LDAP: Shortcut looking up for group members sooner

This patch is a performance enhancement. When looking for entries to
refresh, we always looked up all members in the cache, even if we ended
up dereferencing the whole group. If we are about to try dereference, it
makes sense to shortcut the lookups after the dereference threshold is
reached. In that case, the split_members function returns a special
error code and the caller just dereferences the whole group.

Only if dereference fails, we fall back to looking up all members so
that we can look them up one-by-one.

Also adds an integration test to make sure the dereference code works.

Reviewed-by: Sumit Bose <sbose@redhat.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/src/tests/intg/ldap_test.py b/src/tests/intg/ldap_test.py
index 86a3d6e0e..84f7f2d8a 100644
--- a/src/tests/intg/ldap_test.py
+++ b/src/tests/intg/ldap_test.py
@@ -144,6 +144,21 @@ def format_interactive_conf(ldap_conn, schema):
             entry_cache_timeout                 = {0}
         """).format(INTERACTIVE_TIMEOUT)
 
+def format_rfc2307bis_deref_conf(ldap_conn, schema):
+    """Format an SSSD configuration with all caches refreshing in 4 seconds"""
+    return \
+        format_basic_conf(ldap_conn, schema, enum=False) + \
+        unindent("""
+            [nss]
+            memcache_timeout                    = 0
+            enum_cache_timeout                  = {0}
+            entry_negative_timeout              = 0
+
+            [domain/LDAP]
+            entry_cache_timeout                 = {0}
+            ldap_deref_threshold                = 1
+        """).format(INTERACTIVE_TIMEOUT)
+
 
 def create_conf_file(contents):
     """Create sssd.conf with specified contents"""
@@ -459,6 +474,26 @@ def user_and_groups_rfc2307_bis(request, ldap_conn):
     return None
 
 
+@pytest.fixture
+def rfc2307bis_deref_group_with_users(request, ldap_conn):
+    """
+    Create an RFC2307bis directory fixture with interactive SSSD conf,
+    one user and two groups
+    """
+    ent_list = ldap_ent.List(ldap_conn.ds_inst.base_dn)
+    ent_list.add_user("user1", 1001, 2000)
+    ent_list.add_user("user2", 1001, 2000)
+    ent_list.add_user("user3", 1001, 2000)
+    ent_list.add_group_bis("group1", 20000, member_uids=("user1", "user2"))
+    create_ldap_fixture(request, ldap_conn, ent_list)
+    create_conf_fixture(request,
+                        format_rfc2307bis_deref_conf(
+                            ldap_conn,
+                            SCHEMA_RFC2307_BIS))
+    create_sssd_fixture(request)
+    return None
+
+
 def test_add_remove_user(ldap_conn, blank_rfc2307):
     """Test user addition and removal are reflected by SSSD"""
     e = ldap_ent.user(ldap_conn.ds_inst.base_dn, "user", 2001, 2000)
@@ -555,6 +590,11 @@ def test_add_remove_membership_rfc2307_bis(ldap_conn,
     ent.assert_group_by_name("group1", dict(mem=ent.contains_only()))
 
 
+def test_ldap_group_dereference(ldap_conn, rfc2307bis_deref_group_with_users):
+    ent.assert_group_by_name("group1",
+                             dict(mem=ent.contains_only(
+                                                "user1", "user2")))
+
 @pytest.fixture
 def override_homedir(request, ldap_conn):
     ent_list = ldap_ent.List(ldap_conn.ds_inst.base_dn)