exec/java-exec/src/main/java/org/apache/drill/exec/planner/logical/StoragePlugins.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.drill.exec.planner.logical;

import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Optional;

import org.apache.drill.common.logical.StoragePluginConfig;
import org.apache.drill.common.map.CaseInsensitiveMap;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;

/**
 * Map of storage plugin *configurations* indexed by name.
 * Does not hold the storage plugin *connector* itself.
 * <p>
 * This class is serialized to JSON and represents the set of
 * storage plugin configurations visible to Drill.
 */
public class StoragePlugins implements Iterable<Map.Entry<String, StoragePluginConfig>> {

  private final Map<String, StoragePluginConfig> storage;

  @JsonCreator
  public StoragePlugins(@JsonProperty("storage") Map<String, StoragePluginConfig> storage) {
    Map<String, StoragePluginConfig> caseInsensitiveStorage = CaseInsensitiveMap.newHashMap();
    Optional.ofNullable(storage).ifPresent(caseInsensitiveStorage::putAll);
    this.storage = caseInsensitiveStorage;
  }

  public StoragePlugins() {
    this(new HashMap<>());
  }

  @JsonProperty("storage")
  public Map<String, StoragePluginConfig> getStorage() {
    return storage;
  }

  @Override
  public String toString() {
    final int maxLen = 10;
    return "StoragePlugins [storage=" + (storage != null ? toString(storage.entrySet(), maxLen) : null) + "]";
  }

  @Override
  public Iterator<Entry<String, StoragePluginConfig>> iterator() {
    return storage.entrySet().iterator();
  }

  private String toString(Collection<?> collection, int maxLen) {
    StringBuilder builder = new StringBuilder();
    builder.append("[");
    int i = 0;
    for (Iterator<?> iterator = collection.iterator(); iterator.hasNext() && i < maxLen; i++) {
      if (i > 0) {
        builder.append(", ");
      }
      builder.append(iterator.next());
    }
    builder.append("]");
    return builder.toString();
  }

  @Override
  public boolean equals(Object obj) {
    if (!(obj instanceof StoragePlugins)) {
      return false;
    }
    return storage.equals(((StoragePlugins) obj).getStorage());
  }

  /**
   * Put one plugin into current storage plugins map
   *
   * @param name storage plugin name
   * @param config storage plugin config
   */
  public void put(String name, StoragePluginConfig config) {
    storage.put(name, config);
  }

  /**
   * Put other storage plugins into current storage plugins map
   *
   * @param plugins storage plugins
   */
  public void putAll(StoragePlugins plugins) {
    Optional.ofNullable(plugins)
        .ifPresent(p -> storage.putAll(p.getStorage()));
  }

  /**
   * Put one plugin into current storage plugins map, if it was absent
   *
   * @param name storage plugin name
   * @param config storage plugin config
   * @return the previous storage plugin config, null if it was absent or it had null value
   */
  public StoragePluginConfig putIfAbsent(String name,  StoragePluginConfig config) {
    return storage.putIfAbsent(name, config);
  }

  /**
   * Return storage plugin config for certain plugin name
   *
   * @param pluginName storage plugin name
   * @return storage plugin config
   */
  public StoragePluginConfig getConfig(String pluginName) {
    return storage.get(pluginName);
  }

  public boolean isEmpty() {
    return storage.isEmpty();
  }
}