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Posted to commits@hbase.apache.org by nk...@apache.org on 2015/10/13 11:24:13 UTC
hbase git commit: HBASE-14268 Improve KeyLocker - add missing files
Repository: hbase
Updated Branches:
refs/heads/master 99e99f3b5 -> b63155eac
HBASE-14268 Improve KeyLocker - add missing files
Project: http://git-wip-us.apache.org/repos/asf/hbase/repo
Commit: http://git-wip-us.apache.org/repos/asf/hbase/commit/b63155ea
Tree: http://git-wip-us.apache.org/repos/asf/hbase/tree/b63155ea
Diff: http://git-wip-us.apache.org/repos/asf/hbase/diff/b63155ea
Branch: refs/heads/master
Commit: b63155eac7ec429d584478eed50754abc1c7d935
Parents: 99e99f3
Author: Nicolas Liochon <nk...@gmail.com>
Authored: Tue Oct 13 11:22:28 2015 +0200
Committer: Nicolas Liochon <nk...@gmail.com>
Committed: Tue Oct 13 11:22:28 2015 +0200
----------------------------------------------------------------------
.../hadoop/hbase/util/WeakObjectPool.java | 195 +++++++++++++++++++
.../hadoop/hbase/util/TestWeakObjectPool.java | 134 +++++++++++++
2 files changed, 329 insertions(+)
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http://git-wip-us.apache.org/repos/asf/hbase/blob/b63155ea/hbase-common/src/main/java/org/apache/hadoop/hbase/util/WeakObjectPool.java
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diff --git a/hbase-common/src/main/java/org/apache/hadoop/hbase/util/WeakObjectPool.java b/hbase-common/src/main/java/org/apache/hadoop/hbase/util/WeakObjectPool.java
new file mode 100644
index 0000000..7757c6c
--- /dev/null
+++ b/hbase-common/src/main/java/org/apache/hadoop/hbase/util/WeakObjectPool.java
@@ -0,0 +1,195 @@
+/*
+ * 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.hbase.util;
+
+import java.lang.ref.ReferenceQueue;
+import java.lang.ref.WeakReference;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+
+/**
+ * A {@code WeakReference} based shared object pool.
+ * The objects are kept in weak references and
+ * associated with keys which are identified by the {@code equals} method.
+ * The objects are created by {@link ObjectFactory} on demand.
+ * The object creation is expected to be lightweight,
+ * and the objects may be excessively created and discarded.
+ * Thread safe.
+ */
+@InterfaceAudience.Private
+public class WeakObjectPool<K, V> {
+ /**
+ * An {@code ObjectFactory} object is used to create
+ * new shared objects on demand.
+ */
+ public interface ObjectFactory<K, V> {
+ /**
+ * Creates a new shared object associated with the given {@code key},
+ * identified by the {@code equals} method.
+ * This method may be simultaneously called by multiple threads
+ * with the same key, and the excessive objects are just discarded.
+ */
+ V createObject(K key);
+ }
+
+ private final ReferenceQueue<V> staleRefQueue = new ReferenceQueue<V>();
+
+ private class ObjectReference extends WeakReference<V> {
+ final K key;
+
+ ObjectReference(K key, V obj) {
+ super(obj, staleRefQueue);
+ this.key = key;
+ }
+ }
+
+ private final ObjectFactory<K, V> objectFactory;
+
+ /** Does not permit null keys. */
+ private final ConcurrentMap<K, ObjectReference> referenceCache;
+
+ /**
+ * The default initial capacity,
+ * used when not otherwise specified in a constructor.
+ */
+ public static final int DEFAULT_INITIAL_CAPACITY = 16;
+
+ /**
+ * The default concurrency level,
+ * used when not otherwise specified in a constructor.
+ */
+ public static final int DEFAULT_CONCURRENCY_LEVEL = 16;
+
+ /**
+ * Creates a new pool with the default initial capacity (16)
+ * and the default concurrency level (16).
+ *
+ * @param objectFactory the factory to supply new objects on demand
+ *
+ * @throws NullPointerException if {@code objectFactory} is null
+ */
+ public WeakObjectPool(ObjectFactory<K, V> objectFactory) {
+ this(objectFactory, DEFAULT_INITIAL_CAPACITY, DEFAULT_CONCURRENCY_LEVEL);
+ }
+
+ /**
+ * Creates a new pool with the given initial capacity
+ * and the default concurrency level (16).
+ *
+ * @param objectFactory the factory to supply new objects on demand
+ * @param initialCapacity the initial capacity to keep objects in the pool
+ *
+ * @throws NullPointerException if {@code objectFactory} is null
+ * @throws IllegalArgumentException if {@code initialCapacity} is negative
+ */
+ public WeakObjectPool(ObjectFactory<K, V> objectFactory, int initialCapacity) {
+ this(objectFactory, initialCapacity, DEFAULT_CONCURRENCY_LEVEL);
+ }
+
+ /**
+ * Creates a new pool with the given initial capacity
+ * and the given concurrency level.
+ *
+ * @param objectFactory the factory to supply new objects on demand
+ * @param initialCapacity the initial capacity to keep objects in the pool
+ * @param concurrencyLevel the estimated count of concurrently accessing threads
+ *
+ * @throws NullPointerException if {@code objectFactory} is null
+ * @throws IllegalArgumentException if {@code initialCapacity} is negative or
+ * {@code concurrencyLevel} is non-positive
+ */
+ public WeakObjectPool(
+ ObjectFactory<K, V> objectFactory,
+ int initialCapacity,
+ int concurrencyLevel) {
+
+ if (objectFactory == null) {
+ throw new NullPointerException();
+ }
+ this.objectFactory = objectFactory;
+
+ this.referenceCache = new ConcurrentHashMap<K, ObjectReference>(
+ initialCapacity, 0.75f, concurrencyLevel);
+ // 0.75f is the default load factor threshold of ConcurrentHashMap.
+ }
+
+ /**
+ * Removes stale references of shared objects from the pool.
+ * References newly becoming stale may still remain.
+ * The implementation of this method is expected to be lightweight
+ * when there is no stale reference.
+ */
+ public void purge() {
+ // This method is lightweight while there is no stale reference
+ // with the Oracle (Sun) implementation of {@code ReferenceQueue},
+ // because {@code ReferenceQueue.poll} just checks a volatile instance
+ // variable in {@code ReferenceQueue}.
+
+ while (true) {
+ @SuppressWarnings("unchecked")
+ ObjectReference ref = (ObjectReference)staleRefQueue.poll();
+ if (ref == null) {
+ break;
+ }
+ referenceCache.remove(ref.key, ref);
+ }
+ }
+
+ /**
+ * Returns a shared object associated with the given {@code key},
+ * which is identified by the {@code equals} method.
+ * @throws NullPointerException if {@code key} is null
+ */
+ public V get(K key) {
+ ObjectReference ref = referenceCache.get(key);
+ if (ref != null) {
+ V obj = ref.get();
+ if (obj != null) {
+ return obj;
+ }
+ referenceCache.remove(key, ref);
+ }
+
+ V newObj = objectFactory.createObject(key);
+ ObjectReference newRef = new ObjectReference(key, newObj);
+ while (true) {
+ ObjectReference existingRef = referenceCache.putIfAbsent(key, newRef);
+ if (existingRef == null) {
+ return newObj;
+ }
+
+ V existingObject = existingRef.get();
+ if (existingObject != null) {
+ return existingObject;
+ }
+ referenceCache.remove(key, existingRef);
+ }
+ }
+
+ /**
+ * Returns an estimated count of objects kept in the pool.
+ * This also counts stale references,
+ * and you might want to call {@link #purge()} beforehand.
+ */
+ public int size() {
+ return referenceCache.size();
+ }
+}
http://git-wip-us.apache.org/repos/asf/hbase/blob/b63155ea/hbase-common/src/test/java/org/apache/hadoop/hbase/util/TestWeakObjectPool.java
----------------------------------------------------------------------
diff --git a/hbase-common/src/test/java/org/apache/hadoop/hbase/util/TestWeakObjectPool.java b/hbase-common/src/test/java/org/apache/hadoop/hbase/util/TestWeakObjectPool.java
new file mode 100644
index 0000000..bf1b4eb
--- /dev/null
+++ b/hbase-common/src/test/java/org/apache/hadoop/hbase/util/TestWeakObjectPool.java
@@ -0,0 +1,134 @@
+/*
+ * 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.hbase.util;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.apache.hadoop.hbase.testclassification.MiscTests;
+import org.apache.hadoop.hbase.testclassification.SmallTests;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.experimental.categories.Category;
+
+@Category({MiscTests.class, SmallTests.class})
+public class TestWeakObjectPool {
+ WeakObjectPool<String, Object> pool;
+
+ @Before
+ public void setUp() {
+ pool = new WeakObjectPool<String, Object>(
+ new WeakObjectPool.ObjectFactory<String, Object>() {
+ @Override
+ public Object createObject(String key) {
+ return new Object();
+ }
+ });
+ }
+
+ @Test
+ public void testKeys() {
+ Object obj1 = pool.get("a");
+ Object obj2 = pool.get(new String("a"));
+
+ Assert.assertSame(obj1, obj2);
+
+ Object obj3 = pool.get("b");
+
+ Assert.assertNotSame(obj1, obj3);
+ }
+
+ @Test
+ public void testWeakReference() throws Exception {
+ Object obj1 = pool.get("a");
+ int hash1 = System.identityHashCode(obj1);
+
+ System.gc();
+ System.gc();
+ System.gc();
+
+ Thread.sleep(10);
+ // Sleep a while because references newly becoming stale
+ // may still remain when calling the {@code purge} method.
+ pool.purge();
+ Assert.assertEquals(1, pool.size());
+
+ Object obj2 = pool.get("a");
+ Assert.assertSame(obj1, obj2);
+
+ obj1 = null;
+ obj2 = null;
+
+ System.gc();
+ System.gc();
+ System.gc();
+
+ Thread.sleep(10);
+ pool.purge();
+ Assert.assertEquals(0, pool.size());
+
+ Object obj3 = pool.get("a");
+ Assert.assertNotEquals(hash1, System.identityHashCode(obj3));
+ }
+
+ @Test(timeout=1000)
+ public void testCongestion() throws Exception {
+ final int THREAD_COUNT = 100;
+
+ final AtomicBoolean assertionFailed = new AtomicBoolean();
+ final AtomicReference<Object> expectedObjRef = new AtomicReference<Object>();
+ final CountDownLatch prepareLatch = new CountDownLatch(THREAD_COUNT);
+ final CountDownLatch startLatch = new CountDownLatch(1);
+ final CountDownLatch endLatch = new CountDownLatch(THREAD_COUNT);
+
+ for (int i=0; i<THREAD_COUNT; i++) {
+ new Thread() {
+ @Override
+ public void run() {
+ prepareLatch.countDown();
+ try {
+ startLatch.await();
+
+ Object obj = pool.get("a");
+ if (! expectedObjRef.compareAndSet(null, obj)) {
+ if (expectedObjRef.get() != obj) {
+ assertionFailed.set(true);
+ }
+ }
+ } catch (Exception e) {
+ assertionFailed.set(true);
+
+ } finally {
+ endLatch.countDown();
+ }
+ }
+ }.start();
+ }
+
+ prepareLatch.await();
+ startLatch.countDown();
+ endLatch.await();
+
+ if (assertionFailed.get()) {
+ Assert.fail();
+ }
+ }
+}