001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019package org.apache.hadoop.hbase.quotas;
020
021import java.util.List;
022
023import org.apache.yetus.audience.InterfaceAudience;
024import org.apache.yetus.audience.InterfaceStability;
025import org.apache.hadoop.hbase.client.Mutation;
026import org.apache.hadoop.hbase.client.Result;
027
028/**
029 * Interface that allows to check the quota available for an operation.
030 */
031@InterfaceAudience.Private
032@InterfaceStability.Evolving
033public interface OperationQuota {
034  public enum OperationType { MUTATE, GET, SCAN }
035
036  /**
037   * Checks if it is possible to execute the specified operation.
038   * The quota will be estimated based on the number of operations to perform
039   * and the average size accumulated during time.
040   *
041   * @param numWrites number of write operation that will be performed
042   * @param numReads number of small-read operation that will be performed
043   * @param numScans number of long-read operation that will be performed
044   * @throws RpcThrottlingException if the operation cannot be performed because
045   *   RPC quota is exceeded.
046   */
047  void checkQuota(int numWrites, int numReads, int numScans)
048    throws RpcThrottlingException;
049
050  /** Cleanup method on operation completion */
051  void close();
052
053  /**
054   * Add a get result. This will be used to calculate the exact quota and
055   * have a better short-read average size for the next time.
056   */
057  void addGetResult(Result result);
058
059  /**
060   * Add a scan result. This will be used to calculate the exact quota and
061   * have a better long-read average size for the next time.
062   */
063  void addScanResult(List<Result> results);
064
065  /**
066   * Add a mutation result. This will be used to calculate the exact quota and
067   * have a better mutation average size for the next time.
068   */
069  void addMutation(Mutation mutation);
070
071  /** @return the number of bytes available to read to avoid exceeding the quota */
072  long getReadAvailable();
073
074  /** @return the number of bytes available to write to avoid exceeding the quota */
075  long getWriteAvailable();
076}