test/hotspot/jtreg/runtime/cds/appcds/TestCommon.java
branchdatagramsocketimpl-branch
changeset 58678 9cf78a70fa4f
parent 54927 1512d88b24c6
child 58679 9c3209ff7550
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/hotspot/jtreg/runtime/cds/appcds/TestCommon.java	Thu Oct 17 20:53:35 2019 +0100
@@ -0,0 +1,664 @@
+/*
+ * Copyright (c) 2014, 2019, 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.
+ *
+ */
+
+import jdk.test.lib.Utils;
+import jdk.test.lib.BuildHelper;
+import jdk.test.lib.JDKToolFinder;
+import jdk.test.lib.Platform;
+import jdk.test.lib.cds.CDSOptions;
+import jdk.test.lib.cds.CDSTestUtils;
+import jdk.test.lib.cds.CDSTestUtils.Result;
+import jdk.test.lib.process.ProcessTools;
+import jdk.test.lib.process.OutputAnalyzer;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.InputStream;
+import java.net.URI;
+import java.nio.file.DirectoryStream;
+import java.nio.file.Files;
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+import java.nio.file.Path;
+import java.text.SimpleDateFormat;
+import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.Date;
+import java.util.Enumeration;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+import java.util.zip.ZipOutputStream;
+import jtreg.SkippedException;
+import cdsutils.DynamicDumpHelper;
+
+
+/**
+ * This is a test utility class for common AppCDS test functionality.
+ *
+ * Various methods use (String ...) for passing VM options. Note that the order
+ * of the VM options are important in certain cases. Many methods take arguments like
+ *
+ *    (String prefix[], String suffix[], String... opts)
+ *
+ * Note that the order of the VM options is:
+ *
+ *    prefix + opts + suffix
+ */
+public class TestCommon extends CDSTestUtils {
+    private static final String JSA_FILE_PREFIX = System.getProperty("user.dir") +
+        File.separator;
+
+    private static final SimpleDateFormat timeStampFormat =
+        new SimpleDateFormat("HH'h'mm'm'ss's'SSS");
+
+    private static final String timeoutFactor =
+        System.getProperty("test.timeout.factor", "1.0");
+
+    private static String currentArchiveName;
+
+    // Call this method to start new archive with new unique name
+    public static void startNewArchiveName() {
+        deletePriorArchives();
+        currentArchiveName = getNewArchiveName();
+    }
+
+    // Call this method to get current archive name
+    public static String getCurrentArchiveName() {
+        return currentArchiveName;
+    }
+
+    public static void setCurrentArchiveName(String archiveName) {
+        currentArchiveName = archiveName;
+    }
+
+    public static String getNewArchiveName() {
+        return getNewArchiveName(null);
+    }
+
+    public static String getNewArchiveName(String stem) {
+        if (stem == null) {
+            stem = "appcds";
+        }
+        return JSA_FILE_PREFIX + stem + "-" +
+            timeStampFormat.format(new Date()) + ".jsa";
+    }
+
+    // Attempt to clean old archives to preserve space
+    // Archives are large artifacts (20Mb or more), and much larger than
+    // most other artifacts created in jtreg testing.
+    // Therefore it is a good idea to clean the old archives when they are not needed.
+    // In most cases the deletion attempt will succeed; on rare occasion the
+    // delete operation will fail since the system or VM process still holds a handle
+    // to the file; in such cases the File.delete() operation will silently fail, w/o
+    // throwing an exception, thus allowing testing to continue.
+    public static void deletePriorArchives() {
+        File dir = new File(System.getProperty("user.dir"));
+        String files[] = dir.list();
+        for (String name : files) {
+            if (name.startsWith("appcds-") && name.endsWith(".jsa")) {
+                if (!(new File(dir, name)).delete())
+                    System.out.println("deletePriorArchives(): delete failed for file " + name);
+            }
+        }
+    }
+
+    // Create AppCDS archive using most common args - convenience method
+    // Legacy name preserved for compatibility
+    public static OutputAnalyzer dump(String appJar, String classList[],
+                                               String... suffix) throws Exception {
+        return createArchive(appJar, classList, suffix);
+    }
+
+    public static OutputAnalyzer dump(String appJarDir, String appJar, String classList[],
+                                               String... suffix) throws Exception {
+        return createArchive(appJarDir, appJar, classList, suffix);
+    }
+
+    // Create AppCDS archive using most common args - convenience method
+    public static OutputAnalyzer createArchive(String appJar, String classList[],
+                                               String... suffix) throws Exception {
+        AppCDSOptions opts = (new AppCDSOptions()).setAppJar(appJar);
+        opts.setClassList(classList);
+        opts.addSuffix(suffix);
+        return createArchive(opts);
+    }
+
+    public static OutputAnalyzer createArchive(String appJarDir, String appJar, String classList[],
+                                               String... suffix) throws Exception {
+        AppCDSOptions opts = (new AppCDSOptions()).setAppJar(appJar);
+        opts.setAppJarDir(appJarDir);
+        opts.setClassList(classList);
+        opts.addSuffix(suffix);
+        return createArchive(opts);
+    }
+
+    // Simulate -Xshare:dump with -XX:ArchiveClassesAtExit. See comments around patchJarForDynamicDump()
+    private static final Class tmp = DynamicDumpHelper.class;
+
+    // Create AppCDS archive using appcds options
+    public static OutputAnalyzer createArchive(AppCDSOptions opts)
+        throws Exception {
+        ArrayList<String> cmd = new ArrayList<String>();
+        startNewArchiveName();
+
+        for (String p : opts.prefix) cmd.add(p);
+
+        if (opts.appJar != null) {
+            cmd.add("-cp");
+            cmd.add(opts.appJar);
+            File jf = new File(opts.appJar);
+            if (DYNAMIC_DUMP && !jf.isDirectory()) {
+                patchJarForDynamicDump(opts.appJar);
+            }
+        } else {
+            cmd.add("-Djava.class.path=");
+        }
+
+        if (opts.archiveName == null) {
+            opts.archiveName = getCurrentArchiveName();
+        }
+
+        if (DYNAMIC_DUMP) {
+            cmd.add("-Xshare:on");
+            cmd.add("-XX:ArchiveClassesAtExit=" + opts.archiveName);
+
+            cmd.add("-Xlog:cds");
+            cmd.add("-Xlog:cds+dynamic");
+            boolean mainModuleSpecified = false;
+            boolean patchModuleSpecified = false;
+            for (String s : opts.suffix) {
+                if (s.length() == 0) {
+                    continue;
+                }
+                if (s.equals("-m")) {
+                    mainModuleSpecified = true;
+                }
+                if (s.startsWith("--patch-module=")) {
+                    patchModuleSpecified = true;
+                }
+                cmd.add(s);
+            }
+
+            if (opts.appJar != null) {
+                // classlist is supported only when we have a Jar file to patch (to insert
+                // cdsutils.DynamicDumpHelper)
+                if (opts.classList == null) {
+                    throw new RuntimeException("test.dynamic.dump requires classList file");
+                }
+
+                if (!mainModuleSpecified && !patchModuleSpecified) {
+                    cmd.add("cdsutils.DynamicDumpHelper");
+                    File classListFile = makeClassList(opts.classList);
+                    cmd.add(classListFile.getPath());
+                }
+            } else {
+                if (!mainModuleSpecified && !patchModuleSpecified) {
+                    // If you have an empty classpath, you cannot specify a classlist!
+                    if (opts.classList != null && opts.classList.length > 0) {
+                        throw new RuntimeException("test.dynamic.dump is not supported with an empty classpath while the classlist is not empty");
+                    }
+                    cmd.add("-version");
+                }
+            }
+        } else {
+            // static dump
+            cmd.add("-Xshare:dump");
+            cmd.add("-XX:SharedArchiveFile=" + opts.archiveName);
+
+            if (opts.classList != null) {
+                File classListFile = makeClassList(opts.classList);
+                cmd.add("-XX:ExtraSharedClassListFile=" + classListFile.getPath());
+            }
+            for (String s : opts.suffix) {
+                cmd.add(s);
+            }
+        }
+
+        String[] cmdLine = cmd.toArray(new String[cmd.size()]);
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(true, cmdLine);
+        if (opts.appJarDir != null) {
+            pb.directory(new File(opts.appJarDir));
+        }
+
+        OutputAnalyzer output = executeAndLog(pb, "dump");
+        if (DYNAMIC_DUMP && isUnableToMap(output)) {
+            throw new SkippedException(UnableToMapMsg);
+        }
+        return output;
+    }
+
+    // This allows you to run the AppCDS tests with JFR enabled at runtime (though not at
+    // dump time, as that's uncommon for typical AppCDS users).
+    //
+    // To run in this special mode, add the following to your jtreg command-line
+    //    -Dtest.cds.run.with.jfr=true
+    //
+    // Some AppCDS tests are not compatible with this mode. See the group
+    // hotspot_appcds_with_jfr in ../../TEST.ROOT for details.
+    private static final boolean RUN_WITH_JFR = Boolean.getBoolean("test.cds.run.with.jfr");
+    // This method simulates -Xshare:dump with -XX:ArchiveClassesAtExit. This way, we
+    // can re-use many tests (outside of the ./dynamicArchive directory) for testing
+    // general features of JDK-8215311 (JEP 350: Dynamic CDS Archives).
+    //
+    // We insert the cdsutils/DynamicDumpHelper.class into the first Jar file in
+    // the classpath. We use this class to load all the classes specified in the classlist.
+    //
+    // There's no need to change the run-time command-line: in this special mode, two
+    // archives are involved. The command-line specifies only the top archive. However,
+    // the location of the base archive is recorded in the top archive, so it can be
+    // determined by the JVM at runtime start-up.
+    //
+    // To run in this special mode, specify the following in your jtreg command-line
+    //    -Dtest.dynamic.cds.archive=true
+    //
+    // Note that some tests are not compatible with this special mode, including
+    //    + Tests in ./dynamicArchive: these tests are specifically written for
+    //      dynamic archive, and do not use TestCommon.createArchive(), which works
+    //      together with patchJarForDynamicDump().
+    //    + Tests related to cached objects and shared strings: dynamic dumping
+    //      does not support these.
+    //    + Custom loader tests: DynamicDumpHelper doesn't support the required
+    //      classlist syntax. (FIXME).
+    //    + Extra symbols and extra strings.
+    // See the hotspot_appcds_dynamic in ../../TEST.ROOT for details.
+    //
+    // To run all tests that are compatible with this mode:
+    //    cd test/hotspot/jtreg
+    //    jtreg -Dtest.dynamic.cds.archive=true :hotspot_appcds_dynamic
+    //
+    private static void patchJarForDynamicDump(String cp) throws Exception {
+        System.out.println("patchJarForDynamicDump: classpath = " + cp);
+        String firstJar = cp;
+        int n = firstJar.indexOf(File.pathSeparator);
+        if (n > 0) {
+            firstJar = firstJar.substring(0, n);
+        }
+        String classDir = System.getProperty("test.classes");
+        String expected1 = classDir + File.separator;
+        String expected2 = System.getProperty("user.dir") + File.separator;
+
+        if (!firstJar.startsWith(expected1) && !firstJar.startsWith(expected2)) {
+            throw new RuntimeException("FIXME: jar file not at a supported location ('"
+                                       + expected1 + "', or '" + expected2 + "'): " + firstJar);
+        }
+
+        String replaceJar = firstJar + ".tmp";
+        String patchClass = "cdsutils/DynamicDumpHelper.class";
+        ZipFile zipFile = new ZipFile(firstJar);
+        byte[] buf = new byte[1024];
+        int len;
+        if (zipFile.getEntry(patchClass) == null) {
+            FileOutputStream fout = new FileOutputStream(replaceJar);
+            final ZipOutputStream zos = new ZipOutputStream(fout);
+
+            zos.putNextEntry(new ZipEntry(patchClass));
+            InputStream is = new FileInputStream(classDir + File.separator + patchClass);
+            while ((len = (is.read(buf))) > 0) {
+                zos.write(buf, 0, len);
+            }
+            zos.closeEntry();
+            is.close();
+
+            for (Enumeration e = zipFile.entries(); e.hasMoreElements(); ) {
+                ZipEntry entryIn = (ZipEntry) e.nextElement();
+                zos.putNextEntry(entryIn);
+                is = zipFile.getInputStream(entryIn);
+                while ((len = is.read(buf)) > 0) {
+                    zos.write(buf, 0, len);
+                }
+                zos.closeEntry();
+                is.close();
+            }
+
+            zos.close();
+            fout.close();
+            zipFile.close();
+
+            File oldFile = new File(firstJar);
+            File newFile = new File(replaceJar);
+            oldFile.delete();
+            newFile.renameTo(oldFile);
+            System.out.println("firstJar = " + firstJar + " Modified");
+        } else {
+            System.out.println("firstJar = " + firstJar);
+        }
+    }
+
+    // Execute JVM using AppCDS archive with specified AppCDSOptions
+    public static OutputAnalyzer runWithArchive(AppCDSOptions opts)
+        throws Exception {
+
+        ArrayList<String> cmd = new ArrayList<String>();
+
+        for (String p : opts.prefix) cmd.add(p);
+
+        cmd.add("-Xshare:" + opts.xShareMode);
+        cmd.add("-showversion");
+        cmd.add("-XX:SharedArchiveFile=" + getCurrentArchiveName());
+        cmd.add("-Dtest.timeout.factor=" + timeoutFactor);
+
+        if (opts.appJar != null) {
+            cmd.add("-cp");
+            cmd.add(opts.appJar);
+        }
+
+        for (String s : opts.suffix) cmd.add(s);
+
+        if (RUN_WITH_JFR) {
+            boolean usesJFR = false;
+            for (String s : cmd) {
+                if (s.startsWith("-XX:StartFlightRecording=") || s.startsWith("-XX:FlightRecorderOptions")) {
+                    System.out.println("JFR option might have been specified. Don't interfere: " + s);
+                    usesJFR = true;
+                    break;
+                }
+            }
+            if (!usesJFR) {
+                System.out.println("JFR option not specified. Enabling JFR ...");
+                cmd.add(0, "-XX:StartFlightRecording=dumponexit=true");
+                System.out.println(cmd);
+            }
+        }
+
+        String[] cmdLine = cmd.toArray(new String[cmd.size()]);
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(true, cmdLine);
+        if (opts.appJarDir != null) {
+            pb.directory(new File(opts.appJarDir));
+        }
+        return executeAndLog(pb, "exec");
+    }
+
+
+    public static OutputAnalyzer execCommon(String... suffix) throws Exception {
+        AppCDSOptions opts = (new AppCDSOptions());
+        opts.addSuffix(suffix);
+        return runWithArchive(opts);
+    }
+
+    // This is the new API for running a Java process with CDS enabled.
+    // See comments in the CDSTestUtils.Result class for how to use this method.
+    public static Result run(String... suffix) throws Exception {
+        AppCDSOptions opts = (new AppCDSOptions());
+        opts.addSuffix(suffix);
+        return new Result(opts, runWithArchive(opts));
+    }
+
+    public static Result runWithRelativePath(String jarDir, String... suffix) throws Exception {
+        AppCDSOptions opts = (new AppCDSOptions());
+        opts.setAppJarDir(jarDir);
+        opts.addSuffix(suffix);
+        return new Result(opts, runWithArchive(opts));
+    }
+
+    public static OutputAnalyzer exec(String appJar, String... suffix) throws Exception {
+        AppCDSOptions opts = (new AppCDSOptions()).setAppJar(appJar);
+        opts.addSuffix(suffix);
+        return runWithArchive(opts);
+    }
+
+    public static Result runWithModules(String prefix[], String upgrademodulepath, String modulepath,
+                                            String mid, String... testClassArgs) throws Exception {
+        AppCDSOptions opts = makeModuleOptions(prefix, upgrademodulepath, modulepath,
+                                               mid, testClassArgs);
+        return new Result(opts, runWithArchive(opts));
+    }
+
+    public static OutputAnalyzer execAuto(String... suffix) throws Exception {
+        AppCDSOptions opts = (new AppCDSOptions());
+        opts.addSuffix(suffix).setXShareMode("auto");
+        return runWithArchive(opts);
+    }
+
+    public static OutputAnalyzer execOff(String... suffix) throws Exception {
+        AppCDSOptions opts = (new AppCDSOptions());
+        opts.addSuffix(suffix).setXShareMode("off");
+        return runWithArchive(opts);
+    }
+
+
+    private static AppCDSOptions makeModuleOptions(String prefix[], String upgrademodulepath, String modulepath,
+                                            String mid, String testClassArgs[]) {
+        AppCDSOptions opts = (new AppCDSOptions());
+
+        opts.addPrefix(prefix);
+        if (upgrademodulepath == null) {
+            opts.addSuffix("-p", modulepath, "-m", mid);
+        } else {
+            opts.addSuffix("--upgrade-module-path", upgrademodulepath,
+                           "-p", modulepath, "-m", mid);
+        }
+        opts.addSuffix(testClassArgs);
+        return opts;
+    }
+
+    public static OutputAnalyzer execModule(String prefix[], String upgrademodulepath, String modulepath,
+                                            String mid, String... testClassArgs)
+        throws Exception {
+        AppCDSOptions opts = makeModuleOptions(prefix, upgrademodulepath, modulepath,
+                                               mid, testClassArgs);
+        return runWithArchive(opts);
+    }
+
+    // A common operation: dump, then check results
+    public static OutputAnalyzer testDump(String appJar, String classList[],
+                                          String... suffix) throws Exception {
+        OutputAnalyzer output = dump(appJar, classList, suffix);
+        if (DYNAMIC_DUMP) {
+            output.shouldContain("Written dynamic archive");
+        } else {
+            output.shouldContain("Loading classes to share");
+        }
+        output.shouldHaveExitValue(0);
+        return output;
+    }
+
+    public static OutputAnalyzer testDump(String appJarDir, String appJar, String classList[],
+                                          String... suffix) throws Exception {
+        OutputAnalyzer output = dump(appJarDir, appJar, classList, suffix);
+        if (DYNAMIC_DUMP) {
+            output.shouldContain("Written dynamic archive");
+        } else {
+            output.shouldContain("Loading classes to share");
+        }
+        output.shouldHaveExitValue(0);
+        return output;
+    }
+
+    /**
+     * Simple test -- dump and execute appJar with the given classList in classlist.
+     */
+    public static OutputAnalyzer test(String appJar, String classList[], String... args)
+        throws Exception {
+        testDump(appJar, classList);
+
+        OutputAnalyzer output = exec(appJar, args);
+        return checkExec(output);
+    }
+
+
+    public static OutputAnalyzer checkExecReturn(OutputAnalyzer output, int ret,
+                           boolean checkContain, String... matches) throws Exception {
+        try {
+            for (String s : matches) {
+                if (checkContain) {
+                    output.shouldContain(s);
+                } else {
+                    output.shouldNotContain(s);
+                }
+            }
+            output.shouldHaveExitValue(ret);
+        } catch (Exception e) {
+            checkCommonExecExceptions(output, e);
+        }
+
+        return output;
+    }
+
+    // Convenience concatenation utils
+    public static String[] list(String ...args) {
+        return args;
+    }
+
+
+    public static String[] list(String arg, int count) {
+        ArrayList<String> stringList = new ArrayList<String>();
+        for (int i = 0; i < count; i++) {
+            stringList.add(arg);
+        }
+
+        String outputArray[] = stringList.toArray(new String[stringList.size()]);
+        return outputArray;
+    }
+
+
+    public static String[] concat(String... args) {
+        return list(args);
+    }
+
+
+    public static String[] concat(String prefix[], String... extra) {
+        ArrayList<String> list = new ArrayList<String>();
+        for (String s : prefix) {
+            list.add(s);
+        }
+        for (String s : extra) {
+            list.add(s);
+        }
+
+        return list.toArray(new String[list.size()]);
+    }
+
+    public static String[] concat(String prefix, String[] extra) {
+        ArrayList<String> list = new ArrayList<String>();
+        list.add(prefix);
+        for (String s : extra) {
+            list.add(s);
+        }
+
+        return list.toArray(new String[list.size()]);
+    }
+
+    // ===================== Concatenate paths
+    public static String concatPaths(String... paths) {
+        String prefix = "";
+        String s = "";
+        for (String p : paths) {
+            s += prefix;
+            s += p;
+            prefix = File.pathSeparator;
+        }
+        return s;
+    }
+
+
+    public static String getTestJar(String jar) {
+        File jarFile = CDSTestUtils.getTestArtifact(jar, true);
+        if (!jarFile.isFile()) {
+            throw new RuntimeException("Not a regular file: " + jarFile.getPath());
+        }
+        return jarFile.getPath();
+    }
+
+
+    public static String getTestDir(String d) {
+        File dirFile = CDSTestUtils.getTestArtifact(d, true);
+        if (!dirFile.isDirectory()) {
+            throw new RuntimeException("Not a directory: " + dirFile.getPath());
+        }
+        return dirFile.getPath();
+    }
+
+    public static boolean checkOutputStrings(String outputString1,
+                                             String outputString2,
+                                             String split_regex) {
+        String[] sa1 = outputString1.split(split_regex);
+        String[] sa2 = outputString2.split(split_regex);
+        Arrays.sort(sa1);
+        Arrays.sort(sa2);
+
+        int i = 0;
+        for (String s : sa1) {
+            if (!s.equals(sa2[i])) {
+                throw new RuntimeException(s + " is different from " + sa2[i]);
+            }
+            i ++;
+        }
+        return true;
+    }
+
+    static Pattern pattern;
+
+    static void findAllClasses(ArrayList<String> list) throws Exception {
+        // Find all the classes in the jrt file system
+        pattern = Pattern.compile("/modules/[a-z.]*[a-z]+/([^-]*)[.]class");
+        FileSystem fs = FileSystems.getFileSystem(URI.create("jrt:/"));
+        Path base = fs.getPath("/modules/");
+        findAllClassesAtPath(base, list);
+    }
+
+    private static void findAllClassesAtPath(Path p, ArrayList<String> list) throws Exception {
+        try (DirectoryStream<Path> stream = Files.newDirectoryStream(p)) {
+            for (Path entry: stream) {
+                Matcher matcher = pattern.matcher(entry.toString());
+                if (matcher.find()) {
+                    String className = matcher.group(1);
+                    list.add(className);
+                }
+                try {
+                    findAllClassesAtPath(entry, list);
+                } catch (Exception ex) {}
+            }
+        }
+    }
+
+    public static String composeRelPath(String appJar) {
+         int idx = appJar.lastIndexOf(File.separator);
+         String jarName = appJar.substring(idx + 1);
+         String jarDir = appJar.substring(0, idx);
+         String lastDir = jarDir.substring(jarDir.lastIndexOf(File.separator));
+         String relPath = jarDir + File.separator + ".." + File.separator + lastDir;
+         String newJar = relPath + File.separator + jarName;
+         return newJar;
+    }
+
+
+    public static File createSymLink(String appJar) throws Exception {
+         int idx = appJar.lastIndexOf(File.separator);
+         String jarName = appJar.substring(idx + 1);
+         String jarDir = appJar.substring(0, idx);
+         File origJar = new File(jarDir, jarName);
+         String linkedJarName = "linked_" + jarName;
+         File linkedJar = null;
+         if (!Platform.isWindows()) {
+             linkedJar = new File(jarDir, linkedJarName);
+             if (linkedJar.exists()) {
+                 linkedJar.delete();
+             }
+             Files.createSymbolicLink(linkedJar.toPath(), origJar.toPath());
+         }
+         return linkedJar;
+    }
+}