org.glassfish.grizzly.AbstractTransformer Maven / Gradle / Ivy

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package org.glassfish.grizzly;

import org.glassfish.grizzly.attributes.Attribute;
import org.glassfish.grizzly.attributes.AttributeBuilder;
import org.glassfish.grizzly.memory.MemoryManager;
import org.glassfish.grizzly.attributes.AttributeStorage;

/**
 *
 * @author Alexey Stashok
 */
public abstract class AbstractTransformer implements Transformer {
    protected final AttributeBuilder attributeBuilder =
            Grizzly.DEFAULT_ATTRIBUTE_BUILDER;

    protected final Attribute> stateAttr;

    private MemoryManager memoryManager;

    public AbstractTransformer() {
        String namePrefix = getNamePrefix();

        stateAttr = attributeBuilder.createAttribute(namePrefix + ".state");
    }

    protected String getNamePrefix() {
        return getClass().getName();
    }

    @Override
    public final TransformationResult transform(AttributeStorage storage,
            K input) throws TransformationException {
        return saveLastResult(storage, transformImpl(storage, input));
    }

    protected abstract TransformationResult transformImpl(
            AttributeStorage storage,
            K input) throws TransformationException;

    @Override
    public final TransformationResult getLastResult(
            final AttributeStorage storage) {
        final LastResultAwareState state = stateAttr.get(storage);
        if (state != null) {
            return state.getLastResult();
        }

        return null;
    }

    protected final TransformationResult saveLastResult(
            final AttributeStorage storage,
            final TransformationResult result) {
        obtainStateObject(storage).setLastResult(result);
        return result;
    }

    @Override
    public void release(AttributeStorage storage) {
        stateAttr.remove(storage);
    }

    protected MemoryManager obtainMemoryManager(AttributeStorage storage) {
        if (memoryManager != null) {
            return memoryManager;
        }

        if (storage instanceof Connection) {
            Connection connection = (Connection) storage;
            return connection.getMemoryManager();
        }

        return MemoryManager.DEFAULT_MEMORY_MANAGER;
    }
    
    public MemoryManager getMemoryManager() {
        return memoryManager;
    }

    public void setMemoryManager(MemoryManager memoryManager) {
        this.memoryManager = memoryManager;
    }

    public static  T getValue(final AttributeStorage storage,
            final Attribute attribute,
            final T defaultValue) {
        final T value = attribute.get(storage);
        if (value != null) {
            return value;
        }

        return defaultValue;
    }

    protected final LastResultAwareState obtainStateObject(
            final AttributeStorage storage) {
        
        LastResultAwareState value = stateAttr.get(storage);
        if (value == null) {
            value = createStateObject();
            stateAttr.set(storage, value);
        }

        return value;
    }
    
    protected LastResultAwareState createStateObject() {
        return new LastResultAwareState();
    }

    public static class LastResultAwareState {
        protected TransformationResult lastResult;

        public TransformationResult getLastResult() {
            return lastResult;
        }

        public void setLastResult(TransformationResult lastResult) {
            this.lastResult = lastResult;
        }
    }
}