TransactionVisibilityState.java

/*
 * Copyright © 2015 Cask Data, Inc.
 *
 * 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 co.cask.tephra.persist;

import co.cask.tephra.TransactionManager;

import java.util.Collection;
import java.util.NavigableMap;

/**
 * Transaction Visibility state contains information required by TransactionProcessor CoProcessor
 * to determine cell visibility.
 */
public interface TransactionVisibilityState {

  /**
   * Returns the timestamp from when this snapshot was created.
   */
  long getTimestamp();

  /**
   * Returns the read pointer at the time of the snapshot.
   */
  long getReadPointer();

  /**
   * Returns the next write pointer at the time of the snapshot.
   */
  long getWritePointer();

  /**
   * Returns the list of invalid write pointers at the time of the snapshot.
   */
  Collection<Long> getInvalid();

  /**
   * Returns the map of write pointers to in-progress transactions at the time of the snapshot.
   */
  NavigableMap<Long, TransactionManager.InProgressTx> getInProgress();

  /**
   * @return transaction id {@code X} such that any of the transactions newer than {@code X} might be invisible to
   *         some of the currently in-progress transactions or to those that will be started <p>
   *         NOTE: the returned tx id can be invalid.
   */
  long getVisibilityUpperBound();
}