| /* |
| * 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.commons.pool2; |
| |
| import java.lang.reflect.InvocationHandler; |
| import java.lang.reflect.Method; |
| import java.lang.reflect.Proxy; |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.HashSet; |
| import java.util.Map; |
| import java.util.NoSuchElementException; |
| import java.util.Set; |
| import java.util.Timer; |
| import java.util.TimerTask; |
| |
| /** |
| * This class consists exclusively of static methods that operate on or return ObjectPool |
| * or KeyedObjectPool related interfaces. |
| * |
| * @author Sandy McArthur |
| * @version $Revision$ $Date$ |
| * @since Pool 1.3 |
| */ |
| public final class PoolUtils { |
| |
| /** |
| * Timer used to periodically check pools idle object count. |
| * Because a {@link Timer} creates a {@link Thread} this is lazily instantiated. |
| */ |
| private static Timer MIN_IDLE_TIMER; //@GuardedBy("this") |
| |
| /** |
| * PoolUtils instances should NOT be constructed in standard programming. |
| * Instead, the class should be used procedurally: PoolUtils.adapt(aPool);. |
| * This constructor is public to permit tools that require a JavaBean instance to operate. |
| */ |
| public PoolUtils() { |
| } |
| |
| /** |
| * Should the supplied Throwable be re-thrown (eg if it is an instance of |
| * one of the Throwables that should never be swallowed). Used by the pool |
| * error handling for operations that throw exceptions that normally need to |
| * be ignored. |
| * @param t The Throwable to check |
| * @throws ThreadDeath if that is passed in |
| * @throws VirtualMachineError if that is passed in |
| * @since Pool 1.5.5 |
| */ |
| public static void checkRethrow(Throwable t) { |
| if (t instanceof ThreadDeath) { |
| throw (ThreadDeath) t; |
| } |
| if (t instanceof VirtualMachineError) { |
| throw (VirtualMachineError) t; |
| } |
| // All other instances of Throwable will be silently swallowed |
| } |
| |
| /** |
| * Periodically check the idle object count for the pool. At most one idle object will be added per period. |
| * If there is an exception when calling {@link ObjectPool#addObject()} then no more checks will be performed. |
| * |
| * @param pool the pool to check periodically. |
| * @param minIdle if the {@link ObjectPool#getNumIdle()} is less than this then add an idle object. |
| * @param period the frequency to check the number of idle objects in a pool, see |
| * {@link Timer#schedule(TimerTask, long, long)}. |
| * @return the {@link TimerTask} that will periodically check the pools idle object count. |
| * @throws IllegalArgumentException when <code>pool</code> is <code>null</code> or |
| * when <code>minIdle</code> is negative or when <code>period</code> isn't |
| * valid for {@link Timer#schedule(TimerTask, long, long)}. |
| * @since Pool 1.3 |
| */ |
| public static <T> TimerTask checkMinIdle(final ObjectPool<T> pool, final int minIdle, final long period) throws IllegalArgumentException { |
| if (pool == null) { |
| throw new IllegalArgumentException("keyedPool must not be null."); |
| } |
| if (minIdle < 0) { |
| throw new IllegalArgumentException("minIdle must be non-negative."); |
| } |
| final TimerTask task = new ObjectPoolMinIdleTimerTask<T>(pool, minIdle); |
| getMinIdleTimer().schedule(task, 0L, period); |
| return task; |
| } |
| |
| /** |
| * Periodically check the idle object count for the key in the keyedPool. At most one idle object will be added per period. |
| * If there is an exception when calling {@link KeyedObjectPool#addObject(Object)} then no more checks for that key |
| * will be performed. |
| * |
| * @param keyedPool the keyedPool to check periodically. |
| * @param key the key to check the idle count of. |
| * @param minIdle if the {@link KeyedObjectPool#getNumIdle(Object)} is less than this then add an idle object. |
| * @param period the frequency to check the number of idle objects in a keyedPool, see |
| * {@link Timer#schedule(TimerTask, long, long)}. |
| * @return the {@link TimerTask} that will periodically check the pools idle object count. |
| * @throws IllegalArgumentException when <code>keyedPool</code>, <code>key</code> is <code>null</code> or |
| * when <code>minIdle</code> is negative or when <code>period</code> isn't |
| * valid for {@link Timer#schedule(TimerTask, long, long)}. |
| * @since Pool 1.3 |
| */ |
| public static <K,V> TimerTask checkMinIdle(final KeyedObjectPool<K,V> keyedPool, final K key, final int minIdle, final long period) throws IllegalArgumentException { |
| if (keyedPool == null) { |
| throw new IllegalArgumentException("keyedPool must not be null."); |
| } |
| if (key == null) { |
| throw new IllegalArgumentException("key must not be null."); |
| } |
| if (minIdle < 0) { |
| throw new IllegalArgumentException("minIdle must be non-negative."); |
| } |
| final TimerTask task = new KeyedObjectPoolMinIdleTimerTask<K,V>(keyedPool, key, minIdle); |
| getMinIdleTimer().schedule(task, 0L, period); |
| return task; |
| } |
| |
| /** |
| * Periodically check the idle object count for each key in the <code>Collection</code> <code>keys</code> in the keyedPool. |
| * At most one idle object will be added per period. |
| * |
| * @param keyedPool the keyedPool to check periodically. |
| * @param keys a collection of keys to check the idle object count. |
| * @param minIdle if the {@link KeyedObjectPool#getNumIdle(Object)} is less than this then add an idle object. |
| * @param period the frequency to check the number of idle objects in a keyedPool, see |
| * {@link Timer#schedule(TimerTask, long, long)}. |
| * @return a {@link Map} of key and {@link TimerTask} pairs that will periodically check the pools idle object count. |
| * @throws IllegalArgumentException when <code>keyedPool</code>, <code>keys</code>, or any of the values in the |
| * collection is <code>null</code> or when <code>minIdle</code> is negative or when <code>period</code> isn't |
| * valid for {@link Timer#schedule(TimerTask, long, long)}. |
| * @see #checkMinIdle(KeyedObjectPool, Object, int, long) |
| * @since Pool 1.3 |
| */ |
| public static <K,V> Map<K,TimerTask> checkMinIdle(final KeyedObjectPool<K,V> keyedPool, final Collection<K> keys, final int minIdle, final long period) throws IllegalArgumentException { |
| if (keys == null) { |
| throw new IllegalArgumentException("keys must not be null."); |
| } |
| final Map<K,TimerTask> tasks = new HashMap<K,TimerTask>(keys.size()); |
| for (K key : keys) { |
| tasks.put(key, checkMinIdle(keyedPool, key, minIdle, period)); |
| } |
| return tasks; |
| } |
| |
| /** |
| * Calls {@link ObjectPool#addObject()} on <code>pool</code> <code>count</code> number of times. |
| * |
| * @param pool the pool to prefill. |
| * @param count the number of idle objects to add. |
| * @throws Exception when {@link ObjectPool#addObject()} fails. |
| * @throws IllegalArgumentException when <code>pool</code> is <code>null</code>. |
| * @since Pool 1.3 |
| */ |
| public static <T> void prefill(final ObjectPool<T> pool, final int count) throws Exception, IllegalArgumentException { |
| if (pool == null) { |
| throw new IllegalArgumentException("pool must not be null."); |
| } |
| for (int i = 0; i < count; i++) { |
| pool.addObject(); |
| } |
| } |
| |
| /** |
| * Calls {@link ObjectPool#addObject()} on <code>keyedPool</code> with <code>key</code> <code>count</code> |
| * number of times. |
| * |
| * @param keyedPool the keyedPool to prefill. |
| * @param key the key to add objects for. |
| * @param count the number of idle objects to add for <code>key</code>. |
| * @throws Exception when {@link KeyedObjectPool#addObject(Object)} fails. |
| * @throws IllegalArgumentException when <code>keyedPool</code> or <code>key</code> is <code>null</code>. |
| * @since Pool 1.3 |
| */ |
| public static <K,V> void prefill(final KeyedObjectPool<K,V> keyedPool, final K key, final int count) throws Exception, IllegalArgumentException { |
| if (keyedPool == null) { |
| throw new IllegalArgumentException("keyedPool must not be null."); |
| } |
| if (key == null) { |
| throw new IllegalArgumentException("key must not be null."); |
| } |
| for (int i = 0; i < count; i++) { |
| keyedPool.addObject(key); |
| } |
| } |
| |
| /** |
| * Calls {@link ObjectPool#addObject()} on <code>keyedPool</code> with each key in <code>keys</code> for |
| * <code>count</code> number of times. This has the same effect as calling |
| * {@link #prefill(KeyedObjectPool, Object, int)} for each key in the <code>keys</code> collection. |
| * |
| * @param keyedPool the keyedPool to prefill. |
| * @param keys {@link Collection} of keys to add objects for. |
| * @param count the number of idle objects to add for each <code>key</code>. |
| * @throws Exception when {@link KeyedObjectPool#addObject(Object)} fails. |
| * @throws IllegalArgumentException when <code>keyedPool</code>, <code>keys</code>, or |
| * any value in <code>keys</code> is <code>null</code>. |
| * @see #prefill(KeyedObjectPool, Object, int) |
| * @since Pool 1.3 |
| */ |
| public static <K,V> void prefill(final KeyedObjectPool<K,V> keyedPool, final Collection<K> keys, final int count) throws Exception, IllegalArgumentException { |
| if (keys == null) { |
| throw new IllegalArgumentException("keys must not be null."); |
| } |
| for (K key : keys) { |
| prefill(keyedPool, key, count); |
| } |
| } |
| |
| /** |
| * Returns a synchronized (thread-safe) ObjectPool backed by the specified ObjectPool. |
| * |
| * <p><b>Note:</b> |
| * This should not be used on pool implementations that already provide proper synchronization |
| * such as the pools provided in the Commons Pool library. Wrapping a pool that |
| * {@link #wait() waits} for poolable objects to be returned before allowing another one to be |
| * borrowed with another layer of synchronization will cause liveliness issues or a deadlock. |
| * </p> |
| * |
| * @param pool the ObjectPool to be "wrapped" in a synchronized ObjectPool. |
| * @return a synchronized view of the specified ObjectPool. |
| * @since Pool 1.3 |
| */ |
| @SuppressWarnings("unchecked") // returned proxy is a ObjectPool<T> wrapper |
| public static <T> ObjectPool<T> synchronizedPool(final ObjectPool<T> pool) { |
| if (pool == null) { |
| throw new IllegalArgumentException("pool must not be null."); |
| } |
| /* |
| assert !(pool instanceof GenericObjectPool) |
| : "GenericObjectPool is already thread-safe"; |
| assert !(pool instanceof SoftReferenceObjectPool) |
| : "SoftReferenceObjectPool is already thread-safe"; |
| assert !(pool instanceof StackObjectPool) |
| : "StackObjectPool is already thread-safe"; |
| assert !"org.apache.commons.pool.composite.CompositeObjectPool".equals(pool.getClass().getName()) |
| : "CompositeObjectPools are already thread-safe"; |
| */ |
| return synchronizedObject(pool, ObjectPool.class); |
| } |
| |
| /** |
| * Returns a synchronized (thread-safe) KeyedObjectPool backed by the specified KeyedObjectPool. |
| * |
| * <p><b>Note:</b> |
| * This should not be used on pool implementations that already provide proper synchronization |
| * such as the pools provided in the Commons Pool library. Wrapping a pool that |
| * {@link #wait() waits} for poolable objects to be returned before allowing another one to be |
| * borrowed with another layer of synchronization will cause liveliness issues or a deadlock. |
| * </p> |
| * |
| * @param keyedPool the KeyedObjectPool to be "wrapped" in a synchronized KeyedObjectPool. |
| * @return a synchronized view of the specified KeyedObjectPool. |
| * @since Pool 1.3 |
| */ |
| @SuppressWarnings("unchecked") // returned proxy is a KeyedObjectPool<K,V> wrapper |
| public static <K,V> KeyedObjectPool<K,V> synchronizedPool(final KeyedObjectPool<K,V> keyedPool) { |
| if (keyedPool == null) { |
| throw new IllegalArgumentException("keyedPool must not be null."); |
| } |
| /* |
| assert !(keyedPool instanceof GenericKeyedObjectPool) |
| : "GenericKeyedObjectPool is already thread-safe"; |
| assert !(keyedPool instanceof StackKeyedObjectPool) |
| : "StackKeyedObjectPool is already thread-safe"; |
| assert !"org.apache.commons.pool.composite.CompositeKeyedObjectPool".equals(keyedPool.getClass().getName()) |
| : "CompositeKeyedObjectPools are already thread-safe"; |
| */ |
| return synchronizedObject(keyedPool, KeyedObjectPool.class); |
| } |
| |
| /** |
| * Returns a synchronized (thread-safe) PoolableObjectFactory backed by the specified PoolableObjectFactory. |
| * |
| * @param factory the PoolableObjectFactory to be "wrapped" in a synchronized PoolableObjectFactory. |
| * @return a synchronized view of the specified PoolableObjectFactory. |
| * @since Pool 1.3 |
| */ |
| @SuppressWarnings("unchecked") // returned proxy is a PoolableObjectFactory<T> wrapper |
| public static <T> PoolableObjectFactory<T> synchronizedPoolableFactory(final PoolableObjectFactory<T> factory) { |
| if (factory == null) { |
| throw new IllegalArgumentException("factory must not be null."); |
| } |
| return synchronizedObject(factory, PoolableObjectFactory.class); |
| } |
| |
| /** |
| * Returns a synchronized (thread-safe) KeyedPoolableObjectFactory backed by the specified KeyedPoolableObjectFactory. |
| * |
| * @param keyedFactory the KeyedPoolableObjectFactory to be "wrapped" in a synchronized KeyedPoolableObjectFactory. |
| * @return a synchronized view of the specified KeyedPoolableObjectFactory. |
| * @since Pool 1.3 |
| */ |
| @SuppressWarnings("unchecked") // returned proxy is a KeyedPoolableObjectFactory<K,V> wrapper |
| public static <K,V> KeyedPoolableObjectFactory<K,V> synchronizedPoolableFactory(final KeyedPoolableObjectFactory<K,V> keyedFactory) { |
| if (keyedFactory == null) { |
| throw new IllegalArgumentException("keyedFactory must not be null."); |
| } |
| return synchronizedObject(keyedFactory, KeyedPoolableObjectFactory.class); |
| } |
| |
| /** |
| * Wrap the given object in a proxed one where all methods declared in the given interface will be synchronized. |
| * |
| * @param <T> the object type has to be proxed |
| * @param toBeSynchronized to object which methods have to be synchronized |
| * @param type the interface has to be proxed |
| * @return the dynamic synchronized proxy |
| */ |
| private static <T> T synchronizedObject(final T toBeSynchronized, final Class<T> type) { |
| /* |
| * Used to synchronize method declared on the pool/factory interface only. |
| */ |
| final Set<Method> synchronizedMethods = new HashSet<Method>(); |
| |
| for (Method method : type.getDeclaredMethods()) { |
| synchronizedMethods.add(method); |
| } |
| |
| return type.cast(Proxy.newProxyInstance(type.getClassLoader(), |
| new Class<?>[] { type }, |
| new InvocationHandler() { |
| |
| private final Object lock = new Object(); |
| |
| public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { |
| if (synchronizedMethods.contains(method)) { |
| synchronized (this.lock) { |
| return method.invoke(toBeSynchronized, args); |
| } |
| } |
| return method.invoke(toBeSynchronized, args); |
| } |
| |
| } |
| )); |
| } |
| |
| /** |
| * Returns a pool that adaptively decreases it's size when idle objects are no longer needed. |
| * This is intended as an always thread-safe alternative to using an idle object evictor |
| * provided by many pool implementations. This is also an effective way to shrink FIFO ordered |
| * pools that experience load spikes. |
| * |
| * @param pool the ObjectPool to be decorated so it shrinks it's idle count when possible. |
| * @return a pool that adaptively decreases it's size when idle objects are no longer needed. |
| * @see #erodingPool(ObjectPool, float) |
| * @since Pool 1.4 |
| */ |
| public static <T> ObjectPool<T> erodingPool(final ObjectPool<T> pool) { |
| return erodingPool(pool, 1f); |
| } |
| |
| /** |
| * Returns a pool that adaptively decreases it's size when idle objects are no longer needed. |
| * This is intended as an always thread-safe alternative to using an idle object evictor |
| * provided by many pool implementations. This is also an effective way to shrink FIFO ordered |
| * pools that experience load spikes. |
| * |
| * <p> |
| * The factor parameter provides a mechanism to tweak the rate at which the pool tries to shrink |
| * it's size. Values between 0 and 1 cause the pool to try to shrink it's size more often. |
| * Values greater than 1 cause the pool to less frequently try to shrink it's size. |
| * </p> |
| * |
| * @param pool the ObjectPool to be decorated so it shrinks it's idle count when possible. |
| * @param factor a positive value to scale the rate at which the pool tries to reduce it's size. |
| * If 0 < factor < 1 then the pool shrinks more aggressively. |
| * If 1 < factor then the pool shrinks less aggressively. |
| * @return a pool that adaptively decreases it's size when idle objects are no longer needed. |
| * @see #erodingPool(ObjectPool) |
| * @since Pool 1.4 |
| */ |
| public static <T> ObjectPool<T> erodingPool(final ObjectPool<T> pool, final float factor) { |
| if (pool == null) { |
| throw new IllegalArgumentException("pool must not be null."); |
| } |
| if (factor <= 0f) { |
| throw new IllegalArgumentException("factor must be positive."); |
| } |
| return new ErodingObjectPool<T>(pool, factor); |
| } |
| |
| /** |
| * Returns a pool that adaptively decreases it's size when idle objects are no longer needed. |
| * This is intended as an always thread-safe alternative to using an idle object evictor |
| * provided by many pool implementations. This is also an effective way to shrink FIFO ordered |
| * pools that experience load spikes. |
| * |
| * @param keyedPool the KeyedObjectPool to be decorated so it shrinks it's idle count when |
| * possible. |
| * @return a pool that adaptively decreases it's size when idle objects are no longer needed. |
| * @see #erodingPool(KeyedObjectPool, float) |
| * @see #erodingPool(KeyedObjectPool, float, boolean) |
| * @since Pool 1.4 |
| */ |
| public static <K,V> KeyedObjectPool<K,V> erodingPool(final KeyedObjectPool<K,V> keyedPool) { |
| return erodingPool(keyedPool, 1f); |
| } |
| |
| /** |
| * Returns a pool that adaptively decreases it's size when idle objects are no longer needed. |
| * This is intended as an always thread-safe alternative to using an idle object evictor |
| * provided by many pool implementations. This is also an effective way to shrink FIFO ordered |
| * pools that experience load spikes. |
| * |
| * <p> |
| * The factor parameter provides a mechanism to tweak the rate at which the pool tries to shrink |
| * it's size. Values between 0 and 1 cause the pool to try to shrink it's size more often. |
| * Values greater than 1 cause the pool to less frequently try to shrink it's size. |
| * </p> |
| * |
| * @param keyedPool the KeyedObjectPool to be decorated so it shrinks it's idle count when |
| * possible. |
| * @param factor a positive value to scale the rate at which the pool tries to reduce it's size. |
| * If 0 < factor < 1 then the pool shrinks more aggressively. |
| * If 1 < factor then the pool shrinks less aggressively. |
| * @return a pool that adaptively decreases it's size when idle objects are no longer needed. |
| * @see #erodingPool(KeyedObjectPool, float, boolean) |
| * @since Pool 1.4 |
| */ |
| public static <K,V> KeyedObjectPool<K,V> erodingPool(final KeyedObjectPool<K,V> keyedPool, final float factor) { |
| return erodingPool(keyedPool, factor, false); |
| } |
| |
| /** |
| * Returns a pool that adaptively decreases it's size when idle objects are no longer needed. |
| * This is intended as an always thread-safe alternative to using an idle object evictor |
| * provided by many pool implementations. This is also an effective way to shrink FIFO ordered |
| * pools that experience load spikes. |
| * |
| * <p> |
| * The factor parameter provides a mechanism to tweak the rate at which the pool tries to shrink |
| * it's size. Values between 0 and 1 cause the pool to try to shrink it's size more often. |
| * Values greater than 1 cause the pool to less frequently try to shrink it's size. |
| * </p> |
| * |
| * <p> |
| * The perKey parameter determines if the pool shrinks on a whole pool basis or a per key basis. |
| * When perKey is false, the keys do not have an effect on the rate at which the pool tries to |
| * shrink it's size. When perKey is true, each key is shrunk independently. |
| * </p> |
| * |
| * @param keyedPool the KeyedObjectPool to be decorated so it shrinks it's idle count when |
| * possible. |
| * @param factor a positive value to scale the rate at which the pool tries to reduce it's size. |
| * If 0 < factor < 1 then the pool shrinks more aggressively. |
| * If 1 < factor then the pool shrinks less aggressively. |
| * @param perKey when true, each key is treated independently. |
| * @return a pool that adaptively decreases it's size when idle objects are no longer needed. |
| * @see #erodingPool(KeyedObjectPool) |
| * @see #erodingPool(KeyedObjectPool, float) |
| * @since Pool 1.4 |
| */ |
| public static <K,V> KeyedObjectPool<K,V> erodingPool(final KeyedObjectPool<K,V> keyedPool, final float factor, final boolean perKey) { |
| if (keyedPool == null) { |
| throw new IllegalArgumentException("keyedPool must not be null."); |
| } |
| if (factor <= 0f) { |
| throw new IllegalArgumentException("factor must be positive."); |
| } |
| if (perKey) { |
| return new ErodingPerKeyKeyedObjectPool<K,V>(keyedPool, factor); |
| } else { |
| return new ErodingKeyedObjectPool<K,V>(keyedPool, factor); |
| } |
| } |
| |
| /** |
| * Get the <code>Timer</code> for checking keyedPool's idle count. Lazily create the {@link Timer} as needed. |
| * |
| * @return the {@link Timer} for checking keyedPool's idle count. |
| * @since Pool 1.3 |
| */ |
| private static synchronized Timer getMinIdleTimer() { |
| if (MIN_IDLE_TIMER == null) { |
| MIN_IDLE_TIMER = new Timer(true); |
| } |
| return MIN_IDLE_TIMER; |
| } |
| |
| /** |
| * Timer task that adds objects to the pool until the number of idle |
| * instances reaches the configured minIdle. Note that this is not the |
| * same as the pool's minIdle setting. |
| * |
| */ |
| private static class ObjectPoolMinIdleTimerTask<T> extends TimerTask { |
| |
| /** Minimum number of idle instances. Not the same as pool.getMinIdle(). */ |
| private final int minIdle; |
| |
| /** Object pool */ |
| private final ObjectPool<T> pool; |
| |
| /** |
| * Create a new ObjectPoolMinIdleTimerTask for the given pool with the given minIdle setting. |
| * |
| * @param pool object pool |
| * @param minIdle number of idle instances to maintain |
| * @throws IllegalArgumentException if the pool is null |
| */ |
| ObjectPoolMinIdleTimerTask(final ObjectPool<T> pool, final int minIdle) throws IllegalArgumentException { |
| if (pool == null) { |
| throw new IllegalArgumentException("pool must not be null."); |
| } |
| this.pool = pool; |
| this.minIdle = minIdle; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public void run() { |
| boolean success = false; |
| try { |
| if (pool.getNumIdle() < minIdle) { |
| pool.addObject(); |
| } |
| success = true; |
| |
| } catch (Exception e) { |
| cancel(); |
| |
| } finally { |
| // detect other types of Throwable and cancel this Timer |
| if (!success) { |
| cancel(); |
| } |
| } |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| final StringBuffer sb = new StringBuffer(); |
| sb.append("ObjectPoolMinIdleTimerTask"); |
| sb.append("{minIdle=").append(minIdle); |
| sb.append(", pool=").append(pool); |
| sb.append('}'); |
| return sb.toString(); |
| } |
| } |
| |
| /** |
| * Timer task that adds objects to the pool until the number of idle |
| * instances for the given key reaches the configured minIdle. Note that this is not the |
| * same as the pool's minIdle setting. |
| * |
| */ |
| private static class KeyedObjectPoolMinIdleTimerTask<K,V> extends TimerTask { |
| /** Minimum number of idle instances. Not the same as pool.getMinIdle(). */ |
| private final int minIdle; |
| |
| /** Key to ensure minIdle for */ |
| private final K key; |
| |
| /** Keyed object pool */ |
| private final KeyedObjectPool<K,V> keyedPool; |
| |
| /** |
| * Create a new KeyedObjecPoolMinIdleTimerTask. |
| * |
| * @param keyedPool keyed object pool |
| * @param key key to ensure minimum number of idle instances |
| * @param minIdle minimum number of idle instances |
| * @throws IllegalArgumentException if the key is null |
| */ |
| KeyedObjectPoolMinIdleTimerTask(final KeyedObjectPool<K,V> keyedPool, final K key, final int minIdle) throws IllegalArgumentException { |
| if (keyedPool == null) { |
| throw new IllegalArgumentException("keyedPool must not be null."); |
| } |
| this.keyedPool = keyedPool; |
| this.key = key; |
| this.minIdle = minIdle; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public void run() { |
| boolean success = false; |
| try { |
| if (keyedPool.getNumIdle(key) < minIdle) { |
| keyedPool.addObject(key); |
| } |
| success = true; |
| |
| } catch (Exception e) { |
| cancel(); |
| |
| } finally { |
| // detect other types of Throwable and cancel this Timer |
| if (!success) { |
| cancel(); |
| } |
| } |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| final StringBuffer sb = new StringBuffer(); |
| sb.append("KeyedObjectPoolMinIdleTimerTask"); |
| sb.append("{minIdle=").append(minIdle); |
| sb.append(", key=").append(key); |
| sb.append(", keyedPool=").append(keyedPool); |
| sb.append('}'); |
| return sb.toString(); |
| } |
| } |
| |
| /** |
| * Encapsulate the logic for when the next poolable object should be discarded. |
| * Each time update is called, the next time to shrink is recomputed, based on |
| * the float factor, number of idle instances in the pool and high water mark. |
| * Float factor is assumed to be between 0 and 1. Values closer to 1 cause |
| * less frequent erosion events. Erosion event timing also depends on numIdle. |
| * When this value is relatively high (close to previously established high water |
| * mark), erosion occurs more frequently. |
| */ |
| private static class ErodingFactor { |
| /** Determines frequency of "erosion" events */ |
| private final float factor; |
| |
| /** Time of next shrink event */ |
| private transient volatile long nextShrink; |
| |
| /** High water mark - largest numIdle encountered */ |
| private transient volatile int idleHighWaterMark; |
| |
| /** |
| * Create a new ErodingFactor with the given erosion factor. |
| * |
| * @param factor erosion factor |
| */ |
| public ErodingFactor(final float factor) { |
| this.factor = factor; |
| nextShrink = System.currentTimeMillis() + (long)(900000 * factor); // now + 15 min * factor |
| idleHighWaterMark = 1; |
| } |
| |
| /** |
| * Updates internal state based on numIdle and the current time. |
| * |
| * @param numIdle number of idle elements in the pool |
| */ |
| public void update(final int numIdle) { |
| update(System.currentTimeMillis(), numIdle); |
| } |
| |
| /** |
| * Updates internal state using the supplied time and numIdle. |
| * |
| * @param now current time |
| * @param numIdle number of idle elements in the pool |
| */ |
| public void update(final long now, final int numIdle) { |
| final int idle = Math.max(0, numIdle); |
| idleHighWaterMark = Math.max(idle, idleHighWaterMark); |
| final float maxInterval = 15f; |
| final float minutes = maxInterval + ((1f-maxInterval)/idleHighWaterMark) * idle; |
| nextShrink = now + (long)(minutes * 60000f * factor); |
| } |
| |
| /** |
| * Returns the time of the next erosion event. |
| * |
| * @return next shrink time |
| */ |
| public long getNextShrink() { |
| return nextShrink; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| return "ErodingFactor{" + |
| "factor=" + factor + |
| ", idleHighWaterMark=" + idleHighWaterMark + |
| '}'; |
| } |
| } |
| |
| /** |
| * Decorates an object pool, adding "eroding" behavior. Based on the |
| * configured {@link #factor erosion factor}, objects returning to the pool |
| * may be invalidated instead of being added to idle capacity. |
| * |
| */ |
| private static class ErodingObjectPool<T> implements ObjectPool<T> { |
| /** Underlying object pool */ |
| private final ObjectPool<T> pool; |
| |
| /** Erosion factor */ |
| private final ErodingFactor factor; |
| |
| /** |
| * Create an ErodingObjectPool wrapping the given pool using the specified erosion factor. |
| * |
| * @param pool underlying pool |
| * @param factor erosion factor - determines the frequency of erosion events |
| * @see #factor |
| */ |
| public ErodingObjectPool(final ObjectPool<T> pool, final float factor) { |
| this.pool = pool; |
| this.factor = new ErodingFactor(factor); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public T borrowObject() throws Exception, NoSuchElementException, IllegalStateException { |
| return pool.borrowObject(); |
| } |
| |
| /** |
| * Returns obj to the pool, unless erosion is triggered, in which |
| * case obj is invalidated. Erosion is triggered when there are idle instances in |
| * the pool and more than the {@link #factor erosion factor}-determined time has elapsed |
| * since the last returnObject activation. |
| * |
| * @param obj object to return or invalidate |
| * @see #factor |
| */ |
| public void returnObject(final T obj) { |
| boolean discard = false; |
| final long now = System.currentTimeMillis(); |
| synchronized (pool) { |
| if (factor.getNextShrink() < now) { // XXX: Pool 3: move test out of sync block |
| final int numIdle = pool.getNumIdle(); |
| if (numIdle > 0) { |
| discard = true; |
| } |
| |
| factor.update(now, numIdle); |
| } |
| } |
| try { |
| if (discard) { |
| pool.invalidateObject(obj); |
| } else { |
| pool.returnObject(obj); |
| } |
| } catch (Exception e) { |
| // swallowed |
| } |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void invalidateObject(final T obj) { |
| try { |
| pool.invalidateObject(obj); |
| } catch (Exception e) { |
| // swallowed |
| } |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void addObject() throws Exception, IllegalStateException, UnsupportedOperationException { |
| pool.addObject(); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public int getNumIdle() throws UnsupportedOperationException { |
| return pool.getNumIdle(); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public int getNumActive() throws UnsupportedOperationException { |
| return pool.getNumActive(); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void clear() throws Exception, UnsupportedOperationException { |
| pool.clear(); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void close() { |
| try { |
| pool.close(); |
| } catch (Exception e) { |
| // swallowed |
| } |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| return "ErodingObjectPool{" + |
| "factor=" + factor + |
| ", pool=" + pool + |
| '}'; |
| } |
| } |
| |
| /** |
| * Decorates a keyed object pool, adding "eroding" behavior. Based on the |
| * configured {@link #factor erosion factor}, objects returning to the pool |
| * may be invalidated instead of being added to idle capacity. |
| * |
| */ |
| private static class ErodingKeyedObjectPool<K,V> implements KeyedObjectPool<K,V> { |
| /** Underlying pool */ |
| private final KeyedObjectPool<K,V> keyedPool; |
| |
| /** Erosion factor */ |
| private final ErodingFactor erodingFactor; |
| |
| /** |
| * Create an ErodingObjectPool wrapping the given pool using the specified erosion factor. |
| * |
| * @param keyedPool underlying pool |
| * @param factor erosion factor - determines the frequency of erosion events |
| */ |
| public ErodingKeyedObjectPool(final KeyedObjectPool<K,V> keyedPool, final float factor) { |
| this(keyedPool, new ErodingFactor(factor)); |
| } |
| |
| /** |
| * Create an ErodingObjectPool wrapping the given pool using the specified erosion factor. |
| * |
| * @param keyedPool underlying pool - must not be null |
| * @param erodingFactor erosion factor - determines the frequency of erosion events |
| * @see #factor |
| */ |
| protected ErodingKeyedObjectPool(final KeyedObjectPool<K,V> keyedPool, final ErodingFactor erodingFactor) { |
| if (keyedPool == null) { |
| throw new IllegalArgumentException("keyedPool must not be null."); |
| } |
| this.keyedPool = keyedPool; |
| this.erodingFactor = erodingFactor; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public V borrowObject(final K key) throws Exception, NoSuchElementException, IllegalStateException { |
| return keyedPool.borrowObject(key); |
| } |
| |
| /** |
| * Returns obj to the pool, unless erosion is triggered, in which |
| * case obj is invalidated. Erosion is triggered when there are idle instances in |
| * the pool associated with the given key and more than the configured {@link #getErodingFactor(Object) erosion factor} |
| * time has elapsed since the last returnObject activation. |
| * |
| * @param obj object to return or invalidate |
| * @param key key |
| * @see #getErodingFactor(Object) |
| */ |
| public void returnObject(final K key, final V obj) throws Exception { |
| boolean discard = false; |
| final long now = System.currentTimeMillis(); |
| final ErodingFactor factor = getErodingFactor(key); |
| synchronized (keyedPool) { |
| if (factor.getNextShrink() < now) { |
| final int numIdle = numIdle(key); |
| if (numIdle > 0) { |
| discard = true; |
| } |
| |
| factor.update(now, numIdle); |
| } |
| } |
| try { |
| if (discard) { |
| keyedPool.invalidateObject(key, obj); |
| } else { |
| keyedPool.returnObject(key, obj); |
| } |
| } catch (Exception e) { |
| // swallowed |
| } |
| } |
| |
| protected int numIdle(final K key) { |
| return getKeyedPool().getNumIdle(); |
| } |
| |
| /** |
| * Returns the eroding factor for the given key |
| * @param key key |
| * @return eroding factor for the given keyed pool |
| */ |
| protected ErodingFactor getErodingFactor(final K key) { |
| return erodingFactor; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void invalidateObject(final K key, final V obj) { |
| try { |
| keyedPool.invalidateObject(key, obj); |
| } catch (Exception e) { |
| // swallowed |
| } |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void addObject(final K key) throws Exception, IllegalStateException, UnsupportedOperationException { |
| keyedPool.addObject(key); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public int getNumIdle() throws UnsupportedOperationException { |
| return keyedPool.getNumIdle(); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public int getNumIdle(final K key) throws UnsupportedOperationException { |
| return keyedPool.getNumIdle(key); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public int getNumActive() throws UnsupportedOperationException { |
| return keyedPool.getNumActive(); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public int getNumActive(final K key) throws UnsupportedOperationException { |
| return keyedPool.getNumActive(key); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void clear() throws Exception, UnsupportedOperationException { |
| keyedPool.clear(); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void clear(final K key) throws Exception, UnsupportedOperationException { |
| keyedPool.clear(key); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| public void close() { |
| try { |
| keyedPool.close(); |
| } catch (Exception e) { |
| // swallowed |
| } |
| } |
| |
| /** |
| * Returns the underlying pool |
| * |
| * @return the keyed pool that this ErodingKeyedObjectPool wraps |
| */ |
| protected KeyedObjectPool<K,V> getKeyedPool() { |
| return keyedPool; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| return "ErodingKeyedObjectPool{" + |
| "erodingFactor=" + erodingFactor + |
| ", keyedPool=" + keyedPool + |
| '}'; |
| } |
| } |
| |
| /** |
| * Extends ErodingKeyedObjectPool to allow erosion to take place on a per-key |
| * basis. Timing of erosion events is tracked separately for separate keyed pools. |
| */ |
| private static class ErodingPerKeyKeyedObjectPool<K,V> extends ErodingKeyedObjectPool<K,V> { |
| /** Erosion factor - same for all pools */ |
| private final float factor; |
| |
| /** Map of ErodingFactor instances keyed on pool keys */ |
| private final Map<K,ErodingFactor> factors = Collections.synchronizedMap(new HashMap<K,ErodingFactor>()); |
| |
| /** |
| * Create a new ErordingPerKeyKeyedObjectPool decorating the given keyed pool with |
| * the specified erosion factor. |
| * @param keyedPool underlying keyed pool |
| * @param factor erosion factor |
| */ |
| public ErodingPerKeyKeyedObjectPool(final KeyedObjectPool<K,V> keyedPool, final float factor) { |
| super(keyedPool, null); |
| this.factor = factor; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| protected int numIdle(final K key) { |
| return getKeyedPool().getNumIdle(key); |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| protected ErodingFactor getErodingFactor(final K key) { |
| ErodingFactor factor = factors.get(key); |
| // this may result in two ErodingFactors being created for a key |
| // since they are small and cheap this is okay. |
| if (factor == null) { |
| factor = new ErodingFactor(this.factor); |
| factors.put(key, factor); |
| } |
| return factor; |
| } |
| |
| /** |
| * {@inheritDoc} |
| */ |
| @Override |
| public String toString() { |
| return "ErodingPerKeyKeyedObjectPool{" + |
| "factor=" + factor + |
| ", keyedPool=" + getKeyedPool() + |
| '}'; |
| } |
| } |
| } |
