cache: Add new nl_cache_find api

This patch adds new cache find api

nl_cache_find api was suggested by Thomas.

Unlike nl_cache_search, this patch uses
nl_object_match_filter() to look for an
object match.

Am not sure this matches what was decided
on the list few weeks back. I will be happy
to make any changes.

Signed-off-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: Thomas Graf <tgraf@suug.ch>

3 files changed, 62 insertions, 0 deletions

diff --git a/include/netlink/object.h b/include/netlink/object.h
index f25713e..a95feda 100644
--- a/include/netlink/object.h
+++ b/include/netlink/object.h
@@ -64,6 +64,7 @@ extern struct nl_cache *	nl_object_get_cache(struct nl_object *);
 extern const char *		nl_object_get_type(const struct nl_object *);
 extern int			nl_object_get_msgtype(const struct nl_object *);
 struct nl_object_ops *		nl_object_get_ops(const struct nl_object *);
+uint32_t			nl_object_get_id_attrs(struct nl_object *obj);
 
 
 static inline void *		nl_object_priv(struct nl_object *obj)
diff --git a/lib/cache.c b/lib/cache.c
index 42c0b5e..24ffa31 100644
--- a/lib/cache.c
+++ b/lib/cache.c
@@ -1023,6 +1023,45 @@ struct nl_object *nl_cache_search(struct nl_cache *cache,
 }
 
 /**
+ * Find object in cache
+ * @arg cache		Cache
+ * @arg filter		object acting as a filter
+ *
+ * Searches the cache for an object which matches the object filter.
+ * If the filter attributes matches the object type id attributes,
+ * and the cache supports hash lookups, a faster hashtable lookup
+ * is used to return the object. Else, function nl_object_match_filter() is
+ * used to determine if the objects match. If a matching object is
+ * found, the reference counter is incremented and the object is returned.
+ *
+ * Therefore, if an object is returned, the reference to the object
+ * must be returned by calling nl_object_put() after usage.
+ *
+ * @return Reference to object or NULL if not found.
+ */
+struct nl_object *nl_cache_find(struct nl_cache *cache,
+				struct nl_object *filter)
+{
+	struct nl_object *obj;
+
+	if (cache->c_ops == NULL)
+		BUG();
+
+	if ((nl_object_get_id_attrs(filter) == filter->ce_mask)
+		&& cache->hashtable)
+		return __cache_fast_lookup(cache, filter);
+
+	nl_list_for_each_entry(obj, &cache->c_items, ce_list) {
+		if (nl_object_match_filter(obj, filter)) {
+			nl_object_get(obj);
+			return obj;
+		}
+	}
+
+	return NULL;
+}
+
+/**
  * Mark all objects of a cache
  * @arg cache		Cache
  *
diff --git a/lib/object.c b/lib/object.c
index 806bae6..7361194 100644
--- a/lib/object.c
+++ b/lib/object.c
@@ -506,6 +506,28 @@ struct nl_object_ops *nl_object_get_ops(const struct nl_object *obj)
 	return obj->ce_ops;
 }
 
+/**
+ * Return object id attribute mask
+ * @arg obj		object
+ *
+ * @return object id attribute mask
+ */
+uint32_t nl_object_get_id_attrs(struct nl_object *obj)
+{
+	struct nl_object_ops *ops = obj_ops(obj);
+	uint32_t id_attrs;
+
+	if (!ops)
+		return 0;
+
+	if (ops->oo_id_attrs_get)
+		id_attrs = ops->oo_id_attrs_get(obj);
+	else
+		id_attrs = ops->oo_id_attrs;
+
+	return id_attrs;
+}
+
 /** @} */
 
 /** @} */