Fix some null warnings

[deliverable/tracecompass.git] / statesystem / org.eclipse.tracecompass.statesystem.core / src / org / eclipse / tracecompass / internal / statesystem / core / AttributeTree.java

/*******************************************************************************
 * Copyright (c) 2012, 2015 Ericsson
 * Copyright (c) 2010, 2011 École Polytechnique de Montréal
 * Copyright (c) 2010, 2011 Alexandre Montplaisir <alexandre.montplaisir@gmail.com>
 *
 * All rights reserved. This program and the accompanying materials are
 * made available under the terms of the Eclipse Public License v1.0 which
 * accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Alexandre Montplaisir - Initial API and implementation
 *   Patrick Tasse - Add message to exceptions
 *******************************************************************************/

package org.eclipse.tracecompass.internal.statesystem.core;

import static org.eclipse.tracecompass.common.core.NonNullUtils.checkNotNull;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.PrintWriter;
import java.nio.channels.FileChannel;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import org.eclipse.jdt.annotation.NonNull;
import org.eclipse.tracecompass.statesystem.core.exceptions.AttributeNotFoundException;

/**
 * The Attribute Tree is the /proc-like filesystem used to organize attributes.
 * Each node of this tree is both like a file and a directory in the
 * "file system".
 *
 * @author alexmont
 *
 */
public final class AttributeTree {

    /* "Magic number" for attribute tree files or file sections */
    private static final int ATTRIB_TREE_MAGIC_NUMBER = 0x06EC3671;

    private final StateSystem ss;
    private final List<Attribute> attributeList;
    private final Attribute attributeTreeRoot;

    /**
     * Standard constructor, create a new empty Attribute Tree
     *
     * @param ss
     *            The StateSystem to which this AT is attached
     */
    public AttributeTree(StateSystem ss) {
        this.ss = ss;
        this.attributeList = new ArrayList<>();
        this.attributeTreeRoot = new Attribute(null, "root", -1); //$NON-NLS-1$
    }

    /**
     * "Existing file" constructor. Builds an attribute tree from a
     * "mapping file" or mapping section previously saved somewhere.
     *
     * @param ss
     *            StateSystem to which this AT is attached
     * @param fis
     *            File stream where to read the AT information. Make sure it's
     *            sought at the right place!
     * @throws IOException
     *             If there is a problem reading from the file stream
     */
    public AttributeTree(StateSystem ss, FileInputStream fis) throws IOException {
        this(ss);
        ObjectInputStream ois = new ObjectInputStream(new BufferedInputStream(fis));

        /* Read the header of the Attribute Tree file (or file section) */
        int res = ois.readInt(); /* Magic number */
        if (res != ATTRIB_TREE_MAGIC_NUMBER) {
            throw new IOException("The attribute tree file section is either invalid or corrupted."); //$NON-NLS-1$
        }


        ArrayList<String[]> attribList;
        try {
            @SuppressWarnings("unchecked")
            ArrayList<String[]> list = (ArrayList<String[]>) ois.readObject();
            attribList = list;
        } catch (ClassNotFoundException e) {
            throw new IOException("Unrecognizable attribute list"); //$NON-NLS-1$
        }

        /*
         * Now we have 'list', the ArrayList of String arrays representing all
         * the attributes. Simply create attributes the normal way from them.
         */
        for (String[] attrib : attribList) {
            this.getQuarkAndAdd(-1, attrib);
        }
    }

    /**
     * Tell the Attribute Tree to write itself somewhere in a file.
     *
     * @param file
     *            The file to write to
     * @param pos
     *            The position (in bytes) in the file where to write
     */
    public synchronized void writeSelf(File file, long pos) {
        try (FileOutputStream fos = new FileOutputStream(file, true);
                FileChannel fc = fos.getChannel();) {
            fc.position(pos);
            try (ObjectOutputStream oos = new ObjectOutputStream(fos)) {

                /* Write the almost-magic number */
                oos.writeInt(ATTRIB_TREE_MAGIC_NUMBER);

                /* Compute the serialized list of attributes and write it */
                List<String[]> list = new ArrayList<>(attributeList.size());
                for (Attribute entry : this.attributeList) {
                    list.add(entry.getFullAttribute());
                }
                oos.writeObject(list);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    /**
     * Return the number of attributes this system as seen so far. Note that
     * this also equals the integer value (quark) the next added attribute will
     * have.
     *
     * @return The current number of attributes in the tree
     */
    public synchronized int getNbAttributes() {
        return attributeList.size();
    }

    /**
     * Get the quark for a given attribute path. No new attribute will be
     * created : if the specified path does not exist, throw an error.
     *
     * @param startingNodeQuark
     *            The quark of the attribute from which relative queries will
     *            start. Use '-1' to start at the root node.
     * @param subPath
     *            The path to the attribute, relative to the starting node.
     * @return The quark of the specified attribute
     * @throws AttributeNotFoundException
     *             If the specified path was not found
     */
    public synchronized int getQuarkDontAdd(int startingNodeQuark, String... subPath)
            throws AttributeNotFoundException {
        assert (startingNodeQuark >= -1);

        Attribute prevNode;

        /* If subPath is empty, simply return the starting quark */
        if (subPath == null || subPath.length == 0) {
            return startingNodeQuark;
        }

        /* Get the "starting node" */
        if (startingNodeQuark == -1) {
            prevNode = attributeTreeRoot;
        } else {
            prevNode = attributeList.get(startingNodeQuark);
        }

        int knownQuark = prevNode.getSubAttributeQuark(subPath);
        if (knownQuark == -1) {
            /*
             * The attribute doesn't exist, but we have been specified to NOT
             * add any new attributes.
             */
            throw new AttributeNotFoundException(ss.getSSID() + " Quark:" + startingNodeQuark + ", SubPath:" + Arrays.toString(subPath)); //$NON-NLS-1$ //$NON-NLS-2$
        }
        /*
         * The attribute was already existing, return the quark of that
         * attribute
         */
        return knownQuark;
    }

    /**
     * Get the quark of a given attribute path. If that specified path does not
     * exist, it will be created (and the quark that was just created will be
     * returned).
     *
     * @param startingNodeQuark
     *            The quark of the attribute from which relative queries will
     *            start. Use '-1' to start at the root node.
     * @param subPath
     *            The path to the attribute, relative to the starting node.
     * @return The quark of the attribute represented by the path
     */
    public synchronized int getQuarkAndAdd(int startingNodeQuark, String... subPath) {
        // FIXME synchronized here is probably quite costly... maybe only locking
        // the "for" would be enough?
        assert (subPath != null && subPath.length > 0);
        assert (startingNodeQuark >= -1);

        Attribute nextNode = null;
        Attribute prevNode;

        /* Get the "starting node" */
        if (startingNodeQuark == -1) {
            prevNode = attributeTreeRoot;
        } else {
            prevNode = attributeList.get(startingNodeQuark);
        }

        int knownQuark = prevNode.getSubAttributeQuark(subPath);
        if (knownQuark == -1) {
            /*
             * The attribute was not in the table previously, and we want to add
             * it
             */
            for (String curDirectory : subPath) {
                nextNode = prevNode.getSubAttributeNode(curDirectory);
                if (nextNode == null) {
                    /* This is where we need to start adding */
                    nextNode = new Attribute(prevNode, checkNotNull(curDirectory), attributeList.size());
                    prevNode.addSubAttribute(nextNode);
                    attributeList.add(nextNode);
                    ss.addEmptyAttribute();
                }
                prevNode = nextNode;
            }
            return attributeList.size() - 1;
        }
        /*
         * The attribute was already existing, return the quark of that
         * attribute
         */
        return knownQuark;
    }

    /**
     * Returns the sub-attributes of the quark passed in parameter
     *
     * @param attributeQuark
     *            The quark of the attribute to print the sub-attributes of.
     * @param recursive
     *            Should the query be recursive or not? If false, only children
     *            one level deep will be returned. If true, all descendants will
     *            be returned (depth-first search)
     * @return The list of quarks representing the children attributes
     * @throws AttributeNotFoundException
     *             If 'attributeQuark' is invalid, or if there is no attrbiute
     *             associated to it.
     */
    public synchronized @NonNull List<@NonNull Integer> getSubAttributes(int attributeQuark, boolean recursive)
            throws AttributeNotFoundException {
        List<@NonNull Integer> listOfChildren = new ArrayList<>();
        Attribute startingAttribute;

        /* Check if the quark is valid */
        if (attributeQuark < -1 || attributeQuark >= attributeList.size()) {
            throw new AttributeNotFoundException(ss.getSSID() + " Quark:" + attributeQuark); //$NON-NLS-1$
        }

        /* Set up the node from which we'll start the search */
        if (attributeQuark == -1) {
            startingAttribute = attributeTreeRoot;
        } else {
            startingAttribute = attributeList.get(attributeQuark);
        }

        /* Iterate through the sub-attributes and add them to the list */
        addSubAttributes(listOfChildren, startingAttribute, recursive);

        return listOfChildren;
    }

    /**
     * Returns the parent quark of the attribute. The root attribute has no
     * parent and will return <code>-1</code>
     *
     * @param quark
     *            The quark of the attribute
     * @return Quark of the parent attribute or <code>-1</code> for the root
     *         attribute
     */
    public synchronized int getParentAttributeQuark(int quark) {
        if (quark == -1) {
            return quark;
        }
        return attributeList.get(quark).getParentAttributeQuark();
    }

    private void addSubAttributes(List<Integer> list, Attribute curAttribute,
            boolean recursive) {
        for (Attribute childNode : curAttribute.getSubAttributes()) {
            list.add(childNode.getQuark());
            if (recursive) {
                addSubAttributes(list, childNode, true);
            }
        }
    }

    /**
     * Get then base name of an attribute specified by a quark.
     *
     * @param quark
     *            The quark of the attribute
     * @return The (base) name of the attribute
     */
    public synchronized @NonNull String getAttributeName(int quark) {
        return attributeList.get(quark).getName();
    }

    /**
     * Get the full path name of an attribute specified by a quark.
     *
     * @param quark
     *            The quark of the attribute
     * @return The full path name of the attribute
     */
    public synchronized @NonNull String getFullAttributeName(int quark) {
        return attributeList.get(quark).getFullAttributeName();
    }

    /**
     * Get the full path name (as an array of path elements) of an attribute
     * specified by a quark.
     *
     * @param quark
     *            The quark of the attribute
     * @return The path elements of the full path
     */
    public synchronized String @NonNull [] getFullAttributePathArray(int quark) {
        return attributeList.get(quark).getFullAttribute();
    }

    /**
     * Debug-print all the attributes in the tree.
     *
     * @param writer
     *            The writer where to print the output
     */
    public synchronized void debugPrint(PrintWriter writer) {
        attributeTreeRoot.debugPrint(writer);
    }

}