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From strub...@apache.org
Subject svn commit: r1411269 - in /myfaces/core/branches/2.2.x/impl/src: main/java/org/apache/myfaces/util/ThreadsafeXorShiftRandom.java main/java/org/apache/myfaces/util/XorShiftRandom.java test/java/org/apache/myfaces/util/XorShiftRandomTest.java
Date Mon, 19 Nov 2012 16:04:31 GMT
Author: struberg
Date: Mon Nov 19 16:04:30 2012
New Revision: 1411269

URL: http://svn.apache.org/viewvc?rev=1411269&view=rev
Log:
MYFACES-3654 implement fast threadsafe Random algorithm.

Added:
    myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/ThreadsafeXorShiftRandom.java
    myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/XorShiftRandom.java
  (with props)
    myfaces/core/branches/2.2.x/impl/src/test/java/org/apache/myfaces/util/XorShiftRandomTest.java

Added: myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/ThreadsafeXorShiftRandom.java
URL: http://svn.apache.org/viewvc/myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/ThreadsafeXorShiftRandom.java?rev=1411269&view=auto
==============================================================================
--- myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/ThreadsafeXorShiftRandom.java
(added)
+++ myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/ThreadsafeXorShiftRandom.java
Mon Nov 19 16:04:30 2012
@@ -0,0 +1,66 @@
+/*
+ * 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.myfaces.util;
+
+import java.util.Random;
+
+/**
+ * A threadsafe implementation of {@link XorShiftRandom}.
+ * We use a ThreadLocal to give each thread it's own implementation.
+ */
+public class ThreadsafeXorShiftRandom extends XorShiftRandom
+{
+    /**
+     * Only used for creating the initial seed for each thread!
+     *
+     * We use a threadsafe java.util.Random for making sure that
+     * each thread get it's very own initial seed value.
+     *
+     * If we would not do this then starting dozen Threads at the same time
+     * would result in all having the same seed and thus generate
+     * the same random numbers.
+     */
+    private static Random seedRandom = new Random(System.nanoTime());
+
+    public ThreadsafeXorShiftRandom()
+    {
+        // seed is not used but created by the ThreadLocal
+        super(0);
+    }
+
+    private static final ThreadLocal<XorShiftRandom> random = new ThreadLocal<XorShiftRandom>()
+    {
+        @Override
+        protected XorShiftRandom initialValue()
+        {
+            return new XorShiftRandom(seedRandom.nextLong());
+        }
+    };
+
+    /**
+     * We use the random generator for this very thread.
+     * This method is perfectly threadsafe. It is also guaranteed
+     * that each thread will get own values.
+     */
+    @Override
+    public long random()
+    {
+        return random.get().random();
+    }
+}

Added: myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/XorShiftRandom.java
URL: http://svn.apache.org/viewvc/myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/XorShiftRandom.java?rev=1411269&view=auto
==============================================================================
--- myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/XorShiftRandom.java
(added)
+++ myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/XorShiftRandom.java
Mon Nov 19 16:04:30 2012
@@ -0,0 +1,59 @@
+/*
+ * 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.myfaces.util;
+
+/**
+ * A simple XORShift Random generator.
+ * This class is NOT synchronized, you need to do that yourself if needed!
+ */
+public class XorShiftRandom
+{
+    private long value;
+
+    public XorShiftRandom( long initialSeed )
+    {
+        value = initialSeed;
+    }
+
+    /**
+     * Calculate a random value based on the previous value stored in this instance.
+     * If you use this method in a concurring way, you need to synchronize the access!
+     * @return
+     */
+    public long random()
+    {
+        value = random(value);
+        return value;
+    }
+
+    /**
+     * Calculate a random value based on the given start Value.
+     * @param randomStart the start value. Usually the result of the previous invocation
+     * @return the new random value.
+     */
+    public static long random(final long randomStart)
+    {
+        long randomValue = randomStart;
+        randomValue ^= (randomValue << 21);
+        randomValue ^= (randomValue >>> 35);
+        randomValue ^= (randomValue << 4);
+
+        return randomValue;
+    }
+}

Propchange: myfaces/core/branches/2.2.x/impl/src/main/java/org/apache/myfaces/util/XorShiftRandom.java
------------------------------------------------------------------------------
    svn:eol-style = native

Added: myfaces/core/branches/2.2.x/impl/src/test/java/org/apache/myfaces/util/XorShiftRandomTest.java
URL: http://svn.apache.org/viewvc/myfaces/core/branches/2.2.x/impl/src/test/java/org/apache/myfaces/util/XorShiftRandomTest.java?rev=1411269&view=auto
==============================================================================
--- myfaces/core/branches/2.2.x/impl/src/test/java/org/apache/myfaces/util/XorShiftRandomTest.java
(added)
+++ myfaces/core/branches/2.2.x/impl/src/test/java/org/apache/myfaces/util/XorShiftRandomTest.java
Mon Nov 19 16:04:30 2012
@@ -0,0 +1,64 @@
+/*
+ * 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.myfaces.util;
+
+import org.junit.Test;
+import org.testng.Assert;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class XorShiftRandomTest
+{
+
+    @Test
+    public void testXorShiftRandom()
+    {
+        XorShiftRandom random = new XorShiftRandom(System.nanoTime());
+        Set<Long> randomVals = new HashSet<Long>(10);
+
+        int randomCount = 100;
+
+        for (int i = 0; i < randomCount; i ++)
+        {
+            randomVals.add(random.random());
+        }
+
+        // if the random generator is good then we had no collisions.
+        Assert.assertEquals(randomVals.size(), 100);
+    }
+
+
+    @Test
+    public void testThreadsafeXorShiftRandom()
+    {
+        XorShiftRandom random = new ThreadsafeXorShiftRandom();
+        Set<Long> randomVals = new HashSet<Long>(10);
+
+        int randomCount = 100;
+
+        for (int i = 0; i < randomCount; i ++)
+        {
+            randomVals.add(random.random());
+        }
+
+        // if the random generator is good then we had no collisions.
+        Assert.assertEquals(randomVals.size(), 100);
+    }
+}



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