Delete any leftover usernames in the accounts db

The account username field should not currently be populated

service/src/main/java/org/whispersystems/textsecuregcm/WhisperServerService.java

@@ -185,6 +185,7 @@ import org.whispersystems.textsecuregcm.storage.MessagesCache;
 import org.whispersystems.textsecuregcm.storage.MessagesDynamoDb;
 import org.whispersystems.textsecuregcm.storage.MessagesManager;
 import org.whispersystems.textsecuregcm.storage.NonNormalizedAccountCrawlerListener;
+import org.whispersystems.textsecuregcm.storage.UsernameCleaner;
 import org.whispersystems.textsecuregcm.storage.PhoneNumberIdentifiers;
 import org.whispersystems.textsecuregcm.storage.Profiles;
 import org.whispersystems.textsecuregcm.storage.ProfilesManager;
@@ -531,6 +532,17 @@ public class WhisperServerService extends Application<WhisperServerConfiguration
         config.getAccountDatabaseCrawlerConfiguration().getChunkIntervalMs()
     );
 
+
+    AccountDatabaseCrawlerCache usernameCleanerAccountDatabaseCrawlerCache =
+        new AccountDatabaseCrawlerCache(cacheCluster, AccountDatabaseCrawlerCache.USERNAME_CLEANER_PREFIX);
+    AccountDatabaseCrawler usernameCleanerAccountDatabaseCrawler = new AccountDatabaseCrawler("username cleaner crawler",
+        accountsManager,
+        usernameCleanerAccountDatabaseCrawlerCache,
+        List.of(new UsernameCleaner(accountsManager)),
+        config.getAccountDatabaseCrawlerConfiguration().getChunkSize(),
+        config.getAccountDatabaseCrawlerConfiguration().getChunkIntervalMs()
+    );
+
     // TODO listeners must be ordered so that ones that directly update accounts come last, so that read-only ones are not working with stale data
     final List<AccountDatabaseCrawlerListener> accountDatabaseCrawlerListeners = List.of(
         new NonNormalizedAccountCrawlerListener(accountsManager, metricsCluster),
@@ -560,6 +572,7 @@ public class WhisperServerService extends Application<WhisperServerConfiguration
     environment.lifecycle().manage(accountDatabaseCrawler);
     environment.lifecycle().manage(directoryReconciliationAccountDatabaseCrawler);
     environment.lifecycle().manage(accountCleanerAccountDatabaseCrawler);
+    environment.lifecycle().manage(usernameCleanerAccountDatabaseCrawler);
     environment.lifecycle().manage(deletedAccountsTableCrawler);
     environment.lifecycle().manage(messagesCache);
     environment.lifecycle().manage(messagePersister);

service/src/main/java/org/whispersystems/textsecuregcm/storage/AccountDatabaseCrawlerCache.java

@@ -19,6 +19,7 @@ public class AccountDatabaseCrawlerCache {
   public static final String GENERAL_PURPOSE_PREFIX = "";
   public static final String DIRECTORY_RECONCILER_PREFIX = "directory-reconciler";
   public static final String ACCOUNT_CLEANER_PREFIX = "account-cleaner";
+  public static final String USERNAME_CLEANER_PREFIX = "username-cleaner";
 
   private static final String ACTIVE_WORKER_KEY = "account_database_crawler_cache_active_worker";
   private static final String LAST_UUID_KEY = "account_database_crawler_cache_last_uuid";

service/src/main/java/org/whispersystems/textsecuregcm/storage/UsernameCleaner.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2022 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.storage;
+
+import io.micrometer.core.instrument.Metrics;
+import io.micrometer.core.instrument.Tags;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import java.util.List;
+import java.util.Optional;
+import java.util.UUID;
+
+import static org.whispersystems.textsecuregcm.metrics.MetricsUtil.name;
+
+public class UsernameCleaner extends AccountDatabaseCrawlerListener {
+  private static final String DELETED_USERNAME_COUNTER = name(UsernameCleaner.class, "deletedUsernames");
+  private static final Logger logger = LoggerFactory.getLogger(UsernameCleaner.class);
+
+  private final AccountsManager accountsManager;
+
+  public UsernameCleaner(AccountsManager accountsManager) {
+    this.accountsManager = accountsManager;
+  }
+
+  @Override
+  public void onCrawlStart() {
+  }
+
+  @Override
+  protected void onCrawlChunk(final Optional<UUID> fromUuid, final List<Account> chunkAccounts) {
+    for (Account account : chunkAccounts) {
+      if (account.getUsername().isPresent()) {
+        logger.info("Deleting username present for account {}", account.getUuid());
+        try {
+          this.accountsManager.clearUsername(account);
+          Metrics.counter(DELETED_USERNAME_COUNTER, Tags.of("outcome", "success")).increment();
+        } catch (Exception e) {
+          logger.warn("Failed to clear username on account {}", account.getUuid(), e);
+          Metrics.counter(DELETED_USERNAME_COUNTER, Tags.of("outcome", "error")).increment();
+        }
+      }
+    }
+  }
+
+  @Override
+  public void onCrawlEnd(final Optional<UUID> fromUuid) {
+    logger.info("Username cleaner crawl completed");
+  }
+}

service/src/test/java/org/whispersystems/textsecuregcm/storage/UsernameCleanerTest.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2022 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+package org.whispersystems.textsecuregcm.storage;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import java.util.*;
+import static org.mockito.Mockito.*;
+
+class UsernameCleanerTest {
+
+  private final AccountsManager accountsManager = mock(AccountsManager.class);
+  private final Account hasUsername = mock(Account.class);
+  private final Account noUsername = mock(Account.class);
+
+
+  @BeforeEach
+  void setup() {
+    when(hasUsername.getUsername()).thenReturn(Optional.of("n00bkiller"));
+    when(noUsername.getUsername()).thenReturn(Optional.empty());
+  }
+
+  @Test
+  void testAccounts() throws AccountDatabaseCrawlerRestartException {
+    UsernameCleaner accountCleaner = new UsernameCleaner(accountsManager);
+    accountCleaner.onCrawlStart();
+    accountCleaner.timeAndProcessCrawlChunk(Optional.empty(), Arrays.asList(hasUsername, noUsername));
+    accountCleaner.onCrawlEnd(Optional.empty());
+    verify(accountsManager).clearUsername(hasUsername);
+    verify(accountsManager, never()).clearUsername(noUsername);
+  }
+}