[Qemu-devel] [PATCH 04/29] Introduce QDict

[Luiz Capitulino <lcapitulino@redhat.com>]

QDict is a high-level dictionary data type that can be used to store a
collection of QObjects. A unique key is associated with only one
QObject.

The following functions are available:

- qdict_new()    Create a new dictionary
- qdict_add()    Add a new 'key:object' pair
- qdict_get()    Get the QObject of a given key
- qdict_del()    Delete a 'key:object' pair
- qdict_size()   Return the size of the dictionary
- qdict_exists() Check if a given 'key' exists

Some high-level helpers to operate on QStrings and QInts objects
are also provided.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
---
 Makefile  |    2 +-
 qdict.c   |  311 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 qdict.h   |   40 ++++++++
 qobject.h |    1 +
 4 files changed, 353 insertions(+), 1 deletions(-)
 create mode 100644 qdict.c
 create mode 100644 qdict.h

diff --git a/Makefile b/Makefile
index 6100b35..40fe1b7 100644
--- a/Makefile
+++ b/Makefile
@@ -90,7 +90,7 @@ obj-y += buffered_file.o migration.o migration-tcp.o net.o qemu-sockets.o
 obj-y += qemu-char.o aio.o net-checksum.o savevm.o
 obj-y += msmouse.o ps2.o
 obj-y += qdev.o qdev-properties.o ssi.o
-obj-y += qint.o qstring.o
+obj-y += qint.o qstring.o qdict.o
 
 obj-$(CONFIG_BRLAPI) += baum.o
 obj-$(CONFIG_WIN32) += tap-win32.o
diff --git a/qdict.c b/qdict.c
new file mode 100644
index 0000000..3901c48
--- /dev/null
+++ b/qdict.c
@@ -0,0 +1,311 @@
+/*
+ * QDict data type.
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * Authors:
+ *  Luiz Capitulino <lcapitulino@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "qdict.h"
+#include "qobject.h"
+#include "qemu-common.h"
+
+static const QType qdict_type;
+
+/**
+ * qdict_new(): Create a new dictionary data-type
+ *
+ * Return new reference.
+ */
+QDict *qdict_new(void)
+{
+    QDict *qdict;
+
+    qdict = qemu_mallocz(sizeof(*qdict));
+    QOBJECT_INIT(qdict, &qdict_type);
+
+    return qdict;
+}
+
+/**
+ * qobject_to_qdict(): Convert a QObject into a QDict
+ */
+QDict *qobject_to_qdict(const QObject *obj)
+{
+    if (qobject_type(obj) != QTYPE_QDICT)
+        return NULL;
+
+    return container_of(obj, QDict, base);
+}
+
+/**
+ * tdb_hash(): based on the hash agorithm from gdbm, via tdb
+ * (from module-init-tools)
+ */
+static unsigned int tdb_hash(const char *name)
+{
+    unsigned value;	/* Used to compute the hash value.  */
+    unsigned   i;	/* Used to cycle through random values. */
+
+    /* Set the initial value from the key size. */
+    for (value = 0x238F13AF * strlen(name), i=0; name[i]; i++)
+        value = (value + (((const unsigned char *)name)[i] << (i*5 % 24)));
+
+    return (1103515243 * value + 12345);
+}
+
+/**
+ * alloc_entry(): allocate a new QDictEntry
+ */
+static QDictEntry *alloc_entry(const char *key, QObject *value,
+                               QDictEntry *next)
+{
+    QDictEntry *entry;
+
+    entry = qemu_malloc(sizeof(*entry));
+    entry->key = qemu_strdup(key);
+    entry->value = value;
+    entry->next = next;
+
+    return entry;
+}
+
+/**
+ * qdict_find(): Low-level lookup function
+ */
+static void *qdict_find(const QDict *qdict,
+                        const char *key, unsigned int hash)
+{
+    QDictEntry *e;
+
+    for (e = qdict->table[hash]; e; e = e->next)
+        if (!strcmp(e->key, key))
+            return e->value;
+    return NULL;
+}
+
+/**
+ * qdict_add(): Add a new object into the dictionary
+ *
+ * Add the pair 'key:value' into qdict. Does nothing if 'key' already
+ * exist.
+ *
+ * NOTE: this function 'steals' a reference to 'value'
+ */
+void qdict_add(QDict *qdict, const char *key, QObject *value)
+{
+    unsigned int hash;
+    QDictEntry *entry;
+
+    hash = tdb_hash(key) % QDICT_HASH_SIZE;
+    if (qdict_find(qdict, key, hash)) {
+        /* Don't add again if it's already there */
+        return;
+    }
+
+    entry = alloc_entry(key, value, qdict->table[hash]);
+    qdict->table[hash] = entry;
+    qdict->size++;
+}
+
+/**
+ * qdict_add_qint(): Add a new QInt into the dictionary
+ *
+ * Add the pair 'key:qint' into qdict. Does nothing if 'key' already
+ * exist.
+ *
+ * NOTE: this function 'steals' a reference to 'qi'
+ */
+void qdict_add_qint(QDict *qdict, const char *key, QInt *qi)
+{
+    qdict_add(qdict, key, QOBJECT(qi));
+}
+
+/**
+ * qdict_add_qstring(): Add a new QString into the dictionary
+ *
+ * Add the pair 'key:qstring' into qdict. Does nothing if 'key' already
+ * exist.
+ *
+ * NOTE: this function 'steals' a reference to 'qs'
+ */
+void qdict_add_qstring(QDict *qdict, const char *key, QString *qs)
+{
+    qdict_add(qdict, key, QOBJECT(qs));
+}
+
+/**
+ * qdict_get(): Lookup for a given 'key'
+ *
+ * Return borrowed reference to QObject if 'key' exists,
+ * NULL otherwise.
+ */
+QObject *qdict_get(const QDict *qdict, const char *key)
+{
+    return qdict_find(qdict, key, tdb_hash(key) % QDICT_HASH_SIZE);
+}
+
+/**
+ * qdict_size(): Return the size of the dictionary
+ */
+size_t qdict_size(const QDict *qdict)
+{
+    return qdict->size;
+}
+
+/**
+ * qdict_get_obj(): Get a QObject of a specific type.
+ */
+static QObject *qdict_get_obj(const QDict *qdict, const char *key,
+                              qtype_code type)
+{
+    QObject *obj;
+
+    obj = qdict_get(qdict, key);
+    assert(obj != NULL);
+    assert(qobject_type(obj) == type);
+
+    return obj;
+}
+
+/**
+ * qdict_get_int(): Get an int value mapped by 'key'
+ *
+ * This function assumes that 'key' exists and it stores a
+ * QInt object.
+ */
+int qdict_get_int(const QDict *qdict, const char *key)
+{
+    QObject *obj = qdict_get_obj(qdict, key, QTYPE_QINT);
+    return qint_to_int(qobject_to_qint(obj));
+}
+
+/**
+ * qdict_get_uint32(): Get an uint32_t value mapped by 'key'
+ *
+ * This function assumes that 'key' exists and it stores a
+ * QInt object.
+ */
+uint32_t qdict_get_uint32(const QDict *qdict, const char *key)
+{
+    QObject *obj = qdict_get_obj(qdict, key, QTYPE_QINT);
+    return qint_to_uint32(qobject_to_qint(obj));
+}
+
+/**
+ * qdict_get_uint64(): Get an uint64_t value mapped by 'key'
+ *
+ * This function assumes that 'key' exists and it stores a
+ * QInt object.
+ */
+uint64_t qdict_get_uint64(const QDict *qdict, const char *key)
+{
+    QObject *obj = qdict_get_obj(qdict, key, QTYPE_QINT);
+    return qint_to_uint64(qobject_to_qint(obj));
+}
+
+/**
+ * qdict_get_str(): Get a pointer to the stored string mapped
+ * by 'key'
+ *
+ * return the string pointer on success, NULL if 'key' doesn't
+ * exist.
+ */
+const char *qdict_get_str(const QDict *qdict, const char *key)
+{
+    QObject *obj;
+
+    obj = qdict_get(qdict, key);
+    if (!obj)
+        return NULL;
+
+    assert(qobject_type(obj) == QTYPE_QSTRING);
+    return qstring_get_str(qobject_to_qstring(obj));
+}
+
+/**
+ * qdict_exists(): Check if 'key' exists
+ *
+ * return 1 if 'key' exists in the dict, 0 otherwise
+ */
+int qdict_exists(const QDict *qdict, const char *key)
+{
+    QDictEntry *e;
+
+    for (e = qdict->table[tdb_hash(key) % QDICT_HASH_SIZE]; e; e = e->next)
+        if (!strcmp(e->key, key))
+            return 1;
+    return 0;
+}
+
+/**
+ * qentry_destroy(): Free all the memory allocated by a QDictEntry
+ */
+static void qentry_destroy(QDictEntry *e)
+{
+    assert(e != NULL);
+    assert(e->key != NULL);
+    assert(e->value != NULL);
+
+    qobject_decref(e->value);
+    qemu_free(e->key);
+    qemu_free(e);
+}
+
+/**
+ * qdict_del(): Delete a 'key:value' pair from the dictionary
+ *
+ * This will destroy all data allocated by this entry.
+ */
+void qdict_del(QDict *qdict, const char *key)
+{
+    unsigned int hash;
+    QDictEntry *e, *prev;
+
+    prev = NULL;
+    hash = tdb_hash(key) % QDICT_HASH_SIZE;
+    for (e = qdict->table[hash]; e; e = e->next) {
+        if (!strcmp(e->key, key)) {
+            if (!prev)
+                qdict->table[hash] = e->next;
+            else
+                prev->next = e->next;
+            qentry_destroy(e);
+            qdict->size--;
+            return;
+        }
+        prev = e;
+    }
+}
+
+/**
+ * qdict_destroy_obj(): Free all the memory allocated by a QDict
+ */
+static void qdict_destroy_obj(QObject *obj)
+{
+    int i;
+    QDict *qdict;
+
+    assert(obj != NULL);
+    qdict = qobject_to_qdict(obj);
+
+    for (i = 0; i < QDICT_HASH_SIZE; i++) {
+        QDictEntry *e = qdict->table[i];
+        while (e) {
+            QDictEntry *tmp = e->next;
+            qentry_destroy(e);
+            e = tmp;
+        }
+    }
+
+    qemu_free(qdict);
+}
+
+static const QType qdict_type = {
+    .code = QTYPE_QDICT,
+    .destroy = qdict_destroy_obj,
+};
diff --git a/qdict.h b/qdict.h
new file mode 100644
index 0000000..911117f
--- /dev/null
+++ b/qdict.h
@@ -0,0 +1,40 @@
+#ifndef QDICT_H
+#define QDICT_H
+
+#include "qint.h"
+#include "qstring.h"
+#include "qobject.h"
+#include <stddef.h>
+
+#define QDICT_HASH_SIZE 512
+
+typedef struct QDictEntry {
+    char *key;
+    QObject *value;
+    struct QDictEntry *next;
+} QDictEntry;
+
+typedef struct QDict {
+    QType_HEAD
+    size_t size;
+    QDictEntry *table[QDICT_HASH_SIZE];
+} QDict;
+
+/* Object API */
+QDict *qdict_new(void);
+size_t qdict_size(const QDict *qdict);
+void qdict_add(QDict *qdict, const char *key, QObject *value);
+void qdict_del(QDict *qdict, const char *key);
+int qdict_exists(const QDict *qdict, const char *key);
+QObject *qdict_get(const QDict *qdict, const char *key);
+QDict *qobject_to_qdict(const QObject *obj);
+
+/* High level helpers */
+int qdict_get_int(const QDict *qdict, const char *key);
+uint32_t qdict_get_uint32(const QDict *qdict, const char *key);
+uint64_t qdict_get_uint64(const QDict *qdict, const char *key);
+const char *qdict_get_str(const QDict *qdict, const char *key);
+void qdict_add_qint(QDict *qdict, const char *key, QInt *qi);
+void qdict_add_qstring(QDict *qdict, const char *key, QString *qs);
+
+#endif /* QDICT_H */
diff --git a/qobject.h b/qobject.h
index 61cd4a3..0835a28 100644
--- a/qobject.h
+++ b/qobject.h
@@ -43,6 +43,7 @@ typedef enum {
     QTYPE_NONE,
     QTYPE_QINT,
     QTYPE_QSTRING,
+    QTYPE_QDICT,
 } qtype_code;
 
 struct QObject;
-- 
1.6.4.67.gea5b1