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systemd/src/hashmap.c
Lennart Poettering 8fe914ec81 device: do not merge devices 
Don't try to merge devices that have been created via dependencies when
they appear in the system and can be recognized as the same.  Instead,
simply continue to maintain them independently of each other, however
with the same state cycle. Why? Because otherwise we'd have a hard time
to seperate the dependencies after the devices are unplugged again and
we hence cannot be sure anymore that next time the device is plugged in
it will carry the same names.

Example: if one depndency refers to dev-sda.device and another one to
dev-by-id-xxxyyy.device we only learn at time of plug in of the device
that it is actually the same device that was ment. In the moment the
device is unplugged again we won't know anymore their relation to each
other and the next time the harddisk is plugged it might even appear as
dev-by-id-xxxyyy.device and dev-sdb.service. To ensure the dependencies
continue to have the meaning they were intended to have let's hence keep
the .device objects seperate all the time, even when they are plugged
in.

This patch also introduces a new Following= property which points from
the various .device units of a specific device to the main .device unit
for it. This can be used by the client side to figure out the relation
of the .device units to each other and even filter units from display.
2010-07-20 20:33:24 +02:00

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/*-*- Mode: C; c-basic-offset: 8 -*-*/
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd 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.
systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include "util.h"
#include "hashmap.h"
#include "macro.h"
#define NBUCKETS 127
struct hashmap_entry {
const void *key;
void *value;
struct hashmap_entry *bucket_next, *bucket_previous;
struct hashmap_entry *iterate_next, *iterate_previous;
};
struct Hashmap {
hash_func_t hash_func;
compare_func_t compare_func;
struct hashmap_entry *iterate_list_head, *iterate_list_tail;
unsigned n_entries;
};
#define BY_HASH(h) ((struct hashmap_entry**) ((uint8_t*) (h) + ALIGN(sizeof(Hashmap))))
unsigned string_hash_func(const void *p) {
unsigned hash = 0;
const char *c;
for (c = p; *c; c++)
hash = 31 * hash + (unsigned) *c;
return hash;
}
int string_compare_func(const void *a, const void *b) {
return strcmp(a, b);
}
unsigned trivial_hash_func(const void *p) {
return PTR_TO_UINT(p);
}
int trivial_compare_func(const void *a, const void *b) {
return a < b ? -1 : (a > b ? 1 : 0);
}
Hashmap *hashmap_new(hash_func_t hash_func, compare_func_t compare_func) {
Hashmap *h;
if (!(h = malloc0(ALIGN(sizeof(Hashmap)) + NBUCKETS * ALIGN(sizeof(struct hashmap_entry*)))))
return NULL;
h->hash_func = hash_func ? hash_func : trivial_hash_func;
h->compare_func = compare_func ? compare_func : trivial_compare_func;
h->n_entries = 0;
h->iterate_list_head = h->iterate_list_tail = NULL;
return h;
}
int hashmap_ensure_allocated(Hashmap **h, hash_func_t hash_func, compare_func_t compare_func) {
assert(h);
if (*h)
return 0;
if (!(*h = hashmap_new(hash_func, compare_func)))
return -ENOMEM;
return 0;
}
static void link_entry(Hashmap *h, struct hashmap_entry *e, unsigned hash) {
assert(h);
assert(e);
/* Insert into hash table */
e->bucket_next = BY_HASH(h)[hash];
e->bucket_previous = NULL;
if (BY_HASH(h)[hash])
BY_HASH(h)[hash]->bucket_previous = e;
BY_HASH(h)[hash] = e;
/* Insert into iteration list */
e->iterate_previous = h->iterate_list_tail;
e->iterate_next = NULL;
if (h->iterate_list_tail) {
assert(h->iterate_list_head);
h->iterate_list_tail->iterate_next = e;
} else {
assert(!h->iterate_list_head);
h->iterate_list_head = e;
}
h->iterate_list_tail = e;
h->n_entries++;
assert(h->n_entries >= 1);
}
static void unlink_entry(Hashmap *h, struct hashmap_entry *e, unsigned hash) {
assert(h);
assert(e);
/* Remove from iteration list */
if (e->iterate_next)
e->iterate_next->iterate_previous = e->iterate_previous;
else
h->iterate_list_tail = e->iterate_previous;
if (e->iterate_previous)
e->iterate_previous->iterate_next = e->iterate_next;
else
h->iterate_list_head = e->iterate_next;
/* Remove from hash table bucket list */
if (e->bucket_next)
e->bucket_next->bucket_previous = e->bucket_previous;
if (e->bucket_previous)
e->bucket_previous->bucket_next = e->bucket_next;
else
BY_HASH(h)[hash] = e->bucket_next;
assert(h->n_entries >= 1);
h->n_entries--;
}
static void remove_entry(Hashmap *h, struct hashmap_entry *e) {
unsigned hash;
assert(h);
assert(e);
hash = h->hash_func(e->key) % NBUCKETS;
unlink_entry(h, e, hash);
free(e);
}
void hashmap_free(Hashmap*h) {
if (!h)
return;
hashmap_clear(h);
free(h);
}
void hashmap_clear(Hashmap *h) {
if (!h)
return;
while (h->iterate_list_head)
remove_entry(h, h->iterate_list_head);
}
static struct hashmap_entry *hash_scan(Hashmap *h, unsigned hash, const void *key) {
struct hashmap_entry *e;
assert(h);
assert(hash < NBUCKETS);
for (e = BY_HASH(h)[hash]; e; e = e->bucket_next)
if (h->compare_func(e->key, key) == 0)
return e;
return NULL;
}
int hashmap_put(Hashmap *h, const void *key, void *value) {
struct hashmap_entry *e;
unsigned hash;
assert(h);
hash = h->hash_func(key) % NBUCKETS;
if ((e = hash_scan(h, hash, key))) {
if (e->value == value)
return 0;
return -EEXIST;
}
if (!(e = new(struct hashmap_entry, 1)))
return -ENOMEM;
e->key = key;
e->value = value;
link_entry(h, e, hash);
return 1;
}
int hashmap_replace(Hashmap *h, const void *key, void *value) {
struct hashmap_entry *e;
unsigned hash;
assert(h);
hash = h->hash_func(key) % NBUCKETS;
if ((e = hash_scan(h, hash, key))) {
e->key = key;
e->value = value;
return 0;
}
return hashmap_put(h, key, value);
}
void* hashmap_get(Hashmap *h, const void *key) {
unsigned hash;
struct hashmap_entry *e;
if (!h)
return NULL;
hash = h->hash_func(key) % NBUCKETS;
if (!(e = hash_scan(h, hash, key)))
return NULL;
return e->value;
}
void* hashmap_remove(Hashmap *h, const void *key) {
struct hashmap_entry *e;
unsigned hash;
void *data;
if (!h)
return NULL;
hash = h->hash_func(key) % NBUCKETS;
if (!(e = hash_scan(h, hash, key)))
return NULL;
data = e->value;
remove_entry(h, e);
return data;
}
int hashmap_remove_and_put(Hashmap *h, const void *old_key, const void *new_key, void *value) {
struct hashmap_entry *e;
unsigned old_hash, new_hash;
if (!h)
return -ENOENT;
old_hash = h->hash_func(old_key) % NBUCKETS;
if (!(e = hash_scan(h, old_hash, old_key)))
return -ENOENT;
new_hash = h->hash_func(new_key) % NBUCKETS;
if (hash_scan(h, new_hash, new_key))
return -EEXIST;
unlink_entry(h, e, old_hash);
e->key = new_key;
e->value = value;
link_entry(h, e, new_hash);
return 0;
}
int hashmap_remove_and_replace(Hashmap *h, const void *old_key, const void *new_key, void *value) {
struct hashmap_entry *e, *k;
unsigned old_hash, new_hash;
if (!h)
return -ENOENT;
old_hash = h->hash_func(old_key) % NBUCKETS;
if (!(e = hash_scan(h, old_hash, old_key)))
return -ENOENT;
new_hash = h->hash_func(new_key) % NBUCKETS;
if ((k = hash_scan(h, new_hash, new_key)))
if (e != k)
remove_entry(h, k);
unlink_entry(h, e, old_hash);
e->key = new_key;
e->value = value;
link_entry(h, e, new_hash);
return 0;
}
void* hashmap_remove_value(Hashmap *h, const void *key, void *value) {
struct hashmap_entry *e;
unsigned hash;
if (!h)
return NULL;
hash = h->hash_func(key) % NBUCKETS;
if (!(e = hash_scan(h, hash, key)))
return NULL;
if (e->value != value)
return NULL;
remove_entry(h, e);
return value;
}
void *hashmap_iterate(Hashmap *h, Iterator *i, const void **key) {
struct hashmap_entry *e;
assert(i);
if (!h)
goto at_end;
if (*i == ITERATOR_LAST)
goto at_end;
if (*i == ITERATOR_FIRST && !h->iterate_list_head)
goto at_end;
e = *i == ITERATOR_FIRST ? h->iterate_list_head : (struct hashmap_entry*) *i;
if (e->iterate_next)
*i = (Iterator) e->iterate_next;
else
*i = ITERATOR_LAST;
if (key)
*key = e->key;
return e->value;
at_end:
*i = ITERATOR_LAST;
if (key)
*key = NULL;
return NULL;
}
void *hashmap_iterate_backwards(Hashmap *h, Iterator *i, const void **key) {
struct hashmap_entry *e;
assert(i);
if (!h)
goto at_beginning;
if (*i == ITERATOR_FIRST)
goto at_beginning;
if (*i == ITERATOR_LAST && !h->iterate_list_tail)
goto at_beginning;
e = *i == ITERATOR_LAST ? h->iterate_list_tail : (struct hashmap_entry*) *i;
if (e->iterate_previous)
*i = (Iterator) e->iterate_previous;
else
*i = ITERATOR_FIRST;
if (key)
*key = e->key;
return e->value;
at_beginning:
*i = ITERATOR_FIRST;
if (key)
*key = NULL;
return NULL;
}
void *hashmap_iterate_skip(Hashmap *h, const void *key, Iterator *i) {
unsigned hash;
struct hashmap_entry *e;
if (!h)
return NULL;
hash = h->hash_func(key) % NBUCKETS;
if (!(e = hash_scan(h, hash, key)))
return NULL;
*i = (Iterator) e;
return e->value;
}
void* hashmap_first(Hashmap *h) {
if (!h)
return NULL;
if (!h->iterate_list_head)
return NULL;
return h->iterate_list_head->value;
}
void* hashmap_last(Hashmap *h) {
if (!h)
return NULL;
if (!h->iterate_list_tail)
return NULL;
return h->iterate_list_tail->value;
}
void* hashmap_steal_first(Hashmap *h) {
void *data;
if (!h)
return NULL;
if (!h->iterate_list_head)
return NULL;
data = h->iterate_list_head->value;
remove_entry(h, h->iterate_list_head);
return data;
}
unsigned hashmap_size(Hashmap *h) {
if (!h)
return 0;
return h->n_entries;
}
bool hashmap_isempty(Hashmap *h) {
if (!h)
return true;
return h->n_entries == 0;
}
int hashmap_merge(Hashmap *h, Hashmap *other) {
struct hashmap_entry *e;
assert(h);
if (!other)
return 0;
for (e = other->iterate_list_head; e; e = e->iterate_next) {
int r;
if ((r = hashmap_put(h, e->key, e->value)) < 0)
if (r != -EEXIST)
return r;
}
return 0;
}
void hashmap_move(Hashmap *h, Hashmap *other) {
struct hashmap_entry *e, *n;
assert(h);
/* The same as hashmap_merge(), but every new item from other
* is moved to h. This function is guaranteed to succeed. */
if (!other)
return;
for (e = other->iterate_list_head; e; e = n) {
unsigned h_hash, other_hash;
n = e->iterate_next;
h_hash = h->hash_func(e->key) % NBUCKETS;
if (hash_scan(h, h_hash, e->key))
continue;
other_hash = other->hash_func(e->key) % NBUCKETS;
unlink_entry(other, e, other_hash);
link_entry(h, e, h_hash);
}
}
int hashmap_move_one(Hashmap *h, Hashmap *other, const void *key) {
unsigned h_hash, other_hash;
struct hashmap_entry *e;
if (!other)
return 0;
assert(h);
h_hash = h->hash_func(key) % NBUCKETS;
if (hash_scan(h, h_hash, key))
return -EEXIST;
other_hash = other->hash_func(key) % NBUCKETS;
if (!(e = hash_scan(other, other_hash, key)))
return -ENOENT;
unlink_entry(other, e, other_hash);
link_entry(h, e, h_hash);
return 0;
}
Hashmap *hashmap_copy(Hashmap *h) {
Hashmap *copy;
assert(h);
if (!(copy = hashmap_new(h->hash_func, h->compare_func)))
return NULL;
if (hashmap_merge(copy, h) < 0) {
hashmap_free(copy);
return NULL;
}
return copy;
}
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