minor gc optimization: better DefaultSpdyHeaders.iterator()

codec-http/src/main/java/io/netty/handler/codec/spdy/DefaultSpdyHeaders.java

@@ -15,11 +15,14 @@
  */
 package io.netty.handler.codec.spdy;
 
+import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.TreeSet;
+import java.util.Map.Entry;
 
 
 public class DefaultSpdyHeaders extends SpdyHeaders {
@@ -237,16 +240,8 @@ public class DefaultSpdyHeaders extends SpdyHeaders {
     }
 
     @Override
-    public List<Map.Entry<String, String>> entries() {
+    public Iterator<Map.Entry<String, String>> iterator() {
-        List<Map.Entry<String, String>> all =
+        return new HeaderIterator();
-                new LinkedList<Map.Entry<String, String>>();
-
-        HeaderEntry e = head.after;
-        while (e != head) {
-            all.add(e);
-            e = e.after;
-        }
-        return all;
     }
 
     @Override
@@ -281,7 +276,7 @@ public class DefaultSpdyHeaders extends SpdyHeaders {
 
     @Override
     public boolean isEmpty() {
-        return entries().isEmpty();
+        return head == head.after;
     }
 
     private static String toString(Object value) {
@@ -291,6 +286,32 @@ public class DefaultSpdyHeaders extends SpdyHeaders {
         return value.toString();
     }
 
+    private final class HeaderIterator implements Iterator<Map.Entry<String, String>> {
+
+        private HeaderEntry current = head;
+
+        @Override
+        public boolean hasNext() {
+            return current.after != head;
+        }
+
+        @Override
+        public Entry<String, String> next() {
+            current = current.after;
+
+            if (current == head) {
+                throw new NoSuchElementException();
+            }
+
+            return current;
+        }
+
+        @Override
+        public void remove() {
+            throw new UnsupportedOperationException();
+        }
+    }
+
     private static final class HeaderEntry implements Map.Entry<String, String> {
         final int hash;
         final String key;

codec-http/src/main/java/io/netty/handler/codec/spdy/DefaultSpdyHeadersFrame.java

@@ -98,7 +98,7 @@ public class DefaultSpdyHeadersFrame extends DefaultSpdyStreamFrame
     }
 
     protected void appendHeaders(StringBuilder buf) {
-        for (Map.Entry<String, String> e: headers().entries()) {
+        for (Map.Entry<String, String> e: headers()) {
             buf.append("    ");
             buf.append(e.getKey());
             buf.append(": ");

codec-http/src/main/java/io/netty/handler/codec/spdy/SpdyHeaders.java

@@ -38,11 +38,6 @@ public abstract class SpdyHeaders implements Iterable<Map.Entry<String, String>>
             return Collections.emptyList();
         }
 
-        @Override
-        public List<Map.Entry<String, String>> entries() {
-            return Collections.emptyList();
-        }
-
         @Override
         public boolean contains(String name) {
             return false;
@@ -90,7 +85,7 @@ public abstract class SpdyHeaders implements Iterable<Map.Entry<String, String>>
 
         @Override
         public Iterator<Map.Entry<String, String>> iterator() {
-            return entries().iterator();
+            return Collections.<Map.Entry<String, String>>emptyList().iterator();
         }
 
         @Override
@@ -420,10 +415,6 @@ public abstract class SpdyHeaders implements Iterable<Map.Entry<String, String>>
             frame.headers().set(HttpNames.VERSION, httpVersion.text());
         }
     }
-    @Override
-    public Iterator<Map.Entry<String, String>> iterator() {
-        return entries().iterator();
-    }
 
     /**
      * Returns the header value with the specified header name.  If there is
@@ -442,14 +433,6 @@ public abstract class SpdyHeaders implements Iterable<Map.Entry<String, String>>
      */
     public abstract  List<String> getAll(String name);
 
-    /**
-     * Returns all header names and values that this frame contains.
-     *
-     * @return the {@link List} of the header name-value pairs.  An empty list
-     *         if there is no header in this message.
-     */
-    public abstract  List<Map.Entry<String, String>> entries();
-
     /**
      * Returns {@code true} if and only if there is a header with the specified
      * header name.

codec-http/src/main/java/io/netty/handler/codec/spdy/SpdyHttpDecoder.java

@@ -241,7 +241,7 @@ public class SpdyHttpDecoder extends MessageToMessageDecoder<SpdyFrame> {
 
             // Ignore trailers in a truncated HEADERS frame.
             if (!spdyHeadersFrame.isTruncated()) {
-                for (Map.Entry<String, String> e: spdyHeadersFrame.headers().entries()) {
+                for (Map.Entry<String, String> e: spdyHeadersFrame.headers()) {
                     fullHttpMessage.headers().add(e.getKey(), e.getValue());
                 }
             }
@@ -310,7 +310,7 @@ public class SpdyHttpDecoder extends MessageToMessageDecoder<SpdyFrame> {
             HttpHeaders.setHost(req, host);
         }
 
-        for (Map.Entry<String, String> e: requestFrame.headers().entries()) {
+        for (Map.Entry<String, String> e: requestFrame.headers()) {
             req.headers().add(e.getKey(), e.getValue());
         }
 
@@ -332,7 +332,7 @@ public class SpdyHttpDecoder extends MessageToMessageDecoder<SpdyFrame> {
         SpdyHeaders.removeVersion(spdyVersion, responseFrame);
 
         FullHttpResponse res = new DefaultFullHttpResponse(version, status);
-        for (Map.Entry<String, String> e: responseFrame.headers().entries()) {
+        for (Map.Entry<String, String> e: responseFrame.headers()) {
             res.headers().add(e.getKey(), e.getValue());
         }
 

codec-http/src/test/java/io/netty/handler/codec/spdy/SpdySessionHandlerTest.java

@@ -89,7 +89,7 @@ public class SpdySessionHandlerTest {
             assertTrue(receivedValues.isEmpty());
             spdyHeadersFrame.headers().remove(name);
         }
-        assertTrue(spdyHeadersFrame.headers().entries().isEmpty());
+        assertTrue(spdyHeadersFrame.headers().isEmpty());
     }
 
     private static void testSpdySessionHandler(SpdyVersion version, boolean server) {