Add ResponseTimeAttribute

core/src/main/java/io/undertow/attribute/ResponseTimeAttribute.java

@@ -0,0 +1,43 @@
+package io.undertow.attribute;
+
+import io.undertow.server.HttpServerExchange;
+
+/**
+ * The response time
+ */
+public class ResponseTimeAttribute implements ExchangeAttribute {
+
+    public static final String RESPONSE_TIME_SHORT = "%D";
+    public static final String RESPONSE_TIME = "%{RESPONSE_TIME}";
+
+    public static final ExchangeAttribute INSTANCE = new ResponseTimeAttribute();
+
+    private ResponseTimeAttribute() {}
+
+    @Override
+    public String readAttribute(HttpServerExchange exchange) {
+        return String.valueOf(System.currentTimeMillis() - exchange.getStartTime());
+    }
+
+    @Override
+    public void writeAttribute(HttpServerExchange exchange, String newValue) throws ReadOnlyAttributeException {
+        throw new ReadOnlyAttributeException("Response Time", newValue);
+    }
+
+    public static final class Builder implements ExchangeAttributeBuilder {
+
+        @Override
+        public String name() {
+            return "Response Time";
+        }
+
+        @Override
+        public ExchangeAttribute build(String token) {
+            if (token.equals(RESPONSE_TIME) || token.equals(RESPONSE_TIME_SHORT)) {
+                return ResponseTimeAttribute.INSTANCE;
+            }
+            return null;
+        }
+    }
+
+}

core/src/main/java/io/undertow/server/HttpServerExchange.java

@@ -125,6 +125,7 @@ public final class HttpServerExchange extends AbstractAttachable {
     private int state = 200;
     private HttpString requestMethod;
     private String requestScheme;
+    private long startTime;
 
     /**
      * The original request URI. This will include the host name if it was specified by the client.
@@ -264,11 +265,13 @@ public final class HttpServerExchange extends AbstractAttachable {
     public HttpServerExchange(final ServerConnection connection, long maxEntitySize) {
         this.connection = connection;
         this.maxEntitySize = maxEntitySize;
+        this.startTime = System.currentTimeMillis();
     }
 
     public HttpServerExchange(final ServerConnection connection) {
         this.connection = connection;
         this.maxEntitySize = 0;
+        this.startTime = System.currentTimeMillis();
     }
 
     /**
@@ -390,6 +393,10 @@ public void setRequestURI(final String requestURI, boolean containsHost) {
         }
     }
 
+    public long getStartTime() {
+        return this.startTime;
+    }
+
     /**
      * If a request was submitted to the server with a full URI instead of just a path this
      * will return true. For example:

core/src/main/resources/META-INF/services/io.undertow.attribute.ExchangeAttributeBuilder

@@ -22,3 +22,4 @@ io.undertow.attribute.QueryParameterAttribute$Builder
 io.undertow.attribute.SslClientCertAttribute$Builder
 io.undertow.attribute.SslCipherAttribute$Builder
 io.undertow.attribute.SslSessionIdAttribute$Builder
+io.undertow.attribute.ResponseTimeAttribute$Builder