Remove AccountAccess.anyAccounts and instead check if user branches exist

With change I81491a253 it is ensured that we have a user branch for each
account. Hence to check if any account exists we can check if any user
branch exists.

This is a preparation step for migration the accounts from ReviewDb to
NoteDb.

Change-Id: Ib8117125a29e6b5f954e70e58e0c8b25e51c585c

gerrit-pgm/src/main/java/com/google/gerrit/pgm/init/AccountsOnInit.java

@@ -21,6 +21,7 @@ import com.google.gerrit.pgm.init.api.InitFlags;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.GerritPersonIdentProvider;
+import com.google.gerrit.server.account.Accounts;
 import com.google.gerrit.server.account.AccountsUpdate;
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gwtorm.server.OrmException;
@@ -60,6 +61,17 @@ public class AccountsOnInit {
     }
   }
 
+  public boolean hasAnyAccount() throws IOException {
+    File path = getPath();
+    if (path == null) {
+      return false;
+    }
+
+    try (Repository repo = new FileRepository(path)) {
+      return Accounts.hasAnyAccount(repo);
+    }
+  }
+
   private File getPath() {
     Path basePath = site.resolve(flags.cfg.getString("gerrit", null, "basePath"));
     checkArgument(basePath != null, "gerrit.basePath must be configured");

gerrit-pgm/src/main/java/com/google/gerrit/pgm/init/InitAdminUser.java

@@ -88,7 +88,7 @@ public class InitAdminUser implements InitStep {
     }
 
     try (ReviewDb db = dbFactory.open()) {
-      if (db.accounts().anyAccounts().toList().isEmpty()) {
+      if (!accounts.hasAnyAccount()) {
         ui.header("Gerrit Administrator");
         if (ui.yesno(true, "Create administrator user")) {
           Account.Id id = new Account.Id(db.nextAccountId());

gerrit-reviewdb/src/main/java/com/google/gerrit/reviewdb/server/AccountAccess.java

@@ -41,9 +41,6 @@ public interface AccountAccess extends Access<Account, Account.Id> {
   ResultSet<Account> suggestByPreferredEmail(String nameA, String nameB, int limit)
       throws OrmException;
 
-  @Query("LIMIT 1")
-  ResultSet<Account> anyAccounts() throws OrmException;
-
   @Query("ORDER BY accountId LIMIT ?")
   ResultSet<Account> firstNById(int n) throws OrmException;
 

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

@@ -52,6 +52,7 @@ public class AccountManager {
   private static final Logger log = LoggerFactory.getLogger(AccountManager.class);
 
   private final SchemaFactory<ReviewDb> schema;
+  private final Accounts accounts;
   private final AccountsUpdate.Server accountsUpdateFactory;
   private final AccountCache byIdCache;
   private final AccountByEmailCache byEmailCache;
@@ -68,6 +69,7 @@ public class AccountManager {
   @Inject
   AccountManager(
       SchemaFactory<ReviewDb> schema,
+      Accounts accounts,
       AccountsUpdate.Server accountsUpdateFactory,
       AccountCache byIdCache,
       AccountByEmailCache byEmailCache,
@@ -80,6 +82,7 @@ public class AccountManager {
       ExternalIds externalIds,
       ExternalIdsUpdate.Server externalIdsUpdateFactory) {
     this.schema = schema;
+    this.accounts = accounts;
     this.accountsUpdateFactory = accountsUpdateFactory;
     this.byIdCache = byIdCache;
     this.byEmailCache = byEmailCache;
@@ -226,8 +229,7 @@ public class AccountManager {
     account.setFullName(who.getDisplayName());
     account.setPreferredEmail(extId.email());
 
-    boolean isFirstAccount =
-        awaitsFirstAccountCheck.getAndSet(false) && db.accounts().anyAccounts().toList().isEmpty();
+    boolean isFirstAccount = awaitsFirstAccountCheck.getAndSet(false) && !accounts.hasAnyAccount();
 
     try {
       AccountsUpdate accountsUpdate = accountsUpdateFactory.create();

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

@@ -0,0 +1,60 @@
+// Copyright (C) 2017 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gerrit.server.account;
+
+import com.google.gerrit.reviewdb.client.Account;
+import com.google.gerrit.reviewdb.client.RefNames;
+import com.google.gerrit.server.config.AllUsersName;
+import com.google.gerrit.server.git.GitRepositoryManager;
+import com.google.inject.Inject;
+import com.google.inject.Singleton;
+import java.io.IOException;
+import java.util.Objects;
+import org.eclipse.jgit.lib.Repository;
+
+/** Class to access accounts. */
+@Singleton
+public class Accounts {
+  private final GitRepositoryManager repoManager;
+  private final AllUsersName allUsersName;
+
+  @Inject
+  Accounts(GitRepositoryManager repoManager, AllUsersName allUsersName) {
+    this.repoManager = repoManager;
+    this.allUsersName = allUsersName;
+  }
+
+  /**
+   * Checks if any account exists.
+   *
+   * @return {@code true} if at least one account exists, otherwise {@code false}
+   */
+  public boolean hasAnyAccount() throws IOException {
+    try (Repository repo = repoManager.openRepository(allUsersName)) {
+      return hasAnyAccount(repo);
+    }
+  }
+
+  public static boolean hasAnyAccount(Repository repo) throws IOException {
+    return repo.getRefDatabase()
+        .getRefs(RefNames.REFS_USERS)
+        .values()
+        .stream()
+        .map(r -> Account.Id.fromRef(r.getName()))
+        .filter(Objects::nonNull)
+        .findAny()
+        .isPresent();
+  }
+}