Issue #64 introduced a code cache to support multiple app instances

Whenever 'use_code_cache' is set to 'true' the application's code
resources are copied to a cache directory prior to launching the
application. This is done in order to support multiple open application
instances of different versions.

pom.xml

@@ -90,6 +90,12 @@
       <version>4.8.1</version>
       <scope>test</scope>
     </dependency>
+    <dependency>
+      <groupId>org.mockito</groupId>
+      <artifactId>mockito-core</artifactId>
+      <version>1.10.19</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <build>

src/main/java/com/threerings/getdown/classpath/CacheBasedClassPathBuilder.java

@@ -0,0 +1,61 @@
+package com.threerings.getdown.classpath;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.LinkedHashSet;
+import java.util.concurrent.TimeUnit;
+
+import com.threerings.getdown.classpath.cache.GarbageCollector;
+import com.threerings.getdown.classpath.cache.ResourceCache;
+import com.threerings.getdown.data.Application;
+import com.threerings.getdown.data.Resource;
+import com.threerings.getdown.util.file.FileWalker;
+
+/**
+ * Instead of building the class path from the application directory, this class path builder puts
+ * the files that make up the class path into a cache and assembles the class path from the cache
+ * directory.
+ */
+public class CacheBasedClassPathBuilder extends ClassPathBuilderBase
+{
+    static final String CACHE_DIR = ".cache";
+
+    public CacheBasedClassPathBuilder(Application application)
+    {
+        super(application);
+    }
+
+    @Override
+    public ClassPath buildClassPath () throws IOException
+    {
+        File cacheDir = new File(_application.getAppdir(), CACHE_DIR);
+
+        // a negative value of code_cache_retention_days allows to clean up the cache forcefully
+        if (_application.getCodeCacheRetentionDays() <= 0) {
+            runGarbageCollection(cacheDir);
+        }
+
+        ResourceCache cache = new ResourceCache(cacheDir);
+
+        LinkedHashSet<ClassPathElement> classPathEntries = new LinkedHashSet<ClassPathElement>();
+
+        for (Resource resource: _application.getActiveCodeResources()) {
+            classPathEntries.add(
+                new ClassPathElement(
+                    cache.cacheFile(resource.getFinalTarget(), _application.getDigest(resource))));
+        }
+
+        if (_application.getCodeCacheRetentionDays() > 0) {
+            runGarbageCollection(cacheDir);
+        }
+
+        return new ClassPath(classPathEntries);
+    }
+
+    private void runGarbageCollection(File cacheDir) {
+        GarbageCollector gc = new GarbageCollector(
+                new FileWalker(cacheDir), _application.getCodeCacheRetentionDays(), TimeUnit.DAYS);
+
+        gc.collectGarbage();
+    }
+}

src/main/java/com/threerings/getdown/classpath/ClassPath.java

@@ -0,0 +1,69 @@
+package com.threerings.getdown.classpath;
+
+import java.io.File;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.Collections;
+import java.util.LinkedHashSet;
+import java.util.Set;
+
+/**
+ * Represents the class path and it's elements of the application to be launched. The class path can
+ * either be represented as an {@link #asArgumentString() argument string} for the java command line
+ * or as an {@link #asUrls() array of URLs} to be used by a {@link URLClassLoader}.
+ */
+public class ClassPath
+{
+    public ClassPath (LinkedHashSet<ClassPathElement> classPathEntries)
+    {
+        this._classPathEntries = Collections.unmodifiableSet(classPathEntries);
+    }
+
+    /**
+     * Returns the class path as an java command line argument string, e.g
+     *
+     * <pre>
+     *   /path/to/a.jar:/path/to/b.jar
+     * </pre>
+     */
+    public String asArgumentString ()
+    {
+        StringBuilder builder = new StringBuilder();
+        String delimiter = "";
+
+        for (ClassPathElement entry: _classPathEntries)
+        {
+            builder
+                .append(delimiter)
+                .append(entry.getAbsolutePath());
+
+            delimiter = File.pathSeparator;
+        }
+
+        return builder.toString();
+    }
+
+    /**
+     * Returns the class path entries as an array of URLs to be used for example by an
+     * {@link URLClassLoader}.
+     */
+    public URL[] asUrls ()
+    {
+        URL[] urls = new URL[_classPathEntries.size()];
+
+        int i = 0;
+
+        for (ClassPathElement entry : _classPathEntries) {
+            urls[i++] = entry.getURL();
+        }
+
+        return urls;
+    }
+
+    public Set<ClassPathElement> getClassPathEntries ()
+    {
+        return _classPathEntries;
+    }
+
+    private final Set<ClassPathElement> _classPathEntries;
+}

src/main/java/com/threerings/getdown/classpath/ClassPathBuilder.java

@@ -0,0 +1,13 @@
+package com.threerings.getdown.classpath;
+
+import java.io.IOException;
+
+/**
+ * A class path builder compiles the class path of the application to be launched.
+ */
+public interface ClassPathBuilder {
+    /**
+     * Builds and returns the class path of the application to be launched.
+     */
+    ClassPath buildClassPath () throws IOException;
+}

src/main/java/com/threerings/getdown/classpath/ClassPathBuilderBase.java

@@ -0,0 +1,14 @@
+package com.threerings.getdown.classpath;
+
+import com.threerings.getdown.data.Application;
+
+/**
+ * Base class for {@link ClassPathBuilder class path builders}.
+ */
+abstract class ClassPathBuilderBase implements ClassPathBuilder {
+    public ClassPathBuilderBase(Application _application) {
+        this._application = _application;
+    }
+
+    protected final Application _application;
+}

src/main/java/com/threerings/getdown/classpath/ClassPathBuilderFactory.java

@@ -0,0 +1,22 @@
+package com.threerings.getdown.classpath;
+
+import com.threerings.getdown.data.Application;
+
+/**
+ * A factory for {@link ClassPathBuilder class path builders}.
+ */
+public abstract class ClassPathBuilderFactory {
+    private ClassPathBuilderFactory () {
+    }
+
+    /**
+     * Creates a class path builder that is able to compile the class path of the supplied
+     * {@link Application application}.
+     */
+    public static ClassPathBuilder create (Application application)
+    {
+        return application.isUseCodeCache()
+                ? new CacheBasedClassPathBuilder(application)
+                        : new DefaultClassPathBuilder(application);
+    }
+}

src/main/java/com/threerings/getdown/classpath/ClassPathElement.java

@@ -0,0 +1,47 @@
+package com.threerings.getdown.classpath;
+
+import java.io.File;
+import java.net.MalformedURLException;
+import java.net.URL;
+
+/**
+ * Represents an element of an applications class path.
+ */
+public class ClassPathElement
+{
+    public ClassPathElement (File _file)
+    {
+        this._file = _file;
+    }
+
+    /**
+     * Returns the code resource.
+     */
+    public File getFile ()
+    {
+        return _file;
+    }
+
+
+    /**
+     * Returns the elements absolute path on the file system.
+     */
+    public String getAbsolutePath ()
+    {
+        return _file.getAbsolutePath();
+    }
+
+    /**
+     * Returns the file URL of this class path element.
+     */
+    public URL getURL ()
+    {
+        try {
+            return _file.toURI().toURL();
+        } catch (MalformedURLException e) {
+            throw new IllegalStateException("URL of file is illegal: " + getAbsolutePath(), e);
+        }
+    }
+
+    private final File _file;
+}

src/main/java/com/threerings/getdown/classpath/DefaultClassPathBuilder.java

@@ -0,0 +1,30 @@
+package com.threerings.getdown.classpath;
+
+import java.util.LinkedHashSet;
+
+import com.threerings.getdown.data.Application;
+import com.threerings.getdown.data.Resource;
+
+/**
+ * The default class path builder assembles the class path from the code resources to be found in
+ * the application directory.
+ */
+public class DefaultClassPathBuilder extends ClassPathBuilderBase
+{
+    public DefaultClassPathBuilder(Application _application) {
+        super(_application);
+    }
+
+    @Override
+    public ClassPath buildClassPath ()
+    {
+        LinkedHashSet<ClassPathElement> classPathEntries = new LinkedHashSet<ClassPathElement>();
+
+        for (Resource resource: _application.getActiveCodeResources()) {
+            classPathEntries.add(new ClassPathElement(resource.getFinalTarget()));
+        }
+
+        return new ClassPath(classPathEntries);
+    }
+
+}

src/main/java/com/threerings/getdown/classpath/cache/GarbageCollector.java

@@ -0,0 +1,91 @@
+package com.threerings.getdown.classpath.cache;
+
+import java.io.File;
+import java.util.concurrent.TimeUnit;
+
+import com.threerings.getdown.util.file.FileVisitor;
+import com.threerings.getdown.util.file.FileWalker;
+
+/**
+ * Collects elements in the {@link ResourceCache cache} which became unused and deletes them
+ * afterwards.
+ */
+public class GarbageCollector
+{
+    public GarbageCollector (
+            FileWalker _fileWalker, int retentionPeriod, TimeUnit retentionPeriodTimeUnit)
+    {
+        this._fileWalker = _fileWalker;
+        this._retentionMillis = retentionPeriodTimeUnit.toMillis(retentionPeriod);
+    }
+
+    /**
+     * Collect and delete the garbage in the cache.
+     */
+    public void collectGarbage ()
+    {
+        _fileWalker.walkTree(new FileVisitor() {
+            @Override
+            public void visit(File file)
+            {
+                collect(file);
+            }
+        });
+    }
+
+    private void collect (File file) {
+        File cachedFile = getCachedFile(file);
+        File lastAccessedFile = getLastAccessedFile(file);
+
+        if (!cachedFile.exists() || !lastAccessedFile.exists()) {
+            if (cachedFile.exists()) {
+                cachedFile.delete();
+            } else {
+                lastAccessedFile.delete();
+            }
+        } else if (shouldDelete(lastAccessedFile)) {
+            lastAccessedFile.delete();
+            cachedFile.delete();
+        }
+
+        File folder = file.getParentFile();
+
+        if (folder.list().length == 0) {
+            folder.delete();
+        }
+    }
+
+    private boolean shouldDelete(File lastAccessedFile) {
+        return System.currentTimeMillis() - lastAccessedFile.lastModified() > _retentionMillis;
+    }
+
+    private File getLastAccessedFile (File file)
+    {
+        if (isLastAccessedFile(file)) {
+            return file;
+        }
+
+        return new File(
+                file.getParentFile(),
+                file.getName() + ResourceCache.LAST_ACCESSED_FILE_SUFFIX);
+    }
+
+    private boolean isLastAccessedFile (File file)
+    {
+        return file.getName().endsWith(ResourceCache.LAST_ACCESSED_FILE_SUFFIX);
+    }
+
+    private File getCachedFile (File file)
+    {
+        if (!isLastAccessedFile(file)) {
+            return file;
+        }
+
+        return new File(
+                file.getParentFile(),
+                file.getName().substring(0, file.getName().lastIndexOf(".")));
+    }
+
+    private final FileWalker _fileWalker;
+    private final long _retentionMillis;
+}

src/main/java/com/threerings/getdown/classpath/cache/ResourceCache.java

@@ -0,0 +1,73 @@
+package com.threerings.getdown.classpath.cache;
+
+import java.io.File;
+import java.io.IOException;
+
+import com.threerings.getdown.util.FileUtil;
+
+/**
+ * Maintains a cache of code resources. The cache allows multiple application instances of different
+ * versions to open at the same time.
+ */
+public class ResourceCache
+{
+    public ResourceCache (File _cacheDir) throws IOException
+    {
+        this._cacheDir = _cacheDir;
+
+        createDirectoryIfNecessary(_cacheDir);
+    }
+
+    private void createDirectoryIfNecessary (File dir) throws IOException
+    {
+        if (!dir.exists() && !dir.mkdirs()) {
+            throw new IOException("unable to create directory: " + dir.getAbsolutePath());
+        }
+    }
+
+    /**
+     * Caches the given file under it's {@code digest}.
+     *
+     * @return the cached file
+     */
+    public File cacheFile (File fileToCache, String digest) throws IOException
+    {
+        File cacheLocation = new File(_cacheDir, digest.substring(0, 2));
+        createDirectoryIfNecessary(cacheLocation);
+
+        File cachedFile = new File(cacheLocation, digest + getFileSuffix(fileToCache));
+        File lastAccessedFile = new File(
+                cacheLocation, cachedFile.getName() + LAST_ACCESSED_FILE_SUFFIX);
+
+        if (!cachedFile.exists()) {
+            createNewFile(cachedFile);
+            FileUtil.copy(fileToCache, cachedFile);
+        }
+
+        if (lastAccessedFile.exists()) {
+            lastAccessedFile.setLastModified(System.currentTimeMillis());
+        } else {
+            createNewFile(lastAccessedFile);
+        }
+
+        return cachedFile;
+    }
+
+    private void createNewFile (File fileToCreate) throws IOException
+    {
+        if (!fileToCreate.exists() && !fileToCreate.createNewFile()) {
+            throw new IOException("unable to create new file: " + fileToCreate.getAbsolutePath());
+        }
+    }
+
+    private String getFileSuffix (File fileToCache) {
+        String fileName = fileToCache.getName();
+        int index = fileName.lastIndexOf(".");
+
+        return index > -1 ? fileName.substring(index) : "";
+    }
+
+    private final File _cacheDir;
+
+    static final String LAST_ACCESSED_FILE_SUFFIX = ".lastAccessed";
+}

src/main/java/com/threerings/getdown/data/Application.java

@@ -5,9 +5,21 @@
 
 package com.threerings.getdown.data;
 
+import static com.threerings.getdown.Log.log;
+
 import java.awt.Color;
 import java.awt.Rectangle;
-import java.io.*;
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.FileReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.PrintStream;
+import java.io.RandomAccessFile;
 import java.lang.reflect.Method;
 import java.net.MalformedURLException;
 import java.net.URL;
@@ -16,27 +28,46 @@ import java.net.URLConnection;
 import java.nio.channels.FileChannel;
 import java.nio.channels.FileLock;
 import java.nio.channels.OverlappingFileLockException;
-import java.security.*;
+import java.security.AllPermission;
+import java.security.CodeSource;
+import java.security.GeneralSecurityException;
+import java.security.PermissionCollection;
+import java.security.Permissions;
+import java.security.Signature;
 import java.security.cert.Certificate;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.EnumMap;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 import javax.swing.JApplet;
 
+import org.apache.commons.codec.binary.Base64;
+
 import com.samskivert.io.StreamUtil;
 import com.samskivert.text.MessageUtil;
 import com.samskivert.util.ArrayUtil;
 import com.samskivert.util.RandomUtil;
 import com.samskivert.util.RunAnywhere;
 import com.samskivert.util.StringUtil;
-
-import org.apache.commons.codec.binary.Base64;
-
+import com.threerings.getdown.classpath.ClassPath;
+import com.threerings.getdown.classpath.ClassPathBuilderFactory;
 import com.threerings.getdown.launcher.RotatingBackgrounds;
-import com.threerings.getdown.util.*;
-
-import static com.threerings.getdown.Log.log;
+import com.threerings.getdown.util.ConfigUtil;
+import com.threerings.getdown.util.ConnectionUtil;
+import com.threerings.getdown.util.FileUtil;
+import com.threerings.getdown.util.LaunchUtil;
+import com.threerings.getdown.util.ProgressAggregator;
+import com.threerings.getdown.util.ProgressObserver;
+import com.threerings.getdown.util.VersionUtil;
 
 /**
  * Parses and provide access to the information contained in the <code>getdown.txt</code>
@@ -226,10 +257,10 @@ public class Application
     {
         _appdir = appdir;
         _appid = appid;
-        _signers = (signers == null) ? Collections.<Certificate>emptyList() : signers;
+        _signers = signers == null ? Collections.<Certificate>emptyList() : signers;
         _config = getLocalPath(CONFIG_FILE);
-        _extraJvmArgs = (jvmargs == null) ? ArrayUtil.EMPTY_STRING : jvmargs;
-        _extraAppArgs = (appargs == null) ? ArrayUtil.EMPTY_STRING : appargs;
+        _extraJvmArgs = jvmargs == null ? ArrayUtil.EMPTY_STRING : jvmargs;
+        _extraAppArgs = appargs == null ? ArrayUtil.EMPTY_STRING : appargs;
     }
 
     /**
@@ -352,7 +383,7 @@ public class Application
             return null;
         }
 
-        String infix = (auxgroup == null) ? "" : ("-" + auxgroup);
+        String infix = auxgroup == null ? "" : "-" + auxgroup;
         String pfile = "patch" + infix + _version + ".dat";
         try {
             URL remote = new URL(createVAppBase(_targetVersion), encodePath(pfile));
@@ -514,7 +545,7 @@ public class Application
 
         // if we are a versioned deployment, create a versioned appbase
         try {
-            _vappbase = (_version < 0) ? new URL(_appbase) : createVAppBase(_version);
+            _vappbase = _version < 0 ? new URL(_appbase) : createVAppBase(_version);
         } catch (MalformedURLException mue) {
             String err = MessageUtil.tcompose("m.invalid_appbase", _appbase);
             throw (IOException) new IOException(err).initCause(mue);
@@ -531,7 +562,7 @@ public class Application
             }
         }
 
-        String appPrefix = StringUtil.isBlank(_appid) ? "" : (_appid + ".");
+        String appPrefix = StringUtil.isBlank(_appid) ? "" : _appid + ".";
 
         // determine our application class name
         _class = (String)cdata.get(appPrefix + "class");
@@ -656,6 +687,11 @@ public class Application
         // obtain a thread dump of the running JVM
         _windebug = getLocalPath("debug.txt").exists();
 
+        // whether to cache code resources and launch from cache
+        _useCodeCache = Boolean.parseBoolean((String) cdata.get("use_code_cache"));
+        _codeCacheRetentionDays = cdata.containsKey("code_cache_retention_days")
+                ? Integer.parseInt((String) cdata.get("use_code_cache")) : 7;
+
         // parse and return our application config
         UpdateInterface ui = new UpdateInterface();
         _name = ui.name = (String)cdata.get("ui.name");
@@ -673,9 +709,9 @@ public class Application
         }
         // and now ui.background can refer to the background color, but fall back to black
         // or white, depending on the brightness of the progressText
-        Color defaultBackground = (.5f < Color.RGBtoHSB(
+        Color defaultBackground = .5f < Color.RGBtoHSB(
                 ui.progressText.getRed(), ui.progressText.getGreen(), ui.progressText.getBlue(),
-                null)[2])
+                null)[2]
             ? Color.BLACK
             : Color.WHITE;
         ui.background = parseColor(cdata, "ui.background", defaultBackground);
@@ -690,7 +726,7 @@ public class Application
 
         // On an installation error, where do we point the user.
         String installError = parseUrl(cdata, "ui.install_error", null);
-        ui.installError = (installError == null) ?
+        ui.installError = installError == null ?
             "m.default_install_error" : MessageUtil.taint(installError);
 
         // the patch notes bits
@@ -802,8 +838,8 @@ public class Application
                 }
             }
 
-            boolean minVersionOK = (_javaMinVersion == 0) || (version >= _javaMinVersion);
-            boolean maxVersionOK = (_javaMaxVersion == 0) || (version <= _javaMaxVersion);
+            boolean minVersionOK = _javaMinVersion == 0 || version >= _javaMinVersion;
+            boolean maxVersionOK = _javaMaxVersion == 0 || version <= _javaMaxVersion;
             return minVersionOK && maxVersionOK;
 
         } catch (RuntimeException re) {
@@ -901,16 +937,11 @@ public class Application
         boolean dashJarMode = MANIFEST_CLASS.equals(_class);
 
         // add the -classpath arguments if we're not in -jar mode
-        StringBuilder cpbuf = new StringBuilder();
-        for (Resource rsrc : getActiveCodeResources()) {
-            if (cpbuf.length() > 0) {
-                cpbuf.append(File.pathSeparator);
-            }
-            cpbuf.append(rsrc.getFinalTarget().getAbsolutePath());
-        }
+        ClassPath classPath = ClassPathBuilderFactory.create(this).buildClassPath();
+
         if (!dashJarMode) {
             args.add("-classpath");
-            args.add(cpbuf.toString());
+            args.add(classPath.asArgumentString());
         }
 
         // we love our Mac users, so we do nice things to preserve our application identity
@@ -960,7 +991,7 @@ public class Application
         // if we're in -jar mode add those arguments, otherwise add the app class name
         if (dashJarMode) {
             args.add("-jar");
-            args.add(cpbuf.toString());
+            args.add(classPath.asArgumentString());
         } else {
             args.add(_class);
         }
@@ -1006,20 +1037,17 @@ public class Application
 
     /**
      * Runs this application directly in the current VM.
+     * @throws IOException
      */
-    public void invokeDirect (JApplet applet)
+    public void invokeDirect (JApplet applet) throws IOException
     {
-        // create a custom class loader
-        ArrayList<URL> jars = new ArrayList<URL>();
-        for (Resource rsrc : getActiveCodeResources()) {
-            try {
-                jars.add(new URL("file", "", rsrc.getFinalTarget().getAbsolutePath()));
-            } catch (Exception e) {
-                e.printStackTrace(System.err);
-            }
-        }
+        ClassPath classPath = ClassPathBuilderFactory.create(this).buildClassPath();
+
+        URL[] jarUrls = classPath.asUrls();
+
+        // create custom class loader
         URLClassLoader loader = new URLClassLoader(
-            jars.toArray(new URL[jars.size()]),
+            jarUrls,
             ClassLoader.getSystemClassLoader()) {
             @Override protected PermissionCollection getPermissions (CodeSource code) {
                 Permissions perms = new Permissions();
@@ -1030,7 +1058,9 @@ public class Application
         Thread.currentThread().setContextClassLoader(loader);
 
         log.info("Configured URL class loader:");
-        for (URL url : jars) log.info("  " + url);
+        for (URL url : jarUrls) {
+            log.info("  " + url);
+        }
 
         // configure any system properties that we can
         for (String jvmarg : _jvmargs) {
@@ -1126,12 +1156,6 @@ public class Application
         log.info("Verifying application: " + _vappbase);
         log.info("Version: " + _version);
         log.info("Class: " + _class);
-//         log.info("Code: " +
-//                  StringUtil.toString(getCodeResources().iterator()));
-//         log.info("Resources: " +
-//                  StringUtil.toString(getActiveResources().iterator()));
-//         log.info("JVM Args: " + StringUtil.toString(_jvmargs.iterator()));
-//         log.info("App Args: " + StringUtil.toString(_appargs.iterator()));
 
         // this will read in the contents of the digest file and validate itself
         try {
@@ -1145,7 +1169,7 @@ public class Application
         if (_version == -1) {
             // make a note of the old meta-digest, if this changes we need to revalidate all of our
             // resources as one or more of them have also changed
-            String olddig = (_digest == null) ? "" : _digest.getMetaDigest();
+            String olddig = _digest == null ? "" : _digest.getMetaDigest();
             try {
                 status.updateStatus("m.checking");
                 downloadDigestFile();
@@ -1299,7 +1323,7 @@ public class Application
             failures.add(rsrc);
         }
 
-        return (failures.size() == 0) ? null : failures;
+        return failures.size() == 0 ? null : failures;
     }
 
     /**
@@ -1357,6 +1381,24 @@ public class Application
         return _version;
     }
 
+    /**
+     * Returns whether the application should cache code resources prior to launching the
+     * application.
+     */
+    public boolean isUseCodeCache ()
+    {
+        return _useCodeCache;
+    }
+
+    /**
+     * Returns the number of days a cached code resource is allowed to stay unused before it
+     * becomes eligible for deletion.
+     */
+    public int getCodeCacheRetentionDays ()
+    {
+        return _codeCacheRetentionDays;
+    }
+
     /**
      * Creates a versioned application base URL for the specified version.
      */
@@ -1602,7 +1644,7 @@ public class Application
     {
         String value = (String)cdata.get(name);
         Rectangle rect = parseRect(name, value);
-        return (rect == null) ? def : rect;
+        return rect == null ? def : rect;
     }
 
     /** Helper function to add all values in {@code values} (if non-null) to {@code target}. */
@@ -1647,7 +1689,7 @@ public class Application
     {
         String value = (String)cdata.get(name);
         Color color = parseColor(value);
-        return (color == null) ? def : color;
+        return color == null ? def : color;
     }
 
     /**
@@ -1670,7 +1712,7 @@ public class Application
     protected String[] parseList (Map<String, Object> cdata, String name)
     {
         String value = (String)cdata.get(name);
-        return (value == null) ? ArrayUtil.EMPTY_STRING : StringUtil.parseStringArray(value);
+        return value == null ? ArrayUtil.EMPTY_STRING : StringUtil.parseStringArray(value);
     }
 
     /**
@@ -1746,6 +1788,19 @@ public class Application
         }
     }
 
+    /**
+     * Returns the digest of the given {@code resource}.
+     */
+    public String getDigest (Resource resource)
+    {
+        return _digest.getDigest(resource);
+    }
+
+    public File getAppdir()
+    {
+        return _appdir;
+    }
+
     protected File _appdir;
     protected String _appid;
     protected File _config;
@@ -1780,6 +1835,9 @@ public class Application
     protected List<Resource> _codes = new ArrayList<Resource>();
     protected List<Resource> _resources = new ArrayList<Resource>();
 
+    protected boolean _useCodeCache;
+    protected int _codeCacheRetentionDays;
+
     protected Map<String,AuxGroup> _auxgroups = new HashMap<String,AuxGroup>();
     protected Map<String,Boolean> _auxactive = new HashMap<String,Boolean>();
 

src/main/java/com/threerings/getdown/data/Digest.java

@@ -5,27 +5,24 @@
 
 package com.threerings.getdown.data;
 
+import static com.threerings.getdown.Log.log;
+
 import java.io.File;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
-
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
-
 import java.util.HashMap;
 import java.util.List;
 
 import com.samskivert.io.StreamUtil;
 import com.samskivert.text.MessageUtil;
 import com.samskivert.util.StringUtil;
-
 import com.threerings.getdown.util.ConfigUtil;
 import com.threerings.getdown.util.ProgressObserver;
 
-import static com.threerings.getdown.Log.log;
-
 /**
  * Manages the <code>digest.txt</code> file and the computing and processing of MD5 digests for an
  * application.
@@ -148,6 +145,14 @@ public class Digest
         data.append(path).append(" = ").append(digest).append("\n");
     }
 
+    /**
+     * Returns the digest of the given {@code resource}.
+     */
+    public String getDigest (Resource resource)
+    {
+        return _digests.get(resource.getPath());
+    }
+
     protected HashMap<String, String> _digests = new HashMap<String, String>();
     protected String _metaDigest = "";
 }

src/main/java/com/threerings/getdown/util/FileUtil.java

@@ -5,7 +5,15 @@
 
 package com.threerings.getdown.util;
 
-import java.io.*;
+import static com.threerings.getdown.Log.log;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.Reader;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.jar.JarOutputStream;
@@ -14,8 +22,6 @@ import java.util.zip.GZIPInputStream;
 
 import com.samskivert.io.StreamUtil;
 
-import static com.threerings.getdown.Log.log;
-
 /**
  * File related utilities.
  */
@@ -109,7 +115,6 @@ public class FileUtil extends com.samskivert.util.FileUtil
             Pack200.Unpacker unpacker = Pack200.newUnpacker();
             unpacker.unpack(packedJarIn, jarOutputStream);
             return true;
-
         } catch (IOException e) {
             log.warning("Failed to unpack packed 200 jar file", "jar", packedJar, "error", e);
             return false;
@@ -120,4 +125,22 @@ public class FileUtil extends com.samskivert.util.FileUtil
             StreamUtil.close(packedJarIn);
         }
     }
+
+    /**
+     * Copies the given {@code source} file to the given {@code target}.
+     */
+    public static void copy(File source, File target) throws IOException {
+        FileInputStream in = null;
+        FileOutputStream out = null;
+
+        try {
+            in = new FileInputStream(source);
+            out = new FileOutputStream(target);
+
+            StreamUtil.copy(in, out);
+        } finally {
+            StreamUtil.close(in);
+            StreamUtil.close(out);
+        }
+    }
 }

src/main/java/com/threerings/getdown/util/file/FileVisitor.java

@@ -0,0 +1,6 @@
+package com.threerings.getdown.util.file;
+import java.io.File;
+
+public interface FileVisitor {
+    void visit(File file);
+}

src/main/java/com/threerings/getdown/util/file/FileWalker.java

@@ -0,0 +1,42 @@
+package com.threerings.getdown.util.file;
+
+import java.io.File;
+import java.util.ArrayDeque;
+import java.util.Arrays;
+import java.util.Deque;
+
+/**
+ * Recursively walks over files and folders. A {@link FileVisitor visitor} is informed for each path
+ * traversed.
+ */
+public class FileWalker
+{
+    public FileWalker (File start)
+    {
+        this._start = start;
+    }
+
+    /**
+     * Walks over the directory tree with the provided {@code visitor}.
+     */
+    public void walkTree (FileVisitor visitor)
+    {
+        Deque<File> stack = new ArrayDeque<File>(Arrays.asList(_start.listFiles()));
+
+        while (!stack.isEmpty()) {
+            File currentFile = stack.pop();
+
+            if (currentFile.exists()) {
+                visitor.visit(currentFile);
+
+                if (currentFile.isDirectory()) {
+                    for (File file: currentFile.listFiles()) {
+                        stack.push(file);
+                    }
+                }
+            }
+        }
+    }
+
+    private final File _start;
+}

src/test/java/com/threerings/getdown/classpath/CacheBasedClassPathBuilderTest.java

@@ -0,0 +1,44 @@
+package com.threerings.getdown.classpath;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.when;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.runners.MockitoJUnitRunner;
+
+import com.threerings.getdown.util.FileUtil;
+
+/**
+ * Tests {@link CacheBasedClassPathBuilderTest}.
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class CacheBasedClassPathBuilderTest extends ClassPathBuilderTestBase
+{
+    @Test
+    public void shouldBuildCacheBasedClassPath () throws IOException
+    {
+        when(_application.getDigest(_firstJar)).thenReturn("first");
+        when(_application.getDigest(_secondJar)).thenReturn("second");
+        when(_application.getCodeCacheRetentionDays()).thenReturn(1);
+
+        File firstCachedJarFile = FileUtil.newFile(
+                _appdir.getRoot(),
+                CacheBasedClassPathBuilder.CACHE_DIR, "fi", "first.jar");
+
+        File secondCachedJarFile = FileUtil.newFile(
+                _appdir.getRoot(),
+                CacheBasedClassPathBuilder.CACHE_DIR, "se", "second.jar");
+
+        String expectedClassPath = firstCachedJarFile.getAbsolutePath()
+                + File.pathSeparator
+                + secondCachedJarFile.getAbsolutePath();
+
+        ClassPath classPath = new CacheBasedClassPathBuilder(_application).buildClassPath();
+
+        assertEquals(expectedClassPath, classPath.asArgumentString());
+    }
+}

src/test/java/com/threerings/getdown/classpath/ClassPathBuilderFactoryTest.java

@@ -0,0 +1,37 @@
+package com.threerings.getdown.classpath;
+
+import static org.junit.Assert.assertTrue;
+import static org.mockito.Mockito.when;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.runners.MockitoJUnitRunner;
+
+import com.threerings.getdown.data.Application;
+
+/**
+ * Checks wether the correct {@link ClassPathBuilder class path builders} are created.
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class ClassPathBuilderFactoryTest
+{
+    @Test
+    public void shouldCreateDefaultClassPathBuilder ()
+    {
+        when(_application.isUseCodeCache()).thenReturn(Boolean.FALSE);
+
+        assertTrue(ClassPathBuilderFactory.create(_application) instanceof DefaultClassPathBuilder);
+    }
+
+    @Test
+    public void shouldCreateCacheClassPathBuilder ()
+    {
+        when(_application.isUseCodeCache()).thenReturn(Boolean.TRUE);
+
+        assertTrue(ClassPathBuilderFactory.create(_application) instanceof CacheBasedClassPathBuilder);
+    }
+
+    @Mock
+    private Application _application;
+}

src/test/java/com/threerings/getdown/classpath/ClassPathBuilderTestBase.java

@@ -0,0 +1,48 @@
+package com.threerings.getdown.classpath;
+
+import static org.mockito.Mockito.when;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.rules.TemporaryFolder;
+import org.mockito.Mock;
+
+import com.threerings.getdown.data.Application;
+import com.threerings.getdown.data.Resource;
+
+/**
+ * Base class for {@link ClassPathBuilder} tests.
+ */
+public abstract class ClassPathBuilderTestBase {
+    @Before
+    public void setupFilesAndResources () throws IOException
+    {
+        _firstJarFile = _appdir.newFile("a.jar");
+        _secondJarFile = _appdir.newFile("b.jar");
+
+        when(_firstJar.getFinalTarget()).thenReturn(_firstJarFile);
+        when(_secondJar.getFinalTarget()).thenReturn(_secondJarFile);
+        when(_application.getActiveCodeResources()).thenReturn(Arrays.asList(_firstJar, _secondJar));
+        when(_application.getAppdir()).thenReturn(_appdir.getRoot());
+    }
+
+    @Mock
+    protected Application _application;
+
+    @Mock
+    protected Resource _firstJar;
+
+    protected File _firstJarFile;
+
+    @Mock
+    protected Resource _secondJar;
+
+    protected File _secondJarFile;
+
+    @Rule
+    public TemporaryFolder _appdir = new TemporaryFolder();
+}

src/test/java/com/threerings/getdown/classpath/ClassPathTest.java

@@ -0,0 +1,60 @@
+package com.threerings.getdown.classpath;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.File;
+import java.io.IOException;
+import java.net.MalformedURLException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.util.LinkedHashSet;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+/**
+ * Tests for {@link ClassPath}.
+ */
+public class ClassPathTest
+{
+    @Before
+    public void createJarsAndSetupClassPath () throws IOException
+    {
+        _firstJar = _folder.newFile("a.jar");
+        _secondJar = _folder.newFile("b.jar");
+
+        LinkedHashSet<ClassPathElement> classPathEntries = new LinkedHashSet<ClassPathElement>();
+
+        classPathEntries.add(new ClassPathElement(_firstJar));
+        classPathEntries.add(new ClassPathElement(_secondJar));
+
+        _classPath = new ClassPath(classPathEntries);
+    }
+
+    @Test
+    public void shouldCreateValidArgumentString ()
+    {
+        assertEquals(
+                _firstJar.getAbsolutePath() + File.pathSeparator + _secondJar.getAbsolutePath(),
+                _classPath.asArgumentString());
+    }
+
+    @Test
+    public void shouldProvideJarUrls () throws MalformedURLException, URISyntaxException
+    {
+        URL[] actualUrls = _classPath.asUrls();
+
+        assertEquals(_firstJar, new File(actualUrls[0].toURI()));
+        assertEquals(_secondJar, new File(actualUrls[1].toURI()));
+    }
+
+    @Rule
+    public TemporaryFolder _folder = new TemporaryFolder();
+
+    private File _firstJar;
+    private File _secondJar;
+
+    private ClassPath _classPath;
+}

src/test/java/com/threerings/getdown/classpath/DefaultClassPathBuilderTest.java

@@ -0,0 +1,31 @@
+package com.threerings.getdown.classpath;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.runners.MockitoJUnitRunner;
+
+/**
+ * Tests the {@link DefaultClassPathBuilder}.
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class DefaultClassPathBuilderTest extends ClassPathBuilderTestBase
+{
+    @Test
+    public void shouldBuildClassPath () throws IOException
+    {
+        ClassPath classPath = new DefaultClassPathBuilder(_application).buildClassPath();
+
+        String expectedClassPath = _firstJarFile.getAbsolutePath()
+                + File.pathSeparator
+                + _secondJarFile.getAbsolutePath();
+
+        assertEquals(expectedClassPath, classPath.asArgumentString());
+    }
+
+
+}

src/test/java/com/threerings/getdown/classpath/cache/GarbageCollectorTest.java

@@ -0,0 +1,91 @@
+package com.threerings.getdown.classpath.cache;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import com.threerings.getdown.util.file.FileWalker;
+
+/**
+ * Validates that cache garbage is collected and deleted correctly.
+ */
+public class GarbageCollectorTest
+{
+    @Before
+    public void setupFiles () throws IOException
+    {
+        _cachedFile = _folder.newFile("abc123.jar");
+        _lastAccessedFile = _folder.newFile("abc123.jar" + ResourceCache.LAST_ACCESSED_FILE_SUFFIX);
+    }
+
+    @Test
+    public void shouldDeleteCacheEntryIfRetentionPeriodIsReached ()
+    {
+        gcNow();
+
+        assertFalse(_cachedFile.exists());
+        assertFalse(_lastAccessedFile.exists());
+    }
+
+    @Test
+    public void shouldDeleteCacheFolderIfFolderIsEmpty ()
+    {
+        gcNow();
+
+        assertFalse(_folder.getRoot().exists());
+    }
+
+    private void gcNow() {
+        GarbageCollector collector = new GarbageCollector(
+                new FileWalker(_folder.getRoot()), -1, TimeUnit.MILLISECONDS);
+
+        collector.collectGarbage();
+    }
+
+    @Test
+    public void shouldKeepFilesInCacheIfRententionPeriodIsNotReached ()
+    {
+        GarbageCollector collector = new GarbageCollector(
+                new FileWalker(_folder.getRoot()), 1, TimeUnit.DAYS);
+
+        collector.collectGarbage();
+
+        assertTrue(_cachedFile.exists());
+        assertTrue(_lastAccessedFile.exists());
+    }
+
+    @Test
+    public void shouldDeleteCachedFileIfLastAccessedFileIsMissing ()
+    {
+        assumeTrue(_lastAccessedFile.delete());
+
+        gcNow();
+
+        assertFalse(_cachedFile.exists());
+    }
+
+    @Test
+    public void shouldDeleteLastAccessedFileIfCachedFileIsMissing ()
+    {
+        assumeTrue(_cachedFile.delete());
+
+        gcNow();
+
+        assertFalse(_lastAccessedFile.exists());
+    }
+
+    @Rule
+    public TemporaryFolder _folder = new TemporaryFolder();
+
+    private File _cachedFile;
+    private File _lastAccessedFile;
+}

src/test/java/com/threerings/getdown/classpath/cache/ResourceCacheTest.java

@@ -0,0 +1,81 @@
+package com.threerings.getdown.classpath.cache;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+/**
+ * Asserts the correct functionality of the {@link ResourceCache}.
+ */
+public class ResourceCacheTest
+{
+    @Before
+    public void setupCache () throws IOException {
+        _fileToCache = _folder.newFile("filetocache.jar");
+        _cache = new ResourceCache(_folder.newFolder(".cache"));
+    }
+
+    @Test
+    public void shouldCacheFile () throws IOException
+    {
+        assertEquals("abc123.jar", cacheFile().getName());
+    }
+
+    private File cacheFile() throws IOException
+    {
+        return _cache.cacheFile(_fileToCache, "abc123");
+    }
+
+    @Test
+    public void shouldTrackFileUsage () throws IOException
+    {
+        File lastAccessedFile = new File(
+                cacheFile().getParentFile(),
+                "abc123.jar" + ResourceCache.LAST_ACCESSED_FILE_SUFFIX);
+
+        assertTrue(lastAccessedFile.exists());
+    }
+
+    @Test
+    public void shouldNotCacheTheSameFile () throws Exception
+    {
+        File cachedFile = cacheFile();
+
+        TimeUnit.MILLISECONDS.sleep(5);
+
+        // caching it another time
+        File sameCachedFile = cacheFile();
+
+        assertEquals(cachedFile.lastModified(), sameCachedFile.lastModified());
+    }
+
+    @Test
+    public void shouldRememberWhenFileWasRequested () throws Exception
+    {
+        cacheFile();
+
+        TimeUnit.MILLISECONDS.sleep(5);
+
+        // caching it another time
+        File sameCachedFile = cacheFile();
+        File lastAccessed = new File(
+                sameCachedFile.getParentFile(),
+                sameCachedFile.getName() + ResourceCache.LAST_ACCESSED_FILE_SUFFIX);
+
+        assertTrue(lastAccessed.lastModified() > sameCachedFile.lastModified());
+    }
+
+    @Rule
+    public TemporaryFolder _folder = new TemporaryFolder();
+
+    private File _fileToCache;
+    private ResourceCache _cache;
+}

src/test/java/com/threerings/getdown/util/FileUtilTest.java

@@ -5,26 +5,49 @@
 
 package com.threerings.getdown.util;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.io.File;
 import java.io.IOException;
 import java.io.StringReader;
 import java.util.List;
 
-import org.junit.*;
-import static org.junit.Assert.*;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
 
 /**
  * Tests {@link FileUtil}.
  */
 public class FileUtilTest
 {
-    @Test public void testReadLines () throws IOException
+    @Test
+    public void testReadLines () throws IOException
     {
         String data = "This is a test\nof a file with\na few lines\n";
         List<String> lines = FileUtil.readLines(new StringReader(data));
         String[] linesBySplit = data.split("\n");
         assertEquals(linesBySplit.length, lines.size());
-        for (int ii = 0; ii < lines.size(); ii++) {
-            assertEquals(linesBySplit[ii], lines.get(ii));
+        for (int i = 0; i < lines.size(); i++) {
+            assertEquals(linesBySplit[i], lines.get(i));
         }
     }
+
+    @Test
+    public void shouldCopyFile () throws IOException
+    {
+        File source = _folder.newFile("source.txt");
+        File target = new File(_folder.getRoot(), "target.txt");
+
+        assertFalse(target.exists());
+
+        FileUtil.copy(source, target);
+
+        assertTrue(target.exists());
+    }
+
+    @Rule
+    public TemporaryFolder _folder = new TemporaryFolder();
 }

src/test/java/com/threerings/getdown/util/file/FileWalkerTest.java

@@ -0,0 +1,41 @@
+package com.threerings.getdown.util.file;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+/**
+ * Class under test: {@link FileWalker}.
+ */
+public class FileWalkerTest
+{
+    @Test
+    public void shouldRecursivelyWalkOverFilesAndFolders () throws IOException
+    {
+        _folder.newFile("a.txt");
+        new File(_folder.newFolder("b"), "b.txt").createNewFile();
+
+        CountingVisitor visitor = new CountingVisitor();
+        new FileWalker(_folder.getRoot()).walkTree(visitor);
+
+        assertEquals(3, visitor.fileCount);
+    }
+
+    public static class CountingVisitor implements FileVisitor
+    {
+        int fileCount = 0;
+
+        @Override
+        public void visit(File file) {
+            fileCount++;
+        }
+    }
+
+    @Rule
+    public TemporaryFolder _folder = new TemporaryFolder();
+}