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 * ====================================================================
 * 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/>.
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package org.apache.http.impl.conn;

import java.io.IOException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.HttpClientConnection;
import org.apache.http.annotation.Contract;
import org.apache.http.annotation.ThreadingBehavior;
import org.apache.http.conn.ClientConnectionManager;
import org.apache.http.conn.ClientConnectionOperator;
import org.apache.http.conn.ClientConnectionRequest;
import org.apache.http.conn.ManagedClientConnection;
import org.apache.http.conn.OperatedClientConnection;
import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.conn.scheme.SchemeRegistry;
import org.apache.http.util.Args;
import org.apache.http.util.Asserts;

A connection manager for a single connection. This connection manager maintains only one active
connection. Even though this class is fully thread-safe it ought to be used by one execution
thread only, as only one thread a time can lease the connection at a time.
 This connection manager will make an effort to reuse the connection for subsequent requests with the same route. It will, however, close the existing connection and open it for the given route, if the route of the persistent connection does not match that of the connection request. If the connection has been already been allocated IllegalStateException is thrown. 
 This connection manager implementation should be used inside an EJB container instead of PoolingClientConnectionManager. 
Since:
4.2
Deprecated:
(4.3) use BasicHttpClientConnectionManager./**
 * A connection manager for a single connection. This connection manager maintains only one active
 * connection. Even though this class is fully thread-safe it ought to be used by one execution
 * thread only, as only one thread a time can lease the connection at a time.
 * <p>
 * This connection manager will make an effort to reuse the connection for subsequent requests
 * with the same {@link HttpRoute route}. It will, however, close the existing connection and
 * open it for the given route, if the route of the persistent connection does not match that
 * of the connection request. If the connection has been already been allocated
 * {@link IllegalStateException} is thrown.
 * </p>
 * <p>
 * This connection manager implementation should be used inside an EJB container instead of
 * {@link PoolingClientConnectionManager}.
 * </p>
 *
 * @since 4.2
 *
 * @deprecated (4.3) use {@link BasicHttpClientConnectionManager}.
 */
@Contract(threading = ThreadingBehavior.SAFE)
@Deprecated
public class BasicClientConnectionManager implements ClientConnectionManager {

    private final Log log = LogFactory.getLog(getClass());

    private static final AtomicLong COUNTER = new AtomicLong();

    
The message to be logged on multiple allocation. /** The message to be logged on multiple allocation. */
    public final static String MISUSE_MESSAGE =
    "Invalid use of BasicClientConnManager: connection still allocated.\n" +
    "Make sure to release the connection before allocating another one.";

    
The schemes supported by this connection manager. /** The schemes supported by this connection manager. */
    private final SchemeRegistry schemeRegistry;

    
The operator for opening and updating connections. /** The operator for opening and updating connections. */
    private final ClientConnectionOperator connOperator;

    
The one and only entry in this pool. /** The one and only entry in this pool. */
    private HttpPoolEntry poolEntry;

    
The currently issued managed connection, if any. /** The currently issued managed connection, if any. */
    private ManagedClientConnectionImpl conn;

    
Indicates whether this connection manager is shut down. /** Indicates whether this connection manager is shut down. */
    private volatile boolean shutdown;

    
Creates a new simple connection manager.
Params:
schreg –    the scheme registry/**
     * Creates a new simple connection manager.
     *
     * @param schreg    the scheme registry
     */
    public BasicClientConnectionManager(final SchemeRegistry schreg) {
        Args.notNull(schreg, "Scheme registry");
        this.schemeRegistry = schreg;
        this.connOperator = createConnectionOperator(schreg);
    }

    public BasicClientConnectionManager() {
        this(SchemeRegistryFactory.createDefault());
    }

    @Override
    protected void finalize() throws Throwable {
        try {
            shutdown();
        } finally { // Make sure we call overridden method even if shutdown barfs
            super.finalize();
        }
    }

    @Override
    public SchemeRegistry getSchemeRegistry() {
        return this.schemeRegistry;
    }

    protected ClientConnectionOperator createConnectionOperator(final SchemeRegistry schreg) {
        return new DefaultClientConnectionOperator(schreg);
    }

    @Override
    public final ClientConnectionRequest requestConnection(
            final HttpRoute route,
            final Object state) {

        return new ClientConnectionRequest() {

            @Override
            public void abortRequest() {
                // Nothing to abort, since requests are immediate.
            }

            @Override
            public ManagedClientConnection getConnection(
                    final long timeout, final TimeUnit timeUnit) {
                return BasicClientConnectionManager.this.getConnection(
                        route, state);
            }

        };
    }

    private void assertNotShutdown() {
        Asserts.check(!this.shutdown, "Connection manager has been shut down");
    }

    ManagedClientConnection getConnection(final HttpRoute route, final Object state) {
        Args.notNull(route, "Route");
        synchronized (this) {
            assertNotShutdown();
            if (this.log.isDebugEnabled()) {
                this.log.debug("Get connection for route " + route);
            }
            Asserts.check(this.conn == null, MISUSE_MESSAGE);
            if (this.poolEntry != null && !this.poolEntry.getPlannedRoute().equals(route)) {
                this.poolEntry.close();
                this.poolEntry = null;
            }
            if (this.poolEntry == null) {
                final String id = Long.toString(COUNTER.getAndIncrement());
                final OperatedClientConnection opconn = this.connOperator.createConnection();
                this.poolEntry = new HttpPoolEntry(this.log, id, route, opconn, 0, TimeUnit.MILLISECONDS);
            }
            final long now = System.currentTimeMillis();
            if (this.poolEntry.isExpired(now)) {
                this.poolEntry.close();
                this.poolEntry.getTracker().reset();
            }
            this.conn = new ManagedClientConnectionImpl(this, this.connOperator, this.poolEntry);
            return this.conn;
        }
    }

    private void shutdownConnection(final HttpClientConnection conn) {
        try {
            conn.shutdown();
        } catch (final IOException iox) {
            if (this.log.isDebugEnabled()) {
                this.log.debug("I/O exception shutting down connection", iox);
            }
        }
    }

    @Override
    public void releaseConnection(final ManagedClientConnection conn, final long keepalive, final TimeUnit timeUnit) {
        Args.check(conn instanceof ManagedClientConnectionImpl, "Connection class mismatch, " +
            "connection not obtained from this manager");
        final ManagedClientConnectionImpl managedConn = (ManagedClientConnectionImpl) conn;
        synchronized (managedConn) {
            if (this.log.isDebugEnabled()) {
                this.log.debug("Releasing connection " + conn);
            }
            if (managedConn.getPoolEntry() == null) {
                return; // already released
            }
            final ClientConnectionManager manager = managedConn.getManager();
            Asserts.check(manager == this, "Connection not obtained from this manager");
            synchronized (this) {
                if (this.shutdown) {
                    shutdownConnection(managedConn);
                    return;
                }
                try {
                    if (managedConn.isOpen() && !managedConn.isMarkedReusable()) {
                        shutdownConnection(managedConn);
                    }
                    if (managedConn.isMarkedReusable()) {
                        this.poolEntry.updateExpiry(keepalive, timeUnit != null ? timeUnit : TimeUnit.MILLISECONDS);
                        if (this.log.isDebugEnabled()) {
                            final String s;
                            if (keepalive > 0) {
                                s = "for " + keepalive + " " + timeUnit;
                            } else {
                                s = "indefinitely";
                            }
                            this.log.debug("Connection can be kept alive " + s);
                        }
                    }
                } finally {
                    managedConn.detach();
                    this.conn = null;
                    if (this.poolEntry.isClosed()) {
                        this.poolEntry = null;
                    }
                }
            }
        }
    }

    @Override
    public void closeExpiredConnections() {
        synchronized (this) {
            assertNotShutdown();
            final long now = System.currentTimeMillis();
            if (this.poolEntry != null && this.poolEntry.isExpired(now)) {
                this.poolEntry.close();
                this.poolEntry.getTracker().reset();
            }
        }
    }

    @Override
    public void closeIdleConnections(final long idletime, final TimeUnit timeUnit) {
        Args.notNull(timeUnit, "Time unit");
        synchronized (this) {
            assertNotShutdown();
            long time = timeUnit.toMillis(idletime);
            if (time < 0) {
                time = 0;
            }
            final long deadline = System.currentTimeMillis() - time;
            if (this.poolEntry != null && this.poolEntry.getUpdated() <= deadline) {
                this.poolEntry.close();
                this.poolEntry.getTracker().reset();
            }
        }
    }

    @Override
    public void shutdown() {
        synchronized (this) {
            this.shutdown = true;
            try {
                if (this.poolEntry != null) {
                    this.poolEntry.close();
                }
            } finally {
                this.poolEntry = null;
                this.conn = null;
            }
        }
    }

}