Switch SkyShell to its own ResourceExtractor

sky/shell/android/org/domokit/sky/shell/ResourceExtractor.java

Index: sky/shell/android/org/domokit/sky/shell/ResourceExtractor.java
diff --git a/sky/shell/android/org/domokit/sky/shell/ResourceExtractor.java b/sky/shell/android/org/domokit/sky/shell/ResourceExtractor.java
new file mode 100644
index 0000000000000000000000000000000000000000..3976bb9dd2124a87dd48ca0daea638107b405f22
--- /dev/null
+++ b/sky/shell/android/org/domokit/sky/shell/ResourceExtractor.java
@@ -0,0 +1,186 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.domokit.sky.shell;
+
+import android.content.Context;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
+import android.content.res.AssetManager;
+import android.os.AsyncTask;
+import android.util.Log;
+
+import org.chromium.base.PathUtils;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.FilenameFilter;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.HashSet;
+import java.util.concurrent.CancellationException;
+import java.util.concurrent.ExecutionException;
+
+/**
+ * A class to intialize the native code.
+ **/
+public class ResourceExtractor {
+    private static final String TAG = "ResourceExtractor";
+    private static final String TIMESTAMP_PREFIX = "res_timestamp-";
+
+    private class ExtractTask extends AsyncTask<Void, Void, Void> {
+        private static final int BUFFER_SIZE = 16 * 1024;
+
+        public ExtractTask() { }
+
+        private void extractResources() {
+            final File dataDir = new File(PathUtils.getDataDirectory(mContext));
+
+            final String timestamp = checkTimestamp(dataDir);
+            if (timestamp != null) {
+                deleteFiles();
+            }
+
+            final AssetManager manager = mContext.getResources().getAssets();
+            try {
+                byte[] buffer = null;
+                final String[] assets = manager.list("");
+                for (String asset : assets) {
+                    if (!mResources.contains(asset))
+                        continue;
+                    final File output = new File(dataDir, asset);
+                    if (output.exists())
+                        continue;
+                    InputStream is = null;
+                    OutputStream os = null;
+                    try {
+                        is = manager.open(asset);
+                        os = new FileOutputStream(output);
+                        if (buffer == null) {
+                            buffer = new byte[BUFFER_SIZE];
+                        }
+
+                        int count = 0;
+                        while ((count = is.read(buffer, 0, BUFFER_SIZE)) != -1) {
+                            os.write(buffer, 0, count);
+                        }
+                        os.flush();
+                    } finally {
+                        try {
+                            if (is != null) {
+                                is.close();
+                            }
+                        } finally {
+                            if (os != null) {
+                                os.close();
+                            }
+                        }
+                    }
+                }
+            } catch (IOException e) {
+                Log.w(TAG, "Exception unpacking resources: " + e.getMessage());
+                deleteFiles();
+                return;
+            }
+
+            if (timestamp != null) {
+                try {
+                    new File(dataDir, timestamp).createNewFile();
+                } catch (IOException e) {
+                    Log.w(TAG, "Failed to write resource timestamp");
+                }
+            }
+        }
+
+        private String checkTimestamp(File dataDir) {
+            PackageManager packageManager = mContext.getPackageManager();
+            PackageInfo packageInfo = null;
+
+            try {
+                packageInfo = packageManager.getPackageInfo(mContext.getPackageName(), 0);
+            } catch (PackageManager.NameNotFoundException e) {
+                return TIMESTAMP_PREFIX;
+            }
+
+            if (packageInfo == null) {
+                return TIMESTAMP_PREFIX;
+            }
+
+            String expectedTimestamp =
+                    TIMESTAMP_PREFIX + packageInfo.versionCode + "-" + packageInfo.lastUpdateTime;
+
+            final String[] existingTimestamps = getExistingTimestamps(dataDir);
+            if (existingTimestamps.length != 1
+                    || !expectedTimestamp.equals(existingTimestamps[0])) {
+                return expectedTimestamp;
+            }
+
+            return null;
+        }
+
+        @Override
+        protected Void doInBackground(Void... unused) {
+            extractResources();
+            return null;
+        }
+    }
+
+    private final Context mContext;
+    private final HashSet<String> mResources;
+    private ExtractTask mExtractTask;
+
+    public ResourceExtractor(Context context) {
+        mContext = context;
+        mResources = new HashSet<String>();
+    }
+
+    public void addResources(String[] resources) {
+        for (String resource : resources) {
+            mResources.add(resource);
+        }
+    }
+
+    public void start() {
+        assert mExtractTask == null;
+        mExtractTask = new ExtractTask();
+        mExtractTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
+    }
+
+    public void waitForCompletion() {
+        assert mExtractTask != null;
+
+        try {
+            mExtractTask.get();
+        } catch (CancellationException e) {
+            deleteFiles();
+        } catch (ExecutionException e2) {
+            deleteFiles();
+        } catch (InterruptedException e3) {
+            deleteFiles();
+        }
+    }
+
+    private String[] getExistingTimestamps(File dataDir) {
+        return dataDir.list(new FilenameFilter() {
+            @Override
+            public boolean accept(File dir, String name) {
+                return name.startsWith(TIMESTAMP_PREFIX);
+            }
+        });
+    }
+
+    private void deleteFiles() {
+        final File dataDir = new File(PathUtils.getDataDirectory(mContext));
+        for (String resource : mResources) {
+            final File file = new File(dataDir, resource);
+            if (file.exists()) {
+                file.delete();
+            }
+        }
+        for (String timestamp : getExistingTimestamps(dataDir)) {
+            new File(dataDir, timestamp).delete();
+        }
+    }
+}