Replace AccountAccess#firstNById(int) by looking at user refs

Remove AccountAccess#firstNById(int) and find the first n accounts by
looking at the user refs in All-Users instead. Since change I81491a253
it is ensured that we have a user branch for each account.

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

Change-Id: I0d8a74d6d2de253b4311b8e91517568c1a09f2a8
Signed-off-by: Edwin Kempin <ekempin@google.com>

gerrit-httpd/src/main/java/com/google/gerrit/httpd/auth/become/BecomeAnyAccountLoginServlet.java

@@ -25,16 +25,17 @@ import com.google.gerrit.httpd.WebSession;
 import com.google.gerrit.httpd.template.SiteHeaderFooter;
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.server.ReviewDb;
+import com.google.gerrit.server.account.AccountCache;
 import com.google.gerrit.server.account.AccountException;
 import com.google.gerrit.server.account.AccountManager;
 import com.google.gerrit.server.account.AccountState;
+import com.google.gerrit.server.account.Accounts;
 import com.google.gerrit.server.account.AuthRequest;
 import com.google.gerrit.server.account.AuthResult;
 import com.google.gerrit.server.account.externalids.ExternalId;
 import com.google.gerrit.server.query.account.InternalAccountQuery;
 import com.google.gwtexpui.server.CacheHeaders;
 import com.google.gwtorm.server.OrmException;
-import com.google.gwtorm.server.ResultSet;
 import com.google.gwtorm.server.SchemaFactory;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
@@ -54,8 +55,10 @@ import org.w3c.dom.Element;
 @SuppressWarnings("serial")
 @Singleton
 class BecomeAnyAccountLoginServlet extends HttpServlet {
-  private final SchemaFactory<ReviewDb> schema;
   private final DynamicItem<WebSession> webSession;
+  private final SchemaFactory<ReviewDb> schema;
+  private final Accounts accounts;
+  private final AccountCache accountCache;
   private final AccountManager accountManager;
   private final SiteHeaderFooter headers;
   private final InternalAccountQuery accountQuery;
@@ -64,11 +67,15 @@ class BecomeAnyAccountLoginServlet extends HttpServlet {
   BecomeAnyAccountLoginServlet(
       DynamicItem<WebSession> ws,
       SchemaFactory<ReviewDb> sf,
+      Accounts a,
+      AccountCache ac,
       AccountManager am,
       SiteHeaderFooter shf,
       InternalAccountQuery aq) {
     webSession = ws;
     schema = sf;
+    accounts = a;
+    accountCache = ac;
     accountManager = am;
     headers = shf;
     accountQuery = aq;
@@ -149,8 +156,8 @@ class BecomeAnyAccountLoginServlet extends HttpServlet {
 
     Element userlistElement = HtmlDomUtil.find(doc, "userlist");
     try (ReviewDb db = schema.open()) {
-      ResultSet<Account> accounts = db.accounts().firstNById(100);
-      for (Account a : accounts) {
+      for (Account.Id accountId : accounts.firstNIds(100)) {
+        Account a = accountCache.get(accountId).getAccount();
         String displayName;
         if (a.getUserName() != null) {
           displayName = a.getUserName();
@@ -159,7 +166,7 @@ class BecomeAnyAccountLoginServlet extends HttpServlet {
         } else if (a.getPreferredEmail() != null) {
           displayName = a.getPreferredEmail();
         } else {
-          displayName = a.getId().toString();
+          displayName = accountId.toString();
         }
 
         Element linkElement = doc.createElement("a");

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("ORDER BY accountId LIMIT ?")
-  ResultSet<Account> firstNById(int n) throws OrmException;
-
   @Query("ORDER BY accountId")
   ResultSet<Account> all() throws OrmException;
 }

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

@@ -14,6 +14,9 @@
 
 package com.google.gerrit.server.account;
 
+import static java.util.Comparator.comparing;
+import static java.util.stream.Collectors.toList;
+
 import com.google.gerrit.reviewdb.client.Account;
 import com.google.gerrit.reviewdb.client.RefNames;
 import com.google.gerrit.server.config.AllUsersName;
@@ -21,7 +24,9 @@ import com.google.gerrit.server.git.GitRepositoryManager;
 import com.google.inject.Inject;
 import com.google.inject.Singleton;
 import java.io.IOException;
+import java.util.List;
 import java.util.Objects;
+import java.util.stream.Stream;
 import org.eclipse.jgit.lib.Repository;
 
 /** Class to access accounts. */
@@ -36,6 +41,16 @@ public class Accounts {
     this.allUsersName = allUsersName;
   }
 
+  /**
+   * Returns the first n account IDs.
+   *
+   * @param n the number of account IDs that should be returned
+   * @return first n account IDs
+   */
+  public List<Account.Id> firstNIds(int n) throws IOException {
+    return readUserRefs().sorted(comparing(id -> id.get())).limit(n).collect(toList());
+  }
+
   /**
    * Checks if any account exists.
    *
@@ -48,13 +63,21 @@ public class Accounts {
   }
 
   public static boolean hasAnyAccount(Repository repo) throws IOException {
+    return readUserRefs(repo).findAny().isPresent();
+  }
+
+  private Stream<Account.Id> readUserRefs() throws IOException {
+    try (Repository repo = repoManager.openRepository(allUsersName)) {
+      return readUserRefs(repo);
+    }
+  }
+
+  private static Stream<Account.Id> readUserRefs(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();
+        .filter(Objects::nonNull);
   }
 }