MapReduce using DataFlow library

Question

I am trying to implement a classic map-reduce problem using System.Threading.Tasks.Dataflow, and although I can get something (sort of) working I'm struggling to see how to generalise this functionality.

Given a simple problem

• Produce a stream of integers; and in parallel for each number
  • Square the number
  • add 5
  • divide by 2
• Take the sum of all numbers

The problem im having is that I can get this working using a BufferBlock, but I have to specify the initial size of the set of parallel tasks. This is fine for the test code (below) as I know upfront how many items im going to queue, but say I didnt know... how would I set this pipeline up?

Test code used (Note I added a short delay into the first of the "Parallel" blocks just to see some processing time difference depending on degrees of parallelism):

using System.Diagnostics;
using System.Threading.Tasks.Dataflow;

var input = 10;

var fanOutBlock = new TransformManyBlock<int, int>(x =>
{
    return Enumerable.Range(1, x).Select(x => x);
});

var squareBlock = new TransformBlock<int, int>(async x =>
 {
     await Task.Delay(100);
     return x * x;
 }, new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 5 });

var addFiveBlock = new TransformBlock<int, int>(x =>
{
    return x + 5;
}, new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 5 });

var divTwoBlock = new TransformBlock<int, double>(x =>
{
    return x/2.0;
}, new ExecutionDataflowBlockOptions { MaxDegreeOfParallelism = 5 });

var batchBlock = new BatchBlock<double>(input);

var sumBlock = new TransformBlock<IList<double>,double>(x =>
{
    return x.Sum();
});

var options = new DataflowLinkOptions { PropagateCompletion = true };

fanOutBlock.LinkTo(squareBlock, options);
squareBlock.LinkTo(addFiveBlock, options);
addFiveBlock.LinkTo(divTwoBlock, options);
divTwoBlock.LinkTo(batchBlock, options);
batchBlock.LinkTo(sumBlock, options);


var sw = Stopwatch.StartNew();
fanOutBlock.Post(input);
fanOutBlock.Complete();


var result = sumBlock.Receive();
Console.WriteLine(result);
sw.Stop();
Console.WriteLine($"{sw.ElapsedMilliseconds}ms");

await sumBlock.Completion;

Answer 1

you can hit url for example www.abc.com/logout

and if you want to change redirection or something and you have laravel basicc setup you can find laravel logout function in LoginController.php File Something like thisenter code here

public function logout(Request $request)
    {
        $user = auth()->user();
        activity($user->name)
            ->performedOn($user)
            ->causedBy($user)
            ->log('LoggedOut');
        $this->guard()->logout();
        $request->session()->invalidate();
        return redirect('/');
    }