Issue 6265 - Create shared AdblockEngine instance in AdblockWebView in background

libadblockplus-android/src/org/adblockplus/libadblockplus/android/SingletonEngineProvider.java

-/*
- * This file is part of Adblock Plus <https://adblockplus.org/>,
- * Copyright (C) 2006-present eyeo GmbH
- *
- * Adblock Plus is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 3 as
- * published by the Free Software Foundation.
- *
- * Adblock Plus 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 for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
- */
-package org.adblockplus.libadblockplus.android;
-
-import org.adblockplus.libadblockplus.IsAllowedConnectionCallback;
-
-import android.content.Context;
-import android.content.SharedPreferences;
-import android.net.ConnectivityManager;
-import android.util.Log;
-
-import java.util.Map;
-import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.atomic.AtomicInteger;
-
-/**
- * Provides single instance of AdblockEngine
- */
-public class SingletonEngineProvider implements AdblockEngineProvider
-{
-  private static final String TAG = Utils.getTag(SingletonEngineProvider.class);
-
-  private Context context;
-  private String basePath;
-  private boolean developmentBuild;
-  private String preloadedPreferenceName;
-  private Map<String, Integer> urlToResourceIdMap;
-  private AdblockEngine engine;
-  private CountDownLatch engineCreated;
-  private Long v8IsolateProviderPtr;
-  private Runnable engineCreatedCallback;
-  private Runnable engineDisposedCallback;
-
-  /*
-    Simple ARC management for AdblockEngine
-    Use `retain` and `release`
-   */
-
-  private AtomicInteger referenceCounter = new AtomicInteger(0);
-
-  /**
-   * Init with context
-   * @param context application context
-   * @param basePath file system root to store files
-   *
-   *                 Adblock Plus library will download subscription files and store them on
-   *                 the path passed. The path should exist and the directory content should not be
-   *                 cleared out occasionally. Using `context.getCacheDir().getAbsolutePath()` is not
-   *                 recommended because it can be cleared by the system.
-   * @param developmentBuild debug or release?
-   */
-  public SingletonEngineProvider(Context context, String basePath, boolean developmentBuild)
-  {
-    this.context = context.getApplicationContext();
-    this.basePath = basePath;
-    this.developmentBuild = developmentBuild;
-  }
-
-  @Override
-  public AdblockEngine getAdblockEngine()
-  {
-    return engine;
-  }
-
-  /**
-   * Use preloaded subscriptions
-   * @param preferenceName Shared Preferences name to store intercepted requests stats
-   * @param urlToResourceIdMap
-   */
-  public SingletonEngineProvider preloadSubscriptions(String preferenceName,
-                                                      Map<String, Integer> urlToResourceIdMap)
-  {
-    this.preloadedPreferenceName = preferenceName;
-    this.urlToResourceIdMap = urlToResourceIdMap;
-    return this;
-  }
-
-  public SingletonEngineProvider useV8IsolateProvider(long ptr)
-  {
-    this.v8IsolateProviderPtr = ptr;
-    return this;
-  }
-
-  public SingletonEngineProvider setEngineCreatedCallback(Runnable callback)
-  {
-    this.engineCreatedCallback = callback;
-    return this;
-  }
-
-  public SingletonEngineProvider setEngineDisposedCallback(Runnable callback)
-  {
-    this.engineDisposedCallback = callback;
-    return this;
-  }
-
-  private void createAdblock()
-  {
-    ConnectivityManager connectivityManager =
-      (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
-    IsAllowedConnectionCallback isAllowedConnectionCallback =
-      new IsAllowedConnectionCallbackImpl(connectivityManager);
-
-    Log.d(TAG, "Creating adblock engine ...");
-
-    AdblockEngine.Builder builder = AdblockEngine
-      .builder(
-        AdblockEngine.generateAppInfo(context, developmentBuild),
-        basePath)
-      .setIsAllowedConnectionCallback(isAllowedConnectionCallback)
-      .enableElementHiding(true);
-
-    if (v8IsolateProviderPtr != null)
-    {
-      builder.useV8IsolateProvider(v8IsolateProviderPtr);
-    }
-
-    // if preloaded subscriptions provided
-    if (preloadedPreferenceName != null)
-    {
-      SharedPreferences preloadedSubscriptionsPrefs = context.getSharedPreferences(
-        preloadedPreferenceName,
-        Context.MODE_PRIVATE);
-      builder.preloadSubscriptions(
-        context,
-        urlToResourceIdMap,
-        new AndroidWebRequestResourceWrapper.SharedPrefsStorage(preloadedSubscriptionsPrefs));
-    }
-
-    engine = builder.build();
-
-    Log.d(TAG, "AdblockHelper engine created");
-
-    // sometimes we need to init AdblockEngine instance, eg. set user settings
-    if (engineCreatedCallback != null)
-    {
-      engineCreatedCallback.run();
-    }
-  }
-
-  /**
-   * Wait until everything is ready (used for `retain(true)`)
-   * Warning: locks current thread
-   */
-  public void waitForReady()
-  {
-    if (engineCreated == null)
-    {
-      throw new RuntimeException("AdblockHelper Plus usage exception: call retain(true) first");
-    }
-
-    try
-    {
-      Log.d(TAG, "Waiting for ready ...");
-      engineCreated.await();
-      Log.d(TAG, "Ready");
-    }
-    catch (InterruptedException e)
-    {
-      Log.w(TAG, "Interrupted", e);
-    }
-  }
-
-  private void disposeAdblock()
-  {
-    Log.w(TAG, "Disposing adblock engine");
-
-    engine.dispose();
-    engine = null;
-
-    // sometimes we need to deinit something after AdblockEngine instance disposed
-    // eg. release user settings
-    if (engineDisposedCallback != null)
-    {
-      engineDisposedCallback.run();
-    }
-  }
-
-  /**
-   * Get registered clients count
-   * @return registered clients count
-   */
-  public int getCounter()
-  {
-    return referenceCounter.get();
-  }
-
-  /**
-   * Register AdblockHelper engine client
-   * @param asynchronous If `true` engines will be created in background thread without locking of
-   *                     current thread. Use waitForReady() before getAdblockEngine() later.
-   *                     If `false` locks current thread.
-   * @return if a new instance is allocated
-   */
-  public synchronized boolean retain(boolean asynchronous)
-  {
-    boolean firstInstance = false;
-
-    if (referenceCounter.getAndIncrement() == 0)
-    {
-      firstInstance = true;
-
-      if (!asynchronous)
-      {
-        createAdblock();
-      }
-      else
-      {
-        // latch is required for async (see `waitForReady()`)
-        engineCreated = new CountDownLatch(1);
-
-        new Thread(new Runnable()
-        {
-          @Override
-          public void run()
-          {
-            createAdblock();
-
-            // unlock waiting client thread
-            engineCreated.countDown();
-          }
-        }).start();
-      }
-    }
-    return firstInstance;
-  }
-
-  /**
-   * Unregister AdblockHelper engine client
-   * @return `true` if the last instance is destroyed
-   */
-  public synchronized boolean release()
-  {
-    boolean lastInstance = false;
-
-    if (referenceCounter.decrementAndGet() == 0)
-    {
-      lastInstance = true;
-
-      if (engineCreated != null)
-      {
-        // retained asynchronously
-        waitForReady();
-        disposeAdblock();
-
-        // to unlock waiting client in waitForReady()
-        engineCreated.countDown();
-        engineCreated = null;
-      }
-      else
-      {
-        disposeAdblock();
-      }
-    }
-    return lastInstance;
-  }
-}