Author: daryn
Date: Tue Oct 23 21:01:03 2012
New Revision: 1401473
URL: http://svn.apache.org/viewvc?rev=1401473&view=rev
Log:
MAPREDUCE-4229. Intern counter names in the JT (bobby via daryn)
Added:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringInterner.java
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringInterner.java
Added:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringInterner.java
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringInterner.java?rev=1401473&view=auto
==============================================================================
---
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringInterner.java
(added)
+++
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringInterner.java
Tue Oct 23 21:01:03 2012
@@ -0,0 +1,78 @@
+/**
+ * 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.hadoop.util;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
+import com.google.common.collect.Interner;
+import com.google.common.collect.Interners;
+
+/**
+ * Provides equivalent behavior to String.intern() to optimize performance,
+ * whereby does not consume memory in the permanent generation.
+ */
[email protected]
[email protected]
+public class StringInterner {
+
+ /**
+ * Retains a strong reference to each string instance it has interned.
+ */
+ private final static Interner<String> strongInterner;
+
+ /**
+ * Retains a weak reference to each string instance it has interned.
+ */
+ private final static Interner<String> weakInterner;
+
+
+
+ static {
+ strongInterner = Interners.newStrongInterner();
+ weakInterner = Interners.newWeakInterner();
+ }
+
+ /**
+ * Interns and returns a reference to the representative instance
+ * for any of a collection of string instances that are equal to each other.
+ * Retains strong reference to the instance,
+ * thus preventing it from being garbage-collected.
+ *
+ * @param sample string instance to be interned
+ * @return strong reference to interned string instance
+ */
+ public static String strongIntern(String sample) {
+ return strongInterner.intern(sample);
+ }
+
+ /**
+ * Interns and returns a reference to the representative instance
+ * for any of a collection of string instances that are equal to each other.
+ * Retains weak reference to the instance,
+ * and so does not prevent it from being garbage-collected.
+ *
+ * @param sample string instance to be interned
+ * @return weak reference to interned string instance
+ */
+ public static String weakIntern(String sample) {
+ return weakInterner.intern(sample);
+ }
+
+}
Added:
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringInterner.java
URL:
http://svn.apache.org/viewvc/hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringInterner.java?rev=1401473&view=auto
==============================================================================
---
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringInterner.java
(added)
+++
hadoop/common/trunk/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringInterner.java
Tue Oct 23 21:01:03 2012
@@ -0,0 +1,76 @@
+/**
+ * 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.hadoop.util;
+
+import static org.junit.Assert.*;
+import static org.apache.hadoop.util.StringInterner.*;
+
+import org.junit.Test;
+
+/**
+ *
+ * Tests string interning {@link StringInterner}
+ */
+public class TestStringInterner {
+
+ /**
+ * Test different references are returned for any of string
+ * instances that are equal to each other but not interned.
+ */
+ @Test
+ public void testNoIntern() {
+ String literalABC = "ABC";
+ String substringABC = "ABCDE".substring(0,3);
+ String heapABC = new String("ABC");
+ assertNotSame(literalABC, substringABC);
+ assertNotSame(literalABC, heapABC);
+ assertNotSame(substringABC, heapABC);
+ }
+
+
+ /**
+ * Test the same strong reference is returned for any
+ * of string instances that are equal to each other.
+ */
+ @Test
+ public void testStrongIntern() {
+ String strongInternLiteralABC = strongIntern("ABC");
+ String strongInternSubstringABC = strongIntern("ABCDE".substring(0,3));
+ String strongInternHeapABC = strongIntern(new String("ABC"));
+ assertSame(strongInternLiteralABC, strongInternSubstringABC);
+ assertSame(strongInternLiteralABC, strongInternHeapABC);
+ assertSame(strongInternSubstringABC, strongInternHeapABC);
+ }
+
+
+ /**
+ * Test the same weak reference is returned for any
+ * of string instances that are equal to each other.
+ */
+ @Test
+ public void testWeakIntern() {
+ String weakInternLiteralABC = weakIntern("ABC");
+ String weakInternSubstringABC = weakIntern("ABCDE".substring(0,3));
+ String weakInternHeapABC = weakIntern(new String("ABC"));
+ assertSame(weakInternLiteralABC, weakInternSubstringABC);
+ assertSame(weakInternLiteralABC, weakInternHeapABC);
+ assertSame(weakInternSubstringABC, weakInternHeapABC);
+ }
+
+}
