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Add a hash table for holding packages

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Signed-off-by: Allan McRae <allan@archlinux.org>
This commit is contained in:
Allan McRae 2011-01-07 00:32:17 +10:00
parent f892775366
commit e17b0446bd
4 changed files with 352 additions and 0 deletions
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1
lib/libalpm/Makefile.am
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@ -40,6 +40,7 @@ libalpm_la_SOURCES = \
handle.h handle.c \
log.h log.c \
package.h package.c \
pkghash.h pkghash.c \
remove.h remove.c \
sync.h sync.c \
trans.h trans.c \

1
lib/libalpm/alpm.h
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@ -52,6 +52,7 @@ typedef struct __pmdepend_t pmdepend_t;
typedef struct __pmdepmissing_t pmdepmissing_t;
typedef struct __pmconflict_t pmconflict_t;
typedef struct __pmfileconflict_t pmfileconflict_t;
typedef struct __pmpkghash_t pmpkghash_t;
/*
* Library

292
lib/libalpm/pkghash.c Normal file
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@ -0,0 +1,292 @@
/*
* pkghash.c
*
* Copyright (c) 2011 Pacman Development Team <pacman-dev@archlinux.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "pkghash.h"
#include "util.h"
#include "log.h"
/* List of primes for possible sizes of hash tables.
*
* The maximum table size is the last prime under 1,000,000. That is
* more than an order of magnitude greater than the number of packages
* in any Linux distribution.
*/
static const size_t prime_list[] =
{
11ul, 13ul, 17ul, 19ul, 23ul, 29ul, 31ul, 37ul, 41ul, 43ul, 47ul,
53ul, 59ul, 61ul, 67ul, 71ul, 73ul, 79ul, 83ul, 89ul, 97ul, 103ul,
109ul, 113ul, 127ul, 137ul, 139ul, 149ul, 157ul, 167ul, 179ul, 193ul,
199ul, 211ul, 227ul, 241ul, 257ul, 277ul, 293ul, 313ul, 337ul, 359ul,
383ul, 409ul, 439ul, 467ul, 503ul, 541ul, 577ul, 619ul, 661ul, 709ul,
761ul, 823ul, 887ul, 953ul, 1031ul, 1109ul, 1193ul, 1289ul, 1381ul,
1493ul, 1613ul, 1741ul, 1879ul, 2029ul, 2179ul, 2357ul, 2549ul,
2753ul, 2971ul, 3209ul, 3469ul, 3739ul, 4027ul, 4349ul, 4703ul,
5087ul, 5503ul, 5953ul, 6427ul, 6949ul, 7517ul, 8123ul, 8783ul,
9497ul, 10273ul, 11113ul, 12011ul, 12983ul, 14033ul, 15173ul,
16411ul, 17749ul, 19183ul, 20753ul, 22447ul, 24281ul, 26267ul,
28411ul, 30727ul, 33223ul, 35933ul, 38873ul, 42043ul, 45481ul,
49201ul, 53201ul, 57557ul, 62233ul, 67307ul, 72817ul, 78779ul,
85229ul, 92203ul, 99733ul, 107897ul, 116731ul, 126271ul, 136607ul,
147793ul, 159871ul, 172933ul, 187091ul, 202409ul, 218971ul, 236897ul,
256279ul, 277261ul, 299951ul, 324503ul, 351061ul, 379787ul, 410857ul,
444487ul, 480881ul, 520241ul, 562841ul, 608903ul, 658753ul, 712697ul,
771049ul, 834181ul, 902483ul, 976369ul
};
/* Allocate a hash table with at least "size" buckets */
pmpkghash_t *_alpm_pkghash_create(size_t size)
{
pmpkghash_t *hash = NULL;
size_t i, loopsize;
MALLOC(hash, sizeof(pmpkghash_t), RET_ERR(PM_ERR_MEMORY, NULL));
hash->list = NULL;
hash->entries = 0;
loopsize = sizeof(prime_list) / sizeof(*prime_list);
for(i = 0; i < loopsize; i++) {
if(prime_list[i] > size) {
hash->buckets = prime_list[i];
break;
}
}
CALLOC(hash->hash_table, hash->buckets, sizeof(alpm_list_t*), \
free(hash); RET_ERR(PM_ERR_MEMORY, NULL));
return(hash);
}
/* Expand the hash table size to the next increment and rebin the entries */
static pmpkghash_t *rehash(pmpkghash_t *oldhash)
{
//pmpkghash_t *newhash;
/* TODO - calculate size of newhash */
/* Hash tables will need resized in two cases:
* - adding packages to the local database
* - poor estimation of the number of packages in sync database
*
* For small hash tables sizes (<500) the increase in size is by a
* minimum of a factor of 2 for optimal rehash efficiency. For
* larger database sizes, this increase is reduced to avoid excess
* memory allocation as both scenarios requiring a rehash should not
* require a table size increase that large. */
//newhash = _alpm_pkghash_create(oldhash->buckets);
/* TODO - rebin entries */
//_alpm_pkghash_free(oldhash);
//return newhash;
printf("rehash needed!!!\n");
return(oldhash);
}
pmpkghash_t *_alpm_pkghash_add(pmpkghash_t *hash, pmpkg_t *pkg)
{
alpm_list_t *ptr;
size_t position;
if(pkg == NULL || hash == NULL) {
return(hash);
}
if((hash->entries + 1) / MAX_HASH_LOAD > hash->buckets) {
hash = rehash(hash);
}
position = pkg->name_hash % hash->buckets;
/* collision resolution using open addressing with linear probing */
while((ptr = hash->hash_table[position]) != NULL) {
position = (position + 1) % hash->buckets;
}
ptr = calloc(1, sizeof(alpm_list_t));
if(ptr == NULL) {
return(hash);
}
ptr->data = pkg;
ptr->next = NULL;
ptr->prev = ptr;
hash->hash_table[position] = ptr;
hash->list = alpm_list_join(hash->list, ptr);
hash->entries += 1;
return(hash);
}
pmpkghash_t *_alpm_pkghash_add_sorted(pmpkghash_t *hash, pmpkg_t *pkg)
{
if(!hash) {
return(_alpm_pkghash_add(hash, pkg));
}
alpm_list_t *ptr;
size_t position;
if((hash->entries + 1) / MAX_HASH_LOAD > hash->buckets) {
hash = rehash(hash);
}
position = pkg->name_hash % hash->buckets;
/* collision resolution using open addressing with linear probing */
while((ptr = hash->hash_table[position]) != NULL) {
position = (position + 1) % hash->buckets;
}
ptr = calloc(1, sizeof(alpm_list_t));
if(ptr == NULL) {
return(hash);
}
ptr->data = pkg;
ptr->next = NULL;
ptr->prev = ptr;
hash->hash_table[position] = ptr;
hash->list = alpm_list_mmerge(hash->list, ptr, _alpm_pkg_cmp);
hash->entries += 1;
return(hash);
}
/**
* @brief Remove a package from a pkghash.
*
* @param hash the hash to remove the package from
* @param pkg the package we are removing
* @param data output parameter containing the removed item
*
* @return the resultant hash
*/
pmpkghash_t *_alpm_pkghash_remove(pmpkghash_t *hash, pmpkg_t *pkg, pmpkg_t *data)
{
alpm_list_t *i;
size_t position;
if(pkg == NULL || hash == NULL) {
return(hash);
}
position = pkg->name_hash % hash->buckets;
while((i = hash->hash_table[position]) != NULL) {
pmpkg_t *info = i->data;
if(info->name_hash == pkg->name_hash &&
strcmp(info->name, pkg->name) == 0) {
#if 0 /* Actually removing items is not a good idea with linear probing... */
/* remove from list */
/* TODO - refactor with alpm_list_remove */
if(i == hash->list) {
/* Special case: removing the head node which has a back reference to
* the tail node */
hash->list = i->next;
if(hash->list) {
hash->list->prev = i->prev;
}
i->prev = NULL;
} else if(i == hash->list->prev) {
/* Special case: removing the tail node, so we need to fix the back
* reference on the head node. We also know tail != head. */
if(i->prev) {
/* i->next should always be null */
i->prev->next = i->next;
hash->list->prev = i->prev;
i->prev = NULL;
}
} else {
/* Normal case, non-head and non-tail node */
if(i->next) {
i->next->prev = i->prev;
}
if(i->prev) {
i->prev->next = i->next;
}
}
/* remove from hash */
data = info;
info = NULL;
free(i);
i = NULL;
hash->entries -= 1;
#endif
/* fake removal - pkgname can not be blank so 0 hash is impossible */
info->name_hash = 0;
return(hash);
}
position = (position + 1) % hash->buckets;
}
return(hash);
}
void _alpm_pkghash_free(pmpkghash_t *hash)
{
size_t i;
if(hash != NULL) {
for(i = 0; i < hash->buckets; i++) {
free(hash->hash_table[i]);
}
free(hash->hash_table);
}
free(hash);
}
pmpkg_t *_alpm_pkghash_find(pmpkghash_t *hash, const char *name)
{
alpm_list_t *lp;
unsigned long name_hash;
size_t position;
ALPM_LOG_FUNC;
if(name == NULL || hash == NULL) {
return(NULL);
}
name_hash = _alpm_hash_sdbm(name);
position = name_hash % hash->buckets;
while((lp = hash->hash_table[position]) != NULL) {
pmpkg_t *info = lp->data;
if(info->name_hash == name_hash && strcmp(info->name, name) == 0) {
return(info);
}
position = (position + 1) % hash->buckets;
}
return(NULL);
}

58
lib/libalpm/pkghash.h Normal file
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@ -0,0 +1,58 @@
/*
* pkghash.h
*
* Copyright (c) 2011 Pacman Development Team <pacman-dev@archlinux.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef _ALPM_PKGHASH_H
#define _ALPM_PKGHASH_H
#include <stdlib.h>
#include "alpm.h"
#include "alpm_list.h"
/**
* @brief A hash table for holding pmpkg_t objects.
*
* A combination of a hash table and a list, allowing for fast look-up
* by package name but also iteration over the packages.
*/
struct __pmpkghash_t {
/** data held by the hash table */
alpm_list_t **hash_table;
/** number of buckets in hash table */
size_t buckets;
/** number of entries in hash table */
size_t entries;
/** head node of the hash table data in normal list format */
alpm_list_t *list;
};
pmpkghash_t *_alpm_pkghash_create(size_t size);
pmpkghash_t *_alpm_pkghash_add(pmpkghash_t *hash, pmpkg_t *pkg);
pmpkghash_t *_alpm_pkghash_add_sorted(pmpkghash_t *hash, pmpkg_t *pkg);
pmpkghash_t *_alpm_pkghash_remove(pmpkghash_t *hash, pmpkg_t *pkg, pmpkg_t *data);
void _alpm_pkghash_free(pmpkghash_t *hash);
pmpkg_t *_alpm_pkghash_find(pmpkghash_t *hash, const char *name);
#define MAX_HASH_LOAD 0.7
#endif /* _ALPM_PKGHASH_H */