Also see:

WHEN_EXHAUSTED_BLOCK
WHEN_EXHAUSTED_GROW
setWhenExhaustedAction

Also see:

WHEN_EXHAUSTED_FAIL
WHEN_EXHAUSTED_GROW
setMaxWait
getMaxWait
setWhenExhaustedAction

Also see:

WHEN_EXHAUSTED_FAIL
WHEN_EXHAUSTED_GROW
setWhenExhaustedAction

Also see:

getMaxIdle
setMaxIdle

Also see:

getMinIdle
setMinIdle

Also see:

getMaxActive

Also see:

WHEN_EXHAUSTED_BLOCK
WHEN_EXHAUSTED_FAIL
WHEN_EXHAUSTED_GROW
setWhenExhaustedAction

Also see:

setLifo
since: 1.4 -

Also see:

getMaxWait
setMaxWait

Also see:

getTestOnBorrow
setTestOnBorrow

Also see:

getTestOnReturn
setTestOnReturn

Also see:

getTestWhileIdle
setTestWhileIdle
getTimeBetweenEvictionRunsMillis
setTimeBetweenEvictionRunsMillis

Also see:

getTimeBetweenEvictionRunsMillis
setTimeBetweenEvictionRunsMillis

Also see:

getNumTestsPerEvictionRun
setNumTestsPerEvictionRun
getTimeBetweenEvictionRunsMillis
setTimeBetweenEvictionRunsMillis

Also see:

getMinEvictableIdleTimeMillis
setMinEvictableIdleTimeMillis

Also see:

getSoftMinEvictableIdleTimeMillis
setSoftMinEvictableIdleTimeMillis

 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 with default properties.

 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 factory.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

 public GenericObjectPool(PoolableObjectFactory factory,
    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, 
                config.softMinEvictableIdleTimeMillis, config.lifo);
}

Create a new GenericObjectPool using the specified values.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

config - a non-null GenericObjectPool.Config describing my configuration

 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.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

maxActive - the maximum number of objects that can be borrowed from me at one time (see #setMaxActive )

 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.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

maxActive - the maximum number of objects that can be borrowed from me at one time (see #setMaxActive )

whenExhaustedAction - the action to take when the pool is exhausted (see #getWhenExhaustedAction )

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is #WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see #getMaxWait )

 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.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

maxActive - the maximum number of objects that can be borrowed at one time (see #setMaxActive )

whenExhaustedAction - the action to take when the pool is exhausted (see #getWhenExhaustedAction )

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is #WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see #getMaxWait )

maxIdle - the maximum number of idle objects in my pool (see #getMaxIdle )

 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.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

maxActive - the maximum number of objects that can be borrowed at one time (see #setMaxActive )

whenExhaustedAction - the action to take when the pool is exhausted (see #getWhenExhaustedAction )

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted an and whenExhaustedAction is #WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see #getMaxWait )

testOnBorrow - whether or not to validate objects before they are returned by the #borrowObject method (see #getTestOnBorrow )

testOnReturn - whether or not to validate objects after they are returned to the #returnObject method (see #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.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

maxActive - the maximum number of objects that can be borrowed at one time (see #setMaxActive )

whenExhaustedAction - the action to take when the pool is exhausted (see #getWhenExhaustedAction )

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is #WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see #getMaxWait )

maxIdle - the maximum number of idle objects in my pool (see #getMaxIdle )

testOnBorrow - whether or not to validate objects before they are returned by the #borrowObject method (see #getTestOnBorrow )

testOnReturn - whether or not to validate objects after they are returned to the #returnObject method (see #getTestOnReturn )

 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.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

maxActive - the maximum number of objects that can be borrowed at one time (see #setMaxActive )

whenExhaustedAction - the action to take when the pool is exhausted (see #setWhenExhaustedAction )

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is #WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see #setMaxWait )

maxIdle - the maximum number of idle objects in my pool (see #setMaxIdle )

testOnBorrow - whether or not to validate objects before they are returned by the #borrowObject method (see #setTestOnBorrow )

testOnReturn - whether or not to validate objects after they are returned to the #returnObject method (see #setTestOnReturn )

timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see #setTimeBetweenEvictionRunsMillis )

numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see #setNumTestsPerEvictionRun )

minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see #setMinEvictableIdleTimeMillis )

testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see #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) 
{
        this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, minIdle, testOnBorrow, testOnReturn,
                timeBetweenEvictionRunsMillis, numTestsPerEvictionRun, minEvictableIdleTimeMillis, testWhileIdle,
                DEFAULT_SOFT_MIN_EVICTABLE_IDLE_TIME_MILLIS);
}

Create a new GenericObjectPool using the specified values.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

maxActive - the maximum number of objects that can be borrowed at one time (see #setMaxActive )

whenExhaustedAction - the action to take when the pool is exhausted (see #setWhenExhaustedAction )

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is #WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see #setMaxWait )

maxIdle - the maximum number of idle objects in my pool (see #setMaxIdle )

minIdle - the minimum number of idle objects in my pool (see #setMinIdle )

testOnBorrow - whether or not to validate objects before they are returned by the #borrowObject method (see #setTestOnBorrow )

testOnReturn - whether or not to validate objects after they are returned to the #returnObject method (see #setTestOnReturn )

timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see #setTimeBetweenEvictionRunsMillis )

numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see #setNumTestsPerEvictionRun )

minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see #setMinEvictableIdleTimeMillis )

testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see #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,
    long softMinEvictableIdleTimeMillis) 
{
        this(factory, maxActive, whenExhaustedAction, maxWait, maxIdle, minIdle, testOnBorrow, testOnReturn,
                timeBetweenEvictionRunsMillis, numTestsPerEvictionRun, minEvictableIdleTimeMillis, testWhileIdle,
                softMinEvictableIdleTimeMillis, DEFAULT_LIFO);
}

Create a new GenericObjectPool using the specified values.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

maxActive - the maximum number of objects that can be borrowed at one time (see #setMaxActive )

whenExhaustedAction - the action to take when the pool is exhausted (see #setWhenExhaustedAction )

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is #WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see #setMaxWait )

maxIdle - the maximum number of idle objects in my pool (see #setMaxIdle )

minIdle - the minimum number of idle objects in my pool (see #setMinIdle )

testOnBorrow - whether or not to validate objects before they are returned by the #borrowObject method (see #setTestOnBorrow )

testOnReturn - whether or not to validate objects after they are returned to the #returnObject method (see #setTestOnReturn )

timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see #setTimeBetweenEvictionRunsMillis )

numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see #setNumTestsPerEvictionRun )

minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see #setMinEvictableIdleTimeMillis )

testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see #setTestWhileIdle )

softMinEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction with the extra condition that at least "minIdle" amount of object remain in the pool. (see #setSoftMinEvictableIdleTimeMillis )

since: Pool - 1.3

 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,
    long softMinEvictableIdleTimeMillis,
    boolean lifo) 
{
        _factory = factory;
        _maxActive = maxActive;
        _lifo = lifo;
        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;
        _softMinEvictableIdleTimeMillis = softMinEvictableIdleTimeMillis;
        _testWhileIdle = testWhileIdle;
        _pool = new CursorableLinkedList();
        startEvictor(_timeBetweenEvictionRunsMillis);
}

Create a new GenericObjectPool using the specified values.

Parameters:

factory - the (possibly null)PoolableObjectFactory to use to create, validate and destroy objects

maxActive - the maximum number of objects that can be borrowed at one time (see #setMaxActive )

whenExhaustedAction - the action to take when the pool is exhausted (see #setWhenExhaustedAction )

maxWait - the maximum amount of time to wait for an idle object when the pool is exhausted and whenExhaustedAction is #WHEN_EXHAUSTED_BLOCK (otherwise ignored) (see #setMaxWait )

maxIdle - the maximum number of idle objects in my pool (see #setMaxIdle )

minIdle - the minimum number of idle objects in my pool (see #setMinIdle )

testOnBorrow - whether or not to validate objects before they are returned by the #borrowObject method (see #setTestOnBorrow )

testOnReturn - whether or not to validate objects after they are returned to the #returnObject method (see #setTestOnReturn )

timeBetweenEvictionRunsMillis - the amount of time (in milliseconds) to sleep between examining idle objects for eviction (see #setTimeBetweenEvictionRunsMillis )

numTestsPerEvictionRun - the number of idle objects to examine per run within the idle object eviction thread (if any) (see #setNumTestsPerEvictionRun )

minEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction (see #setMinEvictableIdleTimeMillis )

testWhileIdle - whether or not to validate objects in the idle object eviction thread, if any (see #setTestWhileIdle )

softMinEvictableIdleTimeMillis - the minimum number of milliseconds an object can sit idle in the pool before it is eligible for eviction with the extra condition that at least "minIdle" amount of object remain in the pool. (see #setSoftMinEvictableIdleTimeMillis )

lifo - whether or not objects are returned in last-in-first-out order from the idle object pool (see #setLifo )

since: Pool - 1.4

 public  void addObject() throws Exception 
{
        assertOpen();
        if (_factory == null) {
            throw new IllegalStateException("Cannot add objects without a factory.");
        }
        Object obj = _factory.makeObject();
        try {
            assertOpen();
            addObjectToPool(obj, false);
        } catch (IllegalStateException ex) { // Pool closed
            try {
                _factory.destroyObject(obj);
            } catch (Exception ex2) {
                // swallow
            }
            throw ex;
        }
}

Create an object, and place it into the pool. addObject() is useful for "pre-loading" a pool with idle objects.

 public Object borrowObject() throws Exception 
{
        long starttime = System.currentTimeMillis();
        Latch latch = new Latch();
        byte whenExhaustedAction;
        long maxWait;
        synchronized (this) {
            // Get local copy of current config. Can't sync when used later as
            // it can result in a deadlock. Has the added advantage that config
            // is consistent for entire method execution
            whenExhaustedAction = _whenExhaustedAction;
            maxWait = _maxWait;
            // Add this request to the queue
            _allocationQueue.add(latch);
            // Work the allocation queue, allocating idle instances and
            // instance creation permits in request arrival order
            allocate();
        }
        for(;;) {
            synchronized (this) {
                assertOpen();
            }
            // If no object was allocated from the pool above
            if(latch.getPair() == null) {
                // check if we were allowed to create one
                if(latch.mayCreate()) {
                    // allow new object to be created
                } else {
                    // the pool is exhausted
                    switch(whenExhaustedAction) {
                        case WHEN_EXHAUSTED_GROW:
                            // allow new object to be created
                            synchronized (this) {
                                // Make sure another thread didn't allocate us an object
                                // or permit a new object to be created
                                if (latch.getPair() == null && !latch.mayCreate()) {
                                    _allocationQueue.remove(latch);
                                    _numInternalProcessing++;
                                }
                            }
                            break;
                        case WHEN_EXHAUSTED_FAIL:
                            synchronized (this) {
                                // Make sure allocate hasn't already assigned an object
                                // in a different thread or permitted a new object to be created
                                if (latch.getPair() != null || latch.mayCreate()) {
                                    break;
                                }
                                _allocationQueue.remove(latch);
                            }
                            throw new NoSuchElementException("Pool exhausted");
                        case WHEN_EXHAUSTED_BLOCK:
                            try {
                                synchronized (latch) {
                                    // Before we wait, make sure another thread didn't allocate us an object
                                    // or permit a new object to be created
                                    if (latch.getPair() == null && !latch.mayCreate()) {
                                        if(maxWait < = 0) {
                                            latch.wait();
                                        } else {
                                            // this code may be executed again after a notify then continue cycle
                                            // so, need to calculate the amount of time to wait
                                            final long elapsed = (System.currentTimeMillis() - starttime);
                                            final long waitTime = maxWait - elapsed;
                                            if (waitTime  > 0)
                                            {
                                                latch.wait(waitTime);
                                            }
                                        }
                                    } else {
                                        break;
                                    }
                                }
                            } catch(InterruptedException e) {
                                Thread.currentThread().interrupt();
                                throw e;
                            }
                            if(maxWait  > 0 && ((System.currentTimeMillis() - starttime)  >= maxWait)) {
                                synchronized(this) {
                                    // Make sure allocate hasn't already assigned an object
                                    // in a different thread or permitted a new object to be created
                                    if (latch.getPair() == null && !latch.mayCreate()) {
                                        // Remove latch from the allocation queue
                                        _allocationQueue.remove(latch);
                                    } else {
                                        break;
                                    }
                                }
                                throw new NoSuchElementException("Timeout waiting for idle object");
                            } else {
                                continue; // keep looping
                            }
                        default:
                            throw new IllegalArgumentException("WhenExhaustedAction property " + whenExhaustedAction +
                                    " not recognized.");
                    }
                }
            }
            boolean newlyCreated = false;
            if(null == latch.getPair()) {
                try {
                    Object obj = _factory.makeObject();
                    latch.setPair(new ObjectTimestampPair(obj));
                    newlyCreated = true;
                } finally {
                    if (!newlyCreated) {
                        // object cannot be created
                        synchronized (this) {
                            _numInternalProcessing--;
                            // No need to reset latch - about to throw exception
                            allocate();
                        }
                    }
                }
            }
            // activate & validate the object
            try {
                _factory.activateObject(latch.getPair().value);
                if(_testOnBorrow &&
                        !_factory.validateObject(latch.getPair().value)) {
                    throw new Exception("ValidateObject failed");
                }
                synchronized(this) {
                    _numInternalProcessing--;
                    _numActive++;
                }
                return latch.getPair().value;
            }
            catch (Throwable e) {
                // object cannot be activated or is invalid
                try {
                    _factory.destroyObject(latch.getPair().value);
                } catch (Throwable e2) {
                    // cannot destroy broken object
                }
                synchronized (this) {
                    _numInternalProcessing--;
                    if (!newlyCreated) {
                        latch.reset();
                        _allocationQueue.add(0, latch);
                    }
                    allocate();
                }
                if(newlyCreated) {
                    throw new NoSuchElementException("Could not create a validated object, cause: " + e.getMessage());
                }
                else {
                    continue; // keep looping
                }
            }
        }
}

Borrows an object from the pool.

If there is an idle instance available in the pool, then either the most-recently returned (if lifo == true) or "oldest" (lifo == false) instance sitting idle in the pool will be activated and returned. If activation fails, or testOnBorrow is set to true and validation fails, the instance is destroyed and the next available instance is examined. This continues until either a valid instance is returned or there are no more idle instances available.

If there are no idle instances available in the pool, behavior depends on the maxActive and (if applicable) whenExhaustedAction and maxWait properties. If the number of instances checked out from the pool is less than maxActive, a new instance is created, activated and (if applicable) validated and returned to the caller.

If the pool is exhausted (no available idle instances and no capacity to create new ones), this method will either block (#WHEN_EXHAUSTED_BLOCK ), throw a NoSuchElementException (#WHEN_EXHAUSTED_FAIL ), or grow (#WHEN_EXHAUSTED_GROW - ignoring maxActive). The length of time that this method will block when whenExhaustedAction == WHEN_EXHAUSTED_BLOCK is determined by the maxWait property.

When the pool is exhausted, multiple calling threads may be simultaneously blocked waiting for instances to become available. As of pool 1.5, a "fairness" algorithm has been implemented to ensure that threads receive available instances in request arrival order.

 public  void clear() 
{
        List toDestroy = new ArrayList();
        synchronized(this) {
            toDestroy.addAll(_pool);
            _numInternalProcessing = _numInternalProcessing + _pool._size;
            _pool.clear();
        }
        destroy(toDestroy);
}

Clears any objects sitting idle in the pool by removing them from the idle instance pool and then invoking the configured PoolableObjectFactory#destroyObject(Object) method on each idle instance.

Implementation notes:

• This method does not destroy or effect in any way instances that are checked out of the pool when it is invoked.
• Invoking this method does not prevent objects being returned to the idle instance pool, even during its execution. It locks the pool only during instance removal. Additional instances may be returned while removed items are being destroyed.

 public  void close() throws Exception 
{
        super.close();
        synchronized (this) {
            clear();
            startEvictor(-1L);
        }
}

Closes the pool. Once the pool is closed, #borrowObject() will fail with IllegalStateException, but #returnObject(Object) and #invalidateObject(Object) will continue to work. This method does not #clear() the pool. The method is idempotent - that is, it is OK to call it on a closed pool.

 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();
}

Returns pool info including #getNumActive() , #getNumIdle() and a list of objects idle in the pool with their idle times.

 public  void evict() throws Exception 
{
        assertOpen();
        synchronized (this) {
            if(_pool.isEmpty()) {
                return;
            }
            if (null == _evictionCursor) {
                _evictionCursor = (_pool.cursor(_lifo ? _pool.size() : 0));
            }
        }
        for (int i=0,m=getNumTests();i< m;i++) {
            final ObjectTimestampPair pair;
            synchronized (this) {
                if ((_lifo && !_evictionCursor.hasPrevious()) ||
                        !_lifo && !_evictionCursor.hasNext()) {
                    _evictionCursor.close();
                    _evictionCursor = _pool.cursor(_lifo ? _pool.size() : 0);
                }
                pair = _lifo ?
                        (ObjectTimestampPair) _evictionCursor.previous() :
                        (ObjectTimestampPair) _evictionCursor.next();
                _evictionCursor.remove();
                _numInternalProcessing++;
            }
            boolean removeObject = false;
            final long idleTimeMilis = System.currentTimeMillis() - pair.tstamp;
            if ((getMinEvictableIdleTimeMillis()  > 0) &&
                    (idleTimeMilis  > getMinEvictableIdleTimeMillis())) {
                removeObject = true;
            } else if ((getSoftMinEvictableIdleTimeMillis()  > 0) &&
                    (idleTimeMilis  > getSoftMinEvictableIdleTimeMillis()) &&
                    ((getNumIdle() + 1) > getMinIdle())) { // +1 accounts for object we are processing
                removeObject = true;
            }
            if(getTestWhileIdle() && !removeObject) {
                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 {
                    _factory.destroyObject(pair.value);
                } catch(Exception e) {
                    // ignored
                }
            }
            synchronized (this) {
                if(!removeObject) {
                    _evictionCursor.add(pair);
                    if (_lifo) {
                        // Skip over the element we just added back
                        _evictionCursor.previous();
                    }
                }
                _numInternalProcessing--;
            }
        }
}

Perform numTests idle object eviction tests, evicting examined objects that meet the criteria for eviction. If testWhileIdle is true, examined objects are validated when visited (and removed if invalid); otherwise only objects that have been idle for more than minEvicableIdletimeMillis are removed.

Successive activations of this method examine objects in in sequence, cycling through objects in oldest-to-youngest order.

 public synchronized boolean getLifo() 
{
         return _lifo;
}

Whether or not the idle object pool acts as a LIFO queue. True means that borrowObject returns the most recently used ("last in") idle object in the pool (if there are idle instances available). False means that the pool behaves as a FIFO queue - objects are taken from the idle object pool in the order that they are returned to the pool.

 public synchronized int getMaxActive() 
{
        return _maxActive;
}

Returns the maximum number of objects that can be allocated by the pool (checked out to clients, or idle awaiting checkout) at a given time. When non-positive, there is no limit to the number of objects that can be managed by the pool at one time.

 public synchronized int getMaxIdle() 
{
        return _maxIdle;
}

Returns the cap on the number of "idle" instances in the pool.

 public synchronized long getMaxWait() 
{
        return _maxWait;
}

Returns the maximum amount of time (in milliseconds) the #borrowObject method should block before throwing an exception when the pool is exhausted and the "when exhausted" action is #WHEN_EXHAUSTED_BLOCK . When less than or equal to 0, the #borrowObject method may block indefinitely.

 public synchronized long getMinEvictableIdleTimeMillis() 
{
        return _minEvictableIdleTimeMillis;
}

Returns the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any).

 public synchronized int getMinIdle() 
{
        return _minIdle;
}

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)

 public synchronized int getNumActive() 
{
        return _numActive;
}

Return the number of instances currently borrowed from this pool.

 public synchronized int getNumIdle() 
{
        return _pool.size();
}

Return the number of instances currently idle in this pool.

 public synchronized int getNumTestsPerEvictionRun() 
{
        return _numTestsPerEvictionRun;
}

Returns the max number of objects to examine during each run of the idle object evictor thread (if any).

 public synchronized long getSoftMinEvictableIdleTimeMillis() 
{
        return _softMinEvictableIdleTimeMillis;
}

Returns the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any), with the extra condition that at least "minIdle" amount of object remain in the pool.

 public boolean getTestOnBorrow() 
{
        return _testOnBorrow;
}

When true, objects will be validated before being returned by the #borrowObject method. If the object fails to validate, it will be dropped from the pool, and we will attempt to borrow another.

 public boolean getTestOnReturn() 
{
        return _testOnReturn;
}

When true, objects will be validated before being returned to the pool within the #returnObject .

 public synchronized boolean getTestWhileIdle() 
{
        return _testWhileIdle;
}

When true, objects will be validated by the idle object evictor (if any). If an object fails to validate, it will be dropped from the pool.

 public synchronized long getTimeBetweenEvictionRunsMillis() 
{
        return _timeBetweenEvictionRunsMillis;
}

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.

 public synchronized byte getWhenExhaustedAction() 
{
        return _whenExhaustedAction;
}

Returns the action to take when the #borrowObject method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).

 public  void invalidateObject(Object obj) throws Exception 
{
        try {
            if (_factory != null) {
                _factory.destroyObject(obj);
            }
        } finally {
            synchronized (this) {
                _numActive--;
                allocate();
            }
        }
}

Invalidates the given object instance. Decrements the active count and destroys the instance.

 public  void returnObject(Object obj) throws Exception 
{
        try {
            addObjectToPool(obj, true);
        } catch (Exception e) {
            if (_factory != null) {
                try {
                    _factory.destroyObject(obj);
                } catch (Exception e2) {
                    // swallowed
                }
                // TODO: Correctness here depends on control in addObjectToPool.
                // These two methods should be refactored, removing the
                // "behavior flag", decrementNumActive, from addObjectToPool.
                synchronized(this) {
                    _numActive--;
                    allocate();
                }
            }
        }
}

Returns an object instance to the pool.

If maxIdle is set to a positive value and the number of idle instances has reached this value, the returning instance is destroyed.

If testOnReturn == true, the returning instance is validated before being returned to the idle instance pool. In this case, if validation fails, the instance is destroyed.

Note: There is no guard to prevent an object being returned to the pool multiple times. Clients are expected to discard references to returned objects and ensure that an object is not returned to the pool multiple times in sequence (i.e., without being borrowed again between returns). Violating this contract will result in the same object appearing multiple times in the pool and pool counters (numActive, numIdle) returning incorrect values.

 public synchronized  void setConfig(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);
        setSoftMinEvictableIdleTimeMillis(conf.softMinEvictableIdleTimeMillis);
        setLifo(conf.lifo);
        allocate();
}

Sets my configuration.

 public  void setFactory(PoolableObjectFactory factory) throws IllegalStateException 
{
        List toDestroy = new ArrayList();
        synchronized (this) {
            assertOpen();
            if(0 <  getNumActive()) {
                throw new IllegalStateException("Objects are already active");
            } else {
                toDestroy.addAll(_pool);
                _numInternalProcessing = _numInternalProcessing + _pool._size;
                _pool.clear();
            }
            _factory = factory;
        }
        destroy(toDestroy);
}

Sets the factory this pool uses to create new instances. Trying to change the factory while there are borrowed objects will throw an IllegalStateException .

 public synchronized  void setLifo(boolean lifo) 
{
         this._lifo = lifo;
}

Sets the LIFO property of the pool. True means that borrowObject returns the most recently used ("last in") idle object in the pool (if there are idle instances available). False means that the pool behaves as a FIFO queue - objects are taken from the idle object pool in the order that they are returned to the pool.

 public synchronized  void setMaxActive(int maxActive) 
{
        _maxActive = maxActive;
        allocate();
}

Sets the cap on the number of objects that can be allocated by the pool (checked out to clients, or idle awaiting checkout) at a given time. Use a negative value for no limit.

 public synchronized  void setMaxIdle(int maxIdle) 
{
        _maxIdle = maxIdle;
        allocate();
}

Sets the cap on the number of "idle" instances in the pool. If maxIdle is set too low on heavily loaded systems it is possible you will see objects being destroyed and almost immediately new objects being created. This is a result of the active threads momentarily returning objects faster than they are requesting them them, causing the number of idle objects to rise above maxIdle. The best value for maxIdle for heavily loaded system will vary but the default is a good starting point.

 public synchronized  void setMaxWait(long maxWait) 
{
        _maxWait = maxWait;
        allocate();
}

Sets the maximum amount of time (in milliseconds) the #borrowObject method should block before throwing an exception when the pool is exhausted and the "when exhausted" action is #WHEN_EXHAUSTED_BLOCK . When less than or equal to 0, the #borrowObject method may block indefinitely.

 public synchronized  void setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis) 
{
        _minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;
}

Sets the minimum amount of time an object may sit idle in the pool before it is eligible 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.

 public synchronized  void setMinIdle(int minIdle) 
{
        _minIdle = minIdle;
        allocate();
}

Sets the minimum number of objects allowed in the pool before the evictor thread (if active) spawns new objects. Note that no objects are created when numActive + numIdle >= maxActive. This setting has no effect if the idle object evictor is disabled (i.e. if timeBetweenEvictionRunsMillis <= 0).

 public synchronized  void setNumTestsPerEvictionRun(int numTestsPerEvictionRun) 
{
        _numTestsPerEvictionRun = numTestsPerEvictionRun;
}

Sets the max number of objects to examine during each run of the idle object evictor thread (if any).

When a negative value is supplied, ceil(#getNumIdle )/abs(#getNumTestsPerEvictionRun ) tests will be run. That is, when the value is -n, roughly one nth of the idle objects will be tested per run. When the value is positive, the number of tests actually performed in each run will be the minimum of this value and the number of instances idle in the pool.

 public synchronized  void setSoftMinEvictableIdleTimeMillis(long softMinEvictableIdleTimeMillis) 
{
        _softMinEvictableIdleTimeMillis = softMinEvictableIdleTimeMillis;
}

Sets the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any), with the extra condition that at least "minIdle" object instances remain in the pool. When non-positive, no objects will be evicted from the pool due to idle time alone.

 public  void setTestOnBorrow(boolean testOnBorrow) 
{
        _testOnBorrow = testOnBorrow;
}

When true, objects will be validated before being returned by the #borrowObject method. If the object fails to validate, it will be dropped from the pool, and we will attempt to borrow another.

 public  void setTestOnReturn(boolean testOnReturn) 
{
        _testOnReturn = testOnReturn;
}

When true, objects will be validated before being returned to the pool within the #returnObject .

 public synchronized  void setTestWhileIdle(boolean testWhileIdle) 
{
        _testWhileIdle = testWhileIdle;
}

When true, objects will be validated by the idle object evictor (if any). If an object fails to validate, it will be dropped from the pool.

 public synchronized  void setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis) 
{
        _timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;
        startEvictor(_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.

 public synchronized  void setWhenExhaustedAction(byte whenExhaustedAction) 
{
        switch(whenExhaustedAction) {
            case WHEN_EXHAUSTED_BLOCK:
            case WHEN_EXHAUSTED_FAIL:
            case WHEN_EXHAUSTED_GROW:
                _whenExhaustedAction = whenExhaustedAction;
                allocate();
                break;
            default:
                throw new IllegalArgumentException("whenExhaustedAction " + whenExhaustedAction + " not recognized.");
        }
}

Sets the action to take when the #borrowObject method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).

 protected synchronized  void startEvictor(long delay) 
{
        if(null != _evictor) {
            EvictionTimer.cancel(_evictor);
            _evictor = null;
        }
        if(delay  > 0) {
            _evictor = new Evictor();
            EvictionTimer.schedule(_evictor, delay, delay);
        }
}

Start the eviction thread or service, or when delay is non-positive, stop it if it is already running.