added some generic hashtable code by Christopher Clark

found at http://www.cl.cam.ac.uk/~cwc22/hashtable/

12 files changed, 1285 insertions, 1 deletions

diff --git a/plugins/imuxsock/Makefile.am b/plugins/imuxsock/Makefile.am
index 28f9f9e3..34a0ad9a 100644
--- a/plugins/imuxsock/Makefile.am
+++ b/plugins/imuxsock/Makefile.am
@@ -1,6 +1,6 @@
 pkglib_LTLIBRARIES = imuxsock.la
 
 imuxsock_la_SOURCES = imuxsock.c
-imuxsock_la_CPPFLAGS = -DSD_EXPORT_SYMBOLS -I$(top_srcdir) $(PTHREADS_CFLAGS) $(RSRT_CFLAGS)
+imuxsock_la_CPPFLAGS = -DSD_EXPORT_SYMBOLS -I../../runtime/hashtable -I$(top_srcdir) $(PTHREADS_CFLAGS) $(RSRT_CFLAGS)
 imuxsock_la_LDFLAGS = -module -avoid-version
 imuxsock_la_LIBADD = $(RSRT_LIBS)
diff --git a/plugins/imuxsock/imuxsock.c b/plugins/imuxsock/imuxsock.c
index ccd31b44..b53bb379 100644
--- a/plugins/imuxsock/imuxsock.c
+++ b/plugins/imuxsock/imuxsock.c
@@ -52,6 +52,7 @@
 #include "sd-daemon.h"
 #include "statsobj.h"
 #include "datetime.h"
+#include "hashtable.h"
 
 MODULE_TYPE_INPUT
 
diff --git a/runtime/Makefile.am b/runtime/Makefile.am
index 01b224e7..d657b6ca 100644
--- a/runtime/Makefile.am
+++ b/runtime/Makefile.am
@@ -95,6 +95,8 @@ librsyslog_la_SOURCES = \
 	../parse.c \
 	../parse.h \
 	\
+	hashtable/hashtable.c \
+	\
 	../outchannel.c \
 	../outchannel.h \
 	../template.c \
diff --git a/runtime/hashtable/Makefile b/runtime/hashtable/Makefile
new file mode 100644
index 00000000..3b7b5e9f
--- /dev/null
+++ b/runtime/hashtable/Makefile
@@ -0,0 +1,26 @@
+
+tester: hashtable.o tester.o hashtable_itr.o
+	gcc -g -Wall -O -lm -o tester hashtable.o hashtable_itr.o tester.o
+
+all: tester old_tester
+
+tester.o:	tester.c
+	gcc -g -Wall -O -c tester.c -o tester.o
+
+old_tester: hashtable_powers.o tester.o hashtable_itr.o
+	gcc -g -Wall -O -o old_tester hashtable_powers.o hashtable_itr.o tester.o
+
+hashtable_powers.o:	hashtable_powers.c
+	gcc -g -Wall -O -c hashtable_powers.c -o hashtable_powers.o
+
+hashtable.o:	hashtable.c
+	gcc -g -Wall -O -c hashtable.c -o hashtable.o
+
+hashtable_itr.o: hashtable_itr.c
+	gcc -g -Wall -O -c hashtable_itr.c -o hashtable_itr.o
+
+tidy:
+	rm *.o
+
+clean: tidy
+	rm -f tester old_tester
diff --git a/runtime/hashtable/hashtable.c b/runtime/hashtable/hashtable.c
new file mode 100644
index 00000000..a10e3bc6
--- /dev/null
+++ b/runtime/hashtable/hashtable.c
@@ -0,0 +1,275 @@
+/* Copyright (C) 2004 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */
+/* taken from http://www.cl.cam.ac.uk/~cwc22/hashtable/ */
+
+#include "hashtable.h"
+#include "hashtable_private.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+
+/*
+Credit for primes table: Aaron Krowne
+ http://br.endernet.org/~akrowne/
+ http://planetmath.org/encyclopedia/GoodHashTablePrimes.html
+*/
+static const unsigned int primes[] = {
+53, 97, 193, 389,
+769, 1543, 3079, 6151,
+12289, 24593, 49157, 98317,
+196613, 393241, 786433, 1572869,
+3145739, 6291469, 12582917, 25165843,
+50331653, 100663319, 201326611, 402653189,
+805306457, 1610612741
+};
+const unsigned int prime_table_length = sizeof(primes)/sizeof(primes[0]);
+const float max_load_factor = 0.65;
+
+/*****************************************************************************/
+struct hashtable *
+create_hashtable(unsigned int minsize,
+                 unsigned int (*hashf) (void*),
+                 int (*eqf) (void*,void*))
+{
+    struct hashtable *h;
+    unsigned int pindex, size = primes[0];
+    /* Check requested hashtable isn't too large */
+    if (minsize > (1u << 30)) return NULL;
+    /* Enforce size as prime */
+    for (pindex=0; pindex < prime_table_length; pindex++) {
+        if (primes[pindex] > minsize) { size = primes[pindex]; break; }
+    }
+    h = (struct hashtable *)malloc(sizeof(struct hashtable));
+    if (NULL == h) return NULL; /*oom*/
+    h->table = (struct entry **)malloc(sizeof(struct entry*) * size);
+    if (NULL == h->table) { free(h); return NULL; } /*oom*/
+    memset(h->table, 0, size * sizeof(struct entry *));
+    h->tablelength  = size;
+    h->primeindex   = pindex;
+    h->entrycount   = 0;
+    h->hashfn       = hashf;
+    h->eqfn         = eqf;
+    h->loadlimit    = (unsigned int) ceil(size * max_load_factor);
+    return h;
+}
+
+/*****************************************************************************/
+unsigned int
+hash(struct hashtable *h, void *k)
+{
+    /* Aim to protect against poor hash functions by adding logic here
+     * - logic taken from java 1.4 hashtable source */
+    unsigned int i = h->hashfn(k);
+    i += ~(i << 9);
+    i ^=  ((i >> 14) | (i << 18)); /* >>> */
+    i +=  (i << 4);
+    i ^=  ((i >> 10) | (i << 22)); /* >>> */
+    return i;
+}
+
+/*****************************************************************************/
+static int
+hashtable_expand(struct hashtable *h)
+{
+    /* Double the size of the table to accomodate more entries */
+    struct entry **newtable;
+    struct entry *e;
+    struct entry **pE;
+    unsigned int newsize, i, idx;
+    /* Check we're not hitting max capacity */
+    if (h->primeindex == (prime_table_length - 1)) return 0;
+    newsize = primes[++(h->primeindex)];
+
+    newtable = (struct entry **)malloc(sizeof(struct entry*) * newsize);
+    if (NULL != newtable)
+    {
+        memset(newtable, 0, newsize * sizeof(struct entry *));
+        /* This algorithm is not 'stable'. ie. it reverses the list
+         * when it transfers entries between the tables */
+        for (i = 0; i < h->tablelength; i++) {
+            while (NULL != (e = h->table[i])) {
+                h->table[i] = e->next;
+                idx = indexFor(newsize,e->h);
+                e->next = newtable[idx];
+                newtable[idx] = e;
+            }
+        }
+        free(h->table);
+        h->table = newtable;
+    }
+    /* Plan B: realloc instead */
+    else 
+    {
+        newtable = (struct entry **)
+                   realloc(h->table, newsize * sizeof(struct entry *));
+        if (NULL == newtable) { (h->primeindex)--; return 0; }
+        h->table = newtable;
+        memset(newtable[h->tablelength], 0, newsize - h->tablelength);
+        for (i = 0; i < h->tablelength; i++) {
+            for (pE = &(newtable[i]), e = *pE; e != NULL; e = *pE) {
+                idx = indexFor(newsize,e->h);
+                if (idx == i)
+                {
+                    pE = &(e->next);
+                }
+                else
+                {
+                    *pE = e->next;
+                    e->next = newtable[idx];
+                    newtable[idx] = e;
+                }
+            }
+        }
+    }
+    h->tablelength = newsize;
+    h->loadlimit   = (unsigned int) ceil(newsize * max_load_factor);
+    return -1;
+}
+
+/*****************************************************************************/
+unsigned int
+hashtable_count(struct hashtable *h)
+{
+    return h->entrycount;
+}
+
+/*****************************************************************************/
+int
+hashtable_insert(struct hashtable *h, void *k, void *v)
+{
+    /* This method allows duplicate keys - but they shouldn't be used */
+    unsigned int idx;
+    struct entry *e;
+    if (++(h->entrycount) > h->loadlimit)
+    {
+        /* Ignore the return value. If expand fails, we should
+         * still try cramming just this value into the existing table
+         * -- we may not have memory for a larger table, but one more
+         * element may be ok. Next time we insert, we'll try expanding again.*/
+        hashtable_expand(h);
+    }
+    e = (struct entry *)malloc(sizeof(struct entry));
+    if (NULL == e) { --(h->entrycount); return 0; } /*oom*/
+    e->h = hash(h,k);
+    idx = indexFor(h->tablelength,e->h);
+    e->k = k;
+    e->v = v;
+    e->next = h->table[idx];
+    h->table[idx] = e;
+    return -1;
+}
+
+/*****************************************************************************/
+void * /* returns value associated with key */
+hashtable_search(struct hashtable *h, void *k)
+{
+    struct entry *e;
+    unsigned int hashvalue, idx;
+    hashvalue = hash(h,k);
+    idx = indexFor(h->tablelength,hashvalue);
+    e = h->table[idx];
+    while (NULL != e)
+    {
+        /* Check hash value to short circuit heavier comparison */
+        if ((hashvalue == e->h) && (h->eqfn(k, e->k))) return e->v;
+        e = e->next;
+    }
+    return NULL;
+}
+
+/*****************************************************************************/
+void * /* returns value associated with key */
+hashtable_remove(struct hashtable *h, void *k)
+{
+    /* TODO: consider compacting the table when the load factor drops enough,
+     *       or provide a 'compact' method. */
+
+    struct entry *e;
+    struct entry **pE;
+    void *v;
+    unsigned int hashvalue, idx;
+
+    hashvalue = hash(h,k);
+    idx = indexFor(h->tablelength,hash(h,k));
+    pE = &(h->table[idx]);
+    e = *pE;
+    while (NULL != e)
+    {
+        /* Check hash value to short circuit heavier comparison */
+        if ((hashvalue == e->h) && (h->eqfn(k, e->k)))
+        {
+            *pE = e->next;
+            h->entrycount--;
+            v = e->v;
+            freekey(e->k);
+            free(e);
+            return v;
+        }
+        pE = &(e->next);
+        e = e->next;
+    }
+    return NULL;
+}
+
+/*****************************************************************************/
+/* destroy */
+void
+hashtable_destroy(struct hashtable *h, int free_values)
+{
+    unsigned int i;
+    struct entry *e, *f;
+    struct entry **table = h->table;
+    if (free_values)
+    {
+        for (i = 0; i < h->tablelength; i++)
+        {
+            e = table[i];
+            while (NULL != e)
+            { f = e; e = e->next; freekey(f->k); free(f->v); free(f); }
+        }
+    }
+    else
+    {
+        for (i = 0; i < h->tablelength; i++)
+        {
+            e = table[i];
+            while (NULL != e)
+            { f = e; e = e->next; freekey(f->k); free(f); }
+        }
+    }
+    free(h->table);
+    free(h);
+}
+
+/*
+ * Copyright (c) 2002, Christopher Clark
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * * Neither the name of the original author; nor the names of any contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ * 
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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 COPYRIGHT OWNER
+ * OR CONTRIBUTORS 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.
+*/
diff --git a/runtime/hashtable/hashtable.h b/runtime/hashtable/hashtable.h
new file mode 100644
index 00000000..b90781ab
--- /dev/null
+++ b/runtime/hashtable/hashtable.h
@@ -0,0 +1,199 @@
+/* Copyright (C) 2002 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */
+
+#ifndef __HASHTABLE_CWC22_H__
+#define __HASHTABLE_CWC22_H__
+
+struct hashtable;
+
+/* Example of use:
+ *
+ *      struct hashtable  *h;
+ *      struct some_key   *k;
+ *      struct some_value *v;
+ *
+ *      static unsigned int         hash_from_key_fn( void *k );
+ *      static int                  keys_equal_fn ( void *key1, void *key2 );
+ *
+ *      h = create_hashtable(16, hash_from_key_fn, keys_equal_fn);
+ *      k = (struct some_key *)     malloc(sizeof(struct some_key));
+ *      v = (struct some_value *)   malloc(sizeof(struct some_value));
+ *
+ *      (initialise k and v to suitable values)
+ * 
+ *      if (! hashtable_insert(h,k,v) )
+ *      {     exit(-1);               }
+ *
+ *      if (NULL == (found = hashtable_search(h,k) ))
+ *      {    printf("not found!");                  }
+ *
+ *      if (NULL == (found = hashtable_remove(h,k) ))
+ *      {    printf("Not found\n");                 }
+ *
+ */
+
+/* Macros may be used to define type-safe(r) hashtable access functions, with
+ * methods specialized to take known key and value types as parameters.
+ * 
+ * Example:
+ *
+ * Insert this at the start of your file:
+ *
+ * DEFINE_HASHTABLE_INSERT(insert_some, struct some_key, struct some_value);
+ * DEFINE_HASHTABLE_SEARCH(search_some, struct some_key, struct some_value);
+ * DEFINE_HASHTABLE_REMOVE(remove_some, struct some_key, struct some_value);
+ *
+ * This defines the functions 'insert_some', 'search_some' and 'remove_some'.
+ * These operate just like hashtable_insert etc., with the same parameters,
+ * but their function signatures have 'struct some_key *' rather than
+ * 'void *', and hence can generate compile time errors if your program is
+ * supplying incorrect data as a key (and similarly for value).
+ *
+ * Note that the hash and key equality functions passed to create_hashtable
+ * still take 'void *' parameters instead of 'some key *'. This shouldn't be
+ * a difficult issue as they're only defined and passed once, and the other
+ * functions will ensure that only valid keys are supplied to them.
+ *
+ * The cost for this checking is increased code size and runtime overhead
+ * - if performance is important, it may be worth switching back to the
+ * unsafe methods once your program has been debugged with the safe methods.
+ * This just requires switching to some simple alternative defines - eg:
+ * #define insert_some hashtable_insert
+ *
+ */
+
+/*****************************************************************************
+ * create_hashtable
+   
+ * @name                    create_hashtable
+ * @param   minsize         minimum initial size of hashtable
+ * @param   hashfunction    function for hashing keys
+ * @param   key_eq_fn       function for determining key equality
+ * @return                  newly created hashtable or NULL on failure
+ */
+
+struct hashtable *
+create_hashtable(unsigned int minsize,
+                 unsigned int (*hashfunction) (void*),
+                 int (*key_eq_fn) (void*,void*));
+
+/*****************************************************************************
+ * hashtable_insert
+   
+ * @name        hashtable_insert
+ * @param   h   the hashtable to insert into
+ * @param   k   the key - hashtable claims ownership and will free on removal
+ * @param   v   the value - does not claim ownership
+ * @return      non-zero for successful insertion
+ *
+ * This function will cause the table to expand if the insertion would take
+ * the ratio of entries to table size over the maximum load factor.
+ *
+ * This function does not check for repeated insertions with a duplicate key.
+ * The value returned when using a duplicate key is undefined -- when
+ * the hashtable changes size, the order of retrieval of duplicate key
+ * entries is reversed.
+ * If in doubt, remove before insert.
+ */
+
+int 
+hashtable_insert(struct hashtable *h, void *k, void *v);
+
+#define DEFINE_HASHTABLE_INSERT(fnname, keytype, valuetype) \
+int fnname (struct hashtable *h, keytype *k, valuetype *v) \
+{ \
+    return hashtable_insert(h,k,v); \
+}
+
+/*****************************************************************************
+ * hashtable_search
+   
+ * @name        hashtable_search
+ * @param   h   the hashtable to search
+ * @param   k   the key to search for  - does not claim ownership
+ * @return      the value associated with the key, or NULL if none found
+ */
+
+void *
+hashtable_search(struct hashtable *h, void *k);
+
+#define DEFINE_HASHTABLE_SEARCH(fnname, keytype, valuetype) \
+valuetype * fnname (struct hashtable *h, keytype *k) \
+{ \
+    return (valuetype *) (hashtable_search(h,k)); \
+}
+
+/*****************************************************************************
+ * hashtable_remove
+   
+ * @name        hashtable_remove
+ * @param   h   the hashtable to remove the item from
+ * @param   k   the key to search for  - does not claim ownership
+ * @return      the value associated with the key, or NULL if none found
+ */
+
+void * /* returns value */
+hashtable_remove(struct hashtable *h, void *k);
+
+#define DEFINE_HASHTABLE_REMOVE(fnname, keytype, valuetype) \
+valuetype * fnname (struct hashtable *h, keytype *k) \
+{ \
+    return (valuetype *) (hashtable_remove(h,k)); \
+}
+
+
+/*****************************************************************************
+ * hashtable_count
+   
+ * @name        hashtable_count
+ * @param   h   the hashtable
+ * @return      the number of items stored in the hashtable
+ */
+unsigned int
+hashtable_count(struct hashtable *h);
+
+
+/*****************************************************************************
+ * hashtable_destroy
+   
+ * @name        hashtable_destroy
+ * @param   h   the hashtable
+ * @param       free_values     whether to call 'free' on the remaining values
+ */
+
+void
+hashtable_destroy(struct hashtable *h, int free_values);
+
+#endif /* __HASHTABLE_CWC22_H__ */
+
+/*
+ * Copyright (c) 2002, Christopher Clark
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * * Neither the name of the original author; nor the names of any contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ * 
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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 COPYRIGHT OWNER
+ * OR CONTRIBUTORS 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.
+*/
diff --git a/runtime/hashtable/hashtable_itr.c b/runtime/hashtable/hashtable_itr.c
new file mode 100644
index 00000000..5dced841
--- /dev/null
+++ b/runtime/hashtable/hashtable_itr.c
@@ -0,0 +1,188 @@
+/* Copyright (C) 2002, 2004 Christopher Clark  <firstname.lastname@cl.cam.ac.uk> */
+
+#include "hashtable.h"
+#include "hashtable_private.h"
+#include "hashtable_itr.h"
+#include <stdlib.h> /* defines NULL */
+
+/*****************************************************************************/
+/* hashtable_iterator    - iterator constructor */
+
+struct hashtable_itr *
+hashtable_iterator(struct hashtable *h)
+{
+    unsigned int i, tablelength;
+    struct hashtable_itr *itr = (struct hashtable_itr *)
+        malloc(sizeof(struct hashtable_itr));
+    if (NULL == itr) return NULL;
+    itr->h = h;
+    itr->e = NULL;
+    itr->parent = NULL;
+    tablelength = h->tablelength;
+    itr->index = tablelength;
+    if (0 == h->entrycount) return itr;
+
+    for (i = 0; i < tablelength; i++)
+    {
+        if (NULL != h->table[i])
+        {
+            itr->e = h->table[i];
+            itr->index = i;
+            break;
+        }
+    }
+    return itr;
+}
+
+/*****************************************************************************/
+/* key      - return the key of the (key,value) pair at the current position */
+/* value    - return the value of the (key,value) pair at the current position */
+
+void *
+hashtable_iterator_key(struct hashtable_itr *i)
+{ return i->e->k; }
+
+void *
+hashtable_iterator_value(struct hashtable_itr *i)
+{ return i->e->v; }
+
+/*****************************************************************************/
+/* advance - advance the iterator to the next element
+ *           returns zero if advanced to end of table */
+
+int
+hashtable_iterator_advance(struct hashtable_itr *itr)
+{
+    unsigned int j,tablelength;
+    struct entry **table;
+    struct entry *next;
+    if (NULL == itr->e) return 0; /* stupidity check */
+
+    next = itr->e->next;
+    if (NULL != next)
+    {
+        itr->parent = itr->e;
+        itr->e = next;
+        return -1;
+    }
+    tablelength = itr->h->tablelength;
+    itr->parent = NULL;
+    if (tablelength <= (j = ++(itr->index)))
+    {
+        itr->e = NULL;
+        return 0;
+    }
+    table = itr->h->table;
+    while (NULL == (next = table[j]))
+    {
+        if (++j >= tablelength)
+        {
+            itr->index = tablelength;
+            itr->e = NULL;
+            return 0;
+        }
+    }
+    itr->index = j;
+    itr->e = next;
+    return -1;
+}
+
+/*****************************************************************************/
+/* remove - remove the entry at the current iterator position
+ *          and advance the iterator, if there is a successive
+ *          element.
+ *          If you want the value, read it before you remove:
+ *          beware memory leaks if you don't.
+ *          Returns zero if end of iteration. */
+
+int
+hashtable_iterator_remove(struct hashtable_itr *itr)
+{
+    struct entry *remember_e, *remember_parent;
+    int ret;
+
+    /* Do the removal */
+    if (NULL == (itr->parent))
+    {
+        /* element is head of a chain */
+        itr->h->table[itr->index] = itr->e->next;
+    } else {
+        /* element is mid-chain */
+        itr->parent->next = itr->e->next;
+    }
+    /* itr->e is now outside the hashtable */
+    remember_e = itr->e;
+    itr->h->entrycount--;
+    freekey(remember_e->k);
+
+    /* Advance the iterator, correcting the parent */
+    remember_parent = itr->parent;
+    ret = hashtable_iterator_advance(itr);
+    if (itr->parent == remember_e) { itr->parent = remember_parent; }
+    free(remember_e);
+    return ret;
+}
+
+/*****************************************************************************/
+int /* returns zero if not found */
+hashtable_iterator_search(struct hashtable_itr *itr,
+                          struct hashtable *h, void *k)
+{
+    struct entry *e, *parent;
+    unsigned int hashvalue, index;
+
+    hashvalue = hash(h,k);
+    index = indexFor(h->tablelength,hashvalue);
+
+    e = h->table[index];
+    parent = NULL;
+    while (NULL != e)
+    {
+        /* Check hash value to short circuit heavier comparison */
+        if ((hashvalue == e->h) && (h->eqfn(k, e->k)))
+        {
+            itr->index = index;
+            itr->e = e;
+            itr->parent = parent;
+            itr->h = h;
+            return -1;
+        }
+        parent = e;
+        e = e->next;
+    }
+    return 0;
+}
+
+
+/*
+ * Copyright (c) 2002, 2004, Christopher Clark
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * * Neither the name of the original author; nor the names of any contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ * 
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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 COPYRIGHT OWNER
+ * OR CONTRIBUTORS 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.
+*/
diff --git a/runtime/hashtable/hashtable_itr.h b/runtime/hashtable/hashtable_itr.h
new file mode 100644
index 00000000..eea699a7
--- /dev/null
+++ b/runtime/hashtable/hashtable_itr.h
@@ -0,0 +1,112 @@
+/* Copyright (C) 2002, 2004 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */
+
+#ifndef __HASHTABLE_ITR_CWC22__
+#define __HASHTABLE_ITR_CWC22__
+#include "hashtable.h"
+#include "hashtable_private.h" /* needed to enable inlining */
+
+/*****************************************************************************/
+/* This struct is only concrete here to allow the inlining of two of the
+ * accessor functions. */
+struct hashtable_itr
+{
+    struct hashtable *h;
+    struct entry *e;
+    struct entry *parent;
+    unsigned int index;
+};
+
+
+/*****************************************************************************/
+/* hashtable_iterator
+ */
+
+struct hashtable_itr *
+hashtable_iterator(struct hashtable *h);
+
+/*****************************************************************************/
+/* hashtable_iterator_key
+ * - return the value of the (key,value) pair at the current position */
+
+extern inline void *
+hashtable_iterator_key(struct hashtable_itr *i)
+{
+    return i->e->k;
+}
+
+/*****************************************************************************/
+/* value - return the value of the (key,value) pair at the current position */
+
+extern inline void *
+hashtable_iterator_value(struct hashtable_itr *i)
+{
+    return i->e->v;
+}
+
+/*****************************************************************************/
+/* advance - advance the iterator to the next element
+ *           returns zero if advanced to end of table */
+
+int
+hashtable_iterator_advance(struct hashtable_itr *itr);
+
+/*****************************************************************************/
+/* remove - remove current element and advance the iterator to the next element
+ *          NB: if you need the value to free it, read it before
+ *          removing. ie: beware memory leaks!
+ *          returns zero if advanced to end of table */
+
+int
+hashtable_iterator_remove(struct hashtable_itr *itr);
+
+/*****************************************************************************/
+/* search - overwrite the supplied iterator, to point to the entry
+ *          matching the supplied key.
+            h points to the hashtable to be searched.
+ *          returns zero if not found. */
+int
+hashtable_iterator_search(struct hashtable_itr *itr,
+                          struct hashtable *h, void *k);
+
+#define DEFINE_HASHTABLE_ITERATOR_SEARCH(fnname, keytype) \
+int fnname (struct hashtable_itr *i, struct hashtable *h, keytype *k) \
+{ \
+    return (hashtable_iterator_search(i,h,k)); \
+}
+
+
+
+#endif /* __HASHTABLE_ITR_CWC22__*/
+
+/*
+ * Copyright (c) 2002, 2004, Christopher Clark
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * * Neither the name of the original author; nor the names of any contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ * 
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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 COPYRIGHT OWNER
+ * OR CONTRIBUTORS 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.
+*/
diff --git a/runtime/hashtable/hashtable_private.h b/runtime/hashtable/hashtable_private.h
new file mode 100644
index 00000000..3e95f600
--- /dev/null
+++ b/runtime/hashtable/hashtable_private.h
@@ -0,0 +1,85 @@
+/* Copyright (C) 2002, 2004 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */
+
+#ifndef __HASHTABLE_PRIVATE_CWC22_H__
+#define __HASHTABLE_PRIVATE_CWC22_H__
+
+#include "hashtable.h"
+
+/*****************************************************************************/
+struct entry
+{
+    void *k, *v;
+    unsigned int h;
+    struct entry *next;
+};
+
+struct hashtable {
+    unsigned int tablelength;
+    struct entry **table;
+    unsigned int entrycount;
+    unsigned int loadlimit;
+    unsigned int primeindex;
+    unsigned int (*hashfn) (void *k);
+    int (*eqfn) (void *k1, void *k2);
+};
+
+/*****************************************************************************/
+unsigned int
+hash(struct hashtable *h, void *k);
+
+/*****************************************************************************/
+/* indexFor */
+static inline unsigned int
+indexFor(unsigned int tablelength, unsigned int hashvalue) {
+    return (hashvalue % tablelength);
+};
+
+/* Only works if tablelength == 2^N */
+/*static inline unsigned int
+indexFor(unsigned int tablelength, unsigned int hashvalue)
+{
+    return (hashvalue & (tablelength - 1u));
+}
+*/
+
+/*****************************************************************************/
+#define freekey(X) free(X)
+/*define freekey(X) ; */
+
+
+/*****************************************************************************/
+
+#endif /* __HASHTABLE_PRIVATE_CWC22_H__*/
+
+/*
+ * Copyright (c) 2002, Christopher Clark
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * * Neither the name of the original author; nor the names of any contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ * 
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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 COPYRIGHT OWNER
+ * OR CONTRIBUTORS 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.
+*/
diff --git a/runtime/hashtable/hashtable_utility.c b/runtime/hashtable/hashtable_utility.c
new file mode 100644
index 00000000..c3176709
--- /dev/null
+++ b/runtime/hashtable/hashtable_utility.c
@@ -0,0 +1,71 @@
+/* Copyright (C) 2002 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */
+
+#include "hashtable.h"
+#include "hashtable_private.h"
+#include "hashtable_utility.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+/*****************************************************************************/
+/* hashtable_change
+ *
+ * function to change the value associated with a key, where there already
+ * exists a value bound to the key in the hashtable.
+ * Source due to Holger Schemel.
+ * 
+ *  */
+int
+hashtable_change(struct hashtable *h, void *k, void *v)
+{
+    struct entry *e;
+    unsigned int hashvalue, index;
+    hashvalue = hash(h,k);
+    index = indexFor(h->tablelength,hashvalue);
+    e = h->table[index];
+    while (NULL != e)
+    {
+        /* Check hash value to short circuit heavier comparison */
+        if ((hashvalue == e->h) && (h->eqfn(k, e->k)))
+        {
+            free(e->v);
+            e->v = v;
+            return -1;
+        }
+        e = e->next;
+    }
+    return 0;
+}
+
+/*
+ * Copyright (c) 2002, Christopher Clark
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * * Neither the name of the original author; nor the names of any contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ * 
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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 COPYRIGHT OWNER
+ * OR CONTRIBUTORS 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.
+*/
diff --git a/runtime/hashtable/hashtable_utility.h b/runtime/hashtable/hashtable_utility.h
new file mode 100644
index 00000000..56a0ffd1
--- /dev/null
+++ b/runtime/hashtable/hashtable_utility.h
@@ -0,0 +1,55 @@
+/* Copyright (C) 2002 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */
+
+#ifndef __HASHTABLE_CWC22_UTILITY_H__
+#define __HASHTABLE_CWC22_UTILITY_H__
+
+/*****************************************************************************
+ * hashtable_change
+ *
+ * function to change the value associated with a key, where there already
+ * exists a value bound to the key in the hashtable.
+ * Source due to Holger Schemel.
+ *
+ * @name        hashtable_change
+ * @param   h   the hashtable
+ * @param       key
+ * @param       value
+ *
+ */
+int
+hashtable_change(struct hashtable *h, void *k, void *v);
+
+#endif /* __HASHTABLE_CWC22_H__ */
+
+/*
+ * Copyright (c) 2002, Christopher Clark
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * * Neither the name of the original author; nor the names of any contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ * 
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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 COPYRIGHT OWNER
+ * OR CONTRIBUTORS 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.
+*/
diff --git a/runtime/hashtable/tester.c b/runtime/hashtable/tester.c
new file mode 100644
index 00000000..4678ffa8
--- /dev/null
+++ b/runtime/hashtable/tester.c
@@ -0,0 +1,270 @@
+/* Copyright (C) 2002, 2004 Christopher Clark <firstname.lastname@cl.cam.ac.uk> */
+
+#include "hashtable.h"
+#include "hashtable_itr.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h> /* for memcmp */
+
+static const int ITEM_COUNT = 4000;
+
+typedef unsigned int uint32_t;
+typedef unsigned short uint16_t;
+
+/*****************************************************************************/
+struct key
+{
+    uint32_t one_ip; uint32_t two_ip; uint16_t one_port; uint16_t two_port;
+};
+
+struct value
+{
+    char *id;
+};
+
+DEFINE_HASHTABLE_INSERT(insert_some, struct key, struct value);
+DEFINE_HASHTABLE_SEARCH(search_some, struct key, struct value);
+DEFINE_HASHTABLE_REMOVE(remove_some, struct key, struct value);
+DEFINE_HASHTABLE_ITERATOR_SEARCH(search_itr_some, struct key);
+
+
+/*****************************************************************************/
+static unsigned int
+hashfromkey(void *ky)
+{
+    struct key *k = (struct key *)ky;
+    return (((k->one_ip << 17) | (k->one_ip >> 15)) ^ k->two_ip) +
+            (k->one_port * 17) + (k->two_port * 13 * 29);
+}
+
+static int
+equalkeys(void *k1, void *k2)
+{
+    return (0 == memcmp(k1,k2,sizeof(struct key)));
+}
+
+/*****************************************************************************/
+int
+main(int argc, char **argv)
+{
+    struct key *k, *kk;
+    struct value *v, *found;
+    struct hashtable *h;
+    struct hashtable_itr *itr;
+    int i;
+
+    h = create_hashtable(16, hashfromkey, equalkeys);
+    if (NULL == h) exit(-1); /*oom*/
+
+
+/*****************************************************************************/
+/* Insertion */
+    for (i = 0; i < ITEM_COUNT; i++)
+    {
+        k = (struct key *)malloc(sizeof(struct key));
+        if (NULL == k) {
+            printf("ran out of memory allocating a key\n");
+            return 1;
+        }
+        k->one_ip = 0xcfccee40 + i;
+        k->two_ip = 0xcf0cee67 - (5 * i);
+        k->one_port = 22 + (7 * i);
+        k->two_port = 5522 - (3 * i);
+        
+        v = (struct value *)malloc(sizeof(struct value));
+        v->id = "a value";
+        
+        if (!insert_some(h,k,v)) exit(-1); /*oom*/
+    }
+    printf("After insertion, hashtable contains %u items.\n",
+            hashtable_count(h));
+
+/*****************************************************************************/
+/* Hashtable search */
+    k = (struct key *)malloc(sizeof(struct key));
+    if (NULL == k) {
+        printf("ran out of memory allocating a key\n");
+        return 1;
+    }
+    
+    for (i = 0; i < ITEM_COUNT; i++)
+    {
+        k->one_ip = 0xcfccee40 + i;
+        k->two_ip = 0xcf0cee67 - (5 * i);
+        k->one_port = 22 + (7 * i);
+        k->two_port = 5522 - (3 * i);
+        
+        if (NULL == (found = search_some(h,k))) {
+            printf("BUG: key not found\n");
+        }
+    }
+
+/*****************************************************************************/
+/* Hashtable iteration */
+    /* Iterator constructor only returns a valid iterator if
+     * the hashtable is not empty */
+    itr = hashtable_iterator(h);
+    i = 0;
+    if (hashtable_count(h) > 0)
+    {
+        do {
+            kk = hashtable_iterator_key(itr);
+            v = hashtable_iterator_value(itr);
+            /* here (kk,v) are a valid (key, value) pair */
+            /* We could call 'hashtable_remove(h,kk)' - and this operation
+             * 'free's kk. However, the iterator is then broken.
+             * This is why hashtable_iterator_remove exists - see below.
+             */
+            i++;
+
+        } while (hashtable_iterator_advance(itr));
+    }
+    printf("Iterated through %u entries.\n", i);
+
+/*****************************************************************************/
+/* Hashtable iterator search */
+
+    /* Try the search some method */
+    for (i = 0; i < ITEM_COUNT; i++)
+    {
+        k->one_ip = 0xcfccee40 + i;
+        k->two_ip = 0xcf0cee67 - (5 * i);
+        k->one_port = 22 + (7 * i);
+        k->two_port = 5522 - (3 * i);
+        
+        if (0 == search_itr_some(itr,h,k)) {
+            printf("BUG: key not found searching with iterator");
+        }
+    }
+
+/*****************************************************************************/
+/* Hashtable removal */
+
+    for (i = 0; i < ITEM_COUNT; i++)
+    {
+        k->one_ip = 0xcfccee40 + i;
+        k->two_ip = 0xcf0cee67 - (5 * i);
+        k->one_port = 22 + (7 * i);
+        k->two_port = 5522 - (3 * i);
+        
+        if (NULL == (found = remove_some(h,k))) {
+            printf("BUG: key not found for removal\n");
+        }
+    }
+    printf("After removal, hashtable contains %u items.\n",
+            hashtable_count(h));
+
+/*****************************************************************************/
+/* Hashtable destroy and create */
+
+    hashtable_destroy(h, 1);
+    h = NULL;
+    free(k);
+
+    h = create_hashtable(160, hashfromkey, equalkeys);
+    if (NULL == h) {
+        printf("out of memory allocating second hashtable\n");
+        return 1;
+    }
+
+/*****************************************************************************/
+/* Hashtable insertion */
+
+    for (i = 0; i < ITEM_COUNT; i++)
+    {
+        k = (struct key *)malloc(sizeof(struct key));
+        k->one_ip = 0xcfccee40 + i;
+        k->two_ip = 0xcf0cee67 - (5 * i);
+        k->one_port = 22 + (7 * i);
+        k->two_port = 5522 - (3 * i);
+        
+        v = (struct value *)malloc(sizeof(struct value));
+        v->id = "a value";
+        
+        if (!insert_some(h,k,v))
+        {
+            printf("out of memory inserting into second hashtable\n");
+            return 1;
+        }
+    }
+    printf("After insertion, hashtable contains %u items.\n",
+            hashtable_count(h));
+
+/*****************************************************************************/
+/* Hashtable iterator search and iterator remove */
+
+    k = (struct key *)malloc(sizeof(struct key));
+    if (NULL == k) {
+        printf("ran out of memory allocating a key\n");
+        return 1;
+    }
+    
+    for (i = ITEM_COUNT - 1; i >= 0; i = i - 7)
+    {
+        k->one_ip = 0xcfccee40 + i;
+        k->two_ip = 0xcf0cee67 - (5 * i);
+        k->one_port = 22 + (7 * i);
+        k->two_port = 5522 - (3 * i);
+        
+        if (0 == search_itr_some(itr, h, k)) {
+            printf("BUG: key %u not found for search preremoval using iterator\n", i);
+            return 1;
+        }
+        if (0 == hashtable_iterator_remove(itr)) {
+            printf("BUG: key not found for removal using iterator\n");
+            return 1;
+        }
+    }
+    free(itr);
+
+/*****************************************************************************/
+/* Hashtable iterator remove and advance */
+
+    for (itr = hashtable_iterator(h);
+         hashtable_iterator_remove(itr) != 0; ) {
+        ;
+    }
+    free(itr);
+    printf("After removal, hashtable contains %u items.\n",
+            hashtable_count(h));
+
+/*****************************************************************************/
+/* Hashtable destroy */
+
+    hashtable_destroy(h, 1);
+    free(k);
+    return 0;
+}
+
+/*
+ * Copyright (c) 2002, 2004, Christopher Clark
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 
+ * * Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 
+ * * Neither the name of the original author; nor the names of any contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ * 
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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 COPYRIGHT OWNER
+ * OR CONTRIBUTORS 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.
+*/