Reduced intermediate garbage in HeaderGroup and DefaultConnectionReus…

…eStrategy

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/branches/4.4.x@1673254 13f79535-47bb-0310-9956-ffa450edef68

httpcore-h2/src/main/java/org/apache/hc5/core/http2/stream/MessageEncoder.java

@@ -0,0 +1,36 @@
+/*
+ * ====================================================================
+ * 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.hc5.core.http2.stream;
+
+import org.apache.http.MessageHead;
+
+public interface MessageEncoder<T extends MessageHead> {
+
+    void encode(T message);
+
+}

httpcore/src/main/java/org/apache/http/impl/DefaultConnectionReuseStrategy.java

@@ -37,6 +37,7 @@
 import org.apache.http.ProtocolVersion;
 import org.apache.http.TokenIterator;
 import org.apache.http.annotation.Immutable;
+import org.apache.http.message.BasicHeaderIterator;
 import org.apache.http.message.BasicTokenIterator;
 import org.apache.http.protocol.HTTP;
 import org.apache.http.protocol.HttpContext;
@@ -107,9 +108,9 @@ public boolean keepAlive(final HttpResponse response,
         // Check for the "Connection" header. If that is absent, check for
         // the "Proxy-Connection" header. The latter is an unspecified and
         // broken but unfortunately common extension of HTTP.
-        HeaderIterator hit = response.headerIterator(HTTP.CONN_DIRECTIVE);
-        if (!hit.hasNext()) {
-            hit = response.headerIterator("Proxy-Connection");
+        Header[] connHeaders = response.getHeaders(HTTP.CONN_DIRECTIVE);
+        if (connHeaders.length == 0) {
+            connHeaders = response.getHeaders("Proxy-Connection");
         }
 
         // Experimental usage of the "Connection" header in HTTP/1.0 is
@@ -135,9 +136,9 @@ public boolean keepAlive(final HttpResponse response,
         // it takes precedence and indicates a non-persistent connection.
         // If there is no "close" but a "keep-alive", we take the hint.
 
-        if (hit.hasNext()) {
+        if (connHeaders.length != 0) {
             try {
-                final TokenIterator ti = createTokenIterator(hit);
+                final TokenIterator ti = new BasicTokenIterator(new BasicHeaderIterator(connHeaders, null));
                 boolean keepalive = false;
                 while (ti.hasNext()) {
                     final String token = ti.nextToken();
@@ -148,8 +149,7 @@ public boolean keepAlive(final HttpResponse response,
                         keepalive = true;
                     }
                 }
-                if (keepalive)
-                 {
+                if (keepalive) {
                     return true;
                 // neither "close" nor "keep-alive", use default policy
                 }

httpcore/src/main/java/org/apache/http/message/HeaderGroup.java

@@ -51,6 +51,8 @@ public class HeaderGroup implements Cloneable, Serializable {
 
     private static final long serialVersionUID = 2608834160639271617L;
 
+    private final Header[] EMPTY = new Header[] {};
+
     /** The list of headers for this group, in the order in which they were added */
     private final List<Header> headers;
 
@@ -173,18 +175,20 @@ public Header getCondensedHeader(final String name) {
      * @return an array of length &ge; 0
      */
     public Header[] getHeaders(final String name) {
-        final List<Header> headersFound = new ArrayList<Header>();
+        List<Header> headersFound = null;
         // HTTPCORE-361 : we don't use the for-each syntax, i.e.
         //     for (Header header : headers)
         // as that creates an Iterator that needs to be garbage-collected
         for (int i = 0; i < this.headers.size(); i++) {
             final Header header = this.headers.get(i);
             if (header.getName().equalsIgnoreCase(name)) {
+                if (headersFound == null) {
+                    headersFound = new ArrayList<Header>();
+                }
                 headersFound.add(header);
             }
         }
-
-        return headersFound.toArray(new Header[headersFound.size()]);
+        return headersFound != null ? headersFound.toArray(new Header[headersFound.size()]) : EMPTY;
     }
 
     /**