/*
 * Copyright (c) 2012, 2018, 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.nio.ch;

import java.io.IOException;
import java.nio.channels.*;
import java.nio.channels.spi.*;
import java.util.Map;
import java.util.HashMap;
import java.util.Iterator;

/**
 * Selector implementation based on the Solaris event port mechanism.
 */

class EventPortSelectorImpl
    extends SelectorImpl
{
    private final EventPortWrapper pollWrapper;

    // Maps from file descriptors to keys
    private final Map<Integer, SelectionKeyImpl> fdToKey;

    // True if this Selector has been closed
    private boolean closed;

    // Lock for interrupt triggering and clearing
    private final Object interruptLock = new Object();
    private boolean interruptTriggered;

    /**
     * Package private constructor called by factory method in
     * the abstract superclass Selector.
     */
    EventPortSelectorImpl(SelectorProvider sp) throws IOException {
        super(sp);
        pollWrapper = new EventPortWrapper();
        fdToKey = new HashMap<>();
    }

    private void ensureOpen() {
        if (closed)
            throw new ClosedSelectorException();
    }

    @Override
    protected int doSelect(long timeout) throws IOException {
        ensureOpen();
        processDeregisterQueue();
        int entries;
        try {
            begin();
            entries = pollWrapper.poll(timeout);
        } finally {
            end();
        }
        processDeregisterQueue();
        int numKeysUpdated = updateSelectedKeys(entries);
        if (pollWrapper.interrupted()) {
            synchronized (interruptLock) {
                interruptTriggered = false;
            }
        }
        return numKeysUpdated;
    }

    private int updateSelectedKeys(int entries) {
        int numKeysUpdated = 0;
        for (int i=0; i<entries; i++) {
            int nextFD = pollWrapper.getDescriptor(i);
            SelectionKeyImpl ski = fdToKey.get(Integer.valueOf(nextFD));
            if (ski != null) {
                int rOps = pollWrapper.getEventOps(i);
                if (selectedKeys.contains(ski)) {
                    if (ski.channel.translateAndSetReadyOps(rOps, ski)) {
                        numKeysUpdated++;
                    }
                } else {
                    ski.channel.translateAndSetReadyOps(rOps, ski);
                    if ((ski.nioReadyOps() & ski.nioInterestOps()) != 0) {
                        selectedKeys.add(ski);
                        numKeysUpdated++;
                    }
                }
            }
        }
        return numKeysUpdated;
    }

    @Override
    protected void implClose() throws IOException {
        if (closed)
            return;
        closed = true;

        // prevent further wakeup
        synchronized (interruptLock) {
            interruptTriggered = true;
        }

        pollWrapper.close();

        // Deregister channels
        Iterator<SelectionKey> i = keys.iterator();
        while (i.hasNext()) {
            SelectionKeyImpl ski = (SelectionKeyImpl)i.next();
            deregister(ski);
            SelectableChannel selch = ski.channel();
            if (!selch.isOpen() && !selch.isRegistered())
                ((SelChImpl)selch).kill();
            i.remove();
        }
    }

    @Override
    protected void implRegister(SelectionKeyImpl ski) {
        int fd = IOUtil.fdVal(ski.channel.getFD());
        fdToKey.put(Integer.valueOf(fd), ski);
        keys.add(ski);
    }

    @Override
    protected void implDereg(SelectionKeyImpl ski) throws IOException {
        int i = ski.getIndex();
        assert (i >= 0);
        int fd = ski.channel.getFDVal();
        fdToKey.remove(Integer.valueOf(fd));
        pollWrapper.release(fd);
        ski.setIndex(-1);
        keys.remove(ski);
        selectedKeys.remove(ski);
        deregister((AbstractSelectionKey)ski);
        SelectableChannel selch = ski.channel();
        if (!selch.isOpen() && !selch.isRegistered())
            ((SelChImpl)selch).kill();
    }

    @Override
    public void putEventOps(SelectionKeyImpl sk, int ops) {
        ensureOpen();
        int fd = sk.channel.getFDVal();
        pollWrapper.setInterest(fd, ops);
    }

    @Override
    public Selector wakeup() {
        synchronized (interruptLock) {
            if (!interruptTriggered) {
                pollWrapper.interrupt();
                interruptTriggered = true;
            }
        }
        return this;
    }
}