content: /*
   * 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.ambari.server.topology;
  
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  
  import org.apache.ambari.server.api.predicate.InvalidQueryException;
  import org.apache.ambari.server.api.predicate.PredicateCompiler;
  import org.apache.ambari.server.controller.spi.Predicate;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Host Group information specific to a cluster instance.
   */
  public class HostGroupInfo {
  
    private final static Logger LOG = LoggerFactory.getLogger(HostGroupInfo.class);
  
    /**
     * predicate compiler
     */
    private static PredicateCompiler predicateCompiler = new PredicateCompiler();
  
    /**
     * host group name
     */
    private String hostGroupName;
    /**
     * hosts contained associated with the host group
     */
    private final Collection<String> hostNames = new HashSet<>();
  
    /**
     * maps host names to rack information
     * todo maintain a single structure for hostnames and rack information
     */
    private final Map<String, String> hostRackInfo = new HashMap<>();
  
    /**
     * explicitly specified host count
     */
    private int requested_count = 0;
  
    /**
     * host group scoped configuration
     */
    Configuration configuration;
  
    /**
     * explicitly specified host predicate string
     */
    String predicateString;
  
    /**
     * compiled host predicate
     */
    Predicate predicate;
  
  
    /**
     * Constructor
     *
     * @param hostGroupName  host group name
     */
    public HostGroupInfo(String hostGroupName) {
      this.hostGroupName = hostGroupName;
    }
  
    /**
     * Get the host group name.
     *
     * @return host group name
     */
    public String getHostGroupName() {
      return hostGroupName;
    }
  
    /**
     * Get the collection of user specified host names for the host group.
     * If the user specified a count instead of host names then an empty
     * collection is returned.
     *
     * @return collection of user specified host names; will never be null
     */
    public Collection<String> getHostNames() {
      // needs to be an exclusive lock, not a read lock because collection
      // shouldn't change while copying elements into the new set instance
      synchronized (hostNames) {
        return new HashSet<>(hostNames);
      }
    }
  
    /**
     * Get the requested host count.
     * This is either the user specified value or
     * the number of explicitly specified host names specified by the user.
     *
     * @return number of requested hosts for the group
     */
    public int getRequestedHostCount() {
      synchronized (hostNames) {
        return requested_count == 0 ? hostNames.size() : requested_count;
      }
    }
  
    /**
     * Associate a single host name to the host group.
     *
     * @param hostName  the host name to associate with the host group
     */
    public void addHost(String hostName) {
      synchronized(hostNames) {
        String lowerHostName = hostName.toLowerCase();
        if (!hostName.equals(lowerHostName)) {
          LOG.warn("Host name {} contains upper case letters, will be converted to lowercase!", hostName );
        }
        hostNames.add(lowerHostName);
      }
    }
  
    /**
     * Associate multiple host names to the host group.
     *
     * @param hosts  collection of host names to associate with the host group
     */
    public void addHosts(Collection<String> hosts) {
      synchronized (hostNames) {
        for (String host : hosts) {
          addHost(host);
        }
      }
    }
  
    /**
     * Set the requested host count for the host group.
     *
     * @param num  requested host count
     */
    public void setRequestedCount(int num) {
      requested_count = num;
    }
  
    /**
     * Set host group configuration for the host group.
     *
     * @param configuration configuration instance
     */
    public void setConfiguration(Configuration configuration) {
      this.configuration = configuration;
    }
  
    /**
     * Get the host group configuration associated with the host group.
     *
     * @return associated host group scoped configuration or null if no configuration
     *         is specified for the host group
     */
    public Configuration getConfiguration() {
      return configuration;
    }
  
    /**
     * Set the host predicate for the host group.
     *
     * @param predicateString  host predicate as a string
     *
     * @throws InvalidQueryException if compilation of the predicate fails
     */
    public void setPredicate(String predicateString) throws InvalidQueryException {
      this.predicate = predicateCompiler.compile(predicateString);
      this.predicateString = predicateString;
    }
  
    /**
     * Get the compiled host predicate for the host group.
     *
     * @return the compiled host predicate or null if no predicate was specified
     */
    public Predicate getPredicate() {
      return predicate;
    }
  
    /**
     * Get the host predicate string for the host group.
     *
     * @return the host predicate string or null if no predicate was specified
     */
    public String getPredicateString() {
      return predicateString;
    }
  
    /**
     * Registers host rack information.
     *
     * @param host     the name of the host
     * @param rackInfo the rack information
     */
    public void addHostRackInfo(String host, String rackInfo) {
      synchronized (hostRackInfo) {
        hostRackInfo.put(host, rackInfo);
      }
    }
  
    /**
     * Returns a map with host names mapped to rack information.
     *
     * @return a copy of the current instance' rack information map
     */
    public Map<String, String> getHostRackInfo() {
      synchronized (hostRackInfo) {
        return new HashMap<>(hostRackInfo);
      }
    }
  
    /**
     * Removes hostname from group
     * @param hostname
     */
    public void removeHost(String hostname) {
      synchronized (hostNames) {
        hostNames.remove(hostname);
      }
    }
  
  }
  