Disabling sync/compact combo (#3899)

* Disabling sync/compact combo

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## 2.2.2
 
+### Object Server API Changes (In Beta)
+
+* Disabled `Realm.compactRealm()` when sync is enabled as it might corrupt the Realm (https://github.com/realm/realm-core/issues/2345).
+
 ### Enhancements
 
 * All major public classes are now non-final. This is mostly a compromise to

realm/realm-library/src/androidTestObjectServer/java/io/realm/SyncConfigurationTests.java

@@ -401,4 +401,14 @@ public void toString_nonEmpty() {
         String configStr = config.toString();
         assertTrue(configStr != null && !configStr.isEmpty());
     }
+
+    // FIXME: This test can be removed when https://github.com/realm/realm-core/issues/2345 is resolved
+    @Test(expected = UnsupportedOperationException.class)
+    public void compact_NotAllowed() {
+        SyncUser user = createTestUser();
+        String url = "realm://objectserver.realm.io/default";
+        SyncConfiguration config = new SyncConfiguration.Builder(user, url).build();
+
+        Realm.compactRealm(config);
+    }
 }

realm/realm-library/src/main/java/io/realm/Realm.java

@@ -1555,10 +1555,13 @@ public static boolean deleteRealm(RealmConfiguration configuration) {
      *
      * @param configuration a {@link RealmConfiguration} pointing to a Realm file.
      * @return {@code true} if successful, {@code false} if any file operation failed.
-     * @throws IllegalArgumentException if the realm file is encrypted. Compacting an encrypted Realm file is not
-     *                                  supported yet.
+     * @throws UnsupportedOperationException if Realm is synchronized.
      */
     public static boolean compactRealm(RealmConfiguration configuration) {
+        // FIXME: remove this restriction when https://github.com/realm/realm-core/issues/2345 is resolved
+        if (configuration.isSyncConfiguration()) {
+            throw new UnsupportedOperationException("Compacting is not supported yet on synced Realms. See https://github.com/realm/realm-core/issues/2345");
+        }
         return BaseRealm.compactRealm(configuration);
     }