/**
* {@inheritDoc}
*
* <p>Successive activations of this method examine objects in sequence, cycling through objects
* in oldest-to-youngest order.
*/
@Override
public void evict() throws Exception {
assertOpen();
if (idleObjects.size() > 0) {
PooledObject<T> underTest = null;
EvictionPolicy<T> evictionPolicy = getEvictionPolicy();
synchronized (evictionLock) {
EvictionConfig evictionConfig =
new EvictionConfig(
getMinEvictableIdleTimeMillis(), getSoftMinEvictableIdleTimeMillis(), getMinIdle());
boolean testWhileIdle = getTestWhileIdle();
for (int i = 0, m = getNumTests(); i < m; i++) {
if (evictionIterator == null || !evictionIterator.hasNext()) {
evictionIterator = new EvictionIterator(idleObjects);
}
if (!evictionIterator.hasNext()) {
// Pool exhausted, nothing to do here
return;
}
try {
underTest = evictionIterator.next();
} catch (NoSuchElementException nsee) {
// Object was borrowed in another thread
// Don't count this as an eviction test so reduce i;
i--;
evictionIterator = null;
continue;
}
if (!underTest.startEvictionTest()) {
// Object was borrowed in another thread
// Don't count this as an eviction test so reduce i;
i--;
continue;
}
// User provided eviction policy could throw all sorts of crazy
// exceptions. Protect against such an exception killing the
// eviction thread.
boolean evict;
try {
evict = evictionPolicy.evict(evictionConfig, underTest, idleObjects.size());
} catch (Throwable t) {
// Slightly convoluted as SwallowedExceptionListener uses
// Exception rather than Throwable
PoolUtils.checkRethrow(t);
swallowException(new Exception(t));
// Don't evict on error conditions
evict = false;
}
if (evict) {
destroy(underTest);
destroyedByEvictorCount.incrementAndGet();
} else {
if (testWhileIdle) {
boolean active = false;
try {
factory.activateObject(underTest);
active = true;
} catch (Exception e) {
destroy(underTest);
destroyedByEvictorCount.incrementAndGet();
}
if (active) {
if (!factory.validateObject(underTest)) {
destroy(underTest);
destroyedByEvictorCount.incrementAndGet();
} else {
try {
factory.passivateObject(underTest);
} catch (Exception e) {
destroy(underTest);
destroyedByEvictorCount.incrementAndGet();
}
}
}
}
if (!underTest.endEvictionTest(idleObjects)) {
// TODO - May need to add code here once additional
// states are used
}
}
}
}
}
AbandonedConfig ac = this.abandonedConfig;
if (ac != null && ac.getRemoveAbandonedOnMaintenance()) {
removeAbandoned(ac);
}
}
/**
* Borrow an object from the pool using the specific waiting time which only applies if {@link
* #getBlockWhenExhausted()} is true.
*
* <p>If there is one or more idle instance available in the pool, then an idle instance will be
* selected based on the value of {@link #getLifo()}, activated and returned. If activation fails,
* or {@link #getTestOnBorrow() testOnBorrow} is set to <code>true</code> 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.
*
* <p>If there are no idle instances available in the pool, behavior depends on the {@link
* #getMaxTotal() maxTotal}, (if applicable) {@link #getBlockWhenExhausted()} and the value passed
* in to the <code>borrowMaxWaitMillis</code> parameter. If the number of instances checked out
* from the pool is less than <code>maxTotal,</code> a new instance is created, activated and (if
* applicable) validated and returned to the caller. If validation fails, a <code>
* NoSuchElementException</code> is thrown.
*
* <p>If the pool is exhausted (no available idle instances and no capacity to create new ones),
* this method will either block (if {@link #getBlockWhenExhausted()} is true) or throw a <code>
* NoSuchElementException</code> (if {@link #getBlockWhenExhausted()} is false). The length of
* time that this method will block when {@link #getBlockWhenExhausted()} is true is determined by
* the value passed in to the <code>borrowMaxWaitMillis</code> parameter.
*
* <p>When the pool is exhausted, multiple calling threads may be simultaneously blocked waiting
* for instances to become available. A "fairness" algorithm has been implemented to ensure that
* threads receive available instances in request arrival order.
*
* @param borrowMaxWaitMillis The time to wait in milliseconds for an object to become available
* @return object instance from the pool
* @throws NoSuchElementException if an instance cannot be returned
* @throws Exception if an object instance cannot be returned due to an error
*/
public T borrowObject(long borrowMaxWaitMillis) throws Exception {
assertOpen();
AbandonedConfig ac = this.abandonedConfig;
if (ac != null
&& ac.getRemoveAbandonedOnBorrow()
&& (getNumIdle() < 2)
&& (getNumActive() > getMaxTotal() - 3)) {
removeAbandoned(ac);
}
PooledObject<T> p = null;
// Get local copy of current config so it is consistent for entire
// method execution
boolean blockWhenExhausted = getBlockWhenExhausted();
boolean create;
long waitTime = System.currentTimeMillis();
while (p == null) {
create = false;
if (blockWhenExhausted) {
p = idleObjects.pollFirst();
if (p == null) {
p = create();
if (p != null) {
create = true;
}
}
if (p == null) {
if (borrowMaxWaitMillis < 0) {
p = idleObjects.takeFirst();
} else {
p = idleObjects.pollFirst(borrowMaxWaitMillis, TimeUnit.MILLISECONDS);
}
}
if (p == null) {
throw new NoSuchElementException("Timeout waiting for idle object");
}
if (!p.allocate()) {
p = null;
}
} else {
p = idleObjects.pollFirst();
if (p == null) {
p = create();
if (p != null) {
create = true;
}
}
if (p == null) {
throw new NoSuchElementException("Pool exhausted");
}
if (!p.allocate()) {
p = null;
}
}
if (p != null) {
try {
factory.activateObject(p);
} catch (Exception e) {
try {
destroy(p);
} catch (Exception e1) {
// Ignore - activation failure is more important
}
p = null;
if (create) {
NoSuchElementException nsee = new NoSuchElementException("Unable to activate object");
nsee.initCause(e);
throw nsee;
}
}
if (p != null && (getTestOnBorrow() || create && getTestOnCreate())) {
boolean validate = false;
Throwable validationThrowable = null;
try {
validate = factory.validateObject(p);
} catch (Throwable t) {
PoolUtils.checkRethrow(t);
validationThrowable = t;
}
if (!validate) {
try {
destroy(p);
destroyedByBorrowValidationCount.incrementAndGet();
} catch (Exception e) {
// Ignore - validation failure is more important
}
p = null;
if (create) {
NoSuchElementException nsee = new NoSuchElementException("Unable to validate object");
nsee.initCause(validationThrowable);
throw nsee;
}
}
}
}
}
updateStatsBorrow(p, System.currentTimeMillis() - waitTime);
return p.getObject();
}