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 
20 package org.apache.hadoop.hbase.rest;
21 
22 import java.io.IOException;
23 import java.util.Iterator;
24 import java.util.NoSuchElementException;
25 
26 import org.apache.commons.logging.Log;
27 import org.apache.commons.logging.LogFactory;
28 import org.apache.hadoop.hbase.classification.InterfaceAudience;
29 import org.apache.hadoop.hbase.Cell;
30 import org.apache.hadoop.hbase.DoNotRetryIOException;
31 import org.apache.hadoop.hbase.KeyValue;
32 import org.apache.hadoop.hbase.client.Get;
33 import org.apache.hadoop.hbase.client.NeedUnmanagedConnectionException;
34 import org.apache.hadoop.hbase.client.Result;
35 import org.apache.hadoop.hbase.client.Table;
36 import org.apache.hadoop.hbase.filter.Filter;
37 import org.apache.hadoop.util.StringUtils;
38 
39 @InterfaceAudience.Private
40 public class RowResultGenerator extends ResultGenerator {
41   private static final Log LOG = LogFactory.getLog(RowResultGenerator.class);
42 
43   private Iterator<Cell> valuesI;
44   private Cell cache;
45 
RowResultGenerator(final String tableName, final RowSpec rowspec, final Filter filter, final boolean cacheBlocks)46   public RowResultGenerator(final String tableName, final RowSpec rowspec,
47       final Filter filter, final boolean cacheBlocks)
48       throws IllegalArgumentException, IOException {
49     Table table = RESTServlet.getInstance().getTable(tableName);
50     try {
51       Get get = new Get(rowspec.getRow());
52       if (rowspec.hasColumns()) {
53         for (byte[] col: rowspec.getColumns()) {
54           byte[][] split = KeyValue.parseColumn(col);
55           if (split.length == 1) {
56             get.addFamily(split[0]);
57           } else if (split.length == 2) {
58             get.addColumn(split[0], split[1]);
59           } else {
60             throw new IllegalArgumentException("Invalid column specifier.");
61           }
62         }
63       }
64       get.setTimeRange(rowspec.getStartTime(), rowspec.getEndTime());
65       get.setMaxVersions(rowspec.getMaxVersions());
66       if (filter != null) {
67         get.setFilter(filter);
68       }
69       get.setCacheBlocks(cacheBlocks);
70       Result result = table.get(get);
71       if (result != null && !result.isEmpty()) {
72         valuesI = result.listCells().iterator();
73       }
74     } catch (DoNotRetryIOException | NeedUnmanagedConnectionException e) {
75       // Warn here because Stargate will return 404 in the case if multiple
76       // column families were specified but one did not exist -- currently
77       // HBase will fail the whole Get.
78       // Specifying multiple columns in a URI should be uncommon usage but
79       // help to avoid confusion by leaving a record of what happened here in
80       // the log.
81       LOG.warn(StringUtils.stringifyException(e));
82     } finally {
83       table.close();
84     }
85   }
86 
close()87   public void close() {
88   }
89 
hasNext()90   public boolean hasNext() {
91     if (cache != null) {
92       return true;
93     }
94     if (valuesI == null) {
95       return false;
96     }
97     return valuesI.hasNext();
98   }
99 
next()100   public Cell next() {
101     if (cache != null) {
102       Cell kv = cache;
103       cache = null;
104       return kv;
105     }
106     if (valuesI == null) {
107       return null;
108     }
109     try {
110       return valuesI.next();
111     } catch (NoSuchElementException e) {
112       return null;
113     }
114   }
115 
putBack(Cell kv)116   public void putBack(Cell kv) {
117     this.cache = kv;
118   }
119 
remove()120   public void remove() {
121     throw new UnsupportedOperationException("remove not supported");
122   }
123 }
124