8245307: Update ExchangeImpl to use thread safe DateTimeFormatter

The fix updates sun.net.httpserver.ExchangeImpl to use thread safe DateTimeFormatter for response headers, this replaces DateFormat that was using ThreadLocal.

Reviewed-by: dfuchs, alanb, chegar

src/jdk.httpserver/share/classes/sun/net/httpserver/ExchangeImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2005, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -32,6 +32,9 @@ import java.util.*;
 import java.lang.System.Logger;
 import java.lang.System.Logger.Level;
 import java.text.*;
+import java.time.Instant;
+import java.time.ZoneId;
+import java.time.format.DateTimeFormatter;
 import java.util.stream.Stream;
 import com.sun.net.httpserver.*;
 
@@ -55,16 +58,12 @@ class ExchangeImpl {
     boolean http10 = false;
 
     /* for formatting the Date: header */
-    private static final String pattern = "EEE, dd MMM yyyy HH:mm:ss zzz";
-    private static final TimeZone gmtTZ = TimeZone.getTimeZone("GMT");
-    private static final ThreadLocal<DateFormat> dateFormat =
-         new ThreadLocal<DateFormat>() {
-             @Override protected DateFormat initialValue() {
-                 DateFormat df = new SimpleDateFormat(pattern, Locale.US);
-                 df.setTimeZone(gmtTZ);
-                 return df;
-         }
-     };
+    private static final DateTimeFormatter FORMATTER;
+    static {
+        String pattern = "EEE, dd MMM yyyy HH:mm:ss zzz";
+        FORMATTER = DateTimeFormatter.ofPattern(pattern, Locale.US)
+                                     .withZone(ZoneId.of("GMT"));
+    }
 
     private static final String HEAD = "HEAD";
 
@@ -212,7 +211,7 @@ class ExchangeImpl {
         tmpout.write (bytes(statusLine, 0), 0, statusLine.length());
         boolean noContentToSend = false; // assume there is content
         boolean noContentLengthHeader = false; // must not send Content-length is set
-        rspHdrs.set ("Date", dateFormat.get().format (new Date()));
+        rspHdrs.set("Date", FORMATTER.format(Instant.now()));
 
         /* check for response type that is not allowed to send a body */
 

test/jdk/com/sun/net/httpserver/DateFormatterTest.java

@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2020 Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+import com.sun.net.httpserver.HttpExchange;
+import com.sun.net.httpserver.HttpHandler;
+import com.sun.net.httpserver.HttpServer;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.URI;
+import java.net.URISyntaxException;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.util.concurrent.Executors;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import jdk.test.lib.net.URIBuilder;
+import org.testng.annotations.AfterTest;
+import org.testng.annotations.BeforeTest;
+import org.testng.annotations.Test;
+import static java.net.http.HttpResponse.BodyHandlers.ofString;
+import static org.testng.Assert.assertTrue;
+import static org.testng.Assert.fail;
+
+/**
+ * @test
+ * @bug 8245307
+ * @summary Test for DateFormatter in ExchangeImpl
+ * @modules java.net.http
+ * @library /test/lib
+ * @build DateFormatterTest
+ * @run testng/othervm DateFormatterTest
+ */
+public class DateFormatterTest {
+
+    private HttpServer server;
+
+    static URI httpURI;
+    static final Integer ITERATIONS = 10;
+    static String format;
+    static Pattern pattern;
+
+    @BeforeTest
+    public void setUp() throws IOException, URISyntaxException {
+        String days = "(Mon|Tue|Wed|Thu|Fri|Sat|Sun)(,)";
+        String dayNo = "(\\s\\d\\d\\s)";
+        String month = "(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)";
+        String hour = "(\\s\\d\\d\\d\\d\\s\\d\\d)(:)(\\d\\d)(:)(\\d\\d\\s)";
+        String zone = "(GMT)";
+        format = days + dayNo + month + hour + zone;
+        pattern = Pattern.compile(format);
+        server = HttpServer.create(new InetSocketAddress(InetAddress.getLoopbackAddress(), 0), 10);
+        server.createContext("/server", new DateFormatHandler());
+        server.setExecutor(Executors.newCachedThreadPool());
+        httpURI = URIBuilder.newBuilder()
+                            .host(server.getAddress().getAddress())
+                            .port(server.getAddress().getPort())
+                            .scheme("http")
+                            .path("/server")
+                            .build();
+        server.start();
+    }
+
+    @AfterTest
+    public void cleanUp() {
+        server.stop(1);
+    }
+
+    @Test
+    public void testDateFormat() throws Exception {
+        HttpClient client = HttpClient.newBuilder()
+                                      .build();
+        HttpRequest request = HttpRequest.newBuilder(httpURI)
+                                         .GET()
+                                         .build();
+        for (int i = 0; i < ITERATIONS; i++) {
+            HttpResponse<String> response = client.send(request, ofString());
+            String date = response.headers().firstValue("Date").orElse("null");
+            if (date.equals("null"))
+                fail("Date not present");
+            Matcher matcher = pattern.matcher(date);
+            assertTrue(matcher.matches());
+        }
+    }
+
+    public static class DateFormatHandler implements HttpHandler {
+
+        @Override
+        public void handle(HttpExchange exchange) throws IOException {
+            try (InputStream is = exchange.getRequestBody();
+                OutputStream os = exchange.getResponseBody()) {
+                byte[] bytes = is.readAllBytes();
+                exchange.sendResponseHeaders(200, bytes.length);
+                os.write(bytes);
+            }
+        }
+    }
+}