207 lines
7.1 KiB
Java
207 lines
7.1 KiB
Java
/*
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* Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package nsk.share.gc;
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import java.io.*;
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import java.util.*;
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import nsk.share.test.ExecutionController;
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/**
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* <tt>NonbranchyTree</tt> defines a tree structure. Each node of the tree
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* always has one son. A node may have the second son with probability
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* <tt>branchiness</tt>.
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*/
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public class NonbranchyTree {
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/** Minimal size of each node (in bytes) */
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public final static int MIN_NODE_SIZE = 20;
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private Node root;
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private Random random;
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private int numberOfNodes;
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private float branchiness;
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private int size;
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private ExecutionController controller;
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/**
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* Creates a new tree with number of nodes not more than
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* <tt>numberOfNodes</tt>. The implementation uses recursion to build the
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* tree, so if <tt>StackOverflowError</tt> or <tt>OutOfMemoryError</tt> is
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* thrown, the recursion is stopped and the method finishes building of the
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* tree. Each node consists of <tt>byte[]</tt> of length <tt>size</tt>.
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*
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* @param numberOfNodes maximum number of nodes for the tree.
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* @param branchiness probability for each node to have the second son.
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* @param size number of bytes to store in a node.
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*
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* @throws <i>IllegalArgumentException</i> if <tt>numberOfNodes</tt> is
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* less than 1; or <tt>branchiness</tt> is greater than 1, or less
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* or equal than 0; or <tt>size</tt> is less than 1.
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*
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*/
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public NonbranchyTree(int numberOfNodes, float branchiness, int size) {
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this(numberOfNodes, branchiness, size, new Random(System.currentTimeMillis()), null);
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initTree();
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}
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public NonbranchyTree(int numberOfNodes, float branchiness, int size, ExecutionController controller) {
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this(numberOfNodes, branchiness, size, new Random(System.currentTimeMillis()), controller);
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initTree();
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}
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private NonbranchyTree(int numberOfNodes, float branchiness, int size, Random random, ExecutionController controller) {
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this.numberOfNodes = numberOfNodes;
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this.branchiness = branchiness;
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this.size = size;
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this.random = random;
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this.controller = controller;
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}
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private void initTree() {
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if (numberOfNodes < 1) {
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throw new IllegalArgumentException("Illegal number of nodes: "
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+ numberOfNodes + ", must be at "
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+ "least 1.");
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}
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if ( (branchiness >= 1) || (branchiness <= 0) ) {
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throw new IllegalArgumentException("Illegal value of branchiness: "
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+ numberOfNodes + ", must be at "
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+ "greater than 0 and less than "
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+ " 1.");
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}
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if (size < 1) {
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throw new IllegalArgumentException("Illegal size of nodes: "
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+ size + ", must be at least 1.");
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}
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root = createTree(numberOfNodes, size);
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}
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// Create a new tree with specified number of nodes and size of each node
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private Node createTree(int numberOfNodes, int size) {
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// Make sure we respect the controller and stop test after
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// given time.
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if (controller != null && !controller.continueExecution()) {
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return null;
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}
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Node node = new Node(size);
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try {
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if (numberOfNodes == 0) {
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// No more nodes need to be built
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return null;
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} else if (numberOfNodes == 1) {
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return node;
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} else if (numberOfNodes == 2) {
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node.left = createTree(1, size);
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return node;
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} else {
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// Create a few nodes
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if (makeRightNode()) {
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// The node will have two sons
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int leftNodes = 1 + random.nextInt(numberOfNodes - 2);
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int rightNodes = numberOfNodes - 1 - leftNodes;
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node.left = createTree(leftNodes, size);
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node.right = createTree(rightNodes, size);
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} else {
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// The node will have just one son
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Node leftTree = createTree(numberOfNodes - 1, size);
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node.left = leftTree;
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}
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return node;
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} // if
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} catch(StackOverflowError e) {
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// No more memory for such long tree
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return node;
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} catch(OutOfMemoryError e) {
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// No more memory for such long tree
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return node;
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} // try
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} // createTree()
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// Define the "branchiness" of the tree
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private boolean makeRightNode() {
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return (random.nextFloat() < branchiness);
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}
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/**
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* Bends the tree. A son of a leaf of the tree is set to the root node.
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*
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*/
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public void bend() {
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bend(root);
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}
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// Bend the tree: make a reference from a leat of the tree to the specified
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// node
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private void bend(Node markedNode) {
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Node node = root;
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while ( (node.left != null) || (node.right != null) )
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node = node.left;
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node.right = markedNode;
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}
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/**
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* Prints the whole tree from the root to the defined PrintStream.
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*
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* @param out PrintStream to print the tree in
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*
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*/
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public void print(PrintStream out) {
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print(out, root);
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}
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// Print the sub-tree from the specified node and down
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private void print(PrintStream out, Node node) {
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node.print(out);
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if (node.left != null)
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print(out, node.left);
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if (node.right != null)
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print(out, node.right);
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}
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}
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// The class defines a node of a tree
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class Node {
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Node left;
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Node right;
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byte[] core;
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Node(int size) {
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left = null;
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right = null;
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core = new byte[size];
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// Initizlize the core array
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for (int i = 0; i < size; i++)
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core[i] = (byte) i;
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}
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// Print the node info
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void print(PrintStream out) {
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out.println("node = " + this + " (" + left + ", " + right + ")");
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}
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}
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