Allow users to override connection keep alive logic

Implements AsyncHttpClient#733 for 1.9.x.

Author: barnardb

src/main/java/com/ning/http/client/providers/netty/NettyAsyncHttpProviderConfig.java

@@ -21,6 +21,8 @@
 import com.ning.http.client.AsyncHttpProviderConfig;
 import com.ning.http.client.SSLEngineFactory;
 import com.ning.http.client.providers.netty.channel.pool.ChannelPool;
+import com.ning.http.client.providers.netty.handler.ConnectionStrategy;
+import com.ning.http.client.providers.netty.handler.Http1Point1ConnectionStrategy;
 import com.ning.http.client.providers.netty.ws.NettyWebSocket;
 
 import java.util.Map;
@@ -145,6 +147,8 @@ public Set<Map.Entry<String, Object>> propertiesSet() {
 
     private boolean keepEncodingHeader = false;
 
+    private ConnectionStrategy connectionStrategy = new Http1Point1ConnectionStrategy();
+
     public boolean isUseDeadLockChecker() {
         return useDeadLockChecker;
     }
@@ -305,6 +309,14 @@ public void setKeepEncodingHeader(boolean keepEncodingHeader) {
         this.keepEncodingHeader = keepEncodingHeader;
     }
 
+    public ConnectionStrategy getConnectionStrategy() {
+        return connectionStrategy;
+    }
+
+    public void setConnectionStrategy(ConnectionStrategy connectionStrategy) {
+        this.connectionStrategy = connectionStrategy;
+    }
+
     public static interface NettyWebSocketFactory {
         NettyWebSocket newNettyWebSocket(Channel channel, NettyAsyncHttpProviderConfig nettyConfig);
     }

src/main/java/com/ning/http/client/providers/netty/handler/ConnectionStrategy.java

@@ -0,0 +1,18 @@
+package com.ning.http.client.providers.netty.handler;
+
+import org.jboss.netty.handler.codec.http.HttpRequest;
+import org.jboss.netty.handler.codec.http.HttpResponse;
+
+/**
+ * Provides an interface for decisions about HTTP connections.
+ */
+public interface ConnectionStrategy {
+
+    /**
+     * Determines whether the connection should be kept alive after this HTTP message exchange.
+     * @param request the HTTP request
+     * @param response the HTTP response
+     * @return true if the connection should be kept alive, false if it should be closed.
+     */
+    boolean keepAlive(HttpRequest request, HttpResponse response);
+}

src/main/java/com/ning/http/client/providers/netty/handler/Http1Point1ConnectionStrategy.java

@@ -0,0 +1,18 @@
+package com.ning.http.client.providers.netty.handler;
+
+import org.jboss.netty.handler.codec.http.HttpHeaders;
+import org.jboss.netty.handler.codec.http.HttpMessage;
+import org.jboss.netty.handler.codec.http.HttpRequest;
+import org.jboss.netty.handler.codec.http.HttpResponse;
+
+public class Http1Point1ConnectionStrategy implements ConnectionStrategy {
+
+    @Override
+    public boolean keepAlive(HttpRequest httpRequest, HttpResponse response) {
+        return isConnectionKeepAlive(httpRequest) && isConnectionKeepAlive(response);
+    }
+
+    public boolean isConnectionKeepAlive(HttpMessage message) {
+        return !HttpHeaders.Values.CLOSE.equalsIgnoreCase(message.headers().get(HttpHeaders.Names.CONNECTION));
+    }
+}

src/main/java/com/ning/http/client/providers/netty/handler/HttpProtocol.java

@@ -56,9 +56,13 @@
 
 public final class HttpProtocol extends Protocol {
 
+    private final ConnectionStrategy connectionStrategy;
+
     public HttpProtocol(ChannelManager channelManager, AsyncHttpClientConfig config, NettyAsyncHttpProviderConfig nettyConfig,
             NettyRequestSender requestSender) {
         super(channelManager, config, nettyConfig, requestSender);
+
+        connectionStrategy = nettyConfig.getConnectionStrategy();
     }
 
     private Realm.RealmBuilder newRealmBuilder(Realm realm) {
@@ -402,10 +406,6 @@ private boolean exitAfterHandlingBody(Channel channel, NettyResponseFuture<?> fu
         return false;
     }
 
-    private boolean isConnectionKeepAlive(HttpHeaders headers) {
-        return !HttpHeaders.Values.CLOSE.equalsIgnoreCase(headers.get(HttpHeaders.Names.CONNECTION));
-    }
-    
     private boolean handleHttpResponse(final HttpResponse response,//
             final Channel channel,//
             final NettyResponseFuture<?> future,//
@@ -419,7 +419,7 @@ private boolean handleHttpResponse(final HttpResponse response,//
         // the handler in case of trailing headers
         future.setHttpHeaders(response.headers());
 
-        future.setKeepAlive(isConnectionKeepAlive(httpRequest.headers()) && isConnectionKeepAlive(response.headers()));
+        future.setKeepAlive(connectionStrategy.keepAlive(httpRequest, response));
 
         NettyResponseStatus status = new NettyResponseStatus(future.getUri(), config, response);
         int statusCode = response.getStatus().getCode();