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