library/src/main/java/com/datatorrent/lib/bucket/BucketStore.java

/*
 * Copyright (c) 2014 DataTorrent, Inc. ALL Rights Reserved.
 *
 * 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.datatorrent.lib.bucket;

import java.io.IOException;
import java.util.Map;

import javax.annotation.Nonnull;

/**
 * Bucket store API.<br/>
 *
 * @since 0.9.4
 */
public interface BucketStore<T extends Bucketable>
{
  /**
   * Performs setup operations eg. crate database connections, delete events of windows greater than last committed
   * window, etc.
   */
  void setup();

  /**
   * Performs teardown operations eg. close database connections.
   */
  void teardown();

  /**
   * Stores the un-written bucket data collected in the given window.
   *
   * @param window    window for which data is saved.
   * @param timestamp timestamp corresponding to which data would be saved.
   * @param data      bucket events to be persisted.
   */
  void storeBucketData(long window, long timestamp, Map<Integer, Map<Object, T>> data) throws IOException;

  /**
   * Deletes bucket corresponding to the bucket index from the persistent store.
   *
   * @param bucketIdx index of the bucket to delete.
   */
  void deleteBucket(int bucketIdx) throws IOException;

  /**
   * Fetches events of the bucket corresponding to the bucket index from the store.
   *
   * @param bucketIdx index of bucket.
   * @return bucket events
   * @throws Exception
   */
  @Nonnull
  Map<Object, T> fetchBucket(int bucketIdx) throws Exception;

  /**
   * Sets the total number of buckets.
   *
   * @param noOfBuckets
   */
  void setNoOfBuckets(int noOfBuckets);

  /**
   * Set true for keeping only event keys in memory and store; false otherwise.
   *
   * @param writeEventKeysOnly
   */
  void setWriteEventKeysOnly(boolean writeEventKeysOnly);

  public interface ExpirableBucketStore<T extends Bucketable & Event> extends BucketStore<T>
  {
    void deleteExpiredBuckets(long time) throws IOException;
  }
}