src/jdk.accessibility/windows/native/libwindowsaccessbridge/AccessBridgeMessageQueue.cpp

/*
 * Copyright (c) 2005, 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.
 */

/*
 * A class to manage queueing of messages for IPC
 */

#include "AccessBridgeDebug.h"
#include "AccessBridgeMessageQueue.h"
#include "AccessBridgePackages.h"               // for debugging only
#include <windows.h>
#include <malloc.h>
#include <new>

DEBUG_CODE(extern HWND theDialogWindow);
extern "C" {
    DEBUG_CODE(void AppendToCallInfo(const char *s));
}

// -------------------


AccessBridgeQueueElement::AccessBridgeQueueElement(char *buf, int size) {
    bufsize = size;
    next = (AccessBridgeQueueElement *) 0;
    previous = (AccessBridgeQueueElement *) 0;
    buffer = (char *) malloc(bufsize);
    if (buffer == NULL) {
        throw std::bad_alloc();
    }
    memcpy(buffer, buf, bufsize);
}

AccessBridgeQueueElement::~AccessBridgeQueueElement() {
    //  delete buffer;
    free(buffer);
}


// -------------------


AccessBridgeMessageQueue::AccessBridgeMessageQueue() {
    queueLocked = FALSE;
    queueRemoveLocked = FALSE;
    start = (AccessBridgeQueueElement *) 0;
    end = (AccessBridgeQueueElement *) 0;
    size = 0;
}

AccessBridgeMessageQueue::~AccessBridgeMessageQueue() {
    // empty queue, then exit
}

/**
 * getEventsWaiting - gets the number of events waiting to fire
 */
int
AccessBridgeMessageQueue::getEventsWaiting() {
    return size;
}

/**
 * add - add an element to the queue, which is locked with semaphores
 *
 */
QueueReturns
AccessBridgeMessageQueue::add(AccessBridgeQueueElement *element) {
    PrintDebugString("[INFO]:   in AccessBridgeMessageQueue::add()");
    PrintDebugString("[INFO]:     queue size = %d", size);

    QueueReturns returnVal = cElementPushedOK;
    if (queueLocked) {
        PrintDebugString("[WARN]:     queue was locked; returning cQueueInUse!");
        return cQueueInUse;
    }
    queueLocked = TRUE;
    {
        PrintDebugString("[INFO]:     adding element to queue!");
        if (end == (AccessBridgeQueueElement *) 0) {
            if (start == (AccessBridgeQueueElement *) 0 && size == 0) {
                start = element;
                end = element;
                element->previous = (AccessBridgeQueueElement *) 0;
                element->next = (AccessBridgeQueueElement *) 0;
                size++;
            } else {
                returnVal = cQueueBroken;       // bad voodo!
            }
        } else {
            element->previous = end;
            element->next = (AccessBridgeQueueElement *) 0;
            end->next = element;
            end = element;
            size++;
        }
    }
    queueLocked = FALSE;
    PrintDebugString("[INFO]:     returning from AccessBridgeMessageQueue::add()");
    return returnVal;
}


/**
 * remove - remove an element from the queue, which is locked with semaphores
 *
 */
QueueReturns
AccessBridgeMessageQueue::remove(AccessBridgeQueueElement **element) {
    PrintDebugString("[INFO]:   in AccessBridgeMessageQueue::remove()");
    PrintDebugString("[INFO]:     queue size = %d", size);

    QueueReturns returnVal = cMoreMessages;
    if (queueLocked) {
        PrintDebugString("[WARN]:     queue was locked; returning cQueueInUse!");
        return cQueueInUse;
    }
    queueLocked = TRUE;
    {
        PrintDebugString("[INFO]:     removing element from queue!");
        if (size > 0) {
            if (start != (AccessBridgeQueueElement *) 0) {
                *element = start;
                start = start->next;
                if (start != (AccessBridgeQueueElement *) 0) {
                    start->previous = (AccessBridgeQueueElement *) 0;
                } else {
                    end = (AccessBridgeQueueElement *) 0;
                    if (size != 1) {
                        returnVal = cQueueBroken;       // bad voodo, should only be 1 in this situation
                    }
                }
                size--;
            } else {
                returnVal = cQueueBroken;       // bad voodo!
            }
        } else {
            returnVal = cQueueEmpty;
        }
    }
    queueLocked = FALSE;
    PrintDebugString("[INFO]:     returning from AccessBridgeMessageQueue::remove()");
    return returnVal;
}


/**
 * setRemoveLock - set the state of the removeLock (TRUE or FALSE)
 *
 */
QueueReturns
AccessBridgeMessageQueue::setRemoveLock(BOOL removeLockSetting) {
    if (queueLocked) {
        return cQueueInUse;
    }
    queueRemoveLocked = removeLockSetting;

    return cQueueOK;
}

/**
 * setRemoveLock - set the state of the removeLock (TRUE or FALSE)
 *
 */
BOOL
AccessBridgeMessageQueue::getRemoveLockSetting() {
    return queueRemoveLocked;
}