/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apach3.http.pool;
import java.io.IOException;
import java.util.Date;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.Future;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.apach3.http.annotation.ThreadSafe;
import org.apach3.http.concurrent.FutureCallback;
/**
* Abstract synchronous (blocking) pool of connections.
* <p/>
* Please note that this class does not maintain its own pool of execution {@link Thread}s.
* Therefore, one <b>must</b> call {@link Future#get()} or {@link Future#get(long, TimeUnit)}
* method on the {@link Future} object returned by the
* {@link #lease(Object, Object, FutureCallback)} method in order for the lease operation
* to complete.
*
* @param <T> the route type that represents the opposite endpoint of a pooled
* connection.
* @param <C> the connection type.
* @param <E> the type of the pool entry containing a pooled connection.
* @since 4.2
*/
@ThreadSafe
public abstract class AbstractConnPool<T, C, E extends PoolEntry<T, C>>
implements ConnPool<T, E>, ConnPoolControl<T> {
private final Lock lock;
private final ConnFactory<T, C> connFactory;
private final Map<T, RouteSpecificPool<T, C, E>> routeToPool;
private final Set<E> leased;
private final LinkedList<E> available;
private final LinkedList<PoolEntryFuture<E>> pending;
private final Map<T, Integer> maxPerRoute;
private volatile boolean isShutDown;
private volatile int defaultMaxPerRoute;
private volatile int maxTotal;
public AbstractConnPool(
final ConnFactory<T, C> connFactory,
int defaultMaxPerRoute,
int maxTotal) {
super();
if (connFactory == null) {
throw new IllegalArgumentException("Connection factory may not null");
}
if (defaultMaxPerRoute <= 0) {
throw new IllegalArgumentException("Max per route value may not be negative or zero");
}
if (maxTotal <= 0) {
throw new IllegalArgumentException("Max total value may not be negative or zero");
}
this.lock = new ReentrantLock();
this.connFactory = connFactory;
this.routeToPool = new HashMap<T, RouteSpecificPool<T, C, E>>();
this.leased = new HashSet<E>();
this.available = new LinkedList<E>();
this.pending = new LinkedList<PoolEntryFuture<E>>();
this.maxPerRoute = new HashMap<T, Integer>();
this.defaultMaxPerRoute = defaultMaxPerRoute;
this.maxTotal = maxTotal;
}
/**
* Creates a new entry for the given connection with the given route.
*/
protected abstract E createEntry(T route, C conn);
public boolean isShutdown() {
return this.isShutDown;
}
/**
* Shuts down the pool.
*/
public void shutdown() throws IOException {
if (this.isShutDown) {
return ;
}
this.isShutDown = true;
this.lock.lock();
try {
for (E entry: this.available) {
entry.close();
}
for (E entry: this.leased) {
entry.close();
}
for (RouteSpecificPool<T, C, E> pool: this.routeToPool.values()) {
pool.shutdown();
}
this.routeToPool.clear();
this.leased.clear();
this.available.clear();
} finally {
this.lock.unlock();
}
}
private RouteSpecificPool<T, C, E> getPool(final T route) {
RouteSpecificPool<T, C, E> pool = this.routeToPool.get(route);
if (pool == null) {
pool = new RouteSpecificPool<T, C, E>(route) {
@Override
protected E createEntry(C conn) {
return AbstractConnPool.this.createEntry(route, conn);
}
};
this.routeToPool.put(route, pool);
}
return pool;
}
/**
* {@inheritDoc}
* <p/>
* Please note that this class does not maintain its own pool of execution
* {@link Thread}s. Therefore, one <b>must</b> call {@link Future#get()}
* or {@link Future#get(long, TimeUnit)} method on the {@link Future}
* returned by this method in order for the lease operation to complete.
*/
public Future<E> lease(final T route, final Object state, final FutureCallback<E> callback) {
if (route == null) {
throw new IllegalArgumentException("Route may not be null");
}
if (this.isShutDown) {
throw new IllegalStateException("Connection pool shut down");
}
return new PoolEntryFuture<E>(this.lock, callback) {
@Override
public E getPoolEntry(
long timeout,
TimeUnit tunit)
throws InterruptedException, TimeoutException, IOException {
return getPoolEntryBlocking(route, state, timeout, tunit, this);
}
};
}
/**
* Attempts to lease a connection for the given route and with the given
* state from the pool.
* <p/>
* Please note that this class does not maintain its own pool of execution
* {@link Thread}s. Therefore, one <b>must</b> call {@link Future#get()}
* or {@link Future#get(long, TimeUnit)} method on the {@link Future}
* returned by this method in order for the lease operation to complete.
*
* @param route route of the connection.
* @param state arbitrary object that represents a particular state
* (usually a security principal or a unique token identifying
* the user whose credentials have been used while establishing the connection).
* May be <code>null</code>.
* @return future for a leased pool entry.
*/
public Future<E> lease(final T route, final Object state) {
return lease(route, state, null);
}
private E getPoolEntryBlocking(
final T route, final Object state,
final long timeout, final TimeUnit tunit,
final PoolEntryFuture<E> future)
throws IOException, InterruptedException, TimeoutException {
Date deadline = null;
if (timeout > 0) {
deadline = new Date
(System.currentTimeMillis() + tunit.toMillis(timeout));
}
this.lock.lock();
try {
RouteSpecificPool<T, C, E> pool = getPool(route);
E entry = null;
while (entry == null) {
if (this.isShutDown) {
throw new IllegalStateException("Connection pool shut down");
}
for (;;) {
entry = pool.getFree(state);
if (entry == null) {
break;
}
if (entry.isClosed() || entry.isExpired(System.currentTimeMillis())) {
entry.close();
this.available.remove(entry);
pool.free(entry, false);
} else {
break;
}
}
if (entry != null) {
this.available.remove(entry);
this.leased.add(entry);
return entry;
}
// New connection is needed
int maxPerRoute = getMax(route);
// Shrink the pool prior to allocating a new connection
int excess = Math.max(0, pool.getAllocatedCount() + 1 - maxPerRoute);
if (excess > 0) {
for (int i = 0; i < excess; i++) {
E lastUsed = pool.getLastUsed();
if (lastUsed == null) {
break;
}
lastUsed.close();
this.available.remove(lastUsed);
pool.remove(lastUsed);
}
}
if (pool.getAllocatedCount() < maxPerRoute) {
int totalUsed = this.leased.size();
int freeCapacity = Math.max(this.maxTotal - totalUsed, 0);
if (freeCapacity > 0) {
int totalAvailable = this.available.size();
if (totalAvailable > freeCapacity - 1) {
if (!this.available.isEmpty()) {
E lastUsed = this.available.removeLast();
lastUsed.close();
RouteSpecificPool<T, C, E> otherpool = getPool(lastUsed.getRoute());
otherpool.remove(lastUsed);
}
}
C conn = this.connFactory.create(route);
entry = pool.add(conn);
this.leased.add(entry);
return entry;
}
}
boolean success = false;
try {
pool.queue(future);
this.pending.add(future);
success = future.await(deadline);
} finally {
// In case of 'success', we were woken up by the
// connection pool and should now have a connection
// waiting for us, or else we're shutting down.
// Just continue in the loop, both cases are checked.
pool.unqueue(future);
this.pending.remove(future);
}
// check for spurious wakeup vs. timeout
if (!success && (deadline != null) &&
(deadline.getTime() <= System.currentTimeMillis())) {
break;
}
}
throw new TimeoutException("Timeout waiting for connection");
} finally {
this.lock.unlock();
}
}
private void notifyPending(final RouteSpecificPool<T, C, E> pool) {
PoolEntryFuture<E> future = pool.nextPending();
if (future != null) {
this.pending.remove(future);
} else {
future = this.pending.poll();
}
if (future != null) {
future.wakeup();
}
}
public void release(E entry, boolean reusable) {
this.lock.lock();
try {
if (this.leased.remove(entry)) {
RouteSpecificPool<T, C, E> pool = getPool(entry.getRoute());
pool.free(entry, reusable);
if (reusable && !this.isShutDown) {
this.available.addFirst(entry);
} else {
entry.close();
}
notifyPending(pool);
}
} finally {
this.lock.unlock();
}
}
private int getMax(final T route) {
Integer v = this.maxPerRoute.get(route);
if (v != null) {
return v.intValue();
} else {
return this.defaultMaxPerRoute;
}
}
public void setMaxTotal(int max) {
if (max <= 0) {
throw new IllegalArgumentException("Max value may not be negative or zero");
}
this.lock.lock();
try {
this.maxTotal = max;
} finally {
this.lock.unlock();
}
}
public int getMaxTotal() {
this.lock.lock();
try {
return this.maxTotal;
} finally {
this.lock.unlock();
}
}
public void setDefaultMaxPerRoute(int max) {
if (max <= 0) {
throw new IllegalArgumentException("Max value may not be negative or zero");
}
this.lock.lock();
try {
this.defaultMaxPerRoute = max;
} finally {
this.lock.unlock();
}
}
public int getDefaultMaxPerRoute() {
this.lock.lock();
try {
return this.defaultMaxPerRoute;
} finally {
this.lock.unlock();
}
}
public void setMaxPerRoute(final T route, int max) {
if (route == null) {
throw new IllegalArgumentException("Route may not be null");
}
if (max <= 0) {
throw new IllegalArgumentException("Max value may not be negative or zero");
}
this.lock.lock();
try {
this.maxPerRoute.put(route, max);
} finally {
this.lock.unlock();
}
}
public int getMaxPerRoute(T route) {
if (route == null) {
throw new IllegalArgumentException("Route may not be null");
}
this.lock.lock();
try {
return getMax(route);
} finally {
this.lock.unlock();
}
}
public PoolStats getTotalStats() {
this.lock.lock();
try {
return new PoolStats(
this.leased.size(),
this.pending.size(),
this.available.size(),
this.maxTotal);
} finally {
this.lock.unlock();
}
}
public PoolStats getStats(final T route) {
if (route == null) {
throw new IllegalArgumentException("Route may not be null");
}
this.lock.lock();
try {
RouteSpecificPool<T, C, E> pool = getPool(route);
return new PoolStats(
pool.getLeasedCount(),
pool.getPendingCount(),
pool.getAvailableCount(),
getMax(route));
} finally {
this.lock.unlock();
}
}
/**
* Closes connections that have been idle longer than the given period
* of time and evicts them from the pool.
*
* @param idletime maximum idle time.
* @param tunit time unit.
*/
public void closeIdle(long idletime, final TimeUnit tunit) {
if (tunit == null) {
throw new IllegalArgumentException("Time unit must not be null.");
}
long time = tunit.toMillis(idletime);
if (time < 0) {
time = 0;
}
long deadline = System.currentTimeMillis() - time;
this.lock.lock();
try {
Iterator<E> it = this.available.iterator();
while (it.hasNext()) {
E entry = it.next();
if (entry.getUpdated() <= deadline) {
entry.close();
RouteSpecificPool<T, C, E> pool = getPool(entry.getRoute());
pool.remove(entry);
it.remove();
notifyPending(pool);
}
}
} finally {
this.lock.unlock();
}
}
/**
* Closes expired connections and evicts them from the pool.
*/
public void closeExpired() {
long now = System.currentTimeMillis();
this.lock.lock();
try {
Iterator<E> it = this.available.iterator();
while (it.hasNext()) {
E entry = it.next();
if (entry.isExpired(now)) {
entry.close();
RouteSpecificPool<T, C, E> pool = getPool(entry.getRoute());
pool.remove(entry);
it.remove();
notifyPending(pool);
}
}
} finally {
this.lock.unlock();
}
}
@Override
public String toString() {
StringBuilder buffer = new StringBuilder();
buffer.append("[leased: ");
buffer.append(this.leased);
buffer.append("][available: ");
buffer.append(this.available);
buffer.append("][pending: ");
buffer.append(this.pending);
buffer.append("]");
return buffer.toString();
}
}