142 lines
4.5 KiB
Java
142 lines
4.5 KiB
Java
/*
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* Copyright (c) 2002, 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.sysdict;
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import nsk.share.*;
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/**
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* A binary tree of class loaders.
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*
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* @see TreeNodesDenotation
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*/
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public class ClassLoadersBTree {
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/**
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* Cannot instantiate while a tree root and height
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* are not specified.
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*
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* @see #ClassLoadersBTree(ClassLoader,int)
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*/
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protected ClassLoadersBTree() {
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}
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/**
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* Given the <tt>root</tt> loader, instantiate a binary tree
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* of loaders up to the given tree <tt>height</tt>.
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*
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* @see #getHeight()
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* @see #getRoot()
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* @see #getLoader(String)
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* @see #getLoader(int,int)
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*/
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public ClassLoadersBTree(ClassLoader root, int height) {
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if (height < 1)
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throw new IllegalArgumentException("wrong height: " + height);
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loaders = new ClassLoader [ height ] [];
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for (int level=0; level<height; level++)
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loaders[level] = new ClassLoader [1 << level];
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loaders[0][0] = root;
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generateSubtree("");
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}
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private void generateSubtree(String name) {
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int level = name.length();
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int height = loaders.length;
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if (level+1 == height)
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return;
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String nameL = name + "L";
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String nameR = name + "R";
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int[] index = denotation.indexFor(name);
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int[] indexL = denotation.indexFor(nameL);
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int[] indexR = denotation.indexFor(nameR);
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// assertion: index[0] == level
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// assertion: indexL[0] == indexR[0] == level+1
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int item = index[1];
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int itemL = indexL[1];
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int itemR = indexR[1];
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ClassLoader parent = loaders[level][item];
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ClassLoader childL = new DummyClassLoader(parent);
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ClassLoader childR = new DummyClassLoader(parent); // another item
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loaders[level+1][itemL] = childL;
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loaders[level+1][itemR] = childR;
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generateSubtree(nameL);
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generateSubtree(nameR);
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}
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private ClassLoader loaders[][]; // loaders[0][0] is root
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private Denotation denotation = new TreeNodesDenotation();
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/**
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* Return the loader found at the given <tt>level</tt> of
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* this loaders tree, and having the given <tt>item</tt>
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* number at the enumeration of that <tt>level</tt>.
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*
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* <p>The value of <tt>level</tt> must be from <tt>0</tt>
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* to <tt>getHeight()-1</tt>, and the <tt>item</tt> number
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* must be from <tt>0</tt> to <tt>2<sup>level</sup>-1</tt>.
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*
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* @see #getHeight()
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* @see #getRoot()
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* @see #getLoader(String)
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*/
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public ClassLoader getLoader(int level, int item) {
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return loaders[level][item];
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}
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/**
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* Return the loader having the giving <tt>name</tt> at
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* the standard denotation of binary tree nodes.
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*
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* @see #getHeight()
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* @see #getRoot()
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* @see #getLoader(int,int)
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*/
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public ClassLoader getLoader(String name) {
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int[] index = denotation.indexFor(name);
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int level = index[0];
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int item = index[1];
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return loaders[level][item];
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}
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/**
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* Return the tree's height.
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*
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* @see #ClassLoadersBTree(ClassLoader,int)
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* @see #getLoader(int,int)
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* @see #getLoader(String)
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*/
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public int getHeight() {
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return loaders.length;
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}
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/**
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* Return the tree's root loader.
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*
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* @see #ClassLoadersBTree(ClassLoader,int)
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* @see #getLoader(int,int)
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* @see #getLoader(String)
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*/
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public ClassLoader getRoot() {
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return loaders[0][0];
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}
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}
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