/*

 * Copyright (c) 1998, 2017, 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

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package com.sun.tools.jdi;

import java.io.IOException;

import java.util.ArrayList;

import java.util.Collections;

import java.util.HashMap;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import com.sun.jdi.VMDisconnectedException;

import com.sun.jdi.VirtualMachine;

import com.sun.jdi.connect.spi.Connection;

import com.sun.jdi.event.EventQueue;

import com.sun.jdi.event.EventSet;

public class TargetVM implements Runnable {

    private Map<String, Packet> waitingQueue = new HashMap<>(32,0.75f);

    private volatile boolean shouldListen = true;

    private List<EventQueue> eventQueues = Collections.synchronizedList(new ArrayList<>(2));

    private VirtualMachineImpl vm;

    private Connection connection;

    private Thread readerThread;

    private EventController eventController = null;

    private boolean eventsHeld = false;

    /*

     * TO DO: The limit numbers below are somewhat arbitrary and should

     * be configurable in the future.

     */

    static private final int OVERLOADED_QUEUE = 2000;

    static private final int UNDERLOADED_QUEUE = 100;

    TargetVM(VirtualMachineImpl vm, Connection connection) {

        this.vm = vm;

        this.connection = connection;

        this.readerThread = new Thread(vm.threadGroupForJDI(),

                                       this, "JDI Target VM Interface");

        this.readerThread.setDaemon(true);

    }

    void start() {

        readerThread.start();

    }

    private void dumpPacket(Packet packet, boolean sending) {

        String direction = sending ? "Sending" : "Receiving";

        if (sending) {

            vm.printTrace(direction + " Command. id=" + packet.id +

                          ", length=" + packet.data.length +

                          ", commandSet=" + packet.cmdSet +

                          ", command=" + packet.cmd +

                          ", flags=" + packet.flags);

        } else {

            String type = (packet.flags & Packet.Reply) != 0 ?

                          "Reply" : "Event";

            vm.printTrace(direction + " " + type + ". id=" + packet.id +

                          ", length=" + packet.data.length +

                          ", errorCode=" + packet.errorCode +

                          ", flags=" + packet.flags);

        }

        StringBuilder line = new StringBuilder(80);

        line.append("0000: ");

        for (int i = 0; i < packet.data.length; i++) {

            if ((i > 0) && (i % 16 == 0)) {

                vm.printTrace(line.toString());

                line.setLength(0);

                line.append(String.valueOf(i));

                line.append(": ");

                int len = line.length();

                for (int j = 0; j < 6 - len; j++) {

                    line.insert(0, '0');

                }

            }

            int val = 0xff & packet.data[i];

            String str = Integer.toHexString(val);

            if (str.length() == 1) {

                line.append('0');

            }

            line.append(str);

            line.append(' ');

        }

        if (line.length() > 6) {

            vm.printTrace(line.toString());

        }

    }

    public void run() {

        if ((vm.traceFlags & VirtualMachine.TRACE_SENDS) != 0) {

            vm.printTrace("Target VM interface thread running");

        }

        Packet p=null,p2;

        String idString;

        while (shouldListen) {

            boolean done = false;

            try {

                byte b[] = connection.readPacket();

                if (b.length == 0) {

                    done = true;

                }

                p = Packet.fromByteArray(b);

            } catch (IOException e) {

                done = true;

            }

            if (done) {

                shouldListen = false;

                try {

                    connection.close();

                } catch (IOException ioe) { }

                break;

            }

            if ((vm.traceFlags & VirtualMachineImpl.TRACE_RAW_RECEIVES) != 0)  {

                dumpPacket(p, false);

            }

            if ((p.flags & Packet.Reply) == 0) {

                // It's a command

                handleVMCommand(p);

            } else {

                /*if(p.errorCode != Packet.ReplyNoError) {

                    System.err.println("Packet " + p.id + " returned failure = " + p.errorCode);

                }*/

                vm.state().notifyCommandComplete(p.id);

                idString = String.valueOf(p.id);

                synchronized(waitingQueue) {

                    p2 = waitingQueue.get(idString);

                    if (p2 != null)

                        waitingQueue.remove(idString);

                }

                if (p2 == null) {

                    // Whoa! a reply without a sender. Problem.

                    // FIX ME! Need to post an error.

                    System.err.println("Recieved reply with no sender!");

                    continue;

                }

                p2.errorCode = p.errorCode;

                p2.data = p.data;

                p2.replied = true;

                synchronized(p2) {

                    p2.notify();

                }

            }

        }

        // inform the VM mamager that this VM is history

        vm.vmManager.disposeVirtualMachine(vm);

        if (eventController != null) {

            eventController.release();

        }

        // close down all the event queues

        // Closing a queue causes a VMDisconnectEvent to

        // be put onto the queue.

        synchronized(eventQueues) {

            Iterator<EventQueue> iter = eventQueues.iterator();

            while (iter.hasNext()) {

                ((EventQueueImpl)iter.next()).close();

            }

        }

        // indirectly throw VMDisconnectedException to

        // command requesters.

        synchronized(waitingQueue) {

            Iterator<Packet> iter = waitingQueue.values().iterator();

            while (iter.hasNext()) {

                Packet packet = iter.next();

                synchronized(packet) {

                    packet.notify();

                }

            }

            waitingQueue.clear();

        }

        if ((vm.traceFlags & VirtualMachine.TRACE_SENDS) != 0) {

            vm.printTrace("Target VM interface thread exiting");

        }

    }

    protected void handleVMCommand(Packet p) {

        switch (p.cmdSet) {

            case JDWP.Event.COMMAND_SET:

                handleEventCmdSet(p);

                break;

            default:

                System.err.println("Ignoring cmd " + p.id + "/" +

                                   p.cmdSet + "/" + p.cmd + " from the VM");

                return;

        }

    }

    /* Events should not be constructed on this thread (the thread

     * which reads all data from the transport). This means that the

     * packet cannot be converted to real JDI objects as that may

     * involve further communications with the back end which would

     * deadlock.

     *

     * Instead the whole packet is passed for lazy eval by a queue

     * reading thread.

     */

    protected void handleEventCmdSet(Packet p) {

        EventSet eventSet = new EventSetImpl(vm, p);

        queueEventSet(eventSet);

    }

    private EventController eventController() {

        if (eventController == null) {

            eventController = new EventController();

        }

        return eventController;

    }

    private synchronized void controlEventFlow(int maxQueueSize) {

        if (!eventsHeld && (maxQueueSize > OVERLOADED_QUEUE)) {

            eventController().hold();

            eventsHeld = true;

        } else if (eventsHeld && (maxQueueSize < UNDERLOADED_QUEUE)) {

            eventController().release();

            eventsHeld = false;

        }

    }

    void notifyDequeueEventSet() {

        int maxQueueSize = 0;

        synchronized(eventQueues) {

            Iterator<EventQueue> iter = eventQueues.iterator();

            while (iter.hasNext()) {

                EventQueueImpl queue = (EventQueueImpl)iter.next();

                maxQueueSize = Math.max(maxQueueSize, queue.size());

            }

        }

        controlEventFlow(maxQueueSize);

    }

    private void queueEventSet(EventSet eventSet) {

        int maxQueueSize = 0;

        synchronized(eventQueues) {

            Iterator<EventQueue> iter = eventQueues.iterator();

            while (iter.hasNext()) {

                EventQueueImpl queue = (EventQueueImpl)iter.next();

                queue.enqueue(eventSet);

                maxQueueSize = Math.max(maxQueueSize, queue.size());

            }

        }

        controlEventFlow(maxQueueSize);

    }

    void send(Packet packet) {

        String id = String.valueOf(packet.id);

        synchronized(waitingQueue) {

            waitingQueue.put(id, packet);

        }

        if ((vm.traceFlags & VirtualMachineImpl.TRACE_RAW_SENDS) != 0) {

            dumpPacket(packet, true);

        }

        try {

            connection.writePacket(packet.toByteArray());

        } catch (IOException e) {

            throw new VMDisconnectedException(e.getMessage());

        }

    }

    void waitForReply(Packet packet) {

        synchronized(packet) {

            while ((!packet.replied) && shouldListen) {

                try { packet.wait(); } catch (InterruptedException e) {;}

            }

            if (!packet.replied) {

                throw new VMDisconnectedException();

            }

        }

    }

    void addEventQueue(EventQueueImpl queue) {

        if ((vm.traceFlags & VirtualMachine.TRACE_EVENTS) != 0) {

            vm.printTrace("New event queue added");

        }

        eventQueues.add(queue);

    }

    void stopListening() {

        if ((vm.traceFlags & VirtualMachine.TRACE_EVENTS) != 0) {

            vm.printTrace("Target VM i/f closing event queues");

        }

        shouldListen = false;

        try {

            connection.close();

        } catch (IOException ioe) { }

    }

    private class EventController extends Thread {

        int controlRequest = 0;

        EventController() {

            super(vm.threadGroupForJDI(), "JDI Event Control Thread");

            setDaemon(true);

            setPriority((MAX_PRIORITY + NORM_PRIORITY)/2);

            super.start();

        }

        synchronized void hold() {

            controlRequest++;

            notifyAll();

        }

        synchronized void release() {

            controlRequest--;

            notifyAll();

        }

        public void run() {

            while(true) {

                int currentRequest;

                synchronized(this) {

                    while (controlRequest == 0) {

                        try {wait();} catch (InterruptedException e) {}

                        if (!shouldListen) {

                           return;

                        }

                    }

                    currentRequest = controlRequest;

                    controlRequest = 0;

                }

                try {

                    if (currentRequest > 0) {

                        JDWP.VirtualMachine.HoldEvents.process(vm);

                    } else {

                        JDWP.VirtualMachine.ReleaseEvents.process(vm);

                    }

                } catch (JDWPException e) {

                    /*

                     * Don't want to terminate the thread, so the

                     * stack trace is printed and we continue.

                     */

                    e.toJDIException().printStackTrace(System.err);

                }

            }

        }

    }

}