/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  package org.apache.http.pool;
  
  import java.util.concurrent.TimeUnit;
  
  import org.apache.http.annotation.GuardedBy;
  import org.apache.http.annotation.ThreadSafe;
  
  /**
   * Pool entry containing a pool connection object along with its route.
   * <p/>
   * The connection contained by the pool entry may have an expiration time which
   * can be either set upon construction time or updated with
   * the {@link #updateExpiry(long, TimeUnit)}.
   * <p/>
   * Pool entry may also have an object associated with it that represents
   * a connection state (usually a security principal or a unique token identifying
   * the user whose credentials have been used while establishing the connection).
   *
   * @param <T> the route type that represents the opposite endpoint of a pooled
   *   connection.
   * @param <C> the connection type.
   * @since 4.2
   */
  @ThreadSafe
  public abstract class PoolEntry<T, C> {
  
      private final String id;
      private final T route;
      private final C conn;
      private final long created;
      private final long validUnit;
  
      @GuardedBy("this")
      private long updated;
  
      @GuardedBy("this")
      private long expiry;
  
      private volatile Object state;
  
      /**
       * Creates new <tt>PoolEntry</tt> instance.
       *
       * @param id unique identifier of the pool entry. May be <code>null</code>.
       * @param route route to the opposite endpoint.
       * @param conn the connection.
       * @param timeToLive maximum time to live. May be zero if the connection
       *   does not have an expiry deadline.
       * @param tunit time unit.
       */
      public PoolEntry(final String id, final T route, final C conn,
              final long timeToLive, final TimeUnit tunit) {
          super();
          if (route == null) {
              throw new IllegalArgumentException("Route may not be null");
          }
          if (conn == null) {
              throw new IllegalArgumentException("Connection may not be null");
          }
          if (tunit == null) {
              throw new IllegalArgumentException("Time unit may not be null");
          }
          this.id = id;
          this.route = route;
          this.conn = conn;
          this.created = System.currentTimeMillis();
          if (timeToLive > 0) {
              this.validUnit = this.created + tunit.toMillis(timeToLive);
          } else {
              this.validUnit = Long.MAX_VALUE;
          }
          this.expiry = this.validUnit;
      }
 
     /**
      * Creates new <tt>PoolEntry</tt> instance without an expiry deadline.
      *
      * @param id unique identifier of the pool entry. May be <code>null</code>.
      * @param route route to the opposite endpoint.
      * @param conn the connection.
      */
     public PoolEntry(final String id, final T route, final C conn) {
         this(id, route, conn, 0, TimeUnit.MILLISECONDS);
     }
 
     public String getId() {
         return this.id;
     }
 
     public T getRoute() {
         return this.route;
     }
 
     public C getConnection() {
         return this.conn;
     }
 
     public long getCreated() {
         return this.created;
     }
 
     public long getValidUnit() {
         return this.validUnit;
     }
 
     public Object getState() {
         return this.state;
     }
 
     public void setState(final Object state) {
         this.state = state;
     }
 
     public synchronized long getUpdated() {
         return this.updated;
     }
 
     public synchronized long getExpiry() {
         return this.expiry;
     }
 
     public synchronized void updateExpiry(final long time, final TimeUnit tunit) {
         if (tunit == null) {
             throw new IllegalArgumentException("Time unit may not be null");
         }
         this.updated = System.currentTimeMillis();
         long newExpiry;
         if (time > 0) {
             newExpiry = this.updated + tunit.toMillis(time);
         } else {
             newExpiry = Long.MAX_VALUE;
         }
         this.expiry = Math.min(newExpiry, this.validUnit);
     }
 
     public synchronized boolean isExpired(final long now) {
         return now >= this.expiry;
     }
 
     /**
      * Invalidates the pool entry and closes the pooled connection associated
      * with it.
      */
     public abstract void close();
 
     /**
      * Returns <code>true</code> if the pool entry has been invalidated.
      */
     public abstract boolean isClosed();
 
     @Override
     public String toString() {
         StringBuilder buffer = new StringBuilder();
         buffer.append("[id:");
         buffer.append(this.id);
         buffer.append("][route:");
         buffer.append(this.route);
         buffer.append("][state:");
         buffer.append(this.state);
         buffer.append("]");
         return buffer.toString();
     }
 
 }