+{
+	struct DictionaryElement *delem, *nextnode, *parentofnext;
+
+	dict->dirty = TRUE;
+
+	delem = dict->root;
+	if (delem == NULL)
+		return;
+
+	if (dict->root->left == NULL)
+		dict->root = dict->root->right;
+	else if (dict->root->right == NULL)
+		dict->root = dict->root->left;
+	else
+	{
+		/* Make the node with the next highest key the new root.
+		 * This node has a NULL left pointer. */
+		nextnode = delem->next;
+		s_assert(nextnode->left == NULL);
+		if (nextnode == delem->right)
+		{
+			dict->root = nextnode;
+			dict->root->left = delem->left;
+		}
+		else
+		{
+			parentofnext = delem->right;
+			while (parentofnext->left != NULL && parentofnext->left != nextnode)
+				parentofnext = parentofnext->left;
+			s_assert(parentofnext->left == nextnode);
+			parentofnext->left = nextnode->right;
+			dict->root = nextnode;
+			dict->root->left = delem->left;
+			dict->root->right = delem->right;
+		}
+	}
+
+	/* linked list */
+	if (delem->prev != NULL)
+		delem->prev->next = delem->next;
+
+	if (dict->head == delem)
+		dict->head = delem->next;
+
+	if (delem->next)
+		delem->next->prev = delem->prev;
+
+	if (dict->tail == delem)
+		dict->tail = delem->prev;
+
+	dict->count--;
+}
+
+/*
+ * irc_dictionary_destroy(struct Dictionary *dtree,
+ *     void (*destroy_cb)(dictionary_elem_t *delem, void *privdata),
+ *     void *privdata);
+ *
+ * Recursively destroys all nodes in a dictionary tree.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - optional iteration callback
+ *     - optional opaque/private data to pass to callback
+ *
+ * Outputs:
+ *     - nothing
+ *
+ * Side Effects:
+ *     - on success, a dtree and optionally it's children are destroyed.
+ *
+ * Notes:
+ *     - if this is called without a callback, the objects bound to the
+ *       DTree will not be destroyed.
+ */
+void irc_dictionary_destroy(struct Dictionary *dtree,
+	void (*destroy_cb)(struct DictionaryElement *delem, void *privdata),
+	void *privdata)
+{
+	struct DictionaryElement *n, *tn;
+
+	s_assert(dtree != NULL);
+
+	DLINK_FOREACH_SAFE(n, tn, dtree->head)
+	{
+		if (destroy_cb != NULL)
+			(*destroy_cb)(n, privdata);
+
+		BlockHeapFree(elem_heap, n);
+	}
+
+	MyFree(dtree);
+}
+
+/*
+ * irc_dictionary_foreach(struct Dictionary *dtree,
+ *     void (*destroy_cb)(dictionary_elem_t *delem, void *privdata),
+ *     void *privdata);
+ *
+ * Iterates over all entries in a DTree.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - optional iteration callback
+ *     - optional opaque/private data to pass to callback
+ *
+ * Outputs:
+ *     - nothing
+ *
+ * Side Effects:
+ *     - on success, a dtree is iterated
+ */
+void irc_dictionary_foreach(struct Dictionary *dtree,
+	int (*foreach_cb)(struct DictionaryElement *delem, void *privdata),
+	void *privdata)
+{
+	struct DictionaryElement *n, *tn;
+
+	s_assert(dtree != NULL);
+
+	DLINK_FOREACH_SAFE(n, tn, dtree->head)
+	{
+		/* delem_t is a subclass of node_t. */
+		struct DictionaryElement *delem = (struct DictionaryElement *) n;
+
+		if (foreach_cb != NULL)
+			(*foreach_cb)(delem, privdata);
+	}
+}
+
+/*
+ * irc_dictionary_search(struct Dictionary *dtree,
+ *     void (*destroy_cb)(struct DictionaryElement *delem, void *privdata),
+ *     void *privdata);
+ *
+ * Searches all entries in a DTree using a custom callback.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - optional iteration callback
+ *     - optional opaque/private data to pass to callback
+ *
+ * Outputs:
+ *     - on success, the requested object
+ *     - on failure, NULL.
+ *
+ * Side Effects:
+ *     - a dtree is iterated until the requested conditions are met
+ */
+void *irc_dictionary_search(struct Dictionary *dtree,
+	void *(*foreach_cb)(struct DictionaryElement *delem, void *privdata),
+	void *privdata)
+{
+	struct DictionaryElement *n, *tn;
+	void *ret = NULL;
+
+	s_assert(dtree != NULL);
+
+	DLINK_FOREACH_SAFE(n, tn, dtree->head)
+	{
+		/* delem_t is a subclass of node_t. */
+		struct DictionaryElement *delem = (struct DictionaryElement *) n;
+
+		if (foreach_cb != NULL)
+			ret = (*foreach_cb)(delem, privdata);
+
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+
+/*
+ * irc_dictionary_foreach_start(struct Dictionary *dtree,
+ *     struct DictionaryIter *state);
+ *
+ * Initializes a static DTree iterator.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - static DTree iterator
+ *
+ * Outputs:
+ *     - nothing
+ *
+ * Side Effects:
+ *     - the static iterator, &state, is initialized.
+ */
+void irc_dictionary_foreach_start(struct Dictionary *dtree,
+	struct DictionaryIter *state)
+{
+	s_assert(dtree != NULL);
+	s_assert(state != NULL);
+
+	state->cur = NULL;
+	state->next = NULL;
+
+	/* find first item */
+	state->cur = dtree->head;
+
+	if (state->cur == NULL)
+		return;
+
+	/* make state->cur point to first item and state->next point to
+	 * second item */
+	state->next = state->cur;
+	irc_dictionary_foreach_next(dtree, state);
+}
+
+/*
+ * irc_dictionary_foreach_cur(struct Dictionary *dtree,
+ *     struct DictionaryIter *state);
+ *
+ * Returns the data from the current node being iterated by the
+ * static iterator.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - static DTree iterator
+ *
+ * Outputs:
+ *     - reference to data in the current dtree node being iterated
+ *
+ * Side Effects:
+ *     - none
+ */
+void *irc_dictionary_foreach_cur(struct Dictionary *dtree,
+	struct DictionaryIter *state)
+{
+	s_assert(dtree != NULL);
+	s_assert(state != NULL);
+
+	return state->cur != NULL ? state->cur->data : NULL;
+}
+
+/*
+ * irc_dictionary_foreach_next(struct Dictionary *dtree,
+ *     struct DictionaryIter *state);
+ *
+ * Advances a static DTree iterator.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - static DTree iterator
+ *
+ * Outputs:
+ *     - nothing
+ *
+ * Side Effects:
+ *     - the static iterator, &state, is advanced to a new DTree node.
+ */
+void irc_dictionary_foreach_next(struct Dictionary *dtree,
+	struct DictionaryIter *state)
+{
+	s_assert(dtree != NULL);
+	s_assert(state != NULL);
+
+	if (state->cur == NULL)
+	{
+		ilog(L_MAIN, "irc_dictionary_foreach_next(): called again after iteration finished on dtree<%p>", dtree);
+		return;
+	}
+
+	state->cur = state->next;
+
+	if (state->next == NULL)
+		return;
+
+	state->next = state->next->next;
+}
+
+/*
+ * irc_dictionary_find(struct Dictionary *dtree, const char *key)
+ *
+ * Looks up a DTree node by name.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - name of node to lookup
+ *
+ * Outputs:
+ *     - on success, the dtree node requested
+ *     - on failure, NULL
+ *
+ * Side Effects:
+ *     - none
+ */
+struct DictionaryElement *irc_dictionary_find(struct Dictionary *dict, const char *key)
+{
+	s_assert(dict != NULL);
+	s_assert(key != NULL);
+
+	/* retune for key, key will be the tree's root if it's available */
+	irc_dictionary_retune(dict, key);
+
+	if (dict->root && !dict->compare_cb(key, dict->root->key))
+		return dict->root;
+
+	return NULL;
+}
+
+/*
+ * irc_dictionary_add(struct Dictionary *dtree, const char *key, void *data)
+ *
+ * Creates a new DTree node and binds data to it.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - name for new DTree node
+ *     - data to bind to the new DTree node
+ *
+ * Outputs:
+ *     - on success, a new DTree node
+ *     - on failure, NULL
+ *
+ * Side Effects:
+ *     - data is inserted into the DTree.
+ */
+struct DictionaryElement *irc_dictionary_add(struct Dictionary *dict, char *key, void *data)
+{
+	struct DictionaryElement *delem;
+
+	s_assert(dict != NULL);
+	s_assert(key != NULL);
+	s_assert(data != NULL);
+	s_assert(irc_dictionary_find(dict, key) == NULL);
+
+	delem = BlockHeapAlloc(elem_heap);
+	delem->key = key;
+	delem->data = data;
+
+	/* TBD: is this needed? --nenolod */
+	if (delem->key == NULL)
+	{
+		BlockHeapFree(elem_heap, delem);
+		return NULL;
+	}
+
+	irc_dictionary_link(dict, delem);
+
+	return delem;
+}
+
+/*
+ * irc_dictionary_delete(struct Dictionary *dtree, const char *key)
+ *
+ * Deletes data from a dictionary tree.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - name of DTree node to delete
+ *
+ * Outputs:
+ *     - on success, the remaining data that needs to be mowgli_freed
+ *     - on failure, NULL
+ *
+ * Side Effects:
+ *     - data is removed from the DTree.
+ *
+ * Notes:
+ *     - the returned data needs to be mowgli_freed/released manually!
+ */
+void *irc_dictionary_delete(struct Dictionary *dtree, const char *key)
+{
+	struct DictionaryElement *delem = irc_dictionary_find(dtree, key);
+	void *data;
+
+	if (delem == NULL)
+		return NULL;
+
+	data = delem->data;
+
+	irc_dictionary_unlink_root(dtree);
+	BlockHeapFree(elem_heap, delem);	
+
+	return data;
+}
+
+/*
+ * irc_dictionary_retrieve(struct Dictionary *dtree, const char *key)
+ *
+ * Retrieves data from a dictionary.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - name of node to lookup
+ *
+ * Outputs:
+ *     - on success, the data bound to the DTree node.
+ *     - on failure, NULL
+ *
+ * Side Effects:
+ *     - none
+ */
+void *irc_dictionary_retrieve(struct Dictionary *dtree, const char *key)
+{
+	struct DictionaryElement *delem = irc_dictionary_find(dtree, key);
+
+	if (delem != NULL)
+		return delem->data;
+
+	return NULL;
+}
+
+/*
+ * irc_dictionary_size(struct Dictionary *dict)
+ *
+ * Returns the size of a dictionary.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *
+ * Outputs:
+ *     - size of dictionary
+ *
+ * Side Effects:
+ *     - none
+ */
+unsigned int irc_dictionary_size(struct Dictionary *dict)
+{
+	s_assert(dict != NULL);
+
+	return dict->count;
+}
+
+/* returns the sum of the depths of the subtree rooted in delem at depth depth */
+static int
+stats_recurse(struct DictionaryElement *delem, int depth, int *pmaxdepth)
+{
+	int result;
+
+	if (depth > *pmaxdepth)
+		*pmaxdepth = depth;
+	result = depth;
+	if (delem->left)
+		result += stats_recurse(delem->left, depth + 1, pmaxdepth);
+	if (delem->right)
+		result += stats_recurse(delem->right, depth + 1, pmaxdepth);
+	return result;
+}
+
+/*
+ * irc_dictionary_stats(struct Dictionary *dict, void (*cb)(const char *line, void *privdata), void *privdata)
+ *
+ * Returns the size of a dictionary.
+ *
+ * Inputs:
+ *     - dictionary tree object
+ *     - callback
+ *     - data for callback
+ *
+ * Outputs:
+ *     - none
+ *
+ * Side Effects:
+ *     - callback called with stats text
+ */
+void irc_dictionary_stats(struct Dictionary *dict, void (*cb)(const char *line, void *privdata), void *privdata)
+{
+	char str[256];
+	int sum, maxdepth;
+
+	s_assert(dict != NULL);
+
+	if (dict->id != NULL)
+		snprintf(str, sizeof str, "Dictionary stats for %s (%d)",
+				dict->id, dict->count);
+	else
+		snprintf(str, sizeof str, "Dictionary stats for <%p> (%d)",
+				dict, dict->count);
+	cb(str, privdata);
+	maxdepth = 0;
+	sum = stats_recurse(dict->root, 0, &maxdepth);
+	snprintf(str, sizeof str, "Depth sum %d Avg depth %d Max depth %d", sum, sum / dict->count, maxdepth);
+	cb(str, privdata);
+	return;
+}