Issue 6274 - ANR on cancelling elemhide thread for load error

libadblockplus-android-webview/src/org/adblockplus/libadblockplus/android/webview/AdblockWebView.java

Index: libadblockplus-android-webview/src/org/adblockplus/libadblockplus/android/webview/AdblockWebView.java
diff --git a/libadblockplus-android-webview/src/org/adblockplus/libadblockplus/android/webview/AdblockWebView.java b/libadblockplus-android-webview/src/org/adblockplus/libadblockplus/android/webview/AdblockWebView.java
index 5536696065bf2e3a6310dd9fa0ecfebede4a857a..f6522dd7c419797d0e77fdffbf65d7fff05ef04b 100644
--- a/libadblockplus-android-webview/src/org/adblockplus/libadblockplus/android/webview/AdblockWebView.java
+++ b/libadblockplus-android-webview/src/org/adblockplus/libadblockplus/android/webview/AdblockWebView.java
@@ -973,11 +973,13 @@ public class AdblockWebView extends WebView
   {
     private String selectorsString;
     private CountDownLatch finishedLatch;
+    private AtomicBoolean isFinished;
     private AtomicBoolean isCancelled;
 
     public ElemHideThread(CountDownLatch finishedLatch)
     {
       this.finishedLatch = finishedLatch;
+      isFinished = new AtomicBoolean(false);
       isCancelled = new AtomicBoolean(false);
     }
 
@@ -1053,6 +1055,7 @@ public class AdblockWebView extends WebView
 
     private void finish(String result)
     {
+      isFinished.set(true);
       d("Setting elemhide string " + result.length() + " bytes");
       elemHideSelectorsString = result;
       onFinished();
@@ -1072,9 +1075,15 @@ public class AdblockWebView extends WebView
     public void cancel()
     {
       w("Cancelling elemhide thread " + this);
-      isCancelled.set(true);
-
-      finish(EMPTY_ELEMHIDE_ARRAY_STRING);
+      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

+      {
+        isCancelled.set(true);
+        finish(EMPTY_ELEMHIDE_ARRAY_STRING);
+      }
+      else
+      {
+        w("This thread is finished, exiting silently " + this);
+      }
     }
   }