271 lines
8.9 KiB
Java
271 lines
8.9 KiB
Java
//ReadNode.java
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//
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//This library is free software; you can redistribute it and/or
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//modify it under the terms of the GNU Lesser General Public
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//License as published by the Free Software Foundation; either
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//version 2.1 of the License, or (at your option) any later version.
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//
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//This library is distributed in the hope that it will be useful,
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//but WITHOUT ANY WARRANTY; without even the implied warranty of
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//MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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//Lesser General Public License for more details.
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package rtree;
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import java.io.*;
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/***********************************************************************************************************
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* * *
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* This is a special purpose class that is alowed read only operartion on tree. Any write operation *
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* would give error. *
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* This class was necessary to solve the following problem. Since none of the nodes are cloned when given *
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* to the clients, they can become problematic when multiple reads on the same node is going on. *
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* Because of the new buffer policy we do not clone node, it is like a single node in the whole system. *
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* But the obvious problem is multiple read threads when reading nodes. *
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* No though problem when writing as the whole tree is locked. What we can do is that clients themselves *
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* tell the cache that they need a cloned node and that it willnot be used for write purpose. *
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* This class does exactly that. *
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* @author Prachuryya Barua
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***********************************************************************************************************/
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class ReadNode extends Node
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{
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ReadNode()
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{
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}
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public static ReadNode makeReadNode(Node node)
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{
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ReadNode rdNode = new ReadNode();
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try{
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//Integer intVal;
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rdNode.file = node.file;
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rdNode.dirty = node.dirty;
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rdNode.fileName = new String(node.fileName.toCharArray());
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rdNode.nodeIndex = node.nodeIndex;
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//rdNode.isNodeEmpty = node.isNodeEmpty;
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rdNode.sorted = node.sorted;
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rdNode.nodeMBR = new Rect(node.nodeMBR);//remove
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rdNode.elements = new Element[node.elements.length];
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if(node.elementType == LEAF_NODE){
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for(int i=0; i<node.totalElements; i++)
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rdNode.elements[i] = new LeafElement(new Rect(node.elements[i].getRect()),
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node.elements[i].getPtr());
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}else{
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for(int i=0; i<node.totalElements; i++)
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rdNode.elements[i] = new NonLeafElement(new Rect(node.elements[i].getRect()),
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node.elements[i].getPtr());
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}
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// for(int i=0; i<node.totalElements; i++){
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// if(node.elementType == LEAF_NODE)
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// rdNode.elements[i] = new LeafElement(new Rect(node.elements[i].getRect()),
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// node.elements[i].getPtr());
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// else
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// rdNode.elements[i] = new NonLeafElement(new Rect(node.elements[i].getRect()),
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// node.elements[i].getPtr());
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// }//if
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// }//for
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rdNode.fileHdr = node.fileHdr;
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rdNode.totalElements = node.totalElements;
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rdNode.parent = node.parent;
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rdNode.elementSize = node.elementSize;
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rdNode.elementType = node.elementType;
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return rdNode;
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}
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catch(Exception e){
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e.printStackTrace();
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return null;
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}
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}
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/**
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This method delets the element with the given index from the node.
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It rewrites the node.
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This method now also being used to write the whole node to the file.
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@param index The element to delete. Give -1 if the whole node is to be flushed.
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@param force Whether to force IO. As this method is also used to write the whole node, this was
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required.
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@return thengaa!
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XXX : This is till not correct.
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*/
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@Override
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public void deleteElement(int index, boolean force)
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throws IllegalValueException, NodeWriteException
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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@Override
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public void insertElement(Element elmt)
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throws NodeWriteException, NodeFullException
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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@Override
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public void insertElement(Element[] elmts, boolean updateChldrn)
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throws NodeWriteException, NodeFullException
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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@Override
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public int getElementType()
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{
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return super.getElementType();
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}
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@Override
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public long getNodeIndex()//for new nodes
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{
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return super.getNodeIndex();
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}
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@Override
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Rect[] getAllRectangles()
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throws IllegalValueException
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{
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return super.getAllRectangles();
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}
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@Override
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public Element getLeastEnlargement(Element elmt)
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throws NodeEmptyException, IllegalValueException, NodeWriteException
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{
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return super.getLeastEnlargement(elmt);
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}
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@Override
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boolean isInsertPossible()
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{
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return super.isInsertPossible();
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}
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@Override
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public Node[] splitNode(Element elmtM1, long slotIndex)
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throws RTreeException, NodeWriteException
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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@Override
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public long getParent()
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{
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return super.getParent();
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}
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@Override
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public int getElementIndex(long ptr/*Object ptr*/)
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{
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return super.getElementIndex(ptr);
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}
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/**
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Used to overwrite the old Element with the new one.
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It modifies the element in the disk as well as in the local variables.
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*/
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@Override
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public void modifyElement(int index,Element elmt)
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throws IllegalValueException,IOException, NodeWriteException
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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/**
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Overloaded
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*/
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@Override
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public void modifyElement(int index,long pointer)
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throws IllegalValueException,IOException, NodeWriteException
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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/**
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Overloaded
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*/
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@Override
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public void modifyElement(int index,Rect rect)
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throws IllegalValueException,IOException, NodeWriteException
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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/**
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This function runs a loop on the elements to calculate the total MBR.
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Therefore in case if you already have loop that runs through each of the entries,
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then it is better to calculate MBR in that loop without calling this method.
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@throws IllegalValueException When there are no elements in the node.
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*/
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@Override
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public Rect getNodeMBR()
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throws IllegalValueException
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{
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return super.getNodeMBR();
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}
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/**
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No error echecking at all.
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*/
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@Override
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public void setParent(long /*int*/ prnt)
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throws IOException, NodeWriteException
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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@Override
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public int getTotalElements()
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{
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return super.getTotalElements();
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}
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/**
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Although it returns all the elements but the total elements will not be equal to the length of
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the returned array.Therefore <br><b>Never Use <code>.length</code> field With the Returned Array
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</b>. Instead use <code>getTotalElements()</code>.
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@return An element Array.
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*/
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@Override
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public Element[] getAllElements()
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{
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return super.getAllElements();
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}
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@Override
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Element getElement(int index)
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throws IllegalValueException
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{
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return super.getElement(index);
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}
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/**
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Adds the node to the free stack.
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Be very careful with this method because once called, this node may be
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given to any new node even when you have not destroyed its object.
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If the node is the only node then it updates the file header as well.
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</br><i><b>Once called, there is no turning back!</b></i>.
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*/
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@Override
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public void deleteNode()
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throws NodeWriteException
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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/**
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* This method is added to sort the elements in this node to help sweepline algorithm.
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*/
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@Override
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void sweepSort()//check out for null elements
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{
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super.sweepSort();
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}//sweepSort
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/**
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This is a new methos that will help the phylosophy where one should write to tbe cache only when
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required.
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@return true if needed write and written or false (not dirty).
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*/
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@Override
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public boolean flush()
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throws NodeWriteException
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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@Override
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void setDirty(boolean val)
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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@Override
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public boolean isDirty()
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{
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throw new UnsupportedOperationException("operation not supported");
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}
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}
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