Paging3 uses the MainThread RPC calling that block the ui thread

[bytetang]

I wrap the RecyclerView with a SwipeRefreshLayout, when first enter the list page, set the SwipeRefreshLayout to loading progress, then do the paging refresh call like this,

 @ExperimentalCoroutinesApi
    private fun searchHistoryData() {
        swipe_container.isRefreshing = true

        searchJob?.cancel()
        searchJob = lifecycleScope.launch {
            viewModel?.refreshGameHistory()?.collect {
                swipe_container.isRefreshing = false
                adapter.submitData(it)
            }
        }
    }

Found the loading components not showing expected. profile the process via Android Studio, the RPC call executed after the adapter.submitData() calling, and it's running upon the main thread.

Since the PRC logics are in PagingSource load() suspend function. I can't decide the load function execute in which thread. my PRC function is a GRPC function, If I convert it to an async function, it will not convenient to handle the result.

In addition, the same as loading views, the footer view LoadState also been blocked.

And how should I do about this issue? If can consider adding an IO thread way to support it?

dependencies:
implementation "androidx.paging:paging-runtime:3.0.0-alpha01"
thanks!

[florina-muntenescu]

This is not an issue with the codelab.
Please use the official issue tracker to report issues with the library.
@dlam fyi

[dlam]

suspend functions are async. You can switch the executing context using withContext(Dispatchers.IO) { ... } in any suspend function. However, the right place to do that is probably to make the grpc call itself suspend and then run in the correct context there, rather than at every place it's called (such as in .load)