Flow.collect still receive value after invoke CoroutineContext.cancel

[baoti]

viewLifecycleOwner.lifecycleScope.launchWhenCreated {
    flow {
        while (true) {
            delay(Random.nextLong(50) + 10)
            emit("launchWhenCreated - ${SystemClock.uptimeMillis()}")
        }
    }
        .flowOn(Dispatchers.Default)
        .collect {
            val currentState = viewLifecycleOwnerLiveData.value?.lifecycle?.currentState
            Timber.d("collect: $value - $currentState")
            if (currentState.isAtLeast(Lifecycle.State.CREATED) != true) {
                // this.isActive == false
                Timber.w("Oops! collect: $value - $currentState")
            }
        }
}

In LifecycleCoroutineScopeImpl.onStateChanged(ON_DESTROY), called coroutineContext.cancel(), but collect still receive value on next loop.

[ThanosFisherman]

I encountered the same problem here

https://stackoverflow.com/questions/59680533/how-to-cancel-unsubscribe-from-coroutines-flow

A workaround is mentioned in #1265

I have replaced every single collect with a safeCollect function in my project:

/**
 * Only proceed with the given action if the coroutine has not been cancelled.
 * Necessary because Flow.collect receives items even after coroutine was cancelled
 * https://github.com/Kotlin/kotlinx.coroutines/issues/1265
 */
suspend inline fun <T> Flow<T>.safeCollect(crossinline action: suspend (T) -> Unit) {
  collect {
    coroutineContext.ensureActive()
    action(it)
  }
}

[elizarov]

This is a duplicate of #1265