I'm making a flow that produces a list of files fr...

# coroutines

[David Glasser]

I'm making a flow that produces a list of files from Google Cloud Storage through running paginated executions. The actual RPCs should be in Dispatchers.IO (I think!). I'm not sure if I'm supposed to use withContext for this or flowOn. What I have is:

fun listFiles(bucket: String, prefix: String): Flow<Blob> = flow {
		var page = withContext(<http://Dispatchers.IO|Dispatchers.IO>) {
			gcs.list(bucket, BlobListOption.prefix(prefix))
		}
		while (true) {
			emit(page)
			if (!page.hasNextPage()) {
				break
			}
			page = withContext(<http://Dispatchers.IO|Dispatchers.IO>) { page.nextPage }
		}
	}.flatMapConcat { page ->
		page.values.asFlow()
	}

but I don't know if that is right

[louiscad]

Use flowOn

[David Glasser]

like this?

flow {
		var page = gcs.list(bucket, BlobListOption.prefix(prefix))
		while (true) {
			emit(page)
			if (!page.hasNextPage()) {
				break
			}
			page = page.nextPage
		}
	}
		.flowOn(<http://Dispatchers.IO|Dispatchers.IO>)
		.flatMapConcat { page -> page.values.asFlow() }

[louiscad]

Indent is not standard (should be 4 spaces).

Looks correct to me, but I recommend you to read the docs of flowOn (and Flow) in general to understand what you do and get confidence.