gerrit-index/src/main/java/com/google/gerrit/index/query/DataSource.java

// Copyright (C) 2014 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.gerrit.index.query;

import com.google.gwtorm.server.OrmException;
import com.google.gwtorm.server.ResultSet;

public interface DataSource<T> {
  /** @return an estimate of the number of results from {@link #read()}. */
  int getCardinality();

  /** @return read from the database and return the results. */
  ResultSet<T> read() throws OrmException;
}