RxTextView.textChanges crashes when one of subscriptions produces an error

[netimen]

Hi Jake and everyone! Thanks for excellent job!

When I use RxTextView.textChanges with several subscriptions and one of them produces an error (which I handle properly) the app crashes.

Here is the simple code:

RxTextView.textChanges(editQuery)
        .skip(1) // we need the error to happen when the user changes the text so skipping initial value
        .concatMap(cs -> Observable.error(new Exception("aaa")))
        .subscribe(Observers.create(o -> {}, e -> Log.e(LOG_TAG, "error" + e)));

RxTextView.textChanges(editQuery)
        .subscribe(s -> Log.e(LOG_TAG, "text: " + s));

When I run my app and type something in my EditText the app crashes:

java.lang.IndexOutOfBoundsException: Invalid index 1, size is 1
     at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
     at java.util.ArrayList.get(ArrayList.java:308)
     at android.widget.TextView.sendOnTextChanged(TextView.java:7679)
     at android.widget.TextView.handleTextChanged(TextView.java:7739)
     at android.widget.TextView$ChangeWatcher.onTextChanged(TextView.java:9472)
     at android.text.SpannableStringBuilder.sendTextChanged(SpannableStringBuilder.java:964)
     at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:515)
     at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:454)
     at android.text.SpannableStringBuilder.replace(SpannableStringBuilder.java:33)
     at android.view.inputmethod.BaseInputConnection.replaceText(BaseInputConnection.java:685)
     at android.view.inputmethod.BaseInputConnection.setComposingText(BaseInputConnection.java:445)
     at com.android.internal.view.IInputConnectionWrapper.executeMessage(IInputConnectionWrapper.java:340)
     at com.android.internal.view.IInputConnectionWrapper$MyHandler.handleMessage(IInputConnectionWrapper.java:78)
     at android.os.Handler.dispatchMessage(Handler.java:102)
     at android.os.Looper.loop(Looper.java:135)
     at android.app.ActivityThread.main(ActivityThread.java:5257)
     at java.lang.reflect.Method.invoke(Native Method)
     at java.lang.reflect.Method.invoke(java.lang.reflect.Method.java:372)
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

And it happens because when user types something, the first subscription throws an Exception and then TextView.removeTextChangedListener is called in TextViewTextOnSubscribe.java:39 (because of unsubscribe after error). But the TextView is still iterating over it's watchers in the TextView.sendOnTextChanged method!

[dlew]

Interesting; this seems to be a concurrency issue in the Android listener itself. Having solved an almost identical problem to this recently, it's only really solvable if the emitter uses something like CopyOnWriteArrayList (or equivalent concurrency structure) for the listener list.

A simple workaround would be to share the Observable from textChanges() (via something like publish()). Not sure what RxBinding could do to fix it besides warn users of the dangers here.

[dlew]

(In case anyone is curious, here's the exact same problem in a slightly different context and the fix I settled on for now.)

[JakeWharton]

I believe you could also add .unsubscribeOn(mainThread()) which would delay
unsubscription with a post to the next frame.

On Thu, Nov 12, 2015 at 9:04 AM Daniel Lew [email protected] wrote:

(In case anyone is curious, here's the exact same problem in a slightly
different context trello-archive/navi#15 and the fix
I settled on for now
trello-archive/navi@c541812
.)

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[micdm]

Have spent several hours to locate that bug. The easiest example to reproduce (place it to Activity.onCreate for example):

TextView view = new TextView(this);
RxTextView.textChanges(view).skip(1).take(1).subscribe();
RxTextView.textChanges(view).skip(1).subscribe();
view.setText("hello");

Workaround may be (as @dlew mentioned):

Observable<CharSequence> text = RxTextView.textChanges(view).skip(1).share();
text.take(1).subscribe();
text.subscribe();
view.setText("hello");

[JakeWharton]

Has a bug been filed on b.android.com for this ever? I'm struggling to have any desire to fix this in the library.

[micdm]

https://code.google.com/p/android/issues/detail?id=190399 is about that. Seems pretty dead.

[JakeWharton]

Great! I'll take care of it.

On Fri, Jun 24, 2016, 1:40 AM Mikhail Demerzov [email protected]
wrote:

https://code.google.com/p/android/issues/detail?id=190399 is about that.
Seems pretty dead.

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