Add ability to query for ComputeNodes by their mapped value

Related to blueprint discover-hosts-faster
Change-Id: Ic0068e12cd19824789872e2aa3acaf64c96ccd6b

nova/db/api.py

@@ -254,6 +254,19 @@ def compute_node_get_all(context):
     return IMPL.compute_node_get_all(context)
 
 
+def compute_node_get_all_mapped_less_than(context, mapped_less_than):
+    """Get all ComputeNode objects with specific mapped values.
+
+    :param context: The security context
+    :param mapped_less_than: Get compute nodes with mapped less than this
+                             value
+
+    :returns: List of dictionaries each containing compute node properties
+    """
+    return IMPL.compute_node_get_all_mapped_less_than(context,
+                                                      mapped_less_than)
+
+
 def compute_node_get_all_by_pagination(context, limit=None, marker=None):
     """Get compute nodes by pagination.
     :param context: The security context

nova/db/sqlalchemy/api.py

@@ -625,6 +625,8 @@ def _compute_node_select(context, filters=None, limit=None, marker=None):
     if "hypervisor_hostname" in filters:
         hyp_hostname = filters["hypervisor_hostname"]
         select = select.where(cn_tbl.c.hypervisor_hostname == hyp_hostname)
+    if "mapped" in filters:
+        select = select.where(cn_tbl.c.mapped < filters['mapped'])
     if marker is not None:
         try:
             compute_node_get(context, marker)
@@ -702,6 +704,12 @@ def compute_node_get_all(context):
     return _compute_node_fetchall(context)
 
 
+@pick_context_manager_reader
+def compute_node_get_all_mapped_less_than(context, mapped_less_than):
+    return _compute_node_fetchall(context,
+                                  {'mapped': mapped_less_than})
+
+
 @pick_context_manager_reader
 def compute_node_get_all_by_pagination(context, limit=None, marker=None):
     return _compute_node_fetchall(context, limit=limit, marker=marker)