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• Resource.java

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org.objectfabric.Resource Maven / Gradle / Ivy

/**
 * This file is part of ObjectFabric (http://objectfabric.org).
 *
 * ObjectFabric is licensed under the Apache License, Version 2.0, the terms
 * of which may be found at http://www.apache.org/licenses/LICENSE-2.0.html.
 * 
 * Copyright ObjectFabric Inc.
 * 
 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

package org.objectfabric;

import java.util.Map.Entry;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicReference;

/**
 * A resource can be anything from a text string to a complex object graph. Objects from a
 * resource can only reference objects belonging to the same resource.
 */
public class Resource extends TObject {

    public static final TType TYPE;

    static {
        TYPE = Platform.newTType(Platform.get().defaultObjectModel(), BuiltInClass.RESOURCE_CLASS_ID);
    }

    static final Object NULL = new Object() {

        @Override
        public String toString() {
            return "Resource.NULL";
        }
    };

    private final Workspace _workspace;

    private final URI _uri;

    private final AtomicReference _loadQueue = new AtomicReference();

    //

    private volatile Permission _permission;

    // TODO use long[] + block array?
    private PlatformMap _pending;

    // TODO bench merging this and _pending in concurrent map & load on IO threads
    private long[] _loaded = new long[OpenMap.CAPACITY];

    //

    private final List _ordered = new List();

    private volatile List _goals = new List();

    //

    private final PlatformMap _pendingAcks = new PlatformMap();

    Resource(Workspace workspace, URI uri) {
        super(null, new ResourceVersion());

        if (Debug.ENABLED)
            if (uri == null)
                Debug.assertion(workspace.emptyResource() == null);

        _workspace = workspace;
        _uri = uri;

        if (uri != null)
            setReferencedByURI();
    }

    // For .NET
    void onReferenced(PlatformRef ref) {
    }

    public final URI uri() {
        return _uri;
    }

    /**
     * Location this resource was loaded from.
     */
    public final Origin origin() {
        return _uri.origin();
    }

    public final Permission permission() {
        return _permission;
    }

    //

    final Workspace workspaceImpl() {
        return _workspace;
    }

    final Watcher watcher() {
        return _workspace.watcher();
    }

    final Transaction transaction() {
        return _workspace.transactionThreadLocal().get();
    }

    final PlatformMap pendingAcks() {
        return _pendingAcks;
    }

    final PlatformMap pending() {
        return _pending;
    }

    final List ordered() {
        return _ordered;
    }

    final long[] loaded() {
        return _loaded;
    }

    //

    public final boolean isLoaded() {
        if (_uri == null)
            wrongResource_();

        return _goals == null;
    }

    /**
     * Gets resource synchronously. The calling thread blocks until the first location
     * responds (origin or cache). Returned value might not be the most up to date
     * version, and change when following responses are received from other locations.
     */
    public Object get() {
        if (_uri == null)
            wrongResource_();

        for (;;) {
            Object value = getFromMemory();

            if (value != null)
                return value != NULL ? value : null;

            FutureWithCallbacks