Improve performance when importing database

uhabits-android/src/main/java/org/isoron/uhabits/tasks/ImportDataTask.java

@@ -24,6 +24,8 @@ import android.support.annotation.*;
 import com.google.auto.factory.*;
 
 import org.isoron.uhabits.core.io.*;
+import org.isoron.uhabits.core.models.ModelFactory;
+import org.isoron.uhabits.core.models.sqlite.SQLModelFactory;
 import org.isoron.uhabits.core.tasks.*;
 
 import java.io.*;
@@ -37,21 +39,25 @@ public class ImportDataTask implements Task
 
     public static final int SUCCESS = 1;
 
-    int result;
+    private int result;
 
     @NonNull
     private final File file;
 
     private GenericImporter importer;
 
+    private SQLModelFactory modelFactory;
+
     @NonNull
     private final Listener listener;
 
     public ImportDataTask(@Provided @NonNull GenericImporter importer,
+                          @Provided @NonNull ModelFactory modelFactory,
                           @NonNull File file,
                           @NonNull Listener listener)
     {
         this.importer = importer;
+        this.modelFactory = (SQLModelFactory) modelFactory;
         this.listener = listener;
         this.file = file;
     }
@@ -59,12 +65,15 @@ public class ImportDataTask implements Task
     @Override
     public void doInBackground()
     {
+        modelFactory.db.beginTransaction();
+
         try
         {
             if (importer.canHandle(file))
             {
                 importer.importHabitsFromFile(file);
                 result = SUCCESS;
+                modelFactory.db.setTransactionSuccessful();
             }
             else
             {
@@ -76,6 +85,8 @@ public class ImportDataTask implements Task
             result = FAILED;
             e.printStackTrace();
         }
+
+        modelFactory.db.endTransaction();
     }
 
     @Override

uhabits-core/src/main/java/org/isoron/uhabits/core/database/Repository.java

@@ -246,17 +246,28 @@ public class Repository<T>
         return fields;
     }
 
+    private Field[] cacheFields = null;
+
     @NonNull
     private Field[] getFields()
+    {
+        if (cacheFields == null)
         {
             List<Field> fields = new ArrayList<>();
             List<Pair<Field, Column>> columns = getFieldColumnPairs();
             for (Pair<Field, Column> pair : columns) fields.add(pair.getLeft());
-        return fields.toArray(new Field[]{});
+            cacheFields = fields.toArray(new Field[]{});
+        }
+
+        return cacheFields;
     }
 
+    private String[] cacheColumnNames = null;
+
     @NonNull
     private String[] getColumnNames()
+    {
+        if (cacheColumnNames == null)
         {
             List<String> names = new ArrayList<>();
             List<Pair<Field, Column>> columns = getFieldColumnPairs();
@@ -269,35 +280,64 @@ public class Repository<T>
                 names.add(cname);
             }
 
-        return names.toArray(new String[]{});
+            cacheColumnNames = names.toArray(new String[]{});
         }
 
+        return cacheColumnNames;
+    }
+
+    private String cacheTableName = null;
+
     @NonNull
     private String getTableName()
+    {
+        if (cacheTableName == null)
         {
             String name = getTableAnnotation().name();
             if (name.isEmpty()) throw new RuntimeException("Table name is empty");
-        return name;
+            cacheTableName = name;
+        }
+        return cacheTableName;
     }
 
+    private String cacheIdName = null;
+
     @NonNull
     private String getIdName()
+    {
+        if (cacheIdName == null)
         {
             String id = getTableAnnotation().id();
             if (id.isEmpty()) throw new RuntimeException("Table id is empty");
-        return id;
+            cacheIdName = id;
+        }
+
+        return cacheIdName;
     }
 
+    private Field cacheIdField = null;
+
     @NonNull
     private Field getIdField()
+    {
+        if (cacheIdField == null)
         {
             Field fields[] = getFields();
             String idName = getIdName();
             for (Field f : fields)
-            if (f.getName().equals(idName)) return f;
+                if (f.getName().equals(idName))
+                {
+                    cacheIdField = f;
+                    break;
+                }
+
+            if (cacheIdField == null)
                 throw new RuntimeException("Field not found: " + idName);
         }
 
+        return cacheIdField;
+    }
+
     @NonNull
     private Table getTableAnnotation()
     {

uhabits-core/src/main/java/org/isoron/uhabits/core/models/sqlite/SQLModelFactory.java

@@ -33,7 +33,7 @@ import javax.inject.*;
  */
 public class SQLModelFactory implements ModelFactory
 {
-    private final Database db;
+    public final Database db;
 
     @Inject
     public SQLModelFactory(Database db)