jdk8-mips64-public/langtools: comparison test/tools/javac/scope/HashCollisionTest.java

--1:000000000000
+:959103a6100f
+/*
+* Copyright (c) 2010, 2011, Oracle and/or its affiliates. All rights reserved.
+* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+*
+* This code is free software; you can redistribute it and/or modify it
+* under the terms of the GNU General Public License version 2 only, as
+* published by the Free Software Foundation.
+*
+* This code is distributed in the hope that it will be useful, but WITHOUT
+* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+* FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+* version 2 for more details (a copy is included in the LICENSE file that
+* accompanied this code).
+*
+* You should have received a copy of the GNU General Public License version
+* 2 along with this work; if not, write to the Free Software Foundation,
+* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+*
+* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+* or visit www.oracle.com if you need additional information or have any
+* questions.
+*/
+/*
+* @test
+* @bug 7004029
+* @summary Ensure Scope impl can cope with hash collisions
+*/
+import java.lang.reflect.*;
+import java.io.*;
+import com.sun.tools.javac.util.*;
+import com.sun.tools.javac.code.*;
+import com.sun.tools.javac.code.Scope.*;
+import com.sun.tools.javac.code.Symbol.*;
+import com.sun.tools.javac.file.JavacFileManager;
+import static com.sun.tools.javac.code.Kinds.*;
+public class HashCollisionTest {
+public static void main(String... args) throws Exception {
+new HashCollisionTest().run();
+}
+void run() throws Exception {
+// set up basic environment for test
+Context context = new Context();
+JavacFileManager.preRegister(context); // required by ClassReader which is required by Symtab
+names = Names.instance(context);       // Name.Table impls tied to an instance of Names
+symtab = Symtab.instance(context);
+// determine hashMask for an empty scope
+Scope emptyScope = new Scope(symtab.unnamedPackage); // any owner will do
+Field sHashMask = Scope.class.getDeclaredField("hashMask");
+sHashMask.setAccessible(true);
+scopeHashMask = sHashMask.getInt(emptyScope);
+log("scopeHashMask: " + scopeHashMask);
+// 1. determine the Name.hashCode of "Entry", and therefore the index of
+// Entry in an empty scope.  i.e. name.hashCode() & Scope.hashMask
+Name entry = names.fromString("Entry");
+// 2. create names of the form *$Entry until we find a name with a
+// hashcode which yields the same index as Entry in an empty scope.
+// Since Name.hashCode is a function of position (and not content) it
+// should work to create successively longer names until one with the
+// desired characteristics is found.
+Name outerName;
+Name innerName;
+StringBuilder sb = new StringBuilder("C");
+int i = 0;
+do {
+sb.append(Integer.toString(i % 10));
+innerName = names.fromString(sb + "$Entry");
+} while (!clash(entry, innerName) && (++i) < MAX_TRIES);
+if (clash(entry, innerName)) {
+log("Detected expected hash collision for " + entry + " and " + innerName
++ " after " + i + " tries");
+} else {
+throw new Exception("No potential collision found after " + i + " tries");
+}
+outerName = names.fromString(sb.toString());
+/*
+* Now we can set up the scenario.
+*/
+// 3. Create a nested class named Entry
+ClassSymbol cc = createClass(names.fromString("C"), symtab.unnamedPackage);
+ClassSymbol ce = createClass(entry, cc);
+// 4. Create a package containing a nested class using the name from 2
+PackageSymbol p = new PackageSymbol(names.fromString("p"), symtab.rootPackage);
+p.members_field = new Scope(p);
+ClassSymbol inner = createClass(innerName, p);
+// we'll need this later when we "rename" cn
+ClassSymbol outer = createClass(outerName, p);
+// 5. Create a star-import scope
+log ("createStarImportScope");
+// if StarImportScope exists, use it, otherwise, for testing legacy code,
+// fall back on ImportScope
+Scope starImportScope;
+Method importAll;
+PackageSymbol pkg = new PackageSymbol(names.fromString("pkg"), symtab.rootPackage);
+try {
+Class<?> c = Class.forName("com.sun.tools.javac.code.Scope$StarImportScope");
+Constructor ctor = c.getDeclaredConstructor(new Class[] { Symbol.class });
+importAll = c.getDeclaredMethod("importAll", new Class[] { Scope.class });
+starImportScope = (Scope) ctor.newInstance(new Object[] { pkg });
+} catch (ClassNotFoundException e) {
+starImportScope = new ImportScope(pkg);
+importAll = null;
+}
+dump("initial", starImportScope);
+// 6. Insert the contents of the package from 4.
+Scope p_members = p.members();
+if (importAll != null) {
+importAll.invoke(starImportScope, p_members);
+} else {
+Scope fromScope = p_members;
+Scope toScope = starImportScope;
+// The following lines are taken from MemberEnter.importAll,
+// before the use of StarImportScope.importAll.
+for (Scope.Entry e = fromScope.elems; e != null; e = e.sibling) {
+if (e.sym.kind == TYP && !toScope.includes(e.sym))
+toScope.enter(e.sym, fromScope);
+}
+}
+dump("imported p", starImportScope);
+// 7. Insert the class from 3.
+starImportScope.enter(ce, cc.members_field);
+dump("imported ce", starImportScope);
+/*
+* Set the trap.
+*/
+// 8. Rename the nested class to Entry. so that there is a bogus entry in the star-import scope
+p.members_field.remove(inner);
+inner.name = entry;
+inner.owner = outer;
+outer.members_field.enter(inner);
+// 9. Lookup Entry
+Scope.Entry e = starImportScope.lookup(entry);
+dump("final", starImportScope);
+if (e.sym == null)
+throw new Exception("symbol not found: " + entry);
+}
+/*
+* Check for a (probable) hash collision in an empty scope.
+*/
+boolean clash(Name n1, Name n2) {
+log(n1 + " hc:" + n1.hashCode() + " v:" + (n1.hashCode() & scopeHashMask) + ", " +
+n2 + " hc:" + n2.hashCode() + " v:" + (n2.hashCode() & scopeHashMask));
+return (n1.hashCode() & scopeHashMask) == (n2.hashCode() & scopeHashMask);
+}
+/**
+* Create a class symbol, init the members scope, and add it to owner's scope.
+*/
+ClassSymbol createClass(Name name, Symbol owner) {
+ClassSymbol sym = new ClassSymbol(0, name, owner);
+sym.members_field = new Scope(sym);
+if (owner != symtab.unnamedPackage)
+owner.members().enter(sym);
+return sym;
+}
+/**
+* Dump the contents of a scope to System.err.
+*/
+void dump(String label, Scope s) throws Exception {
+dump(label, s, System.err);
+}
+/**
+* Dump the contents of a scope to a stream.
+*/
+void dump(String label, Scope s, PrintStream out) throws Exception {
+out.println(label);
+Field sTable = Scope.class.getDeclaredField("table");
+sTable.setAccessible(true);
+out.println("owner:" + s.owner);
+Scope.Entry[] table = (Scope.Entry[]) sTable.get(s);
+for (int i = 0; i < table.length; i++) {
+if (i > 0)
+out.print(", ");
+out.print(i + ":" + toString(table[i], table, false));
+}
+out.println();
+}
+/**
+* Create a string showing the contents of an entry, using the table
+* to help identify cross-references to other entries in the table.
+* @param e the entry to be shown
+* @param table the table containing the other entries
+*/
+String toString(Scope.Entry e, Scope.Entry[] table, boolean ref) {
+if (e == null)
+return "null";
+if (e.sym == null)
+return "sent"; // sentinel
+if (ref) {
+int index = indexOf(table, e);
+if (index != -1)
+return String.valueOf(index);
+}
+return "(" + e.sym.name + ":" + e.sym
++ ",shdw:" + toString(e.next(), table, true)
++ ",sibl:" + toString(e.sibling, table, true)
++ ((e.sym.owner != e.scope.owner)
+? (",BOGUS[" + e.sym.owner + "," + e.scope.owner + "]")
+: "")
++ ")";
+}
+<T> int indexOf(T[] array, T item) {
+for (int i = 0; i < array.length; i++) {
+if (array[i] == item)
+return i;
+}
+return -1;
+}
+/**
+* Write a message to stderr.
+*/
+void log(String msg) {
+System.err.println(msg);
+}
+int MAX_TRIES = 100; // max tries to find a hash clash before giving up.
+int scopeHashMask;
+Names names;
+Symtab symtab;
+}

Mercurial > jdk8-mips64-public > langtools / file comparison

comparison: test/tools/javac/scope/HashCollisionTest.java

test/tools/javac/scope/HashCollisionTest.java