Batch CalDAV query

app/src/main/java/org/tasks/data/CaldavDao.java

@@ -1,6 +1,7 @@
 package org.tasks.data;
 
 import static com.todoroo.andlib.utility.AndroidUtilities.atLeastLollipop;
+import static org.tasks.db.DbUtils.collect;
 
 import androidx.lifecycle.LiveData;
 import androidx.room.Dao;
@@ -91,8 +92,12 @@ public abstract class CaldavDao {
   @Query("SELECT cd_object FROM caldav_tasks WHERE cd_calendar = :calendar")
   public abstract List<String> getObjects(String calendar);
 
+  public List<Long> getTasks(String calendar, List<String> objects) {
+    return collect(objects, b -> getTasksInternal(calendar, b));
+  }
+
   @Query("SELECT cd_task FROM caldav_tasks WHERE cd_calendar = :calendar AND cd_object IN (:objects)")
-  public abstract List<Long> getTasks(String calendar, List<String> objects);
+  abstract List<Long> getTasksInternal(String calendar, List<String> objects);
 
   @Query("SELECT * FROM caldav_lists WHERE cdl_account = :account AND cdl_url NOT IN (:urls)")
   public abstract List<CaldavCalendar> findDeletedCalendars(String account, List<String> urls);

app/src/main/java/org/tasks/db/DbUtils.java

@@ -2,13 +2,24 @@ package org.tasks.db;
 
 import static com.google.common.collect.Lists.partition;
 
+import com.google.common.base.Function;
 import com.google.common.collect.Iterables;
+import java.util.ArrayList;
 import java.util.List;
 import org.tasks.Callback;
 
 public class DbUtils {
 
-  private static final int MAX_SQLITE_ARGS = 999;
+  private static final int MAX_SQLITE_ARGS = 990;
+
+  public static <F, T> List<T> collect(List<F> items, Function<List<F>, List<T>> func) {
+    if (items.size() < MAX_SQLITE_ARGS) {
+      return func.apply(items);
+    }
+    List<T> result = new ArrayList<>();
+    batch(items, b -> result.addAll(func.apply(b)));
+    return result;
+  }
 
   public static <T> void batch(List<T> items, Callback<List<T>> callback) {
     batch(items, MAX_SQLITE_ARGS, callback);