qdict.c

   1 /*
   2  * QDict data type.
   3  *
   4  * Copyright (C) 2009 Red Hat Inc.
   5  *
   6  * Authors:
   7  *  Luiz Capitulino <lcapitulino@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qint.h"
  14 #include "qdict.h"
  15 #include "qbool.h"
  16 #include "qstring.h"
  17 #include "qobject.h"
  18 #include "qemu-queue.h"
  19 #include "qemu-common.h"
  20
  21 static void qdict_destroy_obj(QObject *obj);
  22
  23 static const QType qdict_type = {
  24     .code = QTYPE_QDICT,
  25     .destroy = qdict_destroy_obj,
  26 };
  27
  28 /**
  29  * qdict_new(): Create a new QDict
  30  *
  31  * Return strong reference.
  32  */
  33 QDict *qdict_new(void)
  34 {
  35     QDict *qdict;
  36
  37     qdict = qemu_mallocz(sizeof(*qdict));
  38     QOBJECT_INIT(qdict, &qdict_type);
  39
  40     return qdict;
  41 }
  42
  43 /**
  44  * qobject_to_qdict(): Convert a QObject into a QDict
  45  */
  46 QDict *qobject_to_qdict(const QObject *obj)
  47 {
  48     if (qobject_type(obj) != QTYPE_QDICT)
  49         return NULL;
  50
  51     return container_of(obj, QDict, base);
  52 }
  53
  54 /**
  55  * tdb_hash(): based on the hash agorithm from gdbm, via tdb
  56  * (from module-init-tools)
  57  */
  58 static unsigned int tdb_hash(const char *name)
  59 {
  60     unsigned value;     /* Used to compute the hash value.  */
  61     unsigned   i;       /* Used to cycle through random values. */
  62
  63     /* Set the initial value from the key size. */
  64     for (value = 0x238F13AF * strlen(name), i=0; name[i]; i++)
  65         value = (value + (((const unsigned char *)name)[i] << (i*5 % 24)));
  66
  67     return (1103515243 * value + 12345);
  68 }
  69
  70 /**
  71  * alloc_entry(): allocate a new QDictEntry
  72  */
  73 static QDictEntry *alloc_entry(const char *key, QObject *value)
  74 {
  75     QDictEntry *entry;
  76
  77     entry = qemu_mallocz(sizeof(*entry));
  78     entry->key = qemu_strdup(key);
  79     entry->value = value;
  80
  81     return entry;
  82 }
  83
  84 /**
  85  * qdict_find(): List lookup function
  86  */
  87 static QDictEntry *qdict_find(const QDict *qdict,
  88                               const char *key, unsigned int hash)
  89 {
  90     QDictEntry *entry;
  91
  92     QLIST_FOREACH(entry, &qdict->table[hash], next)
  93         if (!strcmp(entry->key, key))
  94             return entry;
  95
  96     return NULL;
  97 }
  98
  99 /**
 100  * qdict_put_obj(): Put a new QObject into the dictionary
 101  *
 102  * Insert the pair 'key:value' into 'qdict', if 'key' already exists
 103  * its 'value' will be replaced.
 104  *
 105  * This is done by freeing the reference to the stored QObject and
 106  * storing the new one in the same entry.
 107  *
 108  * NOTE: ownership of 'value' is transferred to the QDict
 109  */
 110 void qdict_put_obj(QDict *qdict, const char *key, QObject *value)
 111 {
 112     unsigned int hash;
 113     QDictEntry *entry;
 114
 115     hash = tdb_hash(key) % QDICT_HASH_SIZE;
 116     entry = qdict_find(qdict, key, hash);
 117     if (entry) {
 118         /* replace key's value */
 119         qobject_decref(entry->value);
 120         entry->value = value;
 121     } else {
 122         /* allocate a new entry */
 123         entry = alloc_entry(key, value);
 124         QLIST_INSERT_HEAD(&qdict->table[hash], entry, next);
 125     }
 126
 127     qdict->size++;
 128 }
 129
 130 /**
 131  * qdict_get(): Lookup for a given 'key'
 132  *
 133  * Return a weak reference to the QObject associated with 'key' if
 134  * 'key' is present in the dictionary, NULL otherwise.
 135  */
 136 QObject *qdict_get(const QDict *qdict, const char *key)
 137 {
 138     QDictEntry *entry;
 139
 140     entry = qdict_find(qdict, key, tdb_hash(key) % QDICT_HASH_SIZE);
 141     return (entry == NULL ? NULL : entry->value);
 142 }
 143
 144 /**
 145  * qdict_haskey(): Check if 'key' exists
 146  *
 147  * Return 1 if 'key' exists in the dict, 0 otherwise
 148  */
 149 int qdict_haskey(const QDict *qdict, const char *key)
 150 {
 151     unsigned int hash = tdb_hash(key) % QDICT_HASH_SIZE;
 152     return (qdict_find(qdict, key, hash) == NULL ? 0 : 1);
 153 }
 154
 155 /**
 156  * qdict_size(): Return the size of the dictionary
 157  */
 158 size_t qdict_size(const QDict *qdict)
 159 {
 160     return qdict->size;
 161 }
 162
 163 /**
 164  * qdict_get_obj(): Get a QObject of a specific type
 165  */
 166 static QObject *qdict_get_obj(const QDict *qdict, const char *key,
 167                               qtype_code type)
 168 {
 169     QObject *obj;
 170
 171     obj = qdict_get(qdict, key);
 172     assert(obj != NULL);
 173     assert(qobject_type(obj) == type);
 174
 175     return obj;
 176 }
 177
 178 /**
 179  * qdict_get_int(): Get an integer mapped by 'key'
 180  *
 181  * This function assumes that 'key' exists and it stores a
 182  * QInt object.
 183  *
 184  * Return integer mapped by 'key'.
 185  */
 186 int64_t qdict_get_int(const QDict *qdict, const char *key)
 187 {
 188     QObject *obj = qdict_get_obj(qdict, key, QTYPE_QINT);
 189     return qint_get_int(qobject_to_qint(obj));
 190 }
 191
 192 /**
 193  * qdict_get_bool(): Get a bool mapped by 'key'
 194  *
 195  * This function assumes that 'key' exists and it stores a
 196  * QBool object.
 197  *
 198  * Return bool mapped by 'key'.
 199  */
 200 int qdict_get_bool(const QDict *qdict, const char *key)
 201 {
 202     QObject *obj = qdict_get_obj(qdict, key, QTYPE_QBOOL);
 203     return qbool_get_int(qobject_to_qbool(obj));
 204 }
 205
 206 /**
 207  * qdict_get_str(): Get a pointer to the stored string mapped
 208  * by 'key'
 209  *
 210  * This function assumes that 'key' exists and it stores a
 211  * QString object.
 212  *
 213  * Return pointer to the string mapped by 'key'.
 214  */
 215 const char *qdict_get_str(const QDict *qdict, const char *key)
 216 {
 217     QObject *obj = qdict_get_obj(qdict, key, QTYPE_QSTRING);
 218     return qstring_get_str(qobject_to_qstring(obj));
 219 }
 220
 221 /**
 222  * qdict_get_try_int(): Try to get integer mapped by 'key'
 223  *
 224  * Return integer mapped by 'key', if it is not present in
 225  * the dictionary or if the stored object is not of QInt type
 226  * 'err_value' will be returned.
 227  */
 228 int64_t qdict_get_try_int(const QDict *qdict, const char *key,
 229                           int64_t err_value)
 230 {
 231     QObject *obj;
 232
 233     obj = qdict_get(qdict, key);
 234     if (!obj || qobject_type(obj) != QTYPE_QINT)
 235         return err_value;
 236
 237     return qint_get_int(qobject_to_qint(obj));
 238 }
 239
 240 /**
 241  * qdict_get_try_str(): Try to get a pointer to the stored string
 242  * mapped by 'key'
 243  *
 244  * Return a pointer to the string mapped by 'key', if it is not present
 245  * in the dictionary or if the stored object is not of QString type
 246  * NULL will be returned.
 247  */
 248 const char *qdict_get_try_str(const QDict *qdict, const char *key)
 249 {
 250     QObject *obj;
 251
 252     obj = qdict_get(qdict, key);
 253     if (!obj || qobject_type(obj) != QTYPE_QSTRING)
 254         return NULL;
 255
 256     return qstring_get_str(qobject_to_qstring(obj));
 257 }
 258
 259 /**
 260  * qdict_iter(): Iterate over all the dictionary's stored values.
 261  *
 262  * This function allows the user to provide an iterator, which will be
 263  * called for each stored value in the dictionary.
 264  */
 265 void qdict_iter(const QDict *qdict,
 266                 void (*iter)(const char *key, QObject *obj, void *opaque),
 267                 void *opaque)
 268 {
 269     int i;
 270     QDictEntry *entry;
 271
 272     for (i = 0; i < QDICT_HASH_SIZE; i++) {
 273         QLIST_FOREACH(entry, &qdict->table[i], next)
 274             iter(entry->key, entry->value, opaque);
 275     }
 276 }
 277
 278 /**
 279  * qentry_destroy(): Free all the memory allocated by a QDictEntry
 280  */
 281 static void qentry_destroy(QDictEntry *e)
 282 {
 283     assert(e != NULL);
 284     assert(e->key != NULL);
 285     assert(e->value != NULL);
 286
 287     qobject_decref(e->value);
 288     qemu_free(e->key);
 289     qemu_free(e);
 290 }
 291
 292 /**
 293  * qdict_del(): Delete a 'key:value' pair from the dictionary
 294  *
 295  * This will destroy all data allocated by this entry.
 296  */
 297 void qdict_del(QDict *qdict, const char *key)
 298 {
 299     QDictEntry *entry;
 300
 301     entry = qdict_find(qdict, key, tdb_hash(key) % QDICT_HASH_SIZE);
 302     if (entry) {
 303         QLIST_REMOVE(entry, next);
 304         qentry_destroy(entry);
 305         qdict->size--;
 306     }
 307 }
 308
 309 /**
 310  * qdict_destroy_obj(): Free all the memory allocated by a QDict
 311  */
 312 static void qdict_destroy_obj(QObject *obj)
 313 {
 314     int i;
 315     QDict *qdict;
 316
 317     assert(obj != NULL);
 318     qdict = qobject_to_qdict(obj);
 319
 320     for (i = 0; i < QDICT_HASH_SIZE; i++) {
 321         QDictEntry *entry = QLIST_FIRST(&qdict->table[i]);
 322         while (entry) {
 323             QDictEntry *tmp = QLIST_NEXT(entry, next);
 324             QLIST_REMOVE(entry, next);
 325             qentry_destroy(entry);
 326             entry = tmp;
 327         }
 328     }
 329
 330     qemu_free(qdict);
 331 }