scanBleDevices causes memory leak

Summary

Doing a basic scan of ble devices causes a memory leak despite ending the scan subscription at onStop().

Library version

1.10.1

Preconditions

Have sample app cloned & loaded: https://github.com/seljabali/rxandroidble2-leak

Steps to reproduce actual result

1. Enable Bluetooth on device
2. Enable GPS
3. Open app
4. Hit back button
5. Pull system drop down
6. Wait for Canary to analyze heap
7. Canary momentarily shows leak.

Actual result

• Canary showing a memory leak

Expected result

• Canary not showing a memory leak

Minimum code snippet reproducing the issue

scanDisposable = RxBle.get()
    .scanBleDevices(
        ScanSettings.Builder()
            .setScanMode(ScanSettings.SCAN_MODE_LOW_LATENCY)
            .setCallbackType(ScanSettings.CALLBACK_TYPE_ALL_MATCHES)
            .build()
    )
    .subscribeOn(Schedulers.io())
    .observeOn(AndroidSchedulers.mainThread())
    .doOnError {
        onScanError() // commenting this out stops leak
    }
    .doOnNext {
    }
    .subscribe()

Logs from the application running with settings:

https://github.com/seljabali/rxandroidble2-leak/blob/master/leakLog.txt

[dariuszseweryn]

This looks exactly as before, starting the leak at Android’s BleScanCallbackWrapper. I will try to run it once I will get my hands on an API 29 device.

[seotrader]

Hello, I’ve created a PR with a solution to the issue

https://github.com/Polidea/RxAndroidBle/pull/708

Hope it can be merged soon