Remove unused subgroup cache

Subgroups are indirectly cached by the group cache. All former users
of the subgroup cache now directly access the subgroups of a loaded
group. Hence, there is no need to keep the subgroup cache anymore.

Change-Id: Iaa019b5cac87576eaaa0f7bce71dc91fa8f3c775

Documentation/cmd-show-caches.txt

@@ -66,7 +66,6 @@ Intended for interactive use only.
     groups_bysubgroup             |   230               |   2.4ms | 62%     |
     groups_byuuid                 |  5612               |  29.2ms | 99%     |
     groups_external               |     1               |   1.5s  | 98%     |
-    groups_subgroups              |  5714               |  19.7ms | 99%     |
     ldap_group_existence          |                     |         |         |
     ldap_groups                   |   650               | 680.5ms | 99%     |
     ldap_groups_byinclude         |  1024               |         | 83%     |

Documentation/config-gerrit.txt

@@ -858,11 +858,6 @@ cache `"groups_bysubgroups"`::
 Caches the parent groups of a subgroup.  If direct updates are made
 to the `account_group_includes` table, this cache should be flushed.
 
-cache `"groups_subgroups"`::
-+
-Caches subgroups.  If direct updates are made to the
-`account_group_includes` table, this cache should be flushed.
-
 cache `"ldap_groups"`::
 +
 Caches the LDAP groups that a user belongs to, if LDAP has been

Documentation/rest-api-config.txt

@@ -363,16 +363,6 @@ The entries in the map are sorted by cache name.
       "entries": {},
       "hit_ratio": {}
     },
-    groups_subgroups": {
-      "type": "MEM",
-      "entries": {
-        "mem": 4
-      },
-      "average_get": "697.8us",
-      "hit_ratio": {
-        "mem": 82
-      }
-    },
     "permission_sort": {
       "type": "MEM",
       "entries": {
@@ -477,7 +467,6 @@ The cache names are lexicographically sorted.
     "groups_bysubgroup",
     "groups_byuuid",
     "groups_external",
-    "groups_subgroups",
     "permission_sort",
     "plugin_resources",
     "project_list",

gerrit-server/src/main/java/com/google/gerrit/server/account/GroupIncludeCache.java

@@ -29,14 +29,6 @@ public interface GroupIncludeCache {
    */
   Collection<AccountGroup.UUID> getGroupsWithMember(Account.Id memberId);
 
-  /**
-   * Returns the subgroups of a group.
-   *
-   * @param group the UUID of the group
-   * @return the UUIDs of all direct subgroups
-   */
-  Collection<AccountGroup.UUID> subgroupsOf(AccountGroup.UUID group);
-
   /**
    * Returns the parent groups of a subgroup.
    *
@@ -50,7 +42,5 @@ public interface GroupIncludeCache {
 
   void evictGroupsWithMember(Account.Id memberId);
 
-  void evictSubgroupsOf(AccountGroup.UUID groupId);
-
   void evictParentGroupsOf(AccountGroup.UUID groupId);
 }

gerrit-server/src/main/java/com/google/gerrit/server/account/GroupIncludeCacheImpl.java

@@ -22,7 +22,6 @@ import com.google.common.cache.LoadingCache;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Streams;
-import com.google.gerrit.common.errors.NoSuchGroupException;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.AccountGroup;
 import com.google.gerrit.reviewdb.server.ReviewDb;
@@ -52,7 +51,6 @@ import org.slf4j.LoggerFactory;
 public class GroupIncludeCacheImpl implements GroupIncludeCache {
   private static final Logger log = LoggerFactory.getLogger(GroupIncludeCacheImpl.class);
   private static final String PARENT_GROUPS_NAME = "groups_bysubgroup";
-  private static final String SUBGROUPS_NAME = "groups_subgroups";
   private static final String GROUPS_WITH_MEMBER_NAME = "groups_bymember";
   private static final String EXTERNAL_NAME = "groups_external";
 
@@ -72,12 +70,6 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
                 new TypeLiteral<ImmutableList<AccountGroup.UUID>>() {})
             .loader(ParentGroupsLoader.class);
 
-        cache(
-                SUBGROUPS_NAME,
-                AccountGroup.UUID.class,
-                new TypeLiteral<ImmutableList<AccountGroup.UUID>>() {})
-            .loader(SubgroupsLoader.class);
-
         cache(EXTERNAL_NAME, String.class, new TypeLiteral<ImmutableList<AccountGroup.UUID>>() {})
             .loader(AllExternalLoader.class);
 
@@ -88,7 +80,6 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
   }
 
   private final LoadingCache<Account.Id, ImmutableSet<AccountGroup.UUID>> groupsWithMember;
-  private final LoadingCache<AccountGroup.UUID, ImmutableList<AccountGroup.UUID>> subgroups;
   private final LoadingCache<AccountGroup.UUID, ImmutableList<AccountGroup.UUID>> parentGroups;
   private final LoadingCache<String, ImmutableList<AccountGroup.UUID>> external;
 
@@ -96,13 +87,10 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
   GroupIncludeCacheImpl(
       @Named(GROUPS_WITH_MEMBER_NAME)
           LoadingCache<Account.Id, ImmutableSet<AccountGroup.UUID>> groupsWithMember,
-      @Named(SUBGROUPS_NAME)
-          LoadingCache<AccountGroup.UUID, ImmutableList<AccountGroup.UUID>> subgroups,
       @Named(PARENT_GROUPS_NAME)
           LoadingCache<AccountGroup.UUID, ImmutableList<AccountGroup.UUID>> parentGroups,
       @Named(EXTERNAL_NAME) LoadingCache<String, ImmutableList<AccountGroup.UUID>> external) {
     this.groupsWithMember = groupsWithMember;
-    this.subgroups = subgroups;
     this.parentGroups = parentGroups;
     this.external = external;
   }
@@ -117,16 +105,6 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
     }
   }
 
-  @Override
-  public Collection<AccountGroup.UUID> subgroupsOf(AccountGroup.UUID groupId) {
-    try {
-      return subgroups.get(groupId);
-    } catch (ExecutionException e) {
-      log.warn("Cannot load members of group", e);
-      return Collections.emptySet();
-    }
-  }
-
   @Override
   public Collection<AccountGroup.UUID> parentGroupsOf(AccountGroup.UUID groupId) {
     try {
@@ -144,13 +122,6 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
     }
   }
 
-  @Override
-  public void evictSubgroupsOf(AccountGroup.UUID groupId) {
-    if (groupId != null) {
-      subgroups.invalidate(groupId);
-    }
-  }
-
   @Override
   public void evictParentGroupsOf(AccountGroup.UUID groupId) {
     if (groupId != null) {
@@ -192,8 +163,7 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
     }
 
     @Override
-    public ImmutableSet<AccountGroup.UUID> load(Account.Id memberId)
-        throws OrmException, NoSuchGroupException {
+    public ImmutableSet<AccountGroup.UUID> load(Account.Id memberId) throws OrmException {
       GroupIndex groupIndex = groupIndexProvider.get();
       if (groupIndex != null && groupIndex.getSchema().hasField(GroupField.MEMBER)) {
         return groupQueryProvider
@@ -213,26 +183,6 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
     }
   }
 
-  static class SubgroupsLoader
-      extends CacheLoader<AccountGroup.UUID, ImmutableList<AccountGroup.UUID>> {
-    private final SchemaFactory<ReviewDb> schema;
-    private final Groups groups;
-
-    @Inject
-    SubgroupsLoader(SchemaFactory<ReviewDb> sf, Groups groups) {
-      schema = sf;
-      this.groups = groups;
-    }
-
-    @Override
-    public ImmutableList<AccountGroup.UUID> load(AccountGroup.UUID key)
-        throws OrmException, NoSuchGroupException {
-      try (ReviewDb db = schema.open()) {
-        return groups.getSubgroups(db, key).collect(toImmutableList());
-      }
-    }
-  }
-
   static class ParentGroupsLoader
       extends CacheLoader<AccountGroup.UUID, ImmutableList<AccountGroup.UUID>> {
     private final SchemaFactory<ReviewDb> schema;

gerrit-server/src/main/java/com/google/gerrit/server/group/GroupsUpdate.java

@@ -369,7 +369,6 @@ public class GroupsUpdate {
     for (AccountGroupById newIncludedGroup : newSubgroups) {
       groupIncludeCache.evictParentGroupsOf(newIncludedGroup.getIncludeUUID());
     }
-    groupIncludeCache.evictSubgroupsOf(parentGroupUuid);
   }
 
   /**
@@ -412,6 +411,5 @@ public class GroupsUpdate {
     for (AccountGroupById groupToRemove : subgroupsToRemove) {
       groupIncludeCache.evictParentGroupsOf(groupToRemove.getIncludeUUID());
     }
-    groupIncludeCache.evictSubgroupsOf(parentGroupUuid);
   }
 }