GroupIncludeCache: Return Collection instead of Set

All callers of these methods simply iterate over the elements, they
don't perform any set lookups. Returning Collection instead of Set
allows us to store ImmutableLists internally, which have much less
memory overhead on servers with lots of groups.

Change-Id: I12e6ef0d03d9b06c112e4d1203603b23cafaf903

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

@@ -16,18 +16,18 @@ package com.google.gerrit.server.account;
 
 import com.google.gerrit.reviewdb.client.AccountGroup;
 
-import java.util.Set;
+import java.util.Collection;
 
 /** Tracks group inclusions in memory for efficient access. */
 public interface GroupIncludeCache {
   /** @return groups directly a member of the passed group. */
-  Set<AccountGroup.UUID> subgroupsOf(AccountGroup.UUID group);
+  Collection<AccountGroup.UUID> subgroupsOf(AccountGroup.UUID group);
 
   /** @return any groups the passed group belongs to. */
-  Set<AccountGroup.UUID> parentGroupsOf(AccountGroup.UUID groupId);
+  Collection<AccountGroup.UUID> parentGroupsOf(AccountGroup.UUID groupId);
 
   /** @return set of any UUIDs that are not internal groups. */
-  Set<AccountGroup.UUID> allExternalMembers();
+  Collection<AccountGroup.UUID> allExternalMembers();
 
   void evictSubgroupsOf(AccountGroup.UUID groupId);
   void evictParentGroupsOf(AccountGroup.UUID groupId);

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

@@ -16,11 +16,12 @@ package com.google.gerrit.server.account;
 
 import com.google.common.cache.CacheLoader;
 import com.google.common.cache.LoadingCache;
-import com.google.common.collect.ImmutableSet;
+import com.google.common.collect.ImmutableList;
 import com.google.gerrit.reviewdb.client.AccountGroup;
 import com.google.gerrit.reviewdb.client.AccountGroupById;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.cache.CacheModule;
+import com.google.gwtorm.server.OrmException;
 import com.google.gwtorm.server.SchemaFactory;
 import com.google.inject.Inject;
 import com.google.inject.Module;
@@ -31,6 +32,7 @@ import com.google.inject.name.Named;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.List;
@@ -52,17 +54,17 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
       protected void configure() {
         cache(PARENT_GROUPS_NAME,
             AccountGroup.UUID.class,
-            new TypeLiteral<Set<AccountGroup.UUID>>() {})
+            new TypeLiteral<ImmutableList<AccountGroup.UUID>>() {})
           .loader(ParentGroupsLoader.class);
 
         cache(SUBGROUPS_NAME,
             AccountGroup.UUID.class,
-            new TypeLiteral<Set<AccountGroup.UUID>>() {})
+            new TypeLiteral<ImmutableList<AccountGroup.UUID>>() {})
           .loader(SubgroupsLoader.class);
 
         cache(EXTERNAL_NAME,
             String.class,
-            new TypeLiteral<Set<AccountGroup.UUID>>() {})
+            new TypeLiteral<ImmutableList<AccountGroup.UUID>>() {})
           .loader(AllExternalLoader.class);
 
         bind(GroupIncludeCacheImpl.class);
@@ -71,22 +73,31 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
     };
   }
 
-  private final LoadingCache<AccountGroup.UUID, Set<AccountGroup.UUID>> subgroups;
-  private final LoadingCache<AccountGroup.UUID, Set<AccountGroup.UUID>> parentGroups;
-  private final LoadingCache<String, Set<AccountGroup.UUID>> external;
+  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;
 
   @Inject
   GroupIncludeCacheImpl(
-      @Named(SUBGROUPS_NAME) LoadingCache<AccountGroup.UUID, Set<AccountGroup.UUID>> subgroups,
-      @Named(PARENT_GROUPS_NAME) LoadingCache<AccountGroup.UUID, Set<AccountGroup.UUID>> parentGroups,
-      @Named(EXTERNAL_NAME) LoadingCache<String, Set<AccountGroup.UUID>> external) {
+      @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.subgroups = subgroups;
     this.parentGroups = parentGroups;
     this.external = external;
   }
 
   @Override
-  public Set<AccountGroup.UUID> subgroupsOf(AccountGroup.UUID groupId) {
+  public Collection<AccountGroup.UUID> subgroupsOf(AccountGroup.UUID groupId) {
     try {
       return subgroups.get(groupId);
     } catch (ExecutionException e) {
@@ -96,7 +107,8 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
   }
 
   @Override
-  public Set<AccountGroup.UUID> parentGroupsOf(AccountGroup.UUID groupId) {
+  public Collection<AccountGroup.UUID> parentGroupsOf(
+      AccountGroup.UUID groupId) {
     try {
       return parentGroups.get(groupId);
     } catch (ExecutionException e) {
@@ -124,17 +136,17 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
   }
 
   @Override
-  public Set<AccountGroup.UUID> allExternalMembers() {
+  public Collection<AccountGroup.UUID> allExternalMembers() {
     try {
       return external.get(EXTERNAL_NAME);
     } catch (ExecutionException e) {
       log.warn("Cannot load set of non-internal groups", e);
-      return Collections.emptySet();
+      return ImmutableList.of();
     }
   }
 
   static class SubgroupsLoader extends
-      CacheLoader<AccountGroup.UUID, Set<AccountGroup.UUID>> {
+      CacheLoader<AccountGroup.UUID, ImmutableList<AccountGroup.UUID>> {
     private final SchemaFactory<ReviewDb> schema;
 
     @Inject
@@ -143,11 +155,12 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
     }
 
     @Override
-    public Set<AccountGroup.UUID> load(AccountGroup.UUID key) throws Exception {
+    public ImmutableList<AccountGroup.UUID> load(
+        AccountGroup.UUID key) throws OrmException {
       try (ReviewDb db = schema.open()) {
         List<AccountGroup> group = db.accountGroups().byUUID(key).toList();
         if (group.size() != 1) {
-          return Collections.emptySet();
+          return ImmutableList.of();
         }
 
         Set<AccountGroup.UUID> ids = new HashSet<>();
@@ -155,13 +168,13 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
             .byGroup(group.get(0).getId())) {
           ids.add(agi.getIncludeUUID());
         }
-        return ImmutableSet.copyOf(ids);
+        return ImmutableList.copyOf(ids);
       }
     }
   }
 
   static class ParentGroupsLoader extends
-      CacheLoader<AccountGroup.UUID, Set<AccountGroup.UUID>> {
+      CacheLoader<AccountGroup.UUID, ImmutableList<AccountGroup.UUID>> {
     private final SchemaFactory<ReviewDb> schema;
 
     @Inject
@@ -170,7 +183,8 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
     }
 
     @Override
-    public Set<AccountGroup.UUID> load(AccountGroup.UUID key) throws Exception {
+    public ImmutableList<AccountGroup.UUID> load(AccountGroup.UUID key)
+        throws OrmException {
       try (ReviewDb db = schema.open()) {
         Set<AccountGroup.Id> ids = new HashSet<>();
         for (AccountGroupById agi : db.accountGroupById()
@@ -182,13 +196,13 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
         for (AccountGroup g : db.accountGroups().get(ids)) {
           groupArray.add(g.getGroupUUID());
         }
-        return ImmutableSet.copyOf(groupArray);
+        return ImmutableList.copyOf(groupArray);
       }
     }
   }
 
   static class AllExternalLoader extends
-      CacheLoader<String, Set<AccountGroup.UUID>> {
+      CacheLoader<String, ImmutableList<AccountGroup.UUID>> {
     private final SchemaFactory<ReviewDb> schema;
 
     @Inject
@@ -197,7 +211,7 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
     }
 
     @Override
-    public Set<AccountGroup.UUID> load(String key) throws Exception {
+    public ImmutableList<AccountGroup.UUID> load(String key) throws Exception {
       try (ReviewDb db = schema.open()) {
         Set<AccountGroup.UUID> ids = new HashSet<>();
         for (AccountGroupById agi : db.accountGroupById().all()) {
@@ -205,7 +219,7 @@ public class GroupIncludeCacheImpl implements GroupIncludeCache {
             ids.add(agi.getIncludeUUID());
           }
         }
-        return ImmutableSet.copyOf(ids);
+        return ImmutableList.copyOf(ids);
       }
     }
   }

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

@@ -112,7 +112,7 @@ public class IncludingGroupMembership implements GroupMembership {
     return r;
   }
 
-  private boolean search(Set<AccountGroup.UUID> ids) {
+  private boolean search(Iterable<AccountGroup.UUID> ids) {
     return user.getEffectiveGroups().containsAnyOf(ids);
   }