big-data/hadoop
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

MAPREDUCE-4229. Intern counter names in the JT (bobby via daryn)

Browse Source 
git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1401473 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Daryn Sharp 2012-10-23 21:01:03 +00:00
parent def0b949d4
commit 61ffa3adb9
2 changed files with 154 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

78
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/StringInterner.java Normal file
View File

@ -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.
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
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);
}
}

76
hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/TestStringInterner.java Normal file
View File

@ -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);
}
}