ThreadSyncParameter.java

/*
 * Copyright (c) 2013, grossmann
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * * Neither the name of the jo-widgets.org nor the
 *   names of its contributors may be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL jo-widgets.org BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 */

package org.jowidgets.util.concurrent;

import org.jowidgets.util.IObservableValue;
import org.jowidgets.util.IObservableValueListener;
import org.jowidgets.util.parameter.IParameter;
import org.jowidgets.util.parameter.Parameter;
import org.jowidgets.util.parameter.ParameterWrapper;

public final class ThreadSyncParameter<VALUE_TYPE> extends ParameterWrapper<VALUE_TYPE> implements IParameter<VALUE_TYPE> {

    private final IParameter<VALUE_TYPE> originalParameter;
    private final ISingleThreadAccess originalThreadAccess;
    private final ISingleThreadAccess newThreadAccess;

    private final IObservableValueListener<VALUE_TYPE> originalValueListener;
    private final IObservableValueListener<VALUE_TYPE> newValueListener;

    public ThreadSyncParameter(
        final IParameter<VALUE_TYPE> original,
        final ISingleThreadAccess originalThreadAccess,
        final ISingleThreadAccess newThreadAccess) {
        super(Parameter.create(
                original.getValueType(),
                original.getLabel(),
                original.getDescription(),
                original.getDefaultValue()));

        this.originalParameter = original;
        this.originalThreadAccess = originalThreadAccess;
        this.newThreadAccess = newThreadAccess;

        this.originalValueListener = new OriginalValueListener();
        this.newValueListener = new NewValueListener();

        originalThreadAccess.invoke(new Runnable() {
            @Override
            public void run() {
                updateNew(originalParameter.getValue());
                originalParameter.addValueListener(originalValueListener);
            }
        });

        addValueListener(newValueListener);
    }

    @Override
    public void setValue(final VALUE_TYPE value) {
        checkThread();
        super.setValue(value);
    }

    @Override
    public VALUE_TYPE getValue() {
        checkThread();
        return super.getValue();
    }

    @Override
    public void addValueListener(final IObservableValueListener<?> listener) {
        checkThread();
        super.addValueListener(listener);
    }

    @Override
    public void removeValueListener(final IObservableValueListener<?> listener) {
        checkThread();
        super.removeValueListener(listener);
    }

    public void dispose() {
        removeValueListener(newValueListener);
        originalThreadAccess.invoke(new Runnable() {
            @Override
            public void run() {
                originalParameter.removeValueListener(originalValueListener);
            }
        });
    }

    private void updateOriginal(final VALUE_TYPE value) {
        originalThreadAccess.invoke(new Runnable() {
            @Override
            public void run() {
                originalParameter.removeValueListener(originalValueListener);
                originalParameter.setValue(value);
                originalParameter.addValueListener(originalValueListener);
            }
        });
    }

    private void updateNew(final VALUE_TYPE value) {
        newThreadAccess.invoke(new Runnable() {
            @Override
            public void run() {
                removeValueListener(newValueListener);
                setValue(value);
                addValueListener(newValueListener);
            }
        });
    }

    private void checkThread() {
        if (!newThreadAccess.isSingleThread()) {
            throw new IllegalArgumentException("Operation must be invoked in write thread access!");
        }
    }

    @Override
    public String toString() {
        if (originalThreadAccess.isSingleThread()) {
            return originalParameter.toString();
        }
        else if (newThreadAccess.isSingleThread()) {
            return super.toString();
        }
        else {
            return "toString() invoked in wrong thread!";
        }
    }

    private final class OriginalValueListener implements IObservableValueListener<VALUE_TYPE> {
        @Override
        public void changed(final IObservableValue<VALUE_TYPE> observableValue, final VALUE_TYPE value) {
            updateNew(value);
        }
    }

    private final class NewValueListener implements IObservableValueListener<VALUE_TYPE> {
        @Override
        public void changed(final IObservableValue<VALUE_TYPE> observableValue, final VALUE_TYPE value) {
            updateOriginal(value);
        }
    }

}