fix bz #69316 with test case.

check whether cached date and current date are in same second.

java/org/apache/tomcat/util/http/FastHttpDateFormat.java

@@ -64,7 +64,7 @@ public final class FastHttpDateFormat {
     /**
      * Instant on which the currentDate object was generated.
      */
-    private static volatile long currentDateGenerated = 0L;
+    private static volatile long currentDateGeneratedInSeconds = 0L;
 
 
     /**
@@ -94,11 +94,11 @@ public final class FastHttpDateFormat {
      * @return the HTTP date
      */
     public static String getCurrentDate() {
-        long now = System.currentTimeMillis();
-        // Handle case where time moves backwards (e.g. system time corrected)
-        if (Math.abs(now - currentDateGenerated) > 1000) {
-            currentDate = FORMAT_RFC5322.format(new Date(now));
-            currentDateGenerated = now;
+        // according rfc5322, date/time data is accurate to the second.
+        long nowInSeconds = System.currentTimeMillis() / 1000L;
+        if (nowInSeconds != currentDateGeneratedInSeconds) {
+            currentDate = FORMAT_RFC5322.format(new Date(nowInSeconds * 1000L));
+            currentDateGeneratedInSeconds = nowInSeconds;
         }
         return currentDate;
     }

test/org/apache/tomcat/util/http/TestFastHttpDateFormat.java

@@ -0,0 +1,65 @@
+/*
+ * 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.
+ */
+package org.apache.tomcat.util.http;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class TestFastHttpDateFormat {
+
+    @Test
+    public void testGetCurrentDateInSameSecond() {
+        long now = System.currentTimeMillis();
+        try {
+            Thread.sleep(1000L - now % 1000);
+        } catch (InterruptedException e) {
+            // Ignore
+        }
+        now = System.currentTimeMillis();
+        String s1 = FastHttpDateFormat.getCurrentDate();
+        long lastMillisInSameSecond = now - now % 1000 + 900L;
+        try {
+            Thread.sleep(lastMillisInSameSecond - now);
+        } catch (InterruptedException e) {
+            // Ignore
+        }
+        String s2 = FastHttpDateFormat.getCurrentDate();
+        Assert.assertEquals("Two same RFC5322 format dates are expected.", s1, s2);
+    }
+
+    @Test
+    public void testGetCurrentDateNextToAnotherSecond() {
+        long now = System.currentTimeMillis();
+
+        try {
+            Thread.sleep(2000L - now % 1000 + 500L);
+        } catch (InterruptedException e) {
+            // Ignore
+        }
+        now = System.currentTimeMillis();
+        String s1 = FastHttpDateFormat.getCurrentDate();
+        long firstMillisOfNextSecond = now - now % 1000 + 1100L;
+        try {
+            Thread.sleep(firstMillisOfNextSecond - now);
+        } catch (InterruptedException e) {
+            // Ignore
+        }
+
+        String s2 = FastHttpDateFormat.getCurrentDate();
+        Assert.assertFalse("Two different RFC5322 format dates are expected.", s1.equals(s2));
+    }
+}