hbase-client/src/main/java/org/apache/hadoop/hbase/client/Operation.java

   1 /*
   2  *
   3  * Licensed to the Apache Software Foundation (ASF) under one
   4  * or more contributor license agreements.  See the NOTICE file
   5  * distributed with this work for additional information
   6  * regarding copyright ownership.  The ASF licenses this file
   7  * to you under the Apache License, Version 2.0 (the
   8  * "License"); you may not use this file except in compliance
   9  * with the License.  You may obtain a copy of the License at
  10  *
  11  *     http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  * Unless required by applicable law or agreed to in writing, software
  14  * distributed under the License is distributed on an "AS IS" BASIS,
  15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  * See the License for the specific language governing permissions and
  17  * limitations under the License.
  18  */
  19 package org.apache.hadoop.hbase.client;
  20
  21 import java.io.IOException;
  22 import java.util.Map;
  23
  24 import org.apache.hadoop.hbase.classification.InterfaceAudience;
  25 import org.apache.hadoop.hbase.util.JsonMapper;
  26
  27 /**
  28  * Superclass for any type that maps to a potentially application-level query.
  29  * (e.g. Put, Get, Delete, Scan, Next, etc.)
  30  * Contains methods for exposure to logging and debugging tools.
  31  */
  32 @InterfaceAudience.Public
  33 public abstract class Operation {
  34   // TODO make this configurable
  35   // TODO Do we need this anymore now we have protobuffed it all?
  36   private static final int DEFAULT_MAX_COLS = 5;
  37
  38   /**
  39    * Produces a Map containing a fingerprint which identifies the type and
  40    * the static schema components of a query (i.e. column families)
  41    * @return a map containing fingerprint information (i.e. column families)
  42    */
  43   public abstract Map<String, Object> getFingerprint();
  44
  45   /**
  46    * Produces a Map containing a summary of the details of a query
  47    * beyond the scope of the fingerprint (i.e. columns, rows...)
  48    * @param maxCols a limit on the number of columns output prior to truncation
  49    * @return a map containing parameters of a query (i.e. rows, columns...)
  50    */
  51   public abstract Map<String, Object> toMap(int maxCols);
  52
  53   /**
  54    * Produces a Map containing a full summary of a query.
  55    * @return a map containing parameters of a query (i.e. rows, columns...)
  56    */
  57   public Map<String, Object> toMap() {
  58     return toMap(DEFAULT_MAX_COLS);
  59   }
  60
  61   /**
  62    * Produces a JSON object for fingerprint and details exposure in a
  63    * parseable format.
  64    * @param maxCols a limit on the number of columns to include in the JSON
  65    * @return a JSONObject containing this Operation's information, as a string
  66    */
  67   public String toJSON(int maxCols) throws IOException {
  68     return JsonMapper.writeMapAsString(toMap(maxCols));
  69   }
  70
  71   /**
  72    * Produces a JSON object sufficient for description of a query
  73    * in a debugging or logging context.
  74    * @return the produced JSON object, as a string
  75    */
  76   public String toJSON() throws IOException {
  77     return toJSON(DEFAULT_MAX_COLS);
  78   }
  79
  80   /**
  81    * Produces a string representation of this Operation. It defaults to a JSON
  82    * representation, but falls back to a string representation of the
  83    * fingerprint and details in the case of a JSON encoding failure.
  84    * @param maxCols a limit on the number of columns output in the summary
  85    * prior to truncation
  86    * @return a JSON-parseable String
  87    */
  88   public String toString(int maxCols) {
  89     /* for now this is merely a wrapper from producing a JSON string, but
  90      * toJSON is kept separate in case this is changed to be a less parsable
  91      * pretty printed representation.
  92      */
  93     try {
  94       return toJSON(maxCols);
  95     } catch (IOException ioe) {
  96       return toMap(maxCols).toString();
  97     }
  98   }
  99
 100   /**
 101    * Produces a string representation of this Operation. It defaults to a JSON
 102    * representation, but falls back to a string representation of the
 103    * fingerprint and details in the case of a JSON encoding failure.
 104    * @return String
 105    */
 106   @Override
 107   public String toString() {
 108     return toString(DEFAULT_MAX_COLS);
 109   }
 110 }