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Diffstat (limited to 'trunk/qpid/java/junit-toolkit/src/main/org/apache/qpid/junit/extensions/util/SizeOf.java')
-rw-r--r-- | trunk/qpid/java/junit-toolkit/src/main/org/apache/qpid/junit/extensions/util/SizeOf.java | 94 |
1 files changed, 0 insertions, 94 deletions
diff --git a/trunk/qpid/java/junit-toolkit/src/main/org/apache/qpid/junit/extensions/util/SizeOf.java b/trunk/qpid/java/junit-toolkit/src/main/org/apache/qpid/junit/extensions/util/SizeOf.java deleted file mode 100644 index ecc08770a9..0000000000 --- a/trunk/qpid/java/junit-toolkit/src/main/org/apache/qpid/junit/extensions/util/SizeOf.java +++ /dev/null @@ -1,94 +0,0 @@ -/* - * - * 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.qpid.junit.extensions.util; - -/** - * SizeOf provides a static method that does its best to return an accurate measure of the total amount of memory used by - * the virtual machine. This is calculated as the total memory available to the VM minus the actual amount used by it. - * Before this measurement is taken the garbage collector is run many times until the used memory calculation stabilizes. - * Generally, this trick works quite well to provide an accurate reading, however, it cannot be relied upon to be totally - * accurate. It is also quite slow. - * - * <p><table id="crc"><caption>CRC Card</caption> - * <tr><th> Responsibilities <th> Collaborations - * <tr><td> Calculate total memory used. - * </table> - * - * @author Rupert Smith - */ -public class SizeOf -{ - /** Holds a reference to the runtime object. */ - private static final Runtime RUNTIME = Runtime.getRuntime(); - - /** - * Makes 4 calls the {@link #runGCTillStable} method. - */ - public static void runGCTillStableSeveralTimes() - { - // It helps to call Runtime.gc() using several method calls. - for (int r = 0; r < 4; ++r) - { - runGCTillStable(); - } - } - - /** - * Runs the garbage collector until the used memory reading stabilizes. It may run the garbage collector up - * to 500 times. - */ - public static void runGCTillStable() - { - long usedMem1 = usedMemory(), usedMem2 = Long.MAX_VALUE; - - for (int i = 0; (usedMem1 < usedMem2) && (i < 500); ++i) - { - RUNTIME.runFinalization(); - RUNTIME.gc(); - Thread.currentThread().yield(); - - usedMem2 = usedMem1; - usedMem1 = usedMemory(); - } - } - - /** - * Runs the garbage collector until the used memory stabilizes and then measures it. - * - * @return The amount of memory used by the virtual machine. - */ - public static long getUsedMemory() - { - runGCTillStableSeveralTimes(); - - return usedMemory(); - } - - /** - * Returns the amount of memory used by subtracting the free memory from the total available memory. - * - * @return The amount of memory used. - */ - private static long usedMemory() - { - return RUNTIME.totalMemory() - RUNTIME.freeMemory(); - } -} |