【软件工程实践】Hive研究-Blog5

2021SC@SDUSC

本人负责的是负责的是将查询块QB转换成逻辑查询计划（OP Tree）
如下的代码出自apaceh-hive-3.1.2-src/ql/src/java/org/apache/hadoop/hive/ql/plan中，也就是我的分析目标代码。本周的研究计划是解析PlanMapper.java文件源码。

我们首先附上整个java文件的源码。

package org.apache.hadoop.hive.ql.plan.mapper;

import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.Set;

import org.apache.hadoop.hive.ql.exec.Operator;
import org.apache.hadoop.hive.ql.optimizer.signature.OpTreeSignature;
import org.apache.hadoop.hive.ql.optimizer.signature.OpTreeSignatureFactory;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.collect.Sets;


public class PlanMapper {

  Set groups = new HashSet<>();
  private Map objectMap = new CompositeMap<>(OpTreeSignature.class);

  
  private static class CompositeMap implements Map {

    Map comparedMap = new HashMap<>();
    Map identityMap = new IdentityHashMap<>();
    final Set> typeCompared;

    CompositeMap(Class... comparedTypes) {
      for (Class class1 : comparedTypes) {
        if (!Modifier.isFinal(class1.getModifiers())) {
          throw new RuntimeException(class1 + " is not final...for this to reliably work; it should be");
        }
      }
      typeCompared = Sets.newHashSet(comparedTypes);
    }

    @Override
    public int size() {
      return comparedMap.size() + identityMap.size();
    }

    @Override
    public boolean isEmpty() {
      return comparedMap.isEmpty() && identityMap.isEmpty();
    }

    @Override
    public boolean containsKey(Object key) {
      return comparedMap.containsKey(key) || identityMap.containsKey(key);
    }

    @Override
    public boolean containsValue(Object value) {
      return comparedMap.containsValue(value) || identityMap.containsValue(value);
    }

    @Override
    public V get(Object key) {
      V v0 = comparedMap.get(key);
      if (v0 != null) {
        return v0;
      }
      return identityMap.get(key);
    }

    @Override
    public V put(K key, V value) {
      if (shouldCompare(key.getClass())) {
        return comparedMap.put(key, value);
      } else {
        return identityMap.put(key, value);
      }
    }

    @Override
    public V remove(Object key) {
      if (shouldCompare(key.getClass())) {
        return comparedMap.remove(key);
      } else {
        return identityMap.remove(key);
      }
    }

    private boolean shouldCompare(Class key) {
      return typeCompared.contains(key);
    }

    @Override
    public void putAll(Map m) {
      for (Entry e : m.entrySet()) {
        put(e.getKey(), e.getValue());
      }
    }

    @Override
    public void clear() {
      comparedMap.clear();
      identityMap.clear();
    }

    @Override
    public Set keySet() {
      return Sets.union(comparedMap.keySet(), identityMap.keySet());
    }

    @Override
    public Collection values() {
      throw new UnsupportedOperationException("This method is not supported");
    }

    @Override
    public Set> entrySet() {
      return Sets.union(comparedMap.entrySet(), identityMap.entrySet());
    }

  }

  
  public class EquivGroup {
    Set