NPE in ExtractorMediaSource

[ethanblake4]

Stack trace:

java.lang.NullPointerException: Attempt to invoke interface method 'void com.google.android.exoplayer2.source.MediaSource$Listener.onSourceInfoRefreshed(com.google.android.exoplayer2.source.MediaSource, com.google.android.exoplayer2.Timeline, java.lang.Object)' on a null object reference
        at com.google.android.exoplayer2.source.ExtractorMediaSource.notifySourceInfoRefreshed(ExtractorMediaSource.java:380)
        at com.google.android.exoplayer2.source.ExtractorMediaSource.onSourceInfoRefreshed(ExtractorMediaSource.java:372)
        at com.google.android.exoplayer2.source.ExtractorMediaPeriod.maybeFinishPrepare(ExtractorMediaPeriod.java:555)
        at com.google.android.exoplayer2.source.ExtractorMediaPeriod.access$000(ExtractorMediaPeriod.java:51)
        at com.google.android.exoplayer2.source.ExtractorMediaPeriod$1.run(ExtractorMediaPeriod.java:153)
        at android.os.Handler.handleCallback(Handler.java:790)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:164)
        at android.os.HandlerThread.run(HandlerThread.java:65)

This happened randomly when playing a new queue in my music player app. I wasn't doing anything different than usual, but here is the relevant code, slightly edited for clarity, that was executing at the time:

val i = 0; while (i < dynamicSource.size) {
     dynamicSource.removeMediaSource(i)
}
val sources = MutableList(tracks.size, { z -> sourceFromTrack(tracks[z]).second})
dynamicSource.addMediaSources(sources)

dynamicSource is a DynamicConcatenatingMediaSource.

sourceFromTrack returns an ExtractorMediaSource based on a MediaSource that tails from a RandomAccessFile.

This was tested on a Pixel 2 XL running 8.0.1 with ExoPlayer 2.6.1. I've tested the app hundreds of times and never seen this issue before so I cannot reproduce it. It appears that this is the same as #1914 but that issue is closed.

[tonihei]

Thanks for reporting. This is a bug caused by removing a currently playing or loading child MediaSource from the DynamicConcatenatingMediaSource. It seems this bug has been in the code all the time, but only recent changes in version 2.6.1 made the ExtractorMediaSource throw this NPE because of this bug.

We already have a fix which will be pushed to the dev-branch soon.

[tonihei]

Closing because issue is fixed on the dev branch.