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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  
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  
87    public void close() {
88    }
89  
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  
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 
116   public void putBack(Cell kv) {
117     this.cache = kv;
118   }
119 
120   public void remove() {
121     throw new UnsupportedOperationException("remove not supported");
122   }
123 }