AbstractConnPool

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package org.apache.http.impl.conn.tsccm;

import java.io.IOException;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.util.Set;
import java.util.HashSet;
import java.util.Iterator;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import org.apache.http.annotation.GuardedBy;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.conn.ConnectionPoolTimeoutException;
import org.apache.http.conn.OperatedClientConnection;
import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.impl.conn.IdleConnectionHandler;

/**
 * An abstract connection pool.
 * It is used by the {@link ThreadSafeClientConnManager}.
 * The abstract pool includes a {@link #poolLock}, which is used to
 * synchronize access to the internal pool datastructures.
 * Don't use <code>synchronized</code> for that purpose!
 *
 * @since 4.0
 *
 * @deprecated (4.2) use {@link org.apache.http.pool.AbstractConnPool}
 */
@Deprecated
public abstract class AbstractConnPool {

    private final Log log;

    /**
     * The global lock for this pool.
     */
    protected final Lock poolLock;

    /** References to issued connections */
    @GuardedBy("poolLock")
    protected Set<BasicPoolEntry> leasedConnections;

    /** The current total number of connections. */
    @GuardedBy("poolLock")
    protected int numConnections;

    /** Indicates whether this pool is shut down. */
    protected volatile boolean isShutDown;

    protected Set<BasicPoolEntryRef> issuedConnections;

    protected ReferenceQueue<Object> refQueue;

    protected IdleConnectionHandler idleConnHandler;

    /**
     * Creates a new connection pool.
     */
    protected AbstractConnPool() {
        super();
        this.log = LogFactory.getLog(getClass());
        this.leasedConnections = new HashSet<BasicPoolEntry>();
        this.idleConnHandler = new IdleConnectionHandler();
        this.poolLock = new ReentrantLock();
    }

    public void enableConnectionGC()
        throws IllegalStateException {
    }

    /**
     * Obtains a pool entry with a connection within the given timeout.
     *
     * @param route     the route for which to get the connection
     * @param timeout   the timeout, 0 or negative for no timeout
     * @param tunit     the unit for the <code>timeout</code>,
     *                  may be <code>null</code> only if there is no timeout
     *
     * @return  pool entry holding a connection for the route
     *
     * @throws ConnectionPoolTimeoutException
     *         if the timeout expired
     * @throws InterruptedException
     *         if the calling thread was interrupted
     */
    public final
        BasicPoolEntry getEntry(
                HttpRoute route,
                Object state,
                long timeout,
                TimeUnit tunit)
                    throws ConnectionPoolTimeoutException, InterruptedException {
        return requestPoolEntry(route, state).getPoolEntry(timeout, tunit);
    }

    /**
     * Returns a new {@link PoolEntryRequest}, from which a {@link BasicPoolEntry}
     * can be obtained, or the request can be aborted.
     */
    public abstract PoolEntryRequest requestPoolEntry(HttpRoute route, Object state);


    /**
     * Returns an entry into the pool.
     * The connection of the entry is expected to be in a suitable state,
     * either open and re-usable, or closed. The pool will not make any
     * attempt to determine whether it can be re-used or not.
     *
     * @param entry     the entry for the connection to release
     * @param reusable  <code>true</code> if the entry is deemed
     *                  reusable, <code>false</code> otherwise.
     * @param validDuration The duration that the entry should remain free and reusable.
     * @param timeUnit The unit of time the duration is measured in.
     */
    public abstract void freeEntry(BasicPoolEntry entry, boolean reusable, long validDuration, TimeUnit timeUnit)
        ;

    public void handleReference(Reference<?> ref) {
    }

    protected abstract void handleLostEntry(HttpRoute route);

    /**
     * Closes idle connections.
     *
     * @param idletime  the time the connections should have been idle
     *                  in order to be closed now
     * @param tunit     the unit for the <code>idletime</code>
     */
    public void closeIdleConnections(long idletime, TimeUnit tunit) {

        // idletime can be 0 or negative, no problem there
        if (tunit == null) {
            throw new IllegalArgumentException("Time unit must not be null.");
        }

        poolLock.lock();
        try {
            idleConnHandler.closeIdleConnections(tunit.toMillis(idletime));
        } finally {
            poolLock.unlock();
        }
    }

    public void closeExpiredConnections() {
        poolLock.lock();
        try {
            idleConnHandler.closeExpiredConnections();
        } finally {
            poolLock.unlock();
        }
    }


    /**
     * Deletes all entries for closed connections.
     */
    public abstract void deleteClosedConnections();

    /**
     * Shuts down this pool and all associated resources.
     * Overriding methods MUST call the implementation here!
     */
    public void shutdown() {

        poolLock.lock();
        try {

            if (isShutDown)
                return;

            // close all connections that are issued to an application
            Iterator<BasicPoolEntry> iter = leasedConnections.iterator();
            while (iter.hasNext()) {
                BasicPoolEntry entry = iter.next();
                iter.remove();
                closeConnection(entry.getConnection());
            }
            idleConnHandler.removeAll();

            isShutDown = true;

        } finally {
            poolLock.unlock();
        }
    }


    /**
     * Closes a connection from this pool.
     *
     * @param conn      the connection to close, or <code>null</code>
     */
    protected void closeConnection(final OperatedClientConnection conn) {
        if (conn != null) {
            try {
                conn.close();
            } catch (IOException ex) {
                log.debug("I/O error closing connection", ex);
            }
        }
    }

} // class AbstractConnPool