Issue 6274 - ANR on cancelling elemhide thread for load error

libadblockplus-android-webview/src/org/adblockplus/libadblockplus/android/webview/AdblockWebView.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
@@ skipping 1012 matching lines @@
           }
 
           d("Requesting elemhide selectors from AdblockEngine for " + url + " in " + this);
           List<String> selectors = adblockEngine.getElementHidingSelectors(url, domain, referrers);
           d("Finished requesting elemhide selectors, got " + selectors.size() + " in " + this);
           selectorsString = Utils.stringListToJsonArray(selectors);
         }
       }
       finally
       {
-        if (!isCancelled.get())
+        if (isCancelled.get())
         {
-          finish(selectorsString);
+          w("This thread is cancelled, exiting silently " + this);
         }
         else
         {
-          w("This thread is cancelled, exiting silently " + this);
+          finish(selectorsString);
         }
       }
     }
 
     private void onFinished()
     {
       finishedLatch.countDown();
       synchronized (finishedRunnableLockObject)
       {
         if (finishedRunnable != null)
@@ skipping 18 matching lines @@
     {
       synchronized (finishedRunnableLockObject)
       {
         this.finishedRunnable = runnable;
       }
     }
 
     public void cancel()
     {
       w("Cancelling elemhide thread " + this);
-      if (!isFinished.get())

[jens, 2018/01/17 08:28:43]

To make the if statement more readable, I would probably reverse the logic.

[anton, 2018/01/17 08:33:55]

Done. See patch set #2

+      if (isFinished.get())
+      {
+        w("This thread is finished, exiting silently " + this);
+      }
+      else
       {
         isCancelled.set(true);
         finish(EMPTY_ELEMHIDE_ARRAY_STRING);
-      }
-      else
-      {
-        w("This thread is finished, exiting silently " + this);
       }
     }
   }
 
   private Runnable elemHideThreadFinishedRunnable = new Runnable()
   {
     @Override
     public void run()
     {
       synchronized (elemHideThreadLockObject)
@@ skipping 349 matching lines @@
         w("Busy with elemhide selectors, delayed disposing scheduled");
         elemHideThread.setFinishedRunnable(disposeRunnable);
       }
       else
       {
         disposeRunnable.run();
       }
     }
   }
 }