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/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed 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.pool.impl;
import java.util.Iterator;
import java.util.NoSuchElementException;
import org.apache.commons.collections.CursorableLinkedList;
import org.apache.commons.pool.BaseObjectPool;
import org.apache.commons.pool.ObjectPool;
import org.apache.commons.pool.PoolableObjectFactory;
/**
* A configurable {@link ObjectPool} implementation.
*
* When coupled with the appropriate {@link PoolableObjectFactory},
* GenericObjectPool provides robust pooling functionality for
* arbitrary objects.
*
* A GenericObjectPool provides a number of configurable parameters:
*
* -
* {@link #setMaxActive maxActive} controls the maximum number of objects that can
* be borrowed from the pool at one time. When non-positive, there
* is no limit to the number of objects that may be active at one time.
* When {@link #setMaxActive maxActive} is exceeded, the pool is said to be exhausted.
*
* -
* {@link #setMaxIdle maxIdle} controls the maximum number of objects that can
* sit idle in the pool at any time. When negative, there
* is no limit to the number of objects that may be idle at one time.
*
* -
* {@link #setWhenExhaustedAction whenExhaustedAction} specifies the
* behaviour of the {@link #borrowObject} method when the pool is exhausted:
*
* -
* When {@link #setWhenExhaustedAction whenExhaustedAction} is
* {@link #WHEN_EXHAUSTED_FAIL}, {@link #borrowObject} will throw
* a {@link NoSuchElementException}
*
* -
* When {@link #setWhenExhaustedAction whenExhaustedAction} is
* {@link #WHEN_EXHAUSTED_GROW}, {@link #borrowObject} will create a new
* object and return it(essentially making {@link #setMaxActive maxActive}
* meaningless.)
*
* -
* When {@link #setWhenExhaustedAction whenExhaustedAction}
* is {@link #WHEN_EXHAUSTED_BLOCK}, {@link #borrowObject} will block
* (invoke {@link Object#wait} until a new or idle object is available.
* If a positive {@link #setMaxWait maxWait}
* value is supplied, the {@link #borrowObject} will block for at
* most that many milliseconds, after which a {@link NoSuchElementException}
* will be thrown. If {@link #setMaxWait maxWait} is non-positive,
* the {@link #borrowObject} method will block indefinitely.
*
*
*
* -
* When {@link #setTestOnBorrow testOnBorrow} is set, the pool will
* attempt to validate each object before it is returned from the
* {@link #borrowObject} method. (Using the provided factory's
* {@link PoolableObjectFactory#validateObject} method.) Objects that fail
* to validate will be dropped from the pool, and a different object will
* be borrowed.
*
* -
* When {@link #setTestOnReturn testOnReturn} is set, the pool will
* attempt to validate each object before it is returned to the pool in the
* {@link #returnObject} method. (Using the provided factory's
* {@link PoolableObjectFactory#validateObject}
* method.) Objects that fail to validate will be dropped from the pool.
*
*
*
* Optionally, one may configure the pool to examine and possibly evict objects as they
* sit idle in the pool. This is performed by an "idle object eviction" thread, which
* runs asychronously. The idle object eviction thread may be configured using the
* following attributes:
*
* -
* {@link #setTimeBetweenEvictionRunsMillis timeBetweenEvictionRunsMillis}
* indicates how long the eviction thread should sleep before "runs" of examining
* idle objects. When non-positive, no eviction thread will be launched.
*
* -
* {@link #setMinEvictableIdleTimeMillis minEvictableIdleTimeMillis}
* specifies the minimum amount of time that an object may sit idle in the pool
* before it is eligable for eviction due to idle time. When non-positive, no object
* will be dropped from the pool due to idle time alone.
*
* -
* {@link #setTestWhileIdle testWhileIdle} indicates whether or not idle
* objects should be validated using the factory's
* {@link PoolableObjectFactory#validateObject} method. Objects
* that fail to validate will be dropped from the pool.
*
*
*
* GenericObjectPool is not usable without a {@link PoolableObjectFactory}. A
* non-null factory must be provided either as a constructor argument
* or via a call to {@link #setFactory} before the pool is used.
*
* @see GenericKeyedObjectPool
* @author Rodney Waldhoff
* @author Dirk Verbeeck
* @version $Revision: 1.32 $ $Date: 2004/04/27 20:15:56 $
*/
public class GenericObjectPool extends BaseObjectPool implements ObjectPool {
//--- public constants -------------------------------------------
/**
* A "when exhausted action" type indicating that when the pool is
* exhausted (i.e., the maximum number of active objects has
* been reached), the {@link #borrowObject}
* method should fail, throwing a {@link NoSuchElementException}.
* @see #WHEN_EXHAUSTED_BLOCK
* @see #WHEN_EXHAUSTED_GROW
* @see #setWhenExhaustedAction
*/
public static final byte WHEN_EXHAUSTED_FAIL = 0;
/**
* A "when exhausted action" type indicating that when the pool
* is exhausted (i.e., the maximum number
* of active objects has been reached), the {@link #borrowObject}
* method should block until a new object is available, or the
* {@link #getMaxWait maximum wait time} has been reached.
* @see #WHEN_EXHAUSTED_FAIL
* @see #WHEN_EXHAUSTED_GROW
* @see #setMaxWait
* @see #getMaxWait
* @see #setWhenExhaustedAction
*/
public static final byte WHEN_EXHAUSTED_BLOCK = 1;
/**
* A "when exhausted action" type indicating that when the pool is
* exhausted (i.e., the maximum number
* of active objects has been reached), the {@link #borrowObject}
* method should simply create a new object anyway.
* @see #WHEN_EXHAUSTED_FAIL
* @see #WHEN_EXHAUSTED_GROW
* @see #setWhenExhaustedAction
*/
public static final byte WHEN_EXHAUSTED_GROW = 2;
/**
* The default cap on the number of "sleeping" instances in the pool.
* @see #getMaxIdle
* @see #setMaxIdle
*/
public static final int DEFAULT_MAX_IDLE = 8;
/**
* The default minimum number of "sleeping" instances in the pool
* before before the evictor thread (if active) spawns new objects.
* @see #getMinIdle
* @see #setMinIdle
*/
public static final int DEFAULT_MIN_IDLE = 0;
/**
* The default cap on the total number of active instances from the pool.
* @see #getMaxActive
*/
public static final int DEFAULT_MAX_ACTIVE = 8;
/**
* The default "when exhausted action" for the pool.
* @see #WHEN_EXHAUSTED_BLOCK
* @see #WHEN_EXHAUSTED_FAIL
* @see #WHEN_EXHAUSTED_GROW
* @see #setWhenExhaustedAction
*/
public static final byte DEFAULT_WHEN_EXHAUSTED_ACTION = WHEN_EXHAUSTED_BLOCK;
/**
* The default maximum amount of time (in millis) the
* {@link #borrowObject} method should block before throwing
* an exception when the pool is exhausted and the
* {@link #getWhenExhaustedAction "when exhausted" action} is
* {@link #WHEN_EXHAUSTED_BLOCK}.
* @see #getMaxWait
* @see #setMaxWait
*/
public static final long DEFAULT_MAX_WAIT = -1L;
/**
* The default "test on borrow" value.
* @see #getTestOnBorrow
* @see #setTestOnBorrow
*/
public static final boolean DEFAULT_TEST_ON_BORROW = false;
/**
* The default "test on return" value.
* @see #getTestOnReturn
* @see #setTestOnReturn
*/
public static final boolean DEFAULT_TEST_ON_RETURN = false;
/**
* The default "test while idle" value.
* @see #getTestWhileIdle
* @see #setTestWhileIdle
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
public static final boolean DEFAULT_TEST_WHILE_IDLE = false;
/**
* The default "time between eviction runs" value.
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
public static final long DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS = -1L;
/**
* The default number of objects to examine per run in the
* idle object evictor.
* @see #getNumTestsPerEvictionRun
* @see #setNumTestsPerEvictionRun
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
public static final int DEFAULT_NUM_TESTS_PER_EVICTION_RUN = 3;
/**
* The default value for {@link #getMinEvictableIdleTimeMillis}.
* @see #getMinEvictableIdleTimeMillis
* @see #setMinEvictableIdleTimeMillis
*/
public static final long DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS = 1000L * 60L * 30L;
//--- constructors -----------------------------------------------
/**
* Create a new GenericObjectPool.
*/
public GenericObjectPool() {
this(null,DEFAULT_MAX_ACTIVE,DEFAULT_WHEN_EXHAUSTED_ACTION,DEFAULT_MAX_WAIT,DEFAULT_MAX_IDLE,DEFAULT_MIN_IDLE,DEFAULT_TEST_ON_BORROW,DEFAULT_TEST_ON_RETURN,DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,DEFAULT_NUM_TESTS_PER_EVICTION_RUN,DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS,DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericObjectPool using the specified values.
* @param factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
*/
public GenericObjectPool(PoolableObjectFactory factory) {
this(factory,DEFAULT_MAX_ACTIVE,DEFAULT_WHEN_EXHAUSTED_ACTION,DEFAULT_MAX_WAIT,DEFAULT_MAX_IDLE,DEFAULT_MIN_IDLE,DEFAULT_TEST_ON_BORROW,DEFAULT_TEST_ON_RETURN,DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,DEFAULT_NUM_TESTS_PER_EVICTION_RUN,DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS,DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericObjectPool using the specified values.
* @param factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
* @param config a non-null {@link GenericObjectPool.Config} describing my configuration
*/
public GenericObjectPool(PoolableObjectFactory factory, GenericObjectPool.Config config) {
this(factory,config.maxActive,config.whenExhaustedAction,config.maxWait,config.maxIdle,config.minIdle,config.testOnBorrow,config.testOnReturn,config.timeBetweenEvictionRunsMillis,config.numTestsPerEvictionRun,config.minEvictableIdleTimeMillis,config.testWhileIdle);
}
/**
* Create a new GenericObjectPool using the specified values.
* @param factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
* @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
*/
public GenericObjectPool(PoolableObjectFactory factory, int maxActive) {
this(factory,maxActive,DEFAULT_WHEN_EXHAUSTED_ACTION,DEFAULT_MAX_WAIT,DEFAULT_MAX_IDLE,DEFAULT_MIN_IDLE,DEFAULT_TEST_ON_BORROW,DEFAULT_TEST_ON_RETURN,DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,DEFAULT_NUM_TESTS_PER_EVICTION_RUN,DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS,DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericObjectPool using the specified values.
* @param factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
* @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #getWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #getMaxWait})
*/
public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait) {
this(factory,maxActive,whenExhaustedAction,maxWait,DEFAULT_MAX_IDLE,DEFAULT_MIN_IDLE,DEFAULT_TEST_ON_BORROW,DEFAULT_TEST_ON_RETURN,DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,DEFAULT_NUM_TESTS_PER_EVICTION_RUN,DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS,DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericObjectPool using the specified values.
* @param factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
* @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #getWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #getMaxWait})
* @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject} method (see {@link #getTestOnBorrow})
* @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject} method (see {@link #getTestOnReturn})
*/
public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, boolean testOnBorrow, boolean testOnReturn) {
this(factory,maxActive,whenExhaustedAction,maxWait,DEFAULT_MAX_IDLE,DEFAULT_MIN_IDLE,testOnBorrow,testOnReturn,DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,DEFAULT_NUM_TESTS_PER_EVICTION_RUN,DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS,DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericObjectPool using the specified values.
* @param factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
* @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #getWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #getMaxWait})
* @param maxIdle the maximum number of idle objects in my pool (see {@link #getMaxIdle})
*/
public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle) {
this(factory,maxActive,whenExhaustedAction,maxWait,maxIdle,DEFAULT_MIN_IDLE,DEFAULT_TEST_ON_BORROW,DEFAULT_TEST_ON_RETURN,DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,DEFAULT_NUM_TESTS_PER_EVICTION_RUN,DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS,DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericObjectPool using the specified values.
* @param factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
* @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #getWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #getMaxWait})
* @param maxIdle the maximum number of idle objects in my pool (see {@link #getMaxIdle})
* @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject} method (see {@link #getTestOnBorrow})
* @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject} method (see {@link #getTestOnReturn})
*/
public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn) {
this(factory,maxActive,whenExhaustedAction,maxWait,maxIdle,DEFAULT_MIN_IDLE,testOnBorrow,testOnReturn,DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS,DEFAULT_NUM_TESTS_PER_EVICTION_RUN,DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS,DEFAULT_TEST_WHILE_IDLE);
}
/**
* Create a new GenericObjectPool using the specified values.
* @param factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
* @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
* @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
* @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject} method (see {@link #setTestOnBorrow})
* @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject} method (see {@link #setTestOnReturn})
* @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
* @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction thread (if any) (see {@link #setNumTestsPerEvictionRun})
* @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before it is eligable for evcition (see {@link #setMinEvictableIdleTimeMillis})
* @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any (see {@link #setTestWhileIdle})
*/
public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle) {
this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, DEFAULT_MIN_IDLE, testOnBorrow, testOnReturn, timeBetweenEvictionRunsMillis, numTestsPerEvictionRun, minEvictableIdleTimeMillis, testWhileIdle);
}
/**
* Create a new GenericObjectPool using the specified values.
* @param factory the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects
* @param maxActive the maximum number of objects that can be borrowed from me at one time (see {@link #setMaxActive})
* @param whenExhaustedAction the action to take when the pool is exhausted (see {@link #setWhenExhaustedAction})
* @param maxWait the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is {@link #WHEN_EXHAUSTED_BLOCK} (otherwise ignored) (see {@link #setMaxWait})
* @param maxIdle the maximum number of idle objects in my pool (see {@link #setMaxIdle})
* @param minIdle the minimum number of idle objects in my pool (see {@link #setMinIdle})
* @param testOnBorrow whether or not to validate objects before they are returned by the {@link #borrowObject} method (see {@link #setTestOnBorrow})
* @param testOnReturn whether or not to validate objects after they are returned to the {@link #returnObject} method (see {@link #setTestOnReturn})
* @param timeBetweenEvictionRunsMillis the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see {@link #setTimeBetweenEvictionRunsMillis})
* @param numTestsPerEvictionRun the number of idle objects to examine per run within the idle object eviction thread (if any) (see {@link #setNumTestsPerEvictionRun})
* @param minEvictableIdleTimeMillis the minimum number of milliseconds an object can sit idle in the pool before it is eligable for evcition (see {@link #setMinEvictableIdleTimeMillis})
* @param testWhileIdle whether or not to validate objects in the idle object eviction thread, if any (see {@link #setTestWhileIdle})
*/
public GenericObjectPool(PoolableObjectFactory factory, int maxActive, byte whenExhaustedAction, long maxWait, int maxIdle, int minIdle, boolean testOnBorrow, boolean testOnReturn, long timeBetweenEvictionRunsMillis, int numTestsPerEvictionRun, long minEvictableIdleTimeMillis, boolean testWhileIdle) {
_factory = factory;
_maxActive = maxActive;
switch(whenExhaustedAction) {
case WHEN_EXHAUSTED_BLOCK:
case WHEN_EXHAUSTED_FAIL:
case WHEN_EXHAUSTED_GROW:
_whenExhaustedAction = whenExhaustedAction;
break;
default:
throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction + " not recognized.");
}
_maxWait = maxWait;
_maxIdle = maxIdle;
_minIdle = minIdle;
_testOnBorrow = testOnBorrow;
_testOnReturn = testOnReturn;
_timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;
_numTestsPerEvictionRun = numTestsPerEvictionRun;
_minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
_testWhileIdle = testWhileIdle;
_pool = new CursorableLinkedList();
startEvictor(_timeBetweenEvictionRunsMillis);
}
//--- public methods ---------------------------------------------
//--- configuration methods --------------------------------------
/**
* Returns the cap on the total number of active instances from my pool.
* @return the cap on the total number of active instances from my pool.
* @see #setMaxActive
*/
public synchronized int getMaxActive() {
return _maxActive;
}
/**
* Sets the cap on the total number of active instances from my pool.
* @param maxActive The cap on the total number of active instances from my pool.
* Use a negative value for an infinite number of instances.
* @see #getMaxActive
*/
public synchronized void setMaxActive(int maxActive) {
_maxActive = maxActive;
notifyAll();
}
/**
* Returns the action to take when the {@link #borrowObject} method
* is invoked when the pool is exhausted (the maximum number
* of "active" objects has been reached).
*
* @return one of {@link #WHEN_EXHAUSTED_BLOCK}, {@link #WHEN_EXHAUSTED_FAIL} or {@link #WHEN_EXHAUSTED_GROW}
* @see #setWhenExhaustedAction
*/
public synchronized byte getWhenExhaustedAction() {
return _whenExhaustedAction;
}
/**
* Sets the action to take when the {@link #borrowObject} method
* is invoked when the pool is exhausted (the maximum number
* of "active" objects has been reached).
*
* @param whenExhaustedAction the action code, which must be one of
* {@link #WHEN_EXHAUSTED_BLOCK}, {@link #WHEN_EXHAUSTED_FAIL},
* or {@link #WHEN_EXHAUSTED_GROW}
* @see #getWhenExhaustedAction
*/
public synchronized void setWhenExhaustedAction(byte whenExhaustedAction) {
switch(whenExhaustedAction) {
case WHEN_EXHAUSTED_BLOCK:
case WHEN_EXHAUSTED_FAIL:
case WHEN_EXHAUSTED_GROW:
_whenExhaustedAction = whenExhaustedAction;
notifyAll();
break;
default:
throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction + " not recognized.");
}
}
/**
* Returns the maximum amount of time (in milliseconds) the
* {@link #borrowObject} method should block before throwing
* an exception when the pool is exhausted and the
* {@link #setWhenExhaustedAction "when exhausted" action} is
* {@link #WHEN_EXHAUSTED_BLOCK}.
*
* When less than 0, the {@link #borrowObject} method
* may block indefinitely.
*
* @see #setMaxWait
* @see #setWhenExhaustedAction
* @see #WHEN_EXHAUSTED_BLOCK
*/
public synchronized long getMaxWait() {
return _maxWait;
}
/**
* Sets the maximum amount of time (in milliseconds) the
* {@link #borrowObject} method should block before throwing
* an exception when the pool is exhausted and the
* {@link #setWhenExhaustedAction "when exhausted" action} is
* {@link #WHEN_EXHAUSTED_BLOCK}.
*
* When less than 0, the {@link #borrowObject} method
* may block indefinitely.
*
* @see #getMaxWait
* @see #setWhenExhaustedAction
* @see #WHEN_EXHAUSTED_BLOCK
*/
public synchronized void setMaxWait(long maxWait) {
_maxWait = maxWait;
notifyAll();
}
/**
* Returns the cap on the number of "idle" instances in the pool.
* @return the cap on the number of "idle" instances in the pool.
* @see #setMaxIdle
*/
public synchronized int getMaxIdle() {
return _maxIdle;
}
/**
* Sets the cap on the number of "idle" instances in the pool.
* @param maxIdle The cap on the number of "idle" instances in the pool.
* Use a negative value to indicate an unlimited number
* of idle instances.
* @see #getMaxIdle
*/
public synchronized void setMaxIdle(int maxIdle) {
_maxIdle = maxIdle;
notifyAll();
}
/**
* Sets the minimum number of objects allowed in the pool
* before the evictor thread (if active) spawns new objects.
* (Note no objects are created when: numActive + numIdle >= maxActive)
*
* @param minIdle The minimum number of objects.
* @see #getMinIdle
*/
public synchronized void setMinIdle(int minIdle) {
_minIdle = minIdle;
notifyAll();
}
/**
* Returns the minimum number of objects allowed in the pool
* before the evictor thread (if active) spawns new objects.
* (Note no objects are created when: numActive + numIdle >= maxActive)
*
* @return The minimum number of objects.
* @see #setMinIdle
*/
public synchronized int getMinIdle() {
return _minIdle;
}
/**
* When true, objects will be
* {@link PoolableObjectFactory#validateObject validated}
* before being returned by the {@link #borrowObject}
* method. If the object fails to validate,
* it will be dropped from the pool, and we will attempt
* to borrow another.
*
* @see #setTestOnBorrow
*/
public synchronized boolean getTestOnBorrow() {
return _testOnBorrow;
}
/**
* When true, objects will be
* {@link PoolableObjectFactory#validateObject validated}
* before being returned by the {@link #borrowObject}
* method. If the object fails to validate,
* it will be dropped from the pool, and we will attempt
* to borrow another.
*
* @see #getTestOnBorrow
*/
public synchronized void setTestOnBorrow(boolean testOnBorrow) {
_testOnBorrow = testOnBorrow;
}
/**
* When true, objects will be
* {@link PoolableObjectFactory#validateObject validated}
* before being returned to the pool within the
* {@link #returnObject}.
*
* @see #setTestOnReturn
*/
public synchronized boolean getTestOnReturn() {
return _testOnReturn;
}
/**
* When true, objects will be
* {@link PoolableObjectFactory#validateObject validated}
* before being returned to the pool within the
* {@link #returnObject}.
*
* @see #getTestOnReturn
*/
public synchronized void setTestOnReturn(boolean testOnReturn) {
_testOnReturn = testOnReturn;
}
/**
* Returns the number of milliseconds to sleep between runs of the
* idle object evictor thread.
* When non-positive, no idle object evictor thread will be
* run.
*
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized long getTimeBetweenEvictionRunsMillis() {
return _timeBetweenEvictionRunsMillis;
}
/**
* Sets the number of milliseconds to sleep between runs of the
* idle object evictor thread.
* When non-positive, no idle object evictor thread will be
* run.
*
* @see #getTimeBetweenEvictionRunsMillis
*/
public synchronized void setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis) {
_timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;
startEvictor(_timeBetweenEvictionRunsMillis);
}
/**
* Returns the number of objects to examine during each run of the
* idle object evictor thread (if any).
*
* @see #setNumTestsPerEvictionRun
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized int getNumTestsPerEvictionRun() {
return _numTestsPerEvictionRun;
}
/**
* Sets the number of objects to examine during each run of the
* idle object evictor thread (if any).
*
* When a negative value is supplied, ceil({@link #getNumIdle})/abs({@link #getNumTestsPerEvictionRun})
* tests will be run. I.e., when the value is -n, roughly one nth of the
* idle objects will be tested per run.
*
* @see #getNumTestsPerEvictionRun
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized void setNumTestsPerEvictionRun(int numTestsPerEvictionRun) {
_numTestsPerEvictionRun = numTestsPerEvictionRun;
}
/**
* Returns the minimum amount of time an object may sit idle in the pool
* before it is eligable for eviction by the idle object evictor
* (if any).
*
* @see #setMinEvictableIdleTimeMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized long getMinEvictableIdleTimeMillis() {
return _minEvictableIdleTimeMillis;
}
/**
* Sets the minimum amount of time an object may sit idle in the pool
* before it is eligable for eviction by the idle object evictor
* (if any).
* When non-positive, no objects will be evicted from the pool
* due to idle time alone.
*
* @see #getMinEvictableIdleTimeMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized void setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis) {
_minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
}
/**
* When true, objects will be
* {@link PoolableObjectFactory#validateObject validated}
* by the idle object evictor (if any). If an object
* fails to validate, it will be dropped from the pool.
*
* @see #setTestWhileIdle
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized boolean getTestWhileIdle() {
return _testWhileIdle;
}
/**
* When true, objects will be
* {@link PoolableObjectFactory#validateObject validated}
* by the idle object evictor (if any). If an object
* fails to validate, it will be dropped from the pool.
*
* @see #getTestWhileIdle
* @see #setTimeBetweenEvictionRunsMillis
*/
public synchronized void setTestWhileIdle(boolean testWhileIdle) {
_testWhileIdle = testWhileIdle;
}
/**
* Sets my configuration.
* @see GenericObjectPool.Config
*/
public synchronized void setConfig(GenericObjectPool.Config conf) {
setMaxIdle(conf.maxIdle);
setMinIdle(conf.minIdle);
setMaxActive(conf.maxActive);
setMaxWait(conf.maxWait);
setWhenExhaustedAction(conf.whenExhaustedAction);
setTestOnBorrow(conf.testOnBorrow);
setTestOnReturn(conf.testOnReturn);
setTestWhileIdle(conf.testWhileIdle);
setNumTestsPerEvictionRun(conf.numTestsPerEvictionRun);
setMinEvictableIdleTimeMillis(conf.minEvictableIdleTimeMillis);
setTimeBetweenEvictionRunsMillis(conf.timeBetweenEvictionRunsMillis);
notifyAll();
}
//-- ObjectPool methods ------------------------------------------
public Object borrowObject() throws Exception {
long starttime = System.currentTimeMillis();
boolean newlyCreated = false;
for(;;) {
ObjectTimestampPair pair = null;
synchronized(this) {
assertOpen();
// if there are any sleeping, just grab one of those
try {
pair = (ObjectTimestampPair)(_pool.removeFirst());
} catch(NoSuchElementException e) {
; /* ignored */
}
// otherwise
if(null == pair) {
// check if we can create one
// (note we know that the num sleeping is 0, else we wouldn't be here)
if(_maxActive <= 0 || _numActive < _maxActive) {
// allow new object to be created
} else {
// the pool is exhausted
switch(_whenExhaustedAction) {
case WHEN_EXHAUSTED_GROW:
// allow new object to be created
break;
case WHEN_EXHAUSTED_FAIL:
throw new NoSuchElementException();
case WHEN_EXHAUSTED_BLOCK:
try {
if(_maxWait <= 0) {
wait();
} else {
wait(_maxWait);
}
} catch(InterruptedException e) {
// ignored
}
if(_maxWait > 0 && ((System.currentTimeMillis() - starttime) >= _maxWait)) {
throw new NoSuchElementException("Timeout waiting for idle object");
} else {
continue; // keep looping
}
default:
throw new IllegalArgumentException("whenExhaustedAction " + _whenExhaustedAction + " not recognized.");
}
}
}
_numActive++;
} // end synchronized
// create new object when needed
if(null == pair) {
try {
Object obj = _factory.makeObject();
pair = new ObjectTimestampPair(obj);
newlyCreated = true;
}
catch (Exception e) {
// object cannot be created
synchronized(this) {
_numActive--;
notifyAll();
}
throw e;
}
}
// activate & validate the object
try {
_factory.activateObject(pair.value);
if(_testOnBorrow && !_factory.validateObject(pair.value)) {
throw new Exception("validateObject failed");
}
return pair.value;
}
catch (Exception e) {
// object cannot be activated or is invalid
synchronized(this) {
_numActive--;
notifyAll();
}
try {
_factory.destroyObject(pair.value);
}
catch (Exception e2) {
// cannot destroy broken object
}
if(newlyCreated) {
throw new NoSuchElementException("Could not create a validated object, cause: " + e.getMessage());
}
else {
continue; // keep looping
}
}
}
}
public void invalidateObject(Object obj) throws Exception {
assertOpen();
try {
_factory.destroyObject(obj);
}
finally {
synchronized(this) {
_numActive--;
notifyAll(); // _numActive has changed
}
}
}
public synchronized void clear() {
assertOpen();
for(Iterator it = _pool.iterator(); it.hasNext(); ) {
try {
_factory.destroyObject(((ObjectTimestampPair)(it.next())).value);
} catch(Exception e) {
// ignore error, keep destroying the rest
}
it.remove();
}
_pool.clear();
notifyAll(); // num sleeping has changed
}
public synchronized int getNumActive() {
assertOpen();
return _numActive;
}
public synchronized int getNumIdle() {
assertOpen();
return _pool.size();
}
public void returnObject(Object obj) throws Exception {
assertOpen();
addObjectToPool(obj, true);
}
private void addObjectToPool(Object obj, boolean decrementNumActive) throws Exception {
boolean success = true;
if(_testOnReturn && !(_factory.validateObject(obj))) {
success = false;
} else {
try {
_factory.passivateObject(obj);
} catch(Exception e) {
success = false;
}
}
boolean shouldDestroy = !success;
synchronized(this) {
if (decrementNumActive) {
_numActive--;
}
if((_maxIdle >= 0) && (_pool.size() >= _maxIdle)) {
shouldDestroy = true;
} else if(success) {
_pool.addFirst(new ObjectTimestampPair(obj));
}
notifyAll(); // _numActive has changed
}
if(shouldDestroy) {
try {
_factory.destroyObject(obj);
} catch(Exception e) {
// ignored
}
}
}
public synchronized void close() throws Exception {
clear();
_pool = null;
_factory = null;
if(null != _evictionCursor) {
_evictionCursor.close();
_evictionCursor = null;
}
startEvictor(-1L);
super.close();
}
public synchronized void setFactory(PoolableObjectFactory factory) throws IllegalStateException {
assertOpen();
if(0 < getNumActive()) {
throw new IllegalStateException("Objects are already active");
} else {
clear();
_factory = factory;
}
}
public synchronized void evict() throws Exception {
assertOpen();
if(!_pool.isEmpty()) {
if(null == _evictionCursor) {
_evictionCursor = (_pool.cursor(_pool.size()));
} else if(!_evictionCursor.hasPrevious()) {
_evictionCursor.close();
_evictionCursor = (_pool.cursor(_pool.size()));
}
for(int i=0,m=getNumTests();i 0 &&
System.currentTimeMillis() - pair.tstamp > _minEvictableIdleTimeMillis) {
removeObject = true;
} else if(_testWhileIdle) {
boolean active = false;
try {
_factory.activateObject(pair.value);
active = true;
} catch(Exception e) {
removeObject=true;
}
if(active) {
if(!_factory.validateObject(pair.value)) {
removeObject=true;
} else {
try {
_factory.passivateObject(pair.value);
} catch(Exception e) {
removeObject=true;
}
}
}
}
if(removeObject) {
try {
_evictionCursor.remove();
_factory.destroyObject(pair.value);
} catch(Exception e) {
; // ignored
}
}
}
}
} // if !empty
}
/**
* Check to see if we are below our minimum number of objects
* if so enough to bring us back to our minimum.
*/
private void ensureMinIdle() throws Exception {
// this method isn't synchronized so the
// calculateDeficit is done at the beginning
// as a loop limit and a second time inside the loop
// to stop when another thread already returned the
// needed objects
int objectDeficit = calculateDeficit();
for ( int j = 0 ; j < objectDeficit && calculateDeficit() > 0 ; j++ ) {
addObject();
}
}
private synchronized int calculateDeficit() {
int objectDeficit = getMinIdle() - getNumIdle();
if (_maxActive > 0) {
int growLimit = Math.max(0, getMaxActive() - getNumActive() - getNumIdle());
objectDeficit = Math.min(objectDeficit, growLimit);
}
return objectDeficit;
}
/**
* Create an object, and place it into the pool.
* addObject() is useful for "pre-loading" a pool with idle objects.
*/
public void addObject() throws Exception {
Object obj = _factory.makeObject();
addObjectToPool(obj, false);
}
//--- non-public methods ----------------------------------------
/**
* Start the eviction thread or service, or when
* delay is non-positive, stop it
* if it is already running.
*/
protected synchronized void startEvictor(long delay) {
if(null != _evictor) {
_evictor.cancel();
_evictor = null;
}
if(delay > 0) {
_evictor = new Evictor(delay);
Thread t = new Thread(_evictor);
t.setDaemon(true);
t.start();
}
}
synchronized String debugInfo() {
StringBuffer buf = new StringBuffer();
buf.append("Active: ").append(getNumActive()).append("\n");
buf.append("Idle: ").append(getNumIdle()).append("\n");
buf.append("Idle Objects:\n");
Iterator it = _pool.iterator();
long time = System.currentTimeMillis();
while(it.hasNext()) {
ObjectTimestampPair pair = (ObjectTimestampPair)(it.next());
buf.append("\t").append(pair.value).append("\t").append(time - pair.tstamp).append("\n");
}
return buf.toString();
}
private int getNumTests() {
if(_numTestsPerEvictionRun >= 0) {
return _numTestsPerEvictionRun;
} else {
return(int)(Math.ceil((double)_pool.size()/Math.abs((double)_numTestsPerEvictionRun)));
}
}
//--- inner classes ----------------------------------------------
/**
* A simple "struct" encapsulating an object instance and a timestamp.
*/
class ObjectTimestampPair {
Object value;
long tstamp;
ObjectTimestampPair(Object val) {
this(val,System.currentTimeMillis());
}
ObjectTimestampPair(Object val, long time) {
value = val;
tstamp = time;
}
}
/**
* The idle object evictor thread.
* @see #setTimeBetweenEvictionRunsMillis
*/
class Evictor implements Runnable {
private boolean _cancelled = false;
private long _delay = 0L;
public Evictor(long delay) {
_delay = delay;
}
void cancel() {
_cancelled = true;
}
public void run() {
while(!_cancelled) {
try {
Thread.sleep(_delay);
} catch(Exception e) {
// ignored
}
try {
evict();
} catch(Exception e) {
// ignored
}
try {
ensureMinIdle();
} catch(Exception e) {
// ignored
}
}
synchronized(GenericObjectPool.this) {
if(null != _evictionCursor) {
_evictionCursor.close();
_evictionCursor = null;
}
}
}
}
/**
* A simple "struct" encapsulating the
* configuration information for a {@link GenericObjectPool}.
* @see GenericObjectPool#GenericObjectPool(org.apache.commons.pool.PoolableObjectFactory,org.apache.commons.pool.impl.GenericObjectPool.Config)
* @see GenericObjectPool#setConfig
*/
public static class Config {
public int maxIdle = GenericObjectPool.DEFAULT_MAX_IDLE;
public int minIdle = GenericObjectPool.DEFAULT_MIN_IDLE;
public int maxActive = GenericObjectPool.DEFAULT_MAX_ACTIVE;
public long maxWait = GenericObjectPool.DEFAULT_MAX_WAIT;
public byte whenExhaustedAction = GenericObjectPool.DEFAULT_WHEN_EXHAUSTED_ACTION;
public boolean testOnBorrow = GenericObjectPool.DEFAULT_TEST_ON_BORROW;
public boolean testOnReturn = GenericObjectPool.DEFAULT_TEST_ON_RETURN;
public boolean testWhileIdle = GenericObjectPool.DEFAULT_TEST_WHILE_IDLE;
public long timeBetweenEvictionRunsMillis = GenericObjectPool.DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
public int numTestsPerEvictionRun = GenericObjectPool.DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
public long minEvictableIdleTimeMillis = GenericObjectPool.DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
}
//--- private attributes ---------------------------------------
/**
* The cap on the number of idle instances in the pool.
* @see #setMaxIdle
* @see #getMaxIdle
*/
private int _maxIdle = DEFAULT_MAX_IDLE;
/**
* The cap on the minimum number of idle instances in the pool.
* @see #setMinIdle
* @see #getMinIdle
*/
private int _minIdle = DEFAULT_MIN_IDLE;
/**
* The cap on the total number of active instances from the pool.
* @see #setMaxActive
* @see #getMaxActive
*/
private int _maxActive = DEFAULT_MAX_ACTIVE;
/**
* The maximum amount of time (in millis) the
* {@link #borrowObject} method should block before throwing
* an exception when the pool is exhausted and the
* {@link #getWhenExhaustedAction "when exhausted" action} is
* {@link #WHEN_EXHAUSTED_BLOCK}.
*
* When less than 0, the {@link #borrowObject} method
* may block indefinitely.
*
* @see #setMaxWait
* @see #getMaxWait
* @see #WHEN_EXHAUSTED_BLOCK
* @see #setWhenExhaustedAction
* @see #getWhenExhaustedAction
*/
private long _maxWait = DEFAULT_MAX_WAIT;
/**
* The action to take when the {@link #borrowObject} method
* is invoked when the pool is exhausted (the maximum number
* of "active" objects has been reached).
*
* @see #WHEN_EXHAUSTED_BLOCK
* @see #WHEN_EXHAUSTED_FAIL
* @see #WHEN_EXHAUSTED_GROW
* @see #DEFAULT_WHEN_EXHAUSTED_ACTION
* @see #setWhenExhaustedAction
* @see #getWhenExhaustedAction
*/
private byte _whenExhaustedAction = DEFAULT_WHEN_EXHAUSTED_ACTION;
/**
* When true, objects will be
* {@link PoolableObjectFactory#validateObject validated}
* before being returned by the {@link #borrowObject}
* method. If the object fails to validate,
* it will be dropped from the pool, and we will attempt
* to borrow another.
*
* @see #setTestOnBorrow
* @see #getTestOnBorrow
*/
private boolean _testOnBorrow = DEFAULT_TEST_ON_BORROW;
/**
* When true, objects will be
* {@link PoolableObjectFactory#validateObject validated}
* before being returned to the pool within the
* {@link #returnObject}.
*
* @see #getTestOnReturn
* @see #setTestOnReturn
*/
private boolean _testOnReturn = DEFAULT_TEST_ON_RETURN;
/**
* When true, objects will be
* {@link PoolableObjectFactory#validateObject validated}
* by the idle object evictor (if any). If an object
* fails to validate, it will be dropped from the pool.
*
* @see #setTestWhileIdle
* @see #getTestWhileIdle
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
private boolean _testWhileIdle = DEFAULT_TEST_WHILE_IDLE;
/**
* The number of milliseconds to sleep between runs of the
* idle object evictor thread.
* When non-positive, no idle object evictor thread will be
* run.
*
* @see #setTimeBetweenEvictionRunsMillis
* @see #getTimeBetweenEvictionRunsMillis
*/
private long _timeBetweenEvictionRunsMillis = DEFAULT_TIME_BETWEEN_EVICTION_RUNS_MILLIS;
/**
* The number of objects to examine during each run of the
* idle object evictor thread (if any).
*
* When a negative value is supplied, ceil({@link #getNumIdle})/abs({@link #getNumTestsPerEvictionRun})
* tests will be run. I.e., when the value is -n, roughly one nth of the
* idle objects will be tested per run.
*
* @see #setNumTestsPerEvictionRun
* @see #getNumTestsPerEvictionRun
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
private int _numTestsPerEvictionRun = DEFAULT_NUM_TESTS_PER_EVICTION_RUN;
/**
* The minimum amount of time an object may sit idle in the pool
* before it is eligable for eviction by the idle object evictor
* (if any).
* When non-positive, no objects will be evicted from the pool
* due to idle time alone.
*
* @see #setMinEvictableIdleTimeMillis
* @see #getMinEvictableIdleTimeMillis
* @see #getTimeBetweenEvictionRunsMillis
* @see #setTimeBetweenEvictionRunsMillis
*/
private long _minEvictableIdleTimeMillis = DEFAULT_MIN_EVICTABLE_IDLE_TIME_MILLIS;
/** My pool. */
private CursorableLinkedList _pool = null;
/** My {@link PoolableObjectFactory}. */
private PoolableObjectFactory _factory = null;
/**
* The number of objects {@link #borrowObject} borrowed
* from the pool, but not yet returned.
*/
private int _numActive = 0;
/**
* My idle object eviction thread, if any.
*/
private Evictor _evictor = null;
private CursorableLinkedList.Cursor _evictionCursor = null;
}