Add nl hashtable structures and access functions

This patch adds the required structures and access functions to create
and manage hashtables for netlink cache objects

Signed-off-by: Shrijeet Mukherjee <shm@cumulusnetworks.com>
Signed-off-by: Nolan Leake <nolan@cumulusnetworks.com>
Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Reviewed-by: Wilson Kok <wkok@cumulusnetworks.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>

6 files changed, 227 insertions, 1 deletions

diff --git a/include/netlink/hashtable.h b/include/netlink/hashtable.h
new file mode 100644
index 0000000..d9e6ee4
--- /dev/null
+++ b/include/netlink/hashtable.h
@@ -0,0 +1,52 @@
+/*
+ * netlink/hashtable.h       Netlink hashtable Utilities
+ *
+ *      This library is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU Lesser General Public
+ *      License as published by the Free Software Foundation version 2.1
+ *      of the License.
+ *
+ * Copyright (c) 2012 Cumulus Networks, Inc
+ */
+
+#ifndef NETLINK_HASHTABLE_H_
+#define NETLINK_HASHTABLE_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct nl_hash_node {
+    uint32_t			key;
+    uint32_t			key_size;
+    struct nl_object *		obj;
+    struct nl_hash_node *	next;
+} nl_hash_node_t;
+
+typedef struct nl_hash_table {
+    int 			size;
+    nl_hash_node_t **		nodes;
+} nl_hash_table_t;
+
+/* Default hash table size */
+#define NL_MAX_HASH_ENTRIES 1024
+
+/* Access Functions */
+extern nl_hash_table_t *	nl_hash_table_alloc(int size);
+extern void 			nl_hash_table_free(nl_hash_table_t *ht);
+
+extern int			nl_hash_table_add(nl_hash_table_t *ht,
+						  struct nl_object *obj);
+extern int			nl_hash_table_del(nl_hash_table_t *ht,
+						  struct nl_object *obj);
+
+extern struct nl_object *	nl_hash_table_lookup(nl_hash_table_t *ht,
+						     struct nl_object *obj);
+extern uint32_t 		nl_hash(void *k, size_t length,
+					uint32_t initval);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NETLINK_HASHTABLE_H_ */
diff --git a/include/netlink/object-api.h b/include/netlink/object-api.h
index ec2192b..ae6180a 100644
--- a/include/netlink/object-api.h
+++ b/include/netlink/object-api.h
@@ -348,6 +348,16 @@ struct nl_object_ops
 	 */
 	int   (*oo_update)(struct nl_object *, struct nl_object *);
 
+	/**
+	 * Hash Key generator function
+	 *
+	 * When called returns a hash key for the object being
+	 * referenced. This key will be used by higher level hash functions
+	 * to build association lists. Each object type gets to specify
+	 * it's own key formulation
+	 */
+	void   (*oo_keygen)(struct nl_object *, uint32_t *, uint32_t);
+
 	char *(*oo_attrs2str)(int, char *, size_t);
 
 	/**
diff --git a/include/netlink/object.h b/include/netlink/object.h
index 788ae48..f25713e 100644
--- a/include/netlink/object.h
+++ b/include/netlink/object.h
@@ -50,6 +50,8 @@ extern char *			nl_object_attrs2str(struct nl_object *,
 						    size_t);
 extern char *			nl_object_attr_list(struct nl_object *,
 						    char *, size_t);
+extern void			nl_object_keygen(struct nl_object *,
+						 uint32_t *, uint32_t);
 
 /* Marks */
 extern void			nl_object_mark(struct nl_object *);
diff --git a/lib/Makefile.am b/lib/Makefile.am
index c79ba29..7481941 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -18,7 +18,7 @@ lib_LTLIBRARIES = \
 libnl_3_la_SOURCES = \
 	addr.c attr.c cache.c cache_mngr.c cache_mngt.c data.c \
 	error.c handlers.c msg.c nl.c object.c socket.c utils.c \
-	version.c hash.c
+	version.c hash.c hashtable.c
 
 libnl_genl_3_la_LIBADD  = libnl-3.la
 libnl_genl_3_la_SOURCES = \
diff --git a/lib/hashtable.c b/lib/hashtable.c
new file mode 100644
index 0000000..59cd91e
--- /dev/null
+++ b/lib/hashtable.c
@@ -0,0 +1,141 @@
+/*
+ * netlink/hashtable.c      Netlink hashtable Utilities
+ *
+ *      This library is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU Lesser General Public
+ *      License as published by the Free Software Foundation version 2.1
+ *      of the License.
+ *
+ * Copyright (c) 2012 Cumulus Networks, Inc
+ */
+#include <string.h>
+#include <netlink-local.h>
+#include <netlink/object.h>
+#include <netlink/hash.h>
+#include <netlink/hashtable.h>
+
+nl_hash_table_t *nl_hash_table_alloc(int size)
+{
+	nl_hash_table_t *ht;
+
+	ht = calloc(1, sizeof (*ht));
+	if (!ht)
+		goto errout;
+
+	ht->nodes = calloc(size, sizeof (*ht->nodes));
+	if (!ht->nodes) {
+		free(ht);
+		goto errout;
+	}
+
+	ht->size = size;
+
+	return ht;
+errout:
+	return NULL;
+}
+
+void nl_hash_table_free(nl_hash_table_t *ht)
+{
+	int i;
+
+	for(i = 0; i < ht->size; i++) {
+	    nl_hash_node_t *node = ht->nodes[i];
+	    nl_hash_node_t *saved_node;
+
+	    while (node) {
+		   saved_node = node;
+		   node = node->next;
+		   free(saved_node);
+	    }
+	}
+
+	free(ht->nodes);
+	free(ht);
+}
+
+struct nl_object* nl_hash_table_lookup(nl_hash_table_t *ht,
+				       struct nl_object *obj)
+{
+	nl_hash_node_t *node;
+	uint32_t key_hash;
+
+	nl_object_keygen(obj, &key_hash, ht->size);
+	node = ht->nodes[key_hash];
+
+	while (node) {
+	       if (nl_object_identical(node->obj, obj))
+		   return node->obj;
+	       node = node->next;
+	}
+
+	return NULL;
+}
+
+int nl_hash_table_add(nl_hash_table_t *ht, struct nl_object *obj)
+{
+	nl_hash_node_t *node;
+	uint32_t key_hash;
+
+	nl_object_keygen(obj, &key_hash, ht->size);
+	node = ht->nodes[key_hash];
+
+	while (node) {
+	       if (nl_object_identical(node->obj, obj)) {
+		   NL_DBG(2, "Warning: Add to hashtable found duplicate...\n");
+		   return -NLE_EXIST;
+	       }
+	       node = node->next;
+	}
+
+	NL_DBG (5, "adding cache entry of obj %p in table %p, with hash 0x%x\n",
+		obj, ht, key_hash);
+
+	node = malloc(sizeof(nl_hash_node_t));
+	if (!node)
+		return -NLE_NOMEM;
+	nl_object_get(obj);
+	node->obj = obj;
+	node->key = key_hash;
+	node->key_size = sizeof(uint32_t);
+	node->next = ht->nodes[key_hash];
+	ht->nodes[key_hash] = node;
+
+	return 0;
+}
+
+int nl_hash_table_del(nl_hash_table_t *ht, struct nl_object *obj)
+{
+	nl_hash_node_t *node, *prev;
+	uint32_t key_hash;
+
+	nl_object_keygen(obj, &key_hash, ht->size);
+	prev = node = ht->nodes[key_hash];
+
+	while (node) {
+	       if (nl_object_identical(node->obj, obj)) {
+		   nl_object_put(obj);
+
+		   NL_DBG (5, "deleting cache entry of obj %p in table %p, with"
+			   " hash 0x%x\n", obj, ht, key_hash);
+
+	           if (node == ht->nodes[key_hash])
+		       ht->nodes[key_hash] = node->next;
+	           else
+		       prev->next = node->next;
+
+	           free(node);
+
+	           return 0;
+		}
+		prev = node;
+		node = node->next;
+	}
+
+	return -1;
+}
+
+uint32_t nl_hash(void *k, size_t length, uint32_t initval)
+{
+	return(hash(k, length, initval));
+}
diff --git a/lib/object.c b/lib/object.c
index d58f9a7..024062e 100644
--- a/lib/object.c
+++ b/lib/object.c
@@ -413,6 +413,27 @@ char *nl_object_attr_list(struct nl_object *obj, char *buf, size_t len)
 	return nl_object_attrs2str(obj, obj->ce_mask, buf, len);
 }
 
+/**
+ * Generate object hash key
+ * @arg obj		the object
+ * @arg hashkey		destination buffer to be used for key stream
+ * @arg hashtbl_sz	hash table size
+ *
+ * @return hash key in destination buffer
+ */
+void nl_object_keygen(struct nl_object *obj, uint32_t *hashkey,
+		      uint32_t hashtbl_sz)
+{
+	struct nl_object_ops *ops = obj_ops(obj);
+
+	if (ops->oo_keygen)
+		ops->oo_keygen(obj, hashkey, hashtbl_sz);
+	else
+		*hashkey = 0;
+
+	return;
+}
+
 /** @} */
 
 /**