Line data    Source code

       1             : // Copyright (C) 2016 The Android Open Source Project
       2             : //
       3             : // Licensed under the Apache License, Version 2.0 (the "License");
       4             : // you may not use this file except in compliance with the License.
       5             : // You may obtain a copy of the License at
       6             : //
       7             : // http://www.apache.org/licenses/LICENSE-2.0
       8             : //
       9             : // Unless required by applicable law or agreed to in writing, software
      10             : // distributed under the License is distributed on an "AS IS" BASIS,
      11             : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      12             : // See the License for the specific language governing permissions and
      13             : // limitations under the License.
      14             : 
      15             : package com.google.gerrit.index.query;
      16             : 
      17             : import com.google.common.base.MoreObjects;
      18             : import com.google.common.collect.ImmutableList;
      19             : import com.google.gerrit.exceptions.StorageException;
      20             : import com.google.gerrit.index.Index;
      21             : import com.google.gerrit.index.QueryOptions;
      22             : import java.util.Collection;
      23             : import java.util.List;
      24             : 
      25             : /**
      26             :  * Wrapper combining an {@link IndexPredicate} together with a {@link DataSource} that returns
      27             :  * matching results from the index.
      28             :  *
      29             :  * <p>Appropriate to return as the rootmost predicate that can be processed using the secondary
      30             :  * index; such predicates must also implement {@link DataSource} to be chosen by the query
      31             :  * processor.
      32             :  *
      33             :  * @param <I> The type of the IDs by which the entities are stored in the index.
      34             :  * @param <T> The type of the entities that are stored in the index.
      35             :  */
      36             : public class IndexedQuery<I, T> extends Predicate<T> implements DataSource<T>, Paginated<T> {
      37             :   protected final Index<I, T> index;
      38             : 
      39             :   private QueryOptions opts;
      40             :   private final Predicate<T> pred;
      41             :   protected DataSource<T> source;
      42             : 
      43             :   public IndexedQuery(Index<I, T> index, Predicate<T> pred, QueryOptions opts)
      44         151 :       throws QueryParseException {
      45         151 :     this.index = index;
      46         151 :     this.opts = opts;
      47         151 :     this.pred = pred;
      48         151 :     this.source = index.getSource(pred, this.opts);
      49         151 :   }
      50             : 
      51             :   @Override
      52             :   public int getChildCount() {
      53           0 :     return 1;
      54             :   }
      55             : 
      56             :   @Override
      57             :   public Predicate<T> getChild(int i) {
      58         151 :     if (i == 0) {
      59         151 :       return pred;
      60             :     }
      61           0 :     throw new ArrayIndexOutOfBoundsException(i);
      62             :   }
      63             : 
      64             :   @Override
      65             :   public List<Predicate<T>> getChildren() {
      66           0 :     return ImmutableList.of(pred);
      67             :   }
      68             : 
      69             :   @Override
      70             :   public QueryOptions getOptions() {
      71         106 :     return opts;
      72             :   }
      73             : 
      74             :   @Override
      75             :   public int getCardinality() {
      76         120 :     return source != null ? source.getCardinality() : opts.limit();
      77             :   }
      78             : 
      79             :   @Override
      80             :   public ResultSet<T> read() {
      81         151 :     return source.read();
      82             :   }
      83             : 
      84             :   @Override
      85             :   public ResultSet<FieldBundle> readRaw() {
      86           0 :     return source.readRaw();
      87             :   }
      88             : 
      89             :   @Override
      90             :   public ResultSet<T> restart(int start, int pageSize) {
      91           6 :     opts = opts.withStart(start).withPageSize(pageSize);
      92           6 :     return search();
      93             :   }
      94             : 
      95             :   @Override
      96             :   public ResultSet<T> restart(Object searchAfter, int pageSize) {
      97           4 :     opts = opts.withSearchAfter(searchAfter).withPageSize(pageSize);
      98           4 :     return search();
      99             :   }
     100             : 
     101             :   @Override
     102             :   public Predicate<T> copy(Collection<? extends Predicate<T>> children) {
     103           0 :     return this;
     104             :   }
     105             : 
     106             :   @Override
     107             :   public int hashCode() {
     108           0 :     return pred.hashCode();
     109             :   }
     110             : 
     111             :   // Suppress the EqualsGetClass warning as this is legacy code.
     112             :   @SuppressWarnings("EqualsGetClass")
     113             :   @Override
     114             :   public boolean equals(Object other) {
     115           1 :     if (other == null || getClass() != other.getClass()) {
     116           0 :       return false;
     117             :     }
     118           1 :     IndexedQuery<?, ?> o = (IndexedQuery<?, ?>) other;
     119           1 :     return pred.equals(o.pred) && opts.equals(o.opts);
     120             :   }
     121             : 
     122             :   @Override
     123             :   public String toString() {
     124          14 :     return MoreObjects.toStringHelper("index").add("p", pred).add("opts", opts).toString();
     125             :   }
     126             : 
     127             :   private ResultSet<T> search() {
     128             :     try {
     129           6 :       source = index.getSource(pred, opts);
     130           0 :     } catch (QueryParseException e) {
     131             :       // Don't need to show this exception to the user; the only thing that
     132             :       // changed about pred was its start, and any other QPEs that might happen
     133             :       // should have already thrown from the constructor.
     134           0 :       throw new StorageException(e);
     135           6 :     }
     136             :     // Don't convert start to a limit, since the caller of this method (see
     137             :     // AndSource) has calculated the actual number to skip.
     138           6 :     return read();
     139             :   }
     140             : }