Flows: Collecting Latest

Where conflation can be useful

• Consider a scenario, Where the flow has emitted the emission, and the consumer has still not finished processing the consumption.
• Immediately another emission is sent
• So now the first emission is canceled in between and the new emission is received and starts processing

Observation

Note in the output 3 emissions have taken place, those 3 emissions are in process but only the latest which is the last one is completely processed

Output

Emission -> 0
Emission -> 1
Emission -> 2
Processing emission -> 0
Processing emission -> 1
Processing emission -> 2
Processed emission -> 2

Code

    private val collectLatestDemoFlow = flow {
        // Make 10 emissions in iteration
        repeat(3){
            // Give some delay
            println("Emission -> $it")
            emit(it)
        }
    }.flowOn(Dispatchers.Default)

    fun collectLatest() = viewModelScope.launch{
        // It will show the time taken to execute this block of code
        val time = measureTimeMillis {
            collectLatestDemoFlow.collectLatest {
                println("Processing emission -> $it")
                delay(1000)
                println("Processed emission -> $it")
            }
        }
        println("Time Taken:-> $time")
    }