/*

 * Copyright (c) 2005, 2021, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.net.www.http;

import java.io.IOException;

import java.util.LinkedList;

import sun.net.NetProperties;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.locks.Condition;

import java.util.concurrent.locks.ReentrantLock;

/**

 * This class is used to cleanup any remaining data that may be on a KeepAliveStream

 * so that the connection can be cached in the KeepAliveCache.

 * Instances of this class can be used as a FIFO queue for KeepAliveCleanerEntry objects.

 * Executing this Runnable removes each KeepAliveCleanerEntry from the Queue, reads

 * the reamining bytes on its KeepAliveStream, and if successful puts the connection in

 * the KeepAliveCache.

 *

 * @author Chris Hegarty

 */

@SuppressWarnings("serial")  // never serialized

class KeepAliveStreamCleaner

    extends LinkedList<KeepAliveCleanerEntry>

    implements Runnable

{

    // maximum amount of remaining data that we will try to cleanup

    protected static int MAX_DATA_REMAINING = 512;

    // maximum amount of KeepAliveStreams to be queued

    protected static int MAX_CAPACITY = 10;

    // timeout for both socket and poll on the queue

    protected static final int TIMEOUT = 5000;

    // max retries for skipping data

    private static final int MAX_RETRIES = 5;

    static {

        final String maxDataKey = "http.KeepAlive.remainingData";

        @SuppressWarnings("removal")

        int maxData = AccessController.doPrivileged(

            new PrivilegedAction<Integer>() {

                public Integer run() {

                    return NetProperties.getInteger(maxDataKey, MAX_DATA_REMAINING);

                }}).intValue() * 1024;

        MAX_DATA_REMAINING = maxData;

        final String maxCapacityKey = "http.KeepAlive.queuedConnections";

        @SuppressWarnings("removal")

        int maxCapacity = AccessController.doPrivileged(

            new PrivilegedAction<Integer>() {

                public Integer run() {

                    return NetProperties.getInteger(maxCapacityKey, MAX_CAPACITY);

                }}).intValue();

        MAX_CAPACITY = maxCapacity;

    }

    private final ReentrantLock queueLock = new ReentrantLock();

    private final Condition waiter = queueLock.newCondition();

    final void signalAll() {

        waiter.signalAll();

    }

    final void lock() {

        queueLock.lock();

    }

    final void unlock() {

        queueLock.unlock();

    }

    @Override

    public boolean offer(KeepAliveCleanerEntry e) {

        if (size() >= MAX_CAPACITY)

            return false;

        return super.offer(e);

    }

    @Override

    public void run()

    {

        KeepAliveCleanerEntry kace = null;

        do {

            try {

                lock();

                try {

                    long before = System.currentTimeMillis();

                    long timeout = TIMEOUT;

                    while ((kace = poll()) == null) {

                        waiter.await(timeout, TimeUnit.MILLISECONDS);

                        long after = System.currentTimeMillis();

                        long elapsed = after - before;

                        if (elapsed > timeout) {

                            /* one last try */

                            kace = poll();

                            break;

                        }

                        before = after;

                        timeout -= elapsed;

                    }

                } finally {

                    unlock();

                }

                if(kace == null)

                    break;

                KeepAliveStream kas = kace.getKeepAliveStream();

                if (kas != null) {

                    kas.lock();

                    try {

                        HttpClient hc = kace.getHttpClient();

                        try {

                            if (hc != null && !hc.isInKeepAliveCache()) {

                                int oldTimeout = hc.getReadTimeout();

                                hc.setReadTimeout(TIMEOUT);

                                long remainingToRead = kas.remainingToRead();

                                if (remainingToRead > 0) {

                                    long n = 0;

                                    int retries = 0;

                                    while (n < remainingToRead && retries < MAX_RETRIES) {

                                        remainingToRead = remainingToRead - n;

                                        n = kas.skip(remainingToRead);

                                        if (n == 0)

                                            retries++;

                                    }

                                    remainingToRead = remainingToRead - n;

                                }

                                if (remainingToRead == 0) {

                                    hc.setReadTimeout(oldTimeout);

                                    hc.finished();

                                } else

                                    hc.closeServer();

                            }

                        } catch (IOException ioe) {

                            hc.closeServer();

                        } finally {

                            kas.setClosed();

                        }

                    } finally {

                        kas.unlock();

                    }

                }

            } catch (InterruptedException ie) { }

        } while (kace != null);

    }

}