//
   //  ========================================================================
   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.client;
  
  import java.net.CookieManager;
  import java.net.CookiePolicy;
  import java.net.CookieStore;
  import java.net.InetSocketAddress;
  import java.net.Socket;
  import java.net.SocketAddress;
  import java.net.URI;
  import java.nio.channels.SelectionKey;
  import java.nio.channels.SocketChannel;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.Executor;
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.TimeoutException;
  
  import org.eclipse.jetty.client.api.AuthenticationStore;
  import org.eclipse.jetty.client.api.Connection;
  import org.eclipse.jetty.client.api.ContentResponse;
  import org.eclipse.jetty.client.api.Destination;
  import org.eclipse.jetty.client.api.Request;
  import org.eclipse.jetty.client.api.Response;
  import org.eclipse.jetty.client.http.HttpClientTransportOverHTTP;
  import org.eclipse.jetty.client.util.FormContentProvider;
  import org.eclipse.jetty.http.HttpField;
  import org.eclipse.jetty.http.HttpHeader;
  import org.eclipse.jetty.http.HttpMethod;
  import org.eclipse.jetty.http.HttpScheme;
  import org.eclipse.jetty.io.ByteBufferPool;
  import org.eclipse.jetty.io.ClientConnectionFactory;
  import org.eclipse.jetty.io.MappedByteBufferPool;
  import org.eclipse.jetty.util.Fields;
  import org.eclipse.jetty.util.Jetty;
  import org.eclipse.jetty.util.Promise;
  import org.eclipse.jetty.util.SocketAddressResolver;
  import org.eclipse.jetty.util.annotation.ManagedAttribute;
  import org.eclipse.jetty.util.annotation.ManagedObject;
  import org.eclipse.jetty.util.component.ContainerLifeCycle;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.ssl.SslContextFactory;
  import org.eclipse.jetty.util.thread.QueuedThreadPool;
  import org.eclipse.jetty.util.thread.ScheduledExecutorScheduler;
  import org.eclipse.jetty.util.thread.Scheduler;
  
  /**
   * <p>{@link HttpClient} provides an efficient, asynchronous, non-blocking implementation
   * to perform HTTP requests to a server through a simple API that offers also blocking semantic.</p>
   * <p>{@link HttpClient} provides easy-to-use methods such as {@link #GET(String)} that allow to perform HTTP
   * requests in a one-liner, but also gives the ability to fine tune the configuration of requests via
   * {@link HttpClient#newRequest(URI)}.</p>
   * <p>{@link HttpClient} acts as a central configuration point for network parameters (such as idle timeouts)
   * and HTTP parameters (such as whether to follow redirects).</p>
   * <p>{@link HttpClient} transparently pools connections to servers, but allows direct control of connections
   * for cases where this is needed.</p>
   * <p>{@link HttpClient} also acts as a central configuration point for cookies, via {@link #getCookieStore()}.</p>
   * <p>Typical usage:</p>
   * <pre>
   * HttpClient httpClient = new HttpClient();
   * httpClient.start();
   *
   * // One liner:
   * httpClient.GET("http://localhost:8080/").getStatus();
   *
   * // Building a request with a timeout
   * ContentResponse response = httpClient.newRequest("http://localhost:8080")
   *         .timeout(5, TimeUnit.SECONDS)
   *         .send();
   * int status = response.status();
  *
  * // Asynchronously
  * httpClient.newRequest("http://localhost:8080").send(new Response.CompleteListener()
  * {
  *     &#64;Override
  *     public void onComplete(Result result)
  *     {
  *         ...
  *     }
  * });
  * </pre>
  */
 @ManagedObject("The HTTP client")
 public class HttpClient extends ContainerLifeCycle
 {
     private static final Logger LOG = Log.getLogger(HttpClient.class);
 
     private final ConcurrentMap<Origin, HttpDestination> destinations = new ConcurrentHashMap<>();
     private final ProtocolHandlers handlers = new ProtocolHandlers();
     private final List<Request.Listener> requestListeners = new ArrayList<>();
     private final AuthenticationStore authenticationStore = new HttpAuthenticationStore();
     private final Set<ContentDecoder.Factory> decoderFactories = new ContentDecoderFactorySet();
     private final ProxyConfiguration proxyConfig = new ProxyConfiguration();
     private final HttpClientTransport transport;
     private final SslContextFactory sslContextFactory;
     private volatile CookieManager cookieManager;
     private volatile CookieStore cookieStore;
     private volatile Executor executor;
     private volatile ByteBufferPool byteBufferPool;
     private volatile Scheduler scheduler;
     private volatile SocketAddressResolver resolver;
     private volatile HttpField agentField = new HttpField(HttpHeader.USER_AGENT, "Jetty/" + Jetty.VERSION);
     private volatile boolean followRedirects = true;
     private volatile int maxConnectionsPerDestination = 64;
     private volatile int maxRequestsQueuedPerDestination = 1024;
     private volatile int requestBufferSize = 4096;
     private volatile int responseBufferSize = 16384;
     private volatile int maxRedirects = 8;
     private volatile SocketAddress bindAddress;
     private volatile long connectTimeout = 15000;
     private volatile long addressResolutionTimeout = 15000;
     private volatile long idleTimeout;
     private volatile boolean tcpNoDelay = true;
     private volatile boolean strictEventOrdering = false;
     private volatile HttpField encodingField;
     private volatile boolean removeIdleDestinations = false;
     private volatile boolean connectBlocking = false;
 
     /**
      * Creates a {@link HttpClient} instance that can perform requests to non-TLS destinations only
      * (that is, requests with the "http" scheme only, and not "https").
      *
      * @see #HttpClient(SslContextFactory) to perform requests to TLS destinations.
      */
     public HttpClient()
     {
         this(null);
     }
 
     /**
      * Creates a {@link HttpClient} instance that can perform requests to non-TLS and TLS destinations
      * (that is, both requests with the "http" scheme and with the "https" scheme).
      *
      * @param sslContextFactory the {@link SslContextFactory} that manages TLS encryption
      * @see #getSslContextFactory()
      */
     public HttpClient(SslContextFactory sslContextFactory)
     {
         this(new HttpClientTransportOverHTTP(), sslContextFactory);
     }
 
     public HttpClient(HttpClientTransport transport, SslContextFactory sslContextFactory)
     {
         this.transport = transport;
         this.sslContextFactory = sslContextFactory;
     }
 
     public HttpClientTransport getTransport()
     {
         return transport;
     }
 
     /**
      * @return the {@link SslContextFactory} that manages TLS encryption
      * @see #HttpClient(SslContextFactory)
      */
     public SslContextFactory getSslContextFactory()
     {
         return sslContextFactory;
     }
 
     @Override
     protected void doStart() throws Exception
     {
         if (sslContextFactory != null)
             addBean(sslContextFactory);
 
         String name = HttpClient.class.getSimpleName() + "@" + hashCode();
 
         if (executor == null)
         {
             QueuedThreadPool threadPool = new QueuedThreadPool();
             threadPool.setName(name);
             executor = threadPool;
         }
         addBean(executor);
 
         if (byteBufferPool == null)
             byteBufferPool = new MappedByteBufferPool();
         addBean(byteBufferPool);
 
         if (scheduler == null)
             scheduler = new ScheduledExecutorScheduler(name + "-scheduler", false);
         addBean(scheduler);
 
         transport.setHttpClient(this);
         addBean(transport);
 
         if (resolver == null)
             resolver = new SocketAddressResolver.Async(executor, scheduler, getAddressResolutionTimeout());
         addBean(resolver);
 
         handlers.put(new ContinueProtocolHandler());
         handlers.put(new RedirectProtocolHandler(this));
         handlers.put(new WWWAuthenticationProtocolHandler(this));
         handlers.put(new ProxyAuthenticationProtocolHandler(this));
 
         decoderFactories.add(new GZIPContentDecoder.Factory());
 
         cookieManager = newCookieManager();
         cookieStore = cookieManager.getCookieStore();
 
         super.doStart();
     }
 
     private CookieManager newCookieManager()
     {
         return new CookieManager(getCookieStore(), CookiePolicy.ACCEPT_ALL);
     }
 
     @Override
     protected void doStop() throws Exception
     {
         decoderFactories.clear();
         handlers.clear();
 
         for (HttpDestination destination : destinations.values())
             destination.close();
         destinations.clear();
 
         requestListeners.clear();
         authenticationStore.clearAuthentications();
         authenticationStore.clearAuthenticationResults();
 
         super.doStop();
     }
 
     /**
      * Returns a <em>non</em> thread-safe list of {@link org.eclipse.jetty.client.api.Request.Listener}s that can be modified before
      * performing requests.
      *
      * @return a list of {@link org.eclipse.jetty.client.api.Request.Listener} that can be used to add and remove listeners
      */
     public List<Request.Listener> getRequestListeners()
     {
         return requestListeners;
     }
 
     /**
      * @return the cookie store associated with this instance
      */
     public CookieStore getCookieStore()
     {
         return cookieStore;
     }
 
     /**
      * @param cookieStore the cookie store associated with this instance
      */
     public void setCookieStore(CookieStore cookieStore)
     {
         this.cookieStore = Objects.requireNonNull(cookieStore);
         this.cookieManager = newCookieManager();
     }
 
     /**
      * Keep this method package-private because its interface is so ugly
      * that we really don't want to expose it more than strictly needed.
      *
      * @return the cookie manager
      */
     CookieManager getCookieManager()
     {
         return cookieManager;
     }
 
     /**
      * @return the authentication store associated with this instance
      */
     public AuthenticationStore getAuthenticationStore()
     {
         return authenticationStore;
     }
 
     /**
      * Returns a <em>non</em> thread-safe set of {@link ContentDecoder.Factory}s that can be modified before
      * performing requests.
      *
      * @return a set of {@link ContentDecoder.Factory} that can be used to add and remove content decoder factories
      */
     public Set<ContentDecoder.Factory> getContentDecoderFactories()
     {
         return decoderFactories;
     }
 
     /**
      * Performs a GET request to the specified URI.
      *
      * @param uri the URI to GET
      * @return the {@link ContentResponse} for the request
      * @throws InterruptedException if send threading has been interrupted
      * @throws ExecutionException the execution failed
      * @throws TimeoutException the send timed out
      * @see #GET(URI)
      */
     public ContentResponse GET(String uri) throws InterruptedException, ExecutionException, TimeoutException
     {
         return GET(URI.create(uri));
     }
 
     /**
      * Performs a GET request to the specified URI.
      *
      * @param uri the URI to GET
      * @return the {@link ContentResponse} for the request
      * @throws InterruptedException if send threading has been interrupted
      * @throws ExecutionException the execution failed
      * @throws TimeoutException the send timed out
      * @see #newRequest(URI)
      */
     public ContentResponse GET(URI uri) throws InterruptedException, ExecutionException, TimeoutException
     {
         return newRequest(uri).send();
     }
 
     /**
      * Performs a POST request to the specified URI with the given form parameters.
      *
      * @param uri the URI to POST
      * @param fields the fields composing the form name/value pairs
      * @return the {@link ContentResponse} for the request
      * @throws InterruptedException if send threading has been interrupted
      * @throws ExecutionException the execution failed
      * @throws TimeoutException the send timed out
      */
     public ContentResponse FORM(String uri, Fields fields) throws InterruptedException, ExecutionException, TimeoutException
     {
         return FORM(URI.create(uri), fields);
     }
 
     /**
      * Performs a POST request to the specified URI with the given form parameters.
      *
      * @param uri the URI to POST
      * @param fields the fields composing the form name/value pairs
      * @return the {@link ContentResponse} for the request
      * @throws InterruptedException if send threading has been interrupted
      * @throws ExecutionException the execution failed
      * @throws TimeoutException the send timed out
      */
     public ContentResponse FORM(URI uri, Fields fields) throws InterruptedException, ExecutionException, TimeoutException
     {
         return POST(uri).content(new FormContentProvider(fields)).send();
     }
 
     /**
      * Creates a POST request to the specified URI.
      *
      * @param uri the URI to POST to
      * @return the POST request
      * @see #POST(URI)
      */
     public Request POST(String uri)
     {
         return POST(URI.create(uri));
     }
 
     /**
      * Creates a POST request to the specified URI.
      *
      * @param uri the URI to POST to
      * @return the POST request
      */
     public Request POST(URI uri)
     {
         return newRequest(uri).method(HttpMethod.POST);
     }
 
     /**
      * Creates a new request with the "http" scheme and the specified host and port
      *
      * @param host the request host
      * @param port the request port
      * @return the request just created
      */
     public Request newRequest(String host, int port)
     {
         return newRequest(new Origin("http", host, port).asString());
     }
 
     /**
      * Creates a new request with the specified absolute URI in string format.
      *
      * @param uri the request absolute URI
      * @return the request just created
      */
     public Request newRequest(String uri)
     {
         return newRequest(URI.create(uri));
     }
 
     /**
      * Creates a new request with the specified absolute URI.
      *
      * @param uri the request absolute URI
      * @return the request just created
      */
     public Request newRequest(URI uri)
     {
         return newHttpRequest(newConversation(), uri);
     }
 
     protected Request copyRequest(HttpRequest oldRequest, URI newURI)
     {
         Request newRequest = newHttpRequest(oldRequest.getConversation(), newURI);
         newRequest.method(oldRequest.getMethod())
                 .version(oldRequest.getVersion())
                 .content(oldRequest.getContent())
                 .idleTimeout(oldRequest.getIdleTimeout(), TimeUnit.MILLISECONDS)
                 .timeout(oldRequest.getTimeout(), TimeUnit.MILLISECONDS)
                 .followRedirects(oldRequest.isFollowRedirects());
         for (HttpField field : oldRequest.getHeaders())
         {
             HttpHeader header = field.getHeader();
             // We have a new URI, so skip the host header if present.
             if (HttpHeader.HOST == header)
                 continue;
 
             // Remove expectation headers.
             if (HttpHeader.EXPECT == header)
                 continue;
 
             // Remove cookies.
             if (HttpHeader.COOKIE == header)
                 continue;
 
             // Remove authorization headers.
             if (HttpHeader.AUTHORIZATION == header ||
                     HttpHeader.PROXY_AUTHORIZATION == header)
                 continue;
 
             String name = field.getName();
             String value = field.getValue();
             if (!newRequest.getHeaders().contains(name, value))
                 newRequest.header(name, value);
         }
         return newRequest;
     }
 
     protected HttpRequest newHttpRequest(HttpConversation conversation, URI uri)
     {
         return new HttpRequest(this, conversation, checkHost(uri));
     }
 
     /**
      * <p>Checks {@code uri} for the host to be non-null host.</p>
      * <p>URIs built from strings that have an internationalized domain name (IDN)
      * are parsed without errors, but {@code uri.getHost()} returns null.</p>
      *
      * @param uri the URI to check for non-null host
      * @return the same {@code uri} if the host is non-null
      * @throws IllegalArgumentException if the host is null
      */
     private URI checkHost(URI uri)
     {
         if (uri.getHost() == null)
             throw new IllegalArgumentException(String.format("Invalid URI host: null (authority: %s)", uri.getRawAuthority()));
         return uri;
     }
 
     /**
      * Returns a {@link Destination} for the given scheme, host and port.
      * Applications may use {@link Destination}s to create {@link Connection}s
      * that will be outside {@link HttpClient}'s pooling mechanism, to explicitly
      * control the connection lifecycle (in particular their termination with
      * {@link Connection#close()}).
      *
      * @param scheme the destination scheme
      * @param host the destination host
      * @param port the destination port
      * @return the destination
      * @see #getDestinations()
      */
     public Destination getDestination(String scheme, String host, int port)
     {
         return destinationFor(scheme, host, port);
     }
 
     protected HttpDestination destinationFor(String scheme, String host, int port)
     {
         if (!HttpScheme.HTTP.is(scheme) && !HttpScheme.HTTPS.is(scheme))
             throw new IllegalArgumentException("Invalid protocol " + scheme);
 
         scheme = scheme.toLowerCase(Locale.ENGLISH);
         host = host.toLowerCase(Locale.ENGLISH);
         port = normalizePort(scheme, port);
 
         Origin origin = new Origin(scheme, host, port);
         HttpDestination destination = destinations.get(origin);
         if (destination == null)
         {
             destination = transport.newHttpDestination(origin);
             addManaged(destination);
             HttpDestination existing = destinations.putIfAbsent(origin, destination);
             if (existing != null)
             {
                 removeBean(destination);
                 destination = existing;
             }
             else
             {
                 if (LOG.isDebugEnabled())
                     LOG.debug("Created {}", destination);
             }
         }
         return destination;
     }
 
     protected boolean removeDestination(HttpDestination destination)
     {
         removeBean(destination);
         return destinations.remove(destination.getOrigin()) != null;
     }
 
     /**
      * @return the list of destinations known to this {@link HttpClient}.
      */
     public List<Destination> getDestinations()
     {
         return new ArrayList<>(destinations.values());
     }
 
     protected void send(final HttpRequest request, List<Response.ResponseListener> listeners)
     {
         HttpDestination destination = destinationFor(request.getScheme(), request.getHost(), request.getPort());
         destination.send(request, listeners);
     }
 
     protected void newConnection(final HttpDestination destination, final Promise<Connection> promise)
     {
         Origin.Address address = destination.getConnectAddress();
         resolver.resolve(address.getHost(), address.getPort(), new Promise<List<InetSocketAddress>>()
         {
             @Override
             public void succeeded(List<InetSocketAddress> socketAddresses)
             {
                 Map<String, Object> context = new HashMap<>();
                 context.put(ClientConnectionFactory.CONNECTOR_CONTEXT_KEY, HttpClient.this);
                 context.put(HttpClientTransport.HTTP_DESTINATION_CONTEXT_KEY, destination);
                 connect(socketAddresses, 0, context);
             }
 
             @Override
             public void failed(Throwable x)
             {
                 promise.failed(x);
             }
 
             private void connect(List<InetSocketAddress> socketAddresses, int index, Map<String, Object> context)
             {
                 context.put(HttpClientTransport.HTTP_CONNECTION_PROMISE_CONTEXT_KEY, new Promise.Wrapper<Connection>(promise)
                 {
                     @Override
                     public void failed(Throwable x)
                     {
                         int nextIndex = index + 1;
                         if (nextIndex == socketAddresses.size())
                             super.failed(x);
                         else
                             connect(socketAddresses, nextIndex, context);
                     }
                 });
                 transport.connect(socketAddresses.get(index), context);
             }
         });
     }
 
     private HttpConversation newConversation()
     {
         return new HttpConversation();
     }
 
     public ProtocolHandlers getProtocolHandlers()
     {
         return handlers;
     }
 
     protected ProtocolHandler findProtocolHandler(Request request, Response response)
     {
         return handlers.find(request, response);
     }
 
     /**
      * @return the {@link ByteBufferPool} of this {@link HttpClient}
      */
     public ByteBufferPool getByteBufferPool()
     {
         return byteBufferPool;
     }
 
     /**
      * @param byteBufferPool the {@link ByteBufferPool} of this {@link HttpClient}
      */
     public void setByteBufferPool(ByteBufferPool byteBufferPool)
     {
         this.byteBufferPool = byteBufferPool;
     }
 
     /**
      * @return the max time, in milliseconds, a connection can take to connect to destinations
      */
     @ManagedAttribute("The timeout, in milliseconds, for connect() operations")
     public long getConnectTimeout()
     {
         return connectTimeout;
     }
 
     /**
      * @param connectTimeout the max time, in milliseconds, a connection can take to connect to destinations
      * @see java.net.Socket#connect(SocketAddress, int)
      */
     public void setConnectTimeout(long connectTimeout)
     {
         this.connectTimeout = connectTimeout;
     }
 
     /**
      * @return the timeout, in milliseconds, for the default {@link SocketAddressResolver} created at startup
      * @see #getSocketAddressResolver()
      */
     public long getAddressResolutionTimeout()
     {
         return addressResolutionTimeout;
     }
 
     /**
      * <p>Sets the socket address resolution timeout used by the default {@link SocketAddressResolver}
      * created by this {@link HttpClient} at startup.</p>
      * <p>For more fine tuned configuration of socket address resolution, see
      * {@link #setSocketAddressResolver(SocketAddressResolver)}.</p>
      *
      * @param addressResolutionTimeout the timeout, in milliseconds, for the default {@link SocketAddressResolver} created at startup
      * @see #setSocketAddressResolver(SocketAddressResolver)
      */
     public void setAddressResolutionTimeout(long addressResolutionTimeout)
     {
         this.addressResolutionTimeout = addressResolutionTimeout;
     }
 
     /**
      * @return the max time, in milliseconds, a connection can be idle (that is, without traffic of bytes in either direction)
      */
     @ManagedAttribute("The timeout, in milliseconds, to close idle connections")
     public long getIdleTimeout()
     {
         return idleTimeout;
     }
 
     /**
      * @param idleTimeout the max time, in milliseconds, a connection can be idle (that is, without traffic of bytes in either direction)
      */
     public void setIdleTimeout(long idleTimeout)
     {
         this.idleTimeout = idleTimeout;
     }
 
     /**
      * @return the address to bind socket channels to
      * @see #setBindAddress(SocketAddress)
      */
     public SocketAddress getBindAddress()
     {
         return bindAddress;
     }
 
     /**
      * @param bindAddress the address to bind socket channels to
      * @see #getBindAddress()
      * @see SocketChannel#bind(SocketAddress)
      */
     public void setBindAddress(SocketAddress bindAddress)
     {
         this.bindAddress = bindAddress;
     }
 
     /**
      * @return the "User-Agent" HTTP field of this {@link HttpClient}
      */
     public HttpField getUserAgentField()
     {
         return agentField;
     }
 
     /**
      * @param agent the "User-Agent" HTTP header string of this {@link HttpClient}
      */
     public void setUserAgentField(HttpField agent)
     {
         if (agent.getHeader() != HttpHeader.USER_AGENT)
             throw new IllegalArgumentException();
         this.agentField = agent;
     }
 
     /**
      * @return whether this {@link HttpClient} follows HTTP redirects
      * @see Request#isFollowRedirects()
      */
     @ManagedAttribute("Whether HTTP redirects are followed")
     public boolean isFollowRedirects()
     {
         return followRedirects;
     }
 
     /**
      * @param follow whether this {@link HttpClient} follows HTTP redirects
      * @see #setMaxRedirects(int)
      */
     public void setFollowRedirects(boolean follow)
     {
         this.followRedirects = follow;
     }
 
     /**
      * @return the {@link Executor} of this {@link HttpClient}
      */
     public Executor getExecutor()
     {
         return executor;
     }
 
     /**
      * @param executor the {@link Executor} of this {@link HttpClient}
      */
     public void setExecutor(Executor executor)
     {
         this.executor = executor;
     }
 
     /**
      * @return the {@link Scheduler} of this {@link HttpClient}
      */
     public Scheduler getScheduler()
     {
         return scheduler;
     }
 
     /**
      * @param scheduler the {@link Scheduler} of this {@link HttpClient}
      */
     public void setScheduler(Scheduler scheduler)
     {
         this.scheduler = scheduler;
     }
 
     /**
      * @return the {@link SocketAddressResolver} of this {@link HttpClient}
      */
     public SocketAddressResolver getSocketAddressResolver()
     {
         return resolver;
     }
 
     /**
      * @param resolver the {@link SocketAddressResolver} of this {@link HttpClient}
      */
     public void setSocketAddressResolver(SocketAddressResolver resolver)
     {
         this.resolver = resolver;
     }
 
     /**
      * @return the max number of connections that this {@link HttpClient} opens to {@link Destination}s
      */
     @ManagedAttribute("The max number of connections per each destination")
     public int getMaxConnectionsPerDestination()
     {
         return maxConnectionsPerDestination;
     }
 
     /**
      * Sets the max number of connections to open to each destinations.
      * <p>
      * RFC 2616 suggests that 2 connections should be opened per each destination,
      * but browsers commonly open 6.
      * If this {@link HttpClient} is used for load testing, it is common to have only one destination
      * (the server to load test), and it is recommended to set this value to a high value (at least as
      * much as the threads present in the {@link #getExecutor() executor}).
      *
      * @param maxConnectionsPerDestination the max number of connections that this {@link HttpClient} opens to {@link Destination}s
      */
     public void setMaxConnectionsPerDestination(int maxConnectionsPerDestination)
     {
         this.maxConnectionsPerDestination = maxConnectionsPerDestination;
     }
 
     /**
      * @return the max number of requests that may be queued to a {@link Destination}.
      */
     @ManagedAttribute("The max number of requests queued per each destination")
     public int getMaxRequestsQueuedPerDestination()
     {
         return maxRequestsQueuedPerDestination;
     }
 
     /**
      * Sets the max number of requests that may be queued to a destination.
      * <p>
      * If this {@link HttpClient} performs a high rate of requests to a destination,
      * and all the connections managed by that destination are busy with other requests,
      * then new requests will be queued up in the destination.
      * This parameter controls how many requests can be queued before starting to reject them.
      * If this {@link HttpClient} is used for load testing, it is common to have this parameter
      * set to a high value, although this may impact latency (requests sit in the queue for a long
      * time before being sent).
      *
      * @param maxRequestsQueuedPerDestination the max number of requests that may be queued to a {@link Destination}.
      */
     public void setMaxRequestsQueuedPerDestination(int maxRequestsQueuedPerDestination)
     {
         this.maxRequestsQueuedPerDestination = maxRequestsQueuedPerDestination;
     }
 
     /**
      * @return the size of the buffer used to write requests
      */
     @ManagedAttribute("The request buffer size")
     public int getRequestBufferSize()
     {
         return requestBufferSize;
     }
 
     /**
      * @param requestBufferSize the size of the buffer used to write requests
      */
     public void setRequestBufferSize(int requestBufferSize)
     {
         this.requestBufferSize = requestBufferSize;
     }
 
     /**
      * @return the size of the buffer used to read responses
      */
     @ManagedAttribute("The response buffer size")
     public int getResponseBufferSize()
     {
         return responseBufferSize;
     }
 
     /**
      * @param responseBufferSize the size of the buffer used to read responses
      */
     public void setResponseBufferSize(int responseBufferSize)
     {
         this.responseBufferSize = responseBufferSize;
     }
 
     /**
      * @return the max number of HTTP redirects that are followed
      * @see #setMaxRedirects(int)
      */
     public int getMaxRedirects()
     {
         return maxRedirects;
     }
 
     /**
      * @param maxRedirects the max number of HTTP redirects that are followed
      * @see #setFollowRedirects(boolean)
      */
     public void setMaxRedirects(int maxRedirects)
     {
         this.maxRedirects = maxRedirects;
     }
 
     /**
      * @return whether TCP_NODELAY is enabled
      */
     @ManagedAttribute(value = "Whether the TCP_NODELAY option is enabled", name = "tcpNoDelay")
     public boolean isTCPNoDelay()
     {
         return tcpNoDelay;
     }
 
     /**
      * @param tcpNoDelay whether TCP_NODELAY is enabled
      * @see java.net.Socket#setTcpNoDelay(boolean)
      */
     public void setTCPNoDelay(boolean tcpNoDelay)
     {
         this.tcpNoDelay = tcpNoDelay;
     }
 
     /**
      * @return true to dispatch I/O operations in a different thread, false to execute them in the selector thread
      * @see #setDispatchIO(boolean)
      */
     @Deprecated
     public boolean isDispatchIO()
     {
         // TODO this did default to true, so usage needs to be evaluated.
         return false;
     }
 
     /**
      * Whether to dispatch I/O operations from the selector thread to a different thread.
      * <p>
      * This implementation never blocks on I/O operation, but invokes application callbacks that may
      * take time to execute or block on other I/O.
      * If application callbacks are known to take time or block on I/O, then parameter {@code dispatchIO}
      * should be set to true.
      * If application callbacks are known to be quick and never block on I/O, then parameter {@code dispatchIO}
      * may be set to false.
      *
      * @param dispatchIO true to dispatch I/O operations in a different thread,
      *                   false to execute them in the selector thread
      */
     @Deprecated
     public void setDispatchIO(boolean dispatchIO)
     {
     }
 
     /**
      * @return whether request events must be strictly ordered
      * @see #setStrictEventOrdering(boolean)
      */
     @ManagedAttribute("Whether request/response events must be strictly ordered")
     public boolean isStrictEventOrdering()
     {
         return strictEventOrdering;
     }
 
     /**
      * Whether request/response events must be strictly ordered with respect to connection usage.
      * <p>
      * From the point of view of connection usage, the connection can be reused just before the
      * "complete" event notified to {@link org.eclipse.jetty.client.api.Response.CompleteListener}s
      * (but after the "success" event).
      * <p>
      * When a request/response exchange is completing, the destination may have another request
      * queued to be sent to the server.
      * If the connection for that destination is reused for the second request before the "complete"
      * event of the first exchange, it may happen that the "begin" event of the second request
      * happens before the "complete" event of the first exchange.
      * <p>
      * Enforcing strict ordering of events so that a "begin" event of a request can never happen
      * before the "complete" event of the previous exchange comes with the cost of increased
      * connection usage.
      * In case of HTTP redirects and strict event ordering, for example, the redirect request will
      * be forced to open a new connection because it is typically sent from the complete listener
      * when the connection cannot yet be reused.
      * When strict event ordering is not enforced, the redirect request will reuse the already
      * open connection making the system more efficient.
      * <p>
      * The default value for this property is {@code false}.
      *
      * @param strictEventOrdering whether request/response events must be strictly ordered
      */
     public void setStrictEventOrdering(boolean strictEventOrdering)
     {
         this.strictEventOrdering = strictEventOrdering;
     }
 
     /**
      * @return whether destinations that have no connections should be removed
      * @see #setRemoveIdleDestinations(boolean)
      */
     @ManagedAttribute("Whether idle destinations are removed")
     public boolean isRemoveIdleDestinations()
     {
         return removeIdleDestinations;
     }
 
     /**
      * Whether destinations that have no connections (nor active nor idle) should be removed.
      * <p>
      * Applications typically make request to a limited number of destinations so keeping
      * destinations around is not a problem for the memory or the GC.
      * However, for applications that hit millions of different destinations (e.g. a spider
      * bot) it would be useful to be able to remove the old destinations that won't be visited
      * anymore and leave space for new destinations.
      *
      * @param removeIdleDestinations whether destinations that have no connections should be removed
      * @see org.eclipse.jetty.client.DuplexConnectionPool
      */
     public void setRemoveIdleDestinations(boolean removeIdleDestinations)
     {
         this.removeIdleDestinations = removeIdleDestinations;
     }
 
     /**
      * @return whether {@code connect()} operations are performed in blocking mode
      */
     @ManagedAttribute("Whether the connect() operation is blocking")
     public boolean isConnectBlocking()
     {
         return connectBlocking;
     }
 
     /**
      * <p>Whether {@code connect()} operations are performed in blocking mode.</p>
      * <p>If {@code connect()} are performed in blocking mode, then {@link Socket#connect(SocketAddress, int)}
      * will be used to connect to servers.</p>
      * <p>Otherwise, {@link SocketChannel#connect(SocketAddress)} will be used in non-blocking mode,
      * therefore registering for {@link SelectionKey#OP_CONNECT} and finishing the connect operation
      * when the NIO system emits that event.</p>
      *
      * @param connectBlocking whether {@code connect()} operations are performed in blocking mode
      */
     public void setConnectBlocking(boolean connectBlocking)
     {
         this.connectBlocking = connectBlocking;
     }
 
     /**
      * @return the forward proxy configuration
      */
     public ProxyConfiguration getProxyConfiguration()
     {
         return proxyConfig;
     }
 
     protected HttpField getAcceptEncodingField()
     {
         return encodingField;
     }
 
     protected String normalizeHost(String host)
     {
         if (host != null && host.matches("\\[.*\\]"))
             return host.substring(1, host.length() - 1);
         return host;
     }
 
     public static int normalizePort(String scheme, int port)
     {
         return port > 0 ? port : HttpScheme.HTTPS.is(scheme) ? 443 : 80;
     }
 
     public boolean isDefaultPort(String scheme, int port)
     {
         return HttpScheme.HTTPS.is(scheme) ? port == 443 : port == 80;
     }
 
     private class ContentDecoderFactorySet implements Set<ContentDecoder.Factory>
     {
         private final Set<ContentDecoder.Factory> set = new HashSet<>();
 
         @Override
         public boolean add(ContentDecoder.Factory e)
         {
             boolean result = set.add(e);
             invalidate();
             return result;
         }
 
         @Override
         public boolean addAll(Collection<? extends ContentDecoder.Factory> c)
         {
             boolean result = set.addAll(c);
             invalidate();
             return result;
         }
 
         @Override
         public boolean remove(Object o)
         {
             boolean result = set.remove(o);
             invalidate();
             return result;
         }
 
         @Override
         public boolean removeAll(Collection<?> c)
         {
             boolean result = set.removeAll(c);
             invalidate();
             return result;
         }
 
         @Override
         public boolean retainAll(Collection<?> c)
         {
             boolean result = set.retainAll(c);
             invalidate();
             return result;
         }
 
         @Override
         public void clear()
         {
             set.clear();
             invalidate();
         }
 
         @Override
         public int size()
         {
             return set.size();
         }
 
         @Override
         public boolean isEmpty()
         {
             return set.isEmpty();
         }
 
         @Override
         public boolean contains(Object o)
         {
             return set.contains(o);
         }
 
         @Override
         public boolean containsAll(Collection<?> c)
         {
             return set.containsAll(c);
         }
 
         @Override
         public Iterator<ContentDecoder.Factory> iterator()
         {
             final Iterator<ContentDecoder.Factory> iterator = set.iterator();
             return new Iterator<ContentDecoder.Factory>()
             {
                 @Override
                 public boolean hasNext()
                 {
                     return iterator.hasNext();
                 }
 
                 @Override
                 public ContentDecoder.Factory next()
                 {
                     return iterator.next();
                 }
 
                 @Override
                 public void remove()
                 {
                     iterator.remove();
                     invalidate();
                 }
             };
         }
 
         @Override
         public Object[] toArray()
         {
             return set.toArray();
         }
 
         @Override
         public <T> T[] toArray(T[] a)
         {
             return set.toArray(a);
         }
 
         private void invalidate()
         {
             if (set.isEmpty())
             {
                 encodingField = null;
             }
             else
             {
                 StringBuilder value = new StringBuilder();
                 for (Iterator<ContentDecoder.Factory> iterator = set.iterator(); iterator.hasNext();)
                 {
                     ContentDecoder.Factory decoderFactory = iterator.next();
                     value.append(decoderFactory.getEncoding());
                     if (iterator.hasNext())
                         value.append(",");
                 }
                 encodingField = new HttpField(HttpHeader.ACCEPT_ENCODING, value.toString());
             }
         }
     }
 }