/*
    * ====================================================================
    * 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.impl.conn.tsccm;
  
  import java.io.IOException;
  import java.util.Date;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.Map;
  import java.util.Queue;
  import java.util.Set;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.locks.Condition;
  import java.util.concurrent.locks.Lock;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.http.conn.ClientConnectionOperator;
  import org.apache.http.conn.ConnectionPoolTimeoutException;
  import org.apache.http.conn.OperatedClientConnection;
  import org.apache.http.conn.params.ConnManagerParams;
  import org.apache.http.conn.params.ConnPerRoute;
  import org.apache.http.conn.routing.HttpRoute;
  import org.apache.http.params.HttpParams;
  import org.apache.http.util.Args;
  import org.apache.http.util.Asserts;
  
  /**
   * A connection pool that maintains connections by route.
   * This class is derived from {@code MultiThreadedHttpConnectionManager}
   * in HttpClient 3.x, see there for original authors. It implements the same
   * algorithm for connection re-use and connection-per-host enforcement:
   * <ul>
   * <li>connections are re-used only for the exact same route</li>
   * <li>connection limits are enforced per route rather than per host</li>
   * </ul>
   * Note that access to the pool data structures is synchronized via the
   * {@link AbstractConnPool#poolLock poolLock} in the base class,
   * not via {@code synchronized} methods.
   *
   * @since 4.0
   *
   * @deprecated (4.2)  use {@link org.apache.http.pool.AbstractConnPool}
   */
  @Deprecated
  public class ConnPoolByRoute extends AbstractConnPool {
  
      private final Log log = LogFactory.getLog(getClass());
  
      private final Lock poolLock;
  
      /** Connection operator for this pool */
      protected final ClientConnectionOperator operator;
  
      /** Connections per route lookup */
      protected final ConnPerRoute connPerRoute;
  
      /** References to issued connections */
      protected final Set<BasicPoolEntry> leasedConnections;
  
      /** The list of free connections */
      protected final Queue<BasicPoolEntry> freeConnections;
  
      /** The list of WaitingThreads waiting for a connection */
      protected final Queue<WaitingThread> waitingThreads;
  
      /** Map of route-specific pools */
      protected final Map<HttpRoute, RouteSpecificPool> routeToPool;
  
      private final long connTTL;
  
      private final TimeUnit connTTLTimeUnit;
  
      protected volatile boolean shutdown;
 
     protected volatile int maxTotalConnections;
 
     protected volatile int numConnections;
 
     /**
      * Creates a new connection pool, managed by route.
      *
      * @since 4.1
      */
     public ConnPoolByRoute(
             final ClientConnectionOperator operator,
             final ConnPerRoute connPerRoute,
             final int maxTotalConnections) {
         this(operator, connPerRoute, maxTotalConnections, -1, TimeUnit.MILLISECONDS);
     }
 
     /**
      * @since 4.1
      */
     public ConnPoolByRoute(
             final ClientConnectionOperator operator,
             final ConnPerRoute connPerRoute,
             final int maxTotalConnections,
             final long connTTL,
             final TimeUnit connTTLTimeUnit) {
         super();
         Args.notNull(operator, "Connection operator");
         Args.notNull(connPerRoute, "Connections per route");
         this.poolLock = super.poolLock;
         this.leasedConnections = super.leasedConnections;
         this.operator = operator;
         this.connPerRoute = connPerRoute;
         this.maxTotalConnections = maxTotalConnections;
         this.freeConnections = createFreeConnQueue();
         this.waitingThreads  = createWaitingThreadQueue();
         this.routeToPool     = createRouteToPoolMap();
         this.connTTL = connTTL;
         this.connTTLTimeUnit = connTTLTimeUnit;
     }
 
     protected Lock getLock() {
         return this.poolLock;
     }
 
     /**
      * Creates a new connection pool, managed by route.
      *
      * @deprecated (4.1)  use {@link ConnPoolByRoute#ConnPoolByRoute(ClientConnectionOperator, ConnPerRoute, int)}
      */
     @Deprecated
     public ConnPoolByRoute(final ClientConnectionOperator operator, final HttpParams params) {
         this(operator,
                 ConnManagerParams.getMaxConnectionsPerRoute(params),
                 ConnManagerParams.getMaxTotalConnections(params));
     }
 
     /**
      * Creates the queue for {@link #freeConnections}.
      * Called once by the constructor.
      *
      * @return  a queue
      */
     protected Queue<BasicPoolEntry> createFreeConnQueue() {
         return new LinkedList<BasicPoolEntry>();
     }
 
     /**
      * Creates the queue for {@link #waitingThreads}.
      * Called once by the constructor.
      *
      * @return  a queue
      */
     protected Queue<WaitingThread> createWaitingThreadQueue() {
         return new LinkedList<WaitingThread>();
     }
 
     /**
      * Creates the map for {@link #routeToPool}.
      * Called once by the constructor.
      *
      * @return  a map
      */
     protected Map<HttpRoute, RouteSpecificPool> createRouteToPoolMap() {
         return new HashMap<HttpRoute, RouteSpecificPool>();
     }
 
 
     /**
      * Creates a new route-specific pool.
      * Called by {@link #getRoutePool} when necessary.
      *
      * @param route     the route
      *
      * @return  the new pool
      */
     protected RouteSpecificPool newRouteSpecificPool(final HttpRoute route) {
         return new RouteSpecificPool(route, this.connPerRoute);
     }
 
 
     /**
      * Creates a new waiting thread.
      * Called by {@link #getRoutePool} when necessary.
      *
      * @param cond      the condition to wait for
      * @param rospl     the route specific pool, or {@code null}
      *
      * @return  a waiting thread representation
      */
     protected WaitingThread newWaitingThread(final Condition cond,
                                              final RouteSpecificPool rospl) {
         return new WaitingThread(cond, rospl);
     }
 
     private void closeConnection(final BasicPoolEntry entry) {
         final OperatedClientConnection conn = entry.getConnection();
         if (conn != null) {
             try {
                 conn.close();
             } catch (final IOException ex) {
                 log.debug("I/O error closing connection", ex);
             }
         }
     }
 
     /**
      * Get a route-specific pool of available connections.
      *
      * @param route   the route
      * @param create    whether to create the pool if it doesn't exist
      *
      * @return  the pool for the argument route,
      *     never {@code null} if {@code create} is {@code true}
      */
     protected RouteSpecificPool getRoutePool(final HttpRoute route,
                                              final boolean create) {
         RouteSpecificPool rospl = null;
         poolLock.lock();
         try {
 
             rospl = routeToPool.get(route);
             if ((rospl == null) && create) {
                 // no pool for this route yet (or anymore)
                 rospl = newRouteSpecificPool(route);
                 routeToPool.put(route, rospl);
             }
 
         } finally {
             poolLock.unlock();
         }
 
         return rospl;
     }
 
     public int getConnectionsInPool(final HttpRoute route) {
         poolLock.lock();
         try {
             // don't allow a pool to be created here!
             final RouteSpecificPool rospl = getRoutePool(route, false);
             return (rospl != null) ? rospl.getEntryCount() : 0;
 
         } finally {
             poolLock.unlock();
         }
     }
 
     public int getConnectionsInPool() {
         poolLock.lock();
         try {
             return numConnections;
         } finally {
             poolLock.unlock();
         }
     }
 
     @Override
     public PoolEntryRequest requestPoolEntry(
             final HttpRoute route,
             final Object state) {
 
         final WaitingThreadAborterngThreadAborter.html#WaitingThreadAborter">WaitingThreadAborter aborter = new WaitingThreadAborter();
 
         return new PoolEntryRequest() {
 
             @Override
             public void abortRequest() {
                 poolLock.lock();
                 try {
                     aborter.abort();
                 } finally {
                     poolLock.unlock();
                 }
             }
 
             @Override
             public BasicPoolEntry getPoolEntry(
                     final long timeout,
                     final TimeUnit timeUnit)
                         throws InterruptedException, ConnectionPoolTimeoutException {
                 return getEntryBlocking(route, state, timeout, timeUnit, aborter);
             }
 
         };
     }
 
     /**
      * Obtains a pool entry with a connection within the given timeout.
      * If a {@link WaitingThread} is used to block, {@link WaitingThreadAborter#setWaitingThread(WaitingThread)}
      * must be called before blocking, to allow the thread to be interrupted.
      *
      * @param route     the route for which to get the connection
      * @param timeout   the timeout, 0 or negative for no timeout
      * @param timeUnit     the unit for the {@code timeout},
      *                  may be {@code null} only if there is no timeout
      * @param aborter   an object which can abort a {@link WaitingThread}.
      *
      * @return  pool entry holding a connection for the route
      *
      * @throws ConnectionPoolTimeoutException
      *         if the timeout expired
      * @throws InterruptedException
      *         if the calling thread was interrupted
      */
     protected BasicPoolEntry getEntryBlocking(
                                    final HttpRoute route, final Object state,
                                    final long timeout, final TimeUnit timeUnit,
                                    final WaitingThreadAborter aborter)
         throws ConnectionPoolTimeoutException, InterruptedException {
 
         Date deadline = null;
         if (timeout > 0) {
             deadline = new Date
                 (System.currentTimeMillis() + timeUnit.toMillis(timeout));
         }
 
         BasicPoolEntry entry = null;
         poolLock.lock();
         try {
 
             RouteSpecificPool rospl = getRoutePool(route, true);
             WaitingThread waitingThread = null;
 
             while (entry == null) {
                 Asserts.check(!shutdown, "Connection pool shut down");
 
                 if (log.isDebugEnabled()) {
                     log.debug("[" + route + "] total kept alive: " + freeConnections.size() +
                             ", total issued: " + leasedConnections.size() +
                             ", total allocated: " + numConnections + " out of " + maxTotalConnections);
                 }
 
                 // the cases to check for:
                 // - have a free connection for that route
                 // - allowed to create a free connection for that route
                 // - can delete and replace a free connection for another route
                 // - need to wait for one of the things above to come true
 
                 entry = getFreeEntry(rospl, state);
                 if (entry != null) {
                     break;
                 }
 
                 final boolean hasCapacity = rospl.getCapacity() > 0;
 
                 if (log.isDebugEnabled()) {
                     log.debug("Available capacity: " + rospl.getCapacity()
                             + " out of " + rospl.getMaxEntries()
                             + " [" + route + "][" + state + "]");
                 }
 
                 if (hasCapacity && numConnections < maxTotalConnections) {
 
                     entry = createEntry(rospl, operator);
 
                 } else if (hasCapacity && !freeConnections.isEmpty()) {
 
                     deleteLeastUsedEntry();
                     // if least used entry's route was the same as rospl,
                     // rospl is now out of date : we preemptively refresh
                     rospl = getRoutePool(route, true);
                     entry = createEntry(rospl, operator);
 
                 } else {
 
                     if (log.isDebugEnabled()) {
                         log.debug("Need to wait for connection" +
                                 " [" + route + "][" + state + "]");
                     }
 
                     if (waitingThread == null) {
                         waitingThread =
                             newWaitingThread(poolLock.newCondition(), rospl);
                         aborter.setWaitingThread(waitingThread);
                     }
 
                     boolean success = false;
                     try {
                         rospl.queueThread(waitingThread);
                         waitingThreads.add(waitingThread);
                         success = waitingThread.await(deadline);
 
                     } finally {
                         // In case of 'success', we were woken up by the
                         // connection pool and should now have a connection
                         // waiting for us, or else we're shutting down.
                         // Just continue in the loop, both cases are checked.
                         rospl.removeThread(waitingThread);
                         waitingThreads.remove(waitingThread);
                     }
 
                     // check for spurious wakeup vs. timeout
                     if (!success && (deadline != null) &&
                         (deadline.getTime() <= System.currentTimeMillis())) {
                         throw new ConnectionPoolTimeoutException
                             ("Timeout waiting for connection from pool");
                     }
                 }
             } // while no entry
 
         } finally {
             poolLock.unlock();
         }
         return entry;
     }
 
     @Override
     public void freeEntry(final BasicPoolEntry entry, final boolean reusable, final long validDuration, final TimeUnit timeUnit) {
 
         final HttpRoute route = entry.getPlannedRoute();
         if (log.isDebugEnabled()) {
             log.debug("Releasing connection" +
                     " [" + route + "][" + entry.getState() + "]");
         }
 
         poolLock.lock();
         try {
             if (shutdown) {
                 // the pool is shut down, release the
                 // connection's resources and get out of here
                 closeConnection(entry);
                 return;
             }
 
             // no longer issued, we keep a hard reference now
             leasedConnections.remove(entry);
 
             final RouteSpecificPool rospl = getRoutePool(route, true);
 
             if (reusable && rospl.getCapacity() >= 0) {
                 if (log.isDebugEnabled()) {
                     final String s;
                     if (validDuration > 0) {
                         s = "for " + validDuration + " " + timeUnit;
                     } else {
                         s = "indefinitely";
                     }
                     log.debug("Pooling connection" +
                             " [" + route + "][" + entry.getState() + "]; keep alive " + s);
                 }
                 rospl.freeEntry(entry);
                 entry.updateExpiry(validDuration, timeUnit);
                 freeConnections.add(entry);
             } else {
                 closeConnection(entry);
                 rospl.dropEntry();
                 numConnections--;
             }
 
             notifyWaitingThread(rospl);
 
         } finally {
             poolLock.unlock();
         }
     }
 
     /**
      * If available, get a free pool entry for a route.
      *
      * @param rospl       the route-specific pool from which to get an entry
      *
      * @return  an available pool entry for the given route, or
      *          {@code null} if none is available
      */
     protected BasicPoolEntry getFreeEntry(final RouteSpecificPool rospl, final Object state) {
 
         BasicPoolEntry entry = null;
         poolLock.lock();
         try {
             boolean done = false;
             while(!done) {
 
                 entry = rospl.allocEntry(state);
 
                 if (entry != null) {
                     if (log.isDebugEnabled()) {
                         log.debug("Getting free connection"
                                 + " [" + rospl.getRoute() + "][" + state + "]");
 
                     }
                     freeConnections.remove(entry);
                     if (entry.isExpired(System.currentTimeMillis())) {
                         // If the free entry isn't valid anymore, get rid of it
                         // and loop to find another one that might be valid.
                         if (log.isDebugEnabled()) {
                             log.debug("Closing expired free connection"
                                     + " [" + rospl.getRoute() + "][" + state + "]");
                         }
                         closeConnection(entry);
                         // We use dropEntry instead of deleteEntry because the entry
                         // is no longer "free" (we just allocated it), and deleteEntry
                         // can only be used to delete free entries.
                         rospl.dropEntry();
                         numConnections--;
                     } else {
                         leasedConnections.add(entry);
                         done = true;
                     }
 
                 } else {
                     done = true;
                     if (log.isDebugEnabled()) {
                         log.debug("No free connections"
                                 + " [" + rospl.getRoute() + "][" + state + "]");
                     }
                 }
             }
         } finally {
             poolLock.unlock();
         }
         return entry;
     }
 
 
     /**
      * Creates a new pool entry.
      * This method assumes that the new connection will be handed
      * out immediately.
      *
      * @param rospl       the route-specific pool for which to create the entry
      * @param op        the operator for creating a connection
      *
      * @return  the new pool entry for a new connection
      */
     protected BasicPoolEntry createEntry(final RouteSpecificPool rospl,
                                          final ClientConnectionOperator op) {
 
         if (log.isDebugEnabled()) {
             log.debug("Creating new connection [" + rospl.getRoute() + "]");
         }
 
         // the entry will create the connection when needed
         final BasicPoolEntrycm/BasicPoolEntry.html#BasicPoolEntry">BasicPoolEntry entry = new BasicPoolEntry(op, rospl.getRoute(), connTTL, connTTLTimeUnit);
 
         poolLock.lock();
         try {
             rospl.createdEntry(entry);
             numConnections++;
             leasedConnections.add(entry);
         } finally {
             poolLock.unlock();
         }
 
         return entry;
     }
 
 
     /**
      * Deletes a given pool entry.
      * This closes the pooled connection and removes all references,
      * so that it can be GCed.
      *
      * <p><b>Note:</b> Does not remove the entry from the freeConnections list.
      * It is assumed that the caller has already handled this step.</p>
      * <!-- @@@ is that a good idea? or rather fix it? -->
      *
      * @param entry         the pool entry for the connection to delete
      */
     protected void deleteEntry(final BasicPoolEntry entry) {
 
         final HttpRoute route = entry.getPlannedRoute();
 
         if (log.isDebugEnabled()) {
             log.debug("Deleting connection"
                     + " [" + route + "][" + entry.getState() + "]");
         }
 
         poolLock.lock();
         try {
 
             closeConnection(entry);
 
             final RouteSpecificPool rospl = getRoutePool(route, true);
             rospl.deleteEntry(entry);
             numConnections--;
             if (rospl.isUnused()) {
                 routeToPool.remove(route);
             }
 
         } finally {
             poolLock.unlock();
         }
     }
 
 
     /**
      * Delete an old, free pool entry to make room for a new one.
      * Used to replace pool entries with ones for a different route.
      */
     protected void deleteLeastUsedEntry() {
         poolLock.lock();
         try {
 
             final BasicPoolEntry entry = freeConnections.remove();
 
             if (entry != null) {
                 deleteEntry(entry);
             } else if (log.isDebugEnabled()) {
                 log.debug("No free connection to delete");
             }
 
         } finally {
             poolLock.unlock();
         }
     }
 
     @Override
     protected void handleLostEntry(final HttpRoute route) {
 
         poolLock.lock();
         try {
 
             final RouteSpecificPool rospl = getRoutePool(route, true);
             rospl.dropEntry();
             if (rospl.isUnused()) {
                 routeToPool.remove(route);
             }
 
             numConnections--;
             notifyWaitingThread(rospl);
 
         } finally {
             poolLock.unlock();
         }
     }
 
     /**
      * Notifies a waiting thread that a connection is available.
      * This will wake a thread waiting in the specific route pool,
      * if there is one.
      * Otherwise, a thread in the connection pool will be notified.
      *
      * @param rospl     the pool in which to notify, or {@code null}
      */
     protected void notifyWaitingThread(final RouteSpecificPool rospl) {
 
         //@@@ while this strategy provides for best connection re-use,
         //@@@ is it fair? only do this if the connection is open?
         // Find the thread we are going to notify. We want to ensure that
         // each waiting thread is only interrupted once, so we will remove
         // it from all wait queues before interrupting.
         WaitingThread waitingThread = null;
 
         poolLock.lock();
         try {
 
             if ((rospl != null) && rospl.hasThread()) {
                 if (log.isDebugEnabled()) {
                     log.debug("Notifying thread waiting on pool" +
                             " [" + rospl.getRoute() + "]");
                 }
                 waitingThread = rospl.nextThread();
             } else if (!waitingThreads.isEmpty()) {
                 if (log.isDebugEnabled()) {
                     log.debug("Notifying thread waiting on any pool");
                 }
                 waitingThread = waitingThreads.remove();
             } else if (log.isDebugEnabled()) {
                 log.debug("Notifying no-one, there are no waiting threads");
             }
 
             if (waitingThread != null) {
                 waitingThread.wakeup();
             }
 
         } finally {
             poolLock.unlock();
         }
     }
 
 
     @Override
     public void deleteClosedConnections() {
         poolLock.lock();
         try {
             final Iterator<BasicPoolEntry>  iter = freeConnections.iterator();
             while (iter.hasNext()) {
                 final BasicPoolEntry entry = iter.next();
                 if (!entry.getConnection().isOpen()) {
                     iter.remove();
                     deleteEntry(entry);
                 }
             }
         } finally {
             poolLock.unlock();
         }
     }
 
     /**
      * Closes idle connections.
      *
      * @param idletime  the time the connections should have been idle
      *                  in order to be closed now
      * @param timeUnit     the unit for the {@code idletime}
      */
     @Override
     public void closeIdleConnections(final long idletime, final TimeUnit timeUnit) {
         Args.notNull(timeUnit, "Time unit");
         final long t = idletime > 0 ? idletime : 0;
         if (log.isDebugEnabled()) {
             log.debug("Closing connections idle longer than "  + t + " " + timeUnit);
         }
         // the latest time for which connections will be closed
         final long deadline = System.currentTimeMillis() - timeUnit.toMillis(t);
         poolLock.lock();
         try {
             final Iterator<BasicPoolEntry>  iter = freeConnections.iterator();
             while (iter.hasNext()) {
                 final BasicPoolEntry entry = iter.next();
                 if (entry.getUpdated() <= deadline) {
                     if (log.isDebugEnabled()) {
                         log.debug("Closing connection last used @ " + new Date(entry.getUpdated()));
                     }
                     iter.remove();
                     deleteEntry(entry);
                 }
             }
         } finally {
             poolLock.unlock();
         }
     }
 
     @Override
     public void closeExpiredConnections() {
         log.debug("Closing expired connections");
         final long now = System.currentTimeMillis();
 
         poolLock.lock();
         try {
             final Iterator<BasicPoolEntry>  iter = freeConnections.iterator();
             while (iter.hasNext()) {
                 final BasicPoolEntry entry = iter.next();
                 if (entry.isExpired(now)) {
                     if (log.isDebugEnabled()) {
                         log.debug("Closing connection expired @ " + new Date(entry.getExpiry()));
                     }
                     iter.remove();
                     deleteEntry(entry);
                 }
             }
         } finally {
             poolLock.unlock();
         }
     }
 
     @Override
     public void shutdown() {
         poolLock.lock();
         try {
             if (shutdown) {
                 return;
             }
             shutdown = true;
 
             // close all connections that are issued to an application
             final Iterator<BasicPoolEntry> iter1 = leasedConnections.iterator();
             while (iter1.hasNext()) {
                 final BasicPoolEntry entry = iter1.next();
                 iter1.remove();
                 closeConnection(entry);
             }
 
             // close all free connections
             final Iterator<BasicPoolEntry> iter2 = freeConnections.iterator();
             while (iter2.hasNext()) {
                 final BasicPoolEntry entry = iter2.next();
                 iter2.remove();
 
                 if (log.isDebugEnabled()) {
                     log.debug("Closing connection"
                             + " [" + entry.getPlannedRoute() + "][" + entry.getState() + "]");
                 }
                 closeConnection(entry);
             }
 
             // wake up all waiting threads
             final Iterator<WaitingThread> iwth = waitingThreads.iterator();
             while (iwth.hasNext()) {
                 final WaitingThread waiter = iwth.next();
                 iwth.remove();
                 waiter.wakeup();
             }
 
             routeToPool.clear();
 
         } finally {
             poolLock.unlock();
         }
     }
 
     /**
      * since 4.1
      */
     public void setMaxTotalConnections(final int max) {
         poolLock.lock();
         try {
             maxTotalConnections = max;
         } finally {
             poolLock.unlock();
         }
     }
 
 
     /**
      * since 4.1
      */
     public int getMaxTotalConnections() {
         return maxTotalConnections;
     }
 
 }