Speed up sha512_crypt by caching sha512 digesters (thread local)

2 files changed, 69 insertions, 18 deletions

diff --git a/src/main/java/org/openslx/imagemaster/util/Sha512Crypt.java b/src/main/java/org/openslx/imagemaster/util/Sha512Crypt.java
index 472ead9..15cf9ac 100644
--- a/src/main/java/org/openslx/imagemaster/util/Sha512Crypt.java
+++ b/src/main/java/org/openslx/imagemaster/util/Sha512Crypt.java
@@ -44,6 +44,7 @@
 package org.openslx.imagemaster.util;
 
 import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
 
 /*------------------------------------------------------------------------------
                                                                            class
@@ -87,18 +88,33 @@ public final class Sha512Crypt
   static private final int ROUNDS_MAX = 999999999;
   static private final String SALTCHARS = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890";
   static private final String itoa64 = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
-
-  static private MessageDigest getSHA512()
-  {
-    try
-      {
-        return MessageDigest.getInstance("SHA-512");
-      }
-    catch (java.security.NoSuchAlgorithmException ex)
-      {
-        throw new RuntimeException(ex);
-      }
-  }
+  
+	/**
+	 * Cache of sha512 digesters
+	 */
+	private static final ThreadLocal<MessageDigest>
+			sha1 = newThreadLocalSha512(),
+			sha2 = newThreadLocalSha512();
+	
+	/**
+	 * For instantiating TL sha512, so we don't have to copy this stuff twice
+	 * @return thread local sha512 digester
+	 */
+	private static ThreadLocal<MessageDigest> newThreadLocalSha512() {
+		return new ThreadLocal<MessageDigest>() {
+			@Override
+			public MessageDigest initialValue()
+			{
+				try {
+					return MessageDigest.getInstance( "SHA-512" );
+				} catch ( NoSuchAlgorithmException e ) {
+					e.printStackTrace();
+					System.exit(1);
+					return null;
+				}
+			}
+		};
+	}
 
   /**
    * <p>This method actually generates an Sha512 crypted password hash
@@ -120,8 +136,8 @@ public final class Sha512Crypt
 
   public static final String Sha512_crypt(String keyStr, String saltStr, int roundsCount)
   {
-    MessageDigest ctx = getSHA512();
-    MessageDigest alt_ctx = getSHA512();
+    MessageDigest ctx = sha1.get();
+    MessageDigest alt_ctx = sha2.get();
 
     byte[] alt_result;
     byte[] temp_result;
@@ -172,12 +188,11 @@ public final class Sha512Crypt
       }
     else
       {
-        java.util.Random randgen = new java.util.Random();
         StringBuilder saltBuf = new StringBuilder();
 
         while (saltBuf.length() < 16)
           {
-            int index = (int) (randgen.nextFloat() * SALTCHARS.length());
+            int index = Util.randomInt(SALTCHARS.length());
             saltBuf.append(SALTCHARS.substring(index, index+1));
           }
 
diff --git a/src/main/java/org/openslx/imagemaster/util/Util.java b/src/main/java/org/openslx/imagemaster/util/Util.java
index ff0b8c1..4459a3a 100644
--- a/src/main/java/org/openslx/imagemaster/util/Util.java
+++ b/src/main/java/org/openslx/imagemaster/util/Util.java
@@ -1,16 +1,52 @@
 package org.openslx.imagemaster.util;
 
+import java.util.Random;
+
+import org.apache.log4j.Logger;
+
 public class Util
 {
+	private static Logger log = Logger.getLogger( Util.class );
 
+	/**
+	 * Check if the given object is null, abort program if true.
+	 * An optional message to be printed can be passed. A stack trace
+	 * will be printed, too. Finally the application terminates with
+	 * exit code 2.
+	 * 
+	 * This comes in handy if something must not be null, and you want
+	 * user friendsly output. A perfect example would be reading settings
+	 * from a config file. You can use this on mandatory fields.
+	 * 
+	 * @param something the object to compare to null
+	 * @param message the message to be printed if something is null
+	 */
 	public static void notNullFatal( Object something, String message )
 	{
 		if ( something == null ) {
 			if ( message != null )
-				System.out.println( "[NOTNULL] " + message );
-			System.out.println( Thread.currentThread().getStackTrace().toString() );
+				log.fatal( "[NOTNULL] " + message );
+			log.warn( Thread.currentThread().getStackTrace().toString() );
 			System.exit( 2 );
 		}
 	}
+	
+	/**
+	 * Static {@link Random} instance.
+	 */
+	private static final Random random = new Random();
+	
+	/**
+	 * Return a random integer in the range of 0 (inclusive) and
+	 * n (exclusive). Uses the internal static instance of {@link Random},
+	 * so you don't have to deal with instances everywhere.
+	 * 
+	 * @param n the upper bound (exclusive)
+	 * @return number between 0 (inclusive) and n (exclusive)
+	 */
+	public static int randomInt( int n )
+	{
+		return random.nextInt( n );
+	}
 
 }