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sys: remove lib/hashtable.c

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Quoting myself:

> The code of sys/lib/hashtable.c is very badly adapted for embedded
> systems. The used primes are huge, and the limit is entirely
> unrealistic. Why do we ship this file?

In #1564 we came to the conclusion that we don't need this code.

Closes #1564.
This commit is contained in:
René Kijewski 2014-08-13 21:21:39 +02:00
parent a9ded6337e
commit d1d8fb2b68
3 changed files with 0 additions and 612 deletions
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199
sys/include/hashtable.h
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@ -1,199 +0,0 @@
/* 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(uint32_t 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.
*/

85
sys/include/hashtable_private.h
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/* 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.
*/

328
sys/lib/hashtable.c
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/*
* 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.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <math.h>
#if (defined(__MACH__) || defined(__FreeBSD__))
#include <stdlib.h>
#else
#include "malloc.h"
#endif
#include "hashtable.h"
#include "hashtable_private.h"
/*
Credit for primes table: Aaron Krowne
http://br.endernet.org/~akrowne/
http://planetmath.org/encyclopedia/GoodHashTablePrimes.html
*/
static const uint32_t 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(uint32_t 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 > (1UL << 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); /*oom*/
return NULL;
}
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 */
uint32_t 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, index;
/* 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;
index = indexFor(newsize, e->h);
e->next = newtable[index];
newtable[index] = 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) {
index = indexFor(newsize, e->h);
if (index == i) {
pE = &(e->next);
}
else {
*pE = e->next;
e->next = newtable[index];
newtable[index] = 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 index;
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); /*oom*/
return 0;
}
e->h = hash(h, k);
index = indexFor(h->tablelength, e->h);
e->k = k;
e->v = v;
e->next = h->table[index];
h->table[index] = e;
return -1;
}
/*****************************************************************************/
void * /* returns value associated with key */
hashtable_search(struct hashtable *h, void *k)
{
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))) {
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, index;
hashvalue = hash(h, k);
index = indexFor(h->tablelength, hash(h, k));
pE = &(h->table[index]);
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);
}