Add initial implementation of a thread safe MessageDigest helper class

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1180870 13f79535-47bb-0310-9956-ffa450edef68

diff --git a/java/org/apache/catalina/util/MsgDigest.java b/java/org/apache/catalina/util/MsgDigest.java
new file mode 100644 (file)
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+++ b/java/org/apache/catalina/util/MsgDigest.java
@@ -0,0 +1,77 @@
+/*
+ * 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.catalina.util;
+
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.util.Queue;
+import java.util.concurrent.ConcurrentLinkedQueue;
+
+
+/**
+ * Helper class for generating message digests in multi-threaded environments.
+ */
+public class MsgDigest {
+    
+    private static Helper md5 = new Helper("MD5");
+    private static Helper sha1 = new Helper("SHA1");
+
+    public static byte[] getMD5(byte[] input) {
+        return md5.digest(input);
+    }
+
+    public static byte[] getSHA1(byte[] input) {
+        return sha1.digest(input);
+    }
+    
+    private static class Helper {
+        
+        private final String digestName;
+        private final Queue<MessageDigest> digesters =
+                new ConcurrentLinkedQueue<MessageDigest>();
+        
+        public Helper(String digestName) {
+            this.digestName = digestName;
+        }
+        
+        public byte[] digest(byte[] input) {
+            
+            // Get a digest from the queue
+            MessageDigest digest = digesters.poll();
+            if (digest == null) {
+                // Queue empty, create a new one
+                try {
+                    digest = MessageDigest.getInstance(digestName);
+                } catch (NoSuchAlgorithmException e) {
+                    throw new IllegalArgumentException(e);
+                }
+            }
+            
+            // Reset the digest before we use it
+            digest.reset();
+            
+            // Create the digest for the provided input
+            digest.update(input);
+            byte[] result = digest.digest();
+            
+            // Return the digester to the queue
+            digesters.add(digest);
+            
+            return result;
+        }
+    }
+}