simple ETag handling

src/main/java/org/elasticsearch/http/netty/NettyHttpChannel.java

@@ -36,22 +36,36 @@
 import org.jboss.netty.handler.codec.http.*;
 
 import java.io.IOException;
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.GregorianCalendar;
+import java.util.Locale;
 import java.util.Set;
+import java.util.TimeZone;
 
 /**
  *
  */
 public class NettyHttpChannel implements HttpChannel {
+
+    public static final String HTTP_DATE_FORMAT = "EEE, dd MMM yyyy HH:mm:ss zzz";
+    public static final String HTTP_DATE_GMT_TIMEZONE = "GMT";    
+
     private final NettyHttpServerTransport transport;
     private final Channel channel;
     private final org.jboss.netty.handler.codec.http.HttpRequest request;
+    private boolean cacheable;
 
     public NettyHttpChannel(NettyHttpServerTransport transport, Channel channel, org.jboss.netty.handler.codec.http.HttpRequest request) {
         this.transport = transport;
         this.channel = channel;
         this.request = request;
     }
 
+    public void setCacheable(boolean cacheable) {
+        this.cacheable = cacheable;
+    }
+
     @Override
     public void sendResponse(RestResponse response) {
 
@@ -131,6 +145,21 @@ public void sendResponse(RestResponse response) {
         resp.setHeader(HttpHeaders.Names.CONTENT_TYPE, response.contentType());
 
         resp.setHeader(HttpHeaders.Names.CONTENT_LENGTH, String.valueOf(buf.readableBytes()));
+
+        // ETag handling, check if checksums matches, and deliver timestamped HTTP 304 "not modified" if so
+        if (cacheable) {
+            long checksum = response.contentChecksum();
+            resp.addHeader(HttpHeaders.Names.ETAG, checksum);
+            String etag = request.getHeader("If-None-Match");
+            if (etag != null && Long.parseLong(etag) == checksum) {
+                 resp.setContent(null);
+                 resp.setStatus(HttpResponseStatus.NOT_MODIFIED);
+                 SimpleDateFormat dateFormatter = new SimpleDateFormat(HTTP_DATE_FORMAT, Locale.US);
+                 dateFormatter.setTimeZone(TimeZone.getTimeZone(HTTP_DATE_GMT_TIMEZONE));
+                 Calendar time = new GregorianCalendar();
+                 resp.setHeader(HttpHeaders.Names.DATE, dateFormatter.format(time.getTime()));
+            }
+        }
 
         if (transport.resetCookies) {
             String cookieString = request.getHeader(HttpHeaders.Names.COOKIE);
@@ -147,7 +176,7 @@ public void sendResponse(RestResponse response) {
                 }
             }
         }
-
+        
         // Write the response.
         ChannelFuture future = channel.write(resp);
         if (releaseContentListener != null) {

src/main/java/org/elasticsearch/rest/AbstractRestResponse.java

@@ -19,11 +19,16 @@
 
 package org.elasticsearch.rest;
 
+import java.io.IOException;
+import java.util.zip.Adler32;
+
 /**
  *
  */
 public abstract class AbstractRestResponse implements RestResponse {
 
+    private long checksum = -1L;    
+
     @Override
     public byte[] prefixContent() {
         return null;
@@ -53,4 +58,23 @@ public int suffixContentLength() {
     public int suffixContentOffset() {
         return 0;
     }
+
+    @Override
+    public long contentChecksum() {
+        if (checksum == -1L) {
+            checksum = createChecksum();
+        }
+        return checksum;
+    }
+
+    private long createChecksum() {
+        Adler32 adler = new Adler32();
+        try {
+            byte[] b = content();
+            adler.update(b,0,b.length);
+        } catch (IOException e) {
+        }
+        return adler.getValue();
+    }
+
 }

src/main/java/org/elasticsearch/rest/RestChannel.java

@@ -25,4 +25,6 @@
 public interface RestChannel {
 
     void sendResponse(RestResponse response);
+
+    void setCacheable(boolean enabled);
 }

src/main/java/org/elasticsearch/rest/RestController.java

@@ -156,6 +156,7 @@ public void dispatchRequest(final RestRequest request, final RestChannel channel
     void executeHandler(RestRequest request, RestChannel channel) {
         final RestHandler handler = getHandler(request);
         if (handler != null) {
+            channel.setCacheable(settings.getAsBoolean("http.cache.etag."+ handler.getClass().getSimpleName().toLowerCase(), false));
             handler.handleRequest(request, channel);
         } else {
             if (request.method() == RestRequest.Method.OPTIONS) {

src/main/java/org/elasticsearch/rest/RestResponse.java

@@ -45,6 +45,8 @@ public interface RestResponse {
     int contentLength() throws IOException;
 
     int contentOffset() throws IOException;
+
+    long contentChecksum();
 
     byte[] prefixContent();