Browse Source
Cache FileStoreAttributeCache entries since looking up FileStore for a file may be expensive on some platforms. Implement a simple LRU cache based on ConcurrentHashMap using a simple long counter to order access to cache entries. Change-Id: I4881fa938ad2f17712c05da857838073a2fc4ddb Signed-off-by: Matthias Sohn <matthias.sohn@sap.com> Signed-off-by: Marc Strapetz <marc.strapetz@syntevo.com> Also-By: Marc Strapetz <marc.strapetz@syntevo.com>stable-5.1
Matthias Sohn
5 years ago
6 changed files with 428 additions and 1 deletions
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/* |
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* Copyright (C) 2019, Matthias Sohn <matthias.sohn@sap.com> |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
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* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php
|
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
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* names of its contributors may be used to endorse or promote |
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* products derived from this software without specific prior |
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* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package org.eclipse.jgit.util; |
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import static org.junit.Assert.assertEquals; |
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import static org.junit.Assert.assertNotNull; |
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import static org.junit.Assert.assertNull; |
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import java.io.IOException; |
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import java.nio.file.Files; |
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import java.nio.file.Path; |
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import org.junit.After; |
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import org.junit.Before; |
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import org.junit.Test; |
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public class SimpleLruCacheTest { |
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private Path trash; |
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private SimpleLruCache<String, String> cache; |
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@Before |
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public void setup() throws IOException { |
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trash = Files.createTempDirectory("tmp_"); |
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cache = new SimpleLruCache<>(100, 0.2f); |
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} |
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@Before |
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@After |
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public void tearDown() throws Exception { |
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FileUtils.delete(trash.toFile(), |
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FileUtils.RECURSIVE | FileUtils.SKIP_MISSING); |
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} |
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@Test |
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public void testPutGet() { |
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cache.put("a", "A"); |
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cache.put("z", "Z"); |
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assertEquals("A", cache.get("a")); |
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assertEquals("Z", cache.get("z")); |
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} |
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@Test(expected = IllegalArgumentException.class) |
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public void testPurgeFactorTooLarge() { |
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cache.configure(5, 1.01f); |
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} |
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@Test(expected = IllegalArgumentException.class) |
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public void testPurgeFactorTooLarge2() { |
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cache.configure(5, 100); |
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} |
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@Test(expected = IllegalArgumentException.class) |
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public void testPurgeFactorTooSmall() { |
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cache.configure(5, 0); |
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} |
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@Test(expected = IllegalArgumentException.class) |
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public void testPurgeFactorTooSmall2() { |
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cache.configure(5, -100); |
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} |
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@Test |
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public void testGetMissing() { |
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assertEquals(null, cache.get("a")); |
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} |
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@Test |
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public void testPurge() { |
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for (int i = 0; i < 101; i++) { |
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cache.put("a" + i, "a" + i); |
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} |
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assertEquals(80, cache.size()); |
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assertNull(cache.get("a0")); |
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assertNull(cache.get("a20")); |
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assertNotNull(cache.get("a21")); |
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assertNotNull(cache.get("a99")); |
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} |
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@Test |
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public void testConfigure() { |
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for (int i = 0; i < 100; i++) { |
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cache.put("a" + i, "a" + i); |
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} |
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assertEquals(100, cache.size()); |
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cache.configure(10, 0.3f); |
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assertEquals(7, cache.size()); |
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assertNull(cache.get("a0")); |
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assertNull(cache.get("a92")); |
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assertNotNull(cache.get("a93")); |
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assertNotNull(cache.get("a99")); |
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} |
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} |
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@ -0,0 +1,253 @@
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/* |
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* Copyright (C) 2019, Marc Strapetz <marc.strapetz@syntevo.com> |
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* Copyright (C) 2019, Matthias Sohn <matthias.sohn@sap.com> |
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* and other copyright owners as documented in the project's IP log. |
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* |
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* This program and the accompanying materials are made available |
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* under the terms of the Eclipse Distribution License v1.0 which |
||||
* accompanies this distribution, is reproduced below, and is |
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* available at http://www.eclipse.org/org/documents/edl-v10.php
|
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* |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials provided |
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* with the distribution. |
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* |
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* - Neither the name of the Eclipse Foundation, Inc. nor the |
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* names of its contributors may be used to endorse or promote |
||||
* products derived from this software without specific prior |
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* written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
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* CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
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* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
||||
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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*/ |
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package org.eclipse.jgit.util; |
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import java.text.MessageFormat; |
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import java.util.ArrayList; |
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import java.util.Collections; |
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import java.util.Comparator; |
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import java.util.List; |
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import java.util.Map; |
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import java.util.concurrent.ConcurrentHashMap; |
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import java.util.concurrent.locks.Lock; |
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import java.util.concurrent.locks.ReentrantLock; |
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import org.eclipse.jgit.annotations.NonNull; |
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import org.eclipse.jgit.internal.JGitText; |
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/** |
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* Simple limited size cache based on ConcurrentHashMap purging entries in LRU |
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* order when reaching size limit |
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* |
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* @param <K> |
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* the type of keys maintained by this cache |
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* @param <V> |
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* the type of mapped values |
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* |
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* @since 5.1.9 |
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*/ |
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public class SimpleLruCache<K, V> { |
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private static class Entry<K, V> { |
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private final K key; |
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private final V value; |
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// pseudo clock timestamp of the last access to this entry
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private volatile long lastAccessed; |
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private long lastAccessedSorting; |
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Entry(K key, V value, long lastAccessed) { |
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this.key = key; |
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this.value = value; |
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this.lastAccessed = lastAccessed; |
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} |
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void copyAccessTime() { |
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lastAccessedSorting = lastAccessed; |
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} |
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@SuppressWarnings("nls") |
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@Override |
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public String toString() { |
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return "Entry [lastAccessed=" + lastAccessed + ", key=" + key |
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+ ", value=" + value + "]"; |
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} |
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} |
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private Lock lock = new ReentrantLock(); |
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private Map<K, Entry<K,V>> map = new ConcurrentHashMap<>(); |
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private volatile int maximumSize; |
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private int purgeSize; |
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// pseudo clock to implement LRU order of access to entries
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private volatile long time = 0L; |
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private static void checkPurgeFactor(float purgeFactor) { |
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if (purgeFactor <= 0 || purgeFactor >= 1) { |
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throw new IllegalArgumentException( |
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MessageFormat.format(JGitText.get().invalidPurgeFactor, |
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Float.valueOf(purgeFactor))); |
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} |
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} |
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private static int purgeSize(int maxSize, float purgeFactor) { |
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return (int) ((1 - purgeFactor) * maxSize); |
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} |
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/** |
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* Create a new cache |
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* |
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* @param maxSize |
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* maximum size of the cache, to reduce need for synchronization |
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* this is not a hard limit. The real size of the cache could be |
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* slightly above this maximum if multiple threads put new values |
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* concurrently |
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* @param purgeFactor |
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* when the size of the map reaches maxSize the oldest entries |
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* will be purged to free up some space for new entries, |
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* {@code purgeFactor} is the fraction of {@code maxSize} to |
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* purge when this happens |
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*/ |
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public SimpleLruCache(int maxSize, float purgeFactor) { |
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checkPurgeFactor(purgeFactor); |
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this.maximumSize = maxSize; |
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this.purgeSize = purgeSize(maxSize, purgeFactor); |
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} |
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/** |
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* Returns the value to which the specified key is mapped, or {@code null} |
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* if this map contains no mapping for the key. |
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* |
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* <p> |
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* More formally, if this cache contains a mapping from a key {@code k} to a |
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* value {@code v} such that {@code key.equals(k)}, then this method returns |
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* {@code v}; otherwise it returns {@code null}. (There can be at most one |
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* such mapping.) |
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* |
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* @param key |
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* the key |
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* |
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* @throws NullPointerException |
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* if the specified key is null |
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* |
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* @return value mapped for this key, or {@code null} if no value is mapped |
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*/ |
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public V get(Object key) { |
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Entry<K, V> entry = map.get(key); |
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if (entry != null) { |
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entry.lastAccessed = ++time; |
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return entry.value; |
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} |
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return null; |
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} |
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/** |
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* Maps the specified key to the specified value in this cache. Neither the |
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* key nor the value can be null. |
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* |
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* <p> |
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* The value can be retrieved by calling the {@code get} method with a key |
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* that is equal to the original key. |
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* |
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* @param key |
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* key with which the specified value is to be associated |
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* @param value |
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* value to be associated with the specified key |
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* @return the previous value associated with {@code key}, or {@code null} |
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* if there was no mapping for {@code key} |
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* @throws NullPointerException |
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* if the specified key or value is null |
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*/ |
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public V put(@NonNull K key, @NonNull V value) { |
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map.put(key, new Entry<>(key, value, ++time)); |
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if (map.size() > maximumSize) { |
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purge(); |
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} |
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return value; |
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} |
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/** |
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* Returns the current size of this cache |
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* |
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* @return the number of key-value mappings in this cache |
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*/ |
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public int size() { |
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return map.size(); |
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} |
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/** |
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* Reconfigures the cache. If {@code maxSize} is reduced some entries will |
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* be purged. |
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* |
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* @param maxSize |
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* maximum size of the cache |
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* |
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* @param purgeFactor |
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* when the size of the map reaches maxSize the oldest entries |
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* will be purged to free up some space for new entries, |
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* {@code purgeFactor} is the fraction of {@code maxSize} to |
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* purge when this happens |
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*/ |
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public void configure(int maxSize, float purgeFactor) { |
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lock.lock(); |
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try { |
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checkPurgeFactor(purgeFactor); |
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this.maximumSize = maxSize; |
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this.purgeSize = purgeSize(maxSize, purgeFactor); |
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if (map.size() >= maximumSize) { |
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purge(); |
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} |
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} finally { |
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lock.unlock(); |
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} |
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} |
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private void purge() { |
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// don't try to compete if another thread already has the lock
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if (lock.tryLock()) { |
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try { |
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List<Entry> entriesToPurge = new ArrayList<>(map.values()); |
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// copy access times to avoid other threads interfere with
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// sorting
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for (Entry e : entriesToPurge) { |
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e.copyAccessTime(); |
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} |
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Collections.sort(entriesToPurge, |
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Comparator.comparingLong(o -> -o.lastAccessedSorting)); |
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for (int index = purgeSize; index < entriesToPurge |
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.size(); index++) { |
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map.remove(entriesToPurge.get(index).key); |
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} |
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} finally { |
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lock.unlock(); |
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} |
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} |
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} |
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} |
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