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