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[Qemu-devel] [PATCH 01/25] Introduce QEMU dictionary data type
From: |
Luiz Capitulino |
Subject: |
[Qemu-devel] [PATCH 01/25] Introduce QEMU dictionary data type |
Date: |
Tue, 28 Jul 2009 19:04:49 -0300 |
A dictionary is a high-level data type used to store a collection of
values, where a unique key is associated with one value. Usually, the
notation 'key:value' is used to denote this relationship.
This commit adds the qemu-dict module, which implements a dictionary
for QEMU and exports the following functions:
- qemu_dict_create() Create a new dictionary
- qemu_dict_add() Add a new 'key:value' pair
- qemu_dict_get() Get the 'value' of a given 'key'
- qemu_dict_exists() Check if a given 'key' exists
- qemu_dict_del() Delete a 'key:value' pair
- qemu_dict_destroy() Destroy the dictionary
- qemu_dict_walk() Walk through the dictionary values
- qemu_dict_size() Return the size of the dictionary
qemu-dict module uses a chained hash table, whose hash function comes from
module-init-tools program.
Signed-off-by: Luiz Capitulino <address@hidden>
---
Makefile | 1 +
qemu-dict.c | 215 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
qemu-dict.h | 36 ++++++++++
3 files changed, 252 insertions(+), 0 deletions(-)
create mode 100644 qemu-dict.c
create mode 100644 qemu-dict.h
diff --git a/Makefile b/Makefile
index c510ff3..b36786d 100644
--- a/Makefile
+++ b/Makefile
@@ -97,6 +97,7 @@ 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 += qemu-dict.o
obj-$(CONFIG_BRLAPI) += baum.o
diff --git a/qemu-dict.c b/qemu-dict.c
new file mode 100644
index 0000000..ad2d6d9
--- /dev/null
+++ b/qemu-dict.c
@@ -0,0 +1,215 @@
+/*
+ * QEMU dictionary data type.
+ *
+ * Copyright (C) 2009 Red Hat Inc.
+ *
+ * Authors:
+ * Luiz Capitulino <address@hidden>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "qemu-dict.h"
+#include "qemu-common.h"
+
+/**
+ * qemu_dict_create(): Create a new dictionary data-type
+ */
+struct qemu_dict *qemu_dict_create(void)
+{
+ return qemu_mallocz(sizeof(struct qemu_dict));
+}
+
+/**
+ * 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);
+}
+
+/**
+ * __qemu_dict_get(): Low-level lookup function
+ */
+static void *__qemu_dict_get(const struct qemu_dict *qdict,
+ const char *key, unsigned int hash)
+{
+ struct qemu_dict_entry *e;
+
+ for (e = qdict->table[hash]; e; e = e->next)
+ if (!strcmp(e->key, key))
+ return e->value;
+ return NULL;
+}
+
+/**
+ * qemu_dict_get(): Lookup for a given 'key'
+ *
+ * return corresponding 'value' or NULL if 'key' doesn't exist.
+ */
+void *qemu_dict_get(const struct qemu_dict *qdict, const char *key)
+{
+ assert(qdict != NULL);
+ assert(key != NULL);
+ return __qemu_dict_get(qdict, key, tdb_hash(key) % QEMU_DICT_HASH_SIZE);
+}
+
+/**
+ * qemu_dict_exists(): Check if 'key' exists
+ *
+ * return 1 if 'key' exists in the dict, 0 otherwise
+ */
+int qemu_dict_exists(const struct qemu_dict *qdict, const char *key)
+{
+ struct qemu_dict_entry *e;
+
+ assert(qdict != NULL);
+ assert(key != NULL);
+
+ for (e = qdict->table[tdb_hash(key) % QEMU_DICT_HASH_SIZE]; e; e = e->next)
+ if (!strcmp(e->key, key))
+ return 1;
+ return 0;
+}
+
+/**
+ * alloc_entry(): allocate a new qemu_dict_entry
+ */
+static struct qemu_dict_entry *alloc_entry(const char *key, void *value)
+{
+ struct qemu_dict_entry *entry;
+
+ entry = qemu_malloc(sizeof(*entry));
+ entry->key = qemu_strdup(key);
+ entry->value = value;
+ entry->next = NULL;
+
+ return entry;
+}
+
+/**
+ * qemu_dict_add(): Add a new value into the dictionary
+ *
+ * Add the pair 'key:value' into qdict. Does nothing if 'key' already
+ * exist.
+ */
+void qemu_dict_add(struct qemu_dict *qdict, const char *key, void *value)
+{
+ unsigned int hash;
+ struct qemu_dict_entry *entry;
+
+ assert(qdict != NULL);
+ assert(key != NULL);
+
+ hash = tdb_hash(key) % QEMU_DICT_HASH_SIZE;
+ if (__qemu_dict_get(qdict, key, hash)) {
+ /* Don't add again if it's already there */
+ return;
+ }
+
+ entry = alloc_entry(key, value);
+ entry->next = qdict->table[hash];
+ qdict->table[hash] = entry;
+ qdict->size++;
+}
+
+/**
+ * qemu_dict_del(): Delete a given 'key' from the dictionary
+ *
+ * This will destroy all data allocated by 'key', except 'value'
+ * which is returned.
+ */
+void *qemu_dict_del(struct qemu_dict *qdict, const char *key)
+{
+ unsigned int hash;
+ struct qemu_dict_entry *e, *prev;
+
+ assert(qdict != NULL);
+ assert(key != NULL);
+
+ prev = NULL;
+ hash = tdb_hash(key) % QEMU_DICT_HASH_SIZE;
+ for (e = qdict->table[hash]; e; e = e->next) {
+ if (!strcmp(e->key, key)) {
+ void *value = e->value;
+ if (!prev)
+ qdict->table[hash] = e->next;
+ else
+ prev->next = e->next;
+ qemu_free(e->key);
+ qemu_free(e);
+ qdict->size--;
+ return value;
+ }
+
+ prev = e;
+ }
+
+ return NULL;
+}
+
+/**
+ * qemu_dict_destroy(): Destroy given 'qdict'
+ *
+ * This will destroy all data allocated by 'qdict', but added
+ * values must be freed by the caller.
+ */
+void qemu_dict_destroy(struct qemu_dict *qdict)
+{
+ int i;
+
+ assert(qdict != NULL);
+
+ for (i = 0; i < QEMU_DICT_HASH_SIZE; i++) {
+ struct qemu_dict_entry *e = qdict->table[i];
+ while (e) {
+ struct qemu_dict_entry *tmp = e->next;
+ qemu_free(e->key);
+ qemu_free(e);
+ e = tmp;
+ }
+ }
+
+ qemu_free(qdict);
+}
+
+/**
+ * qemu_dict_walk(): Walk through dictionary contents
+ *
+ * This function can be used by users to "walk through"
+ * the data stored in the dictionary.
+ *
+ * In order to use this the caller has pass a pointer
+ * to a function with the following signature:
+ *
+ * void walkf(const char *key, void *value);
+ *
+ * Then, when qemu_dict_walk() is called, it will
+ * "walk through" all the dictionary data, passing
+ * each stored value to walkf().
+ */
+void qemu_dict_walk(const struct qemu_dict *qdict,
+ void (*walkf)(const char *key, void *value))
+{
+ int i;
+
+ assert(qdict != NULL);
+ assert(walkf != NULL);
+
+ for (i = 0; i < QEMU_DICT_HASH_SIZE; i++) {
+ struct qemu_dict_entry *e = qdict->table[i];
+ while (e) {
+ walkf(e->key, e->value);
+ e = e->next;
+ }
+ }
+}
diff --git a/qemu-dict.h b/qemu-dict.h
new file mode 100644
index 0000000..89324db
--- /dev/null
+++ b/qemu-dict.h
@@ -0,0 +1,36 @@
+#ifndef __QEMU_DICT_H__
+#define __QEMU_DICT_H__
+
+#include <stddef.h>
+
+#define QEMU_DICT_HASH_SIZE 512
+
+struct qemu_dict_entry {
+ struct qemu_dict_entry *next;
+ char *key;
+ void *value;
+};
+
+struct qemu_dict {
+ size_t size;
+ struct qemu_dict_entry *table[QEMU_DICT_HASH_SIZE];
+};
+
+/**
+ * qemu_dict_size(): return the size of the dictionary
+ */
+static inline size_t qemu_dict_size(const struct qemu_dict *qdict)
+{
+ return qdict->size;
+}
+
+struct qemu_dict *qemu_dict_create(void);
+void qemu_dict_add(struct qemu_dict *qdict, const char *key, void *value);
+void *qemu_dict_get(const struct qemu_dict *qdict, const char *key);
+int qemu_dict_exists(const struct qemu_dict *qdict, const char *key);
+void *qemu_dict_del(struct qemu_dict *qdict, const char *key);
+void qemu_dict_destroy(struct qemu_dict *qdict);
+void qemu_dict_walk(const struct qemu_dict *qdict,
+ void (*walkf)(const char *key, void *value));
+
+#endif /* __QEMU_DICT_H__ */
--
1.6.4.rc3.12.gdf73a