futures.coffee

module futures

import gololang.Async
import java.util.concurrent.TimeUnit
import java.util.concurrent.Executors
import java.lang.Math

# Properties
struct promiseStructure = {
    promise
  , callback
  , executor
}
# Methods
augment futures.types.promiseStructure {
  function task = |this, work| { #this is a setter
    this: promise(): future(): onSet(work)
    return this
  }
  function done = |this, callback| { #this is a setter
    this: callback(callback)
    return this
  }
  function submit = |this, value| {
    this: executor(): submit({
      this: promise(): set(value)
      this: callback()(this: promise(): get())
    })
  }
}
# Constructor
function Promise = |executor| {
  return promiseStructure(promise(), null, executor)
}

struct value = { parameter, result, start, end }

function piCalculus = |howManyIterations| {
  let startTime = System.currentTimeMillis()
  var unQuartDePi = 0.0
  var pi = 0.0
  var k = 0.0

  let term = |k| ->(Math.pow(-1.0, k))/(2*k+1)
  for (var i = 0, i < howManyIterations, i = i + 1) {
      unQuartDePi = unQuartDePi + term(k)
      pi = 4 * unQuartDePi
      k=k+1.0
  }
  return pi
}

function main = |args| {

  let executor = Executors.newCachedThreadPool()

  let p1 = Promise(executor)
    : task(|value| {
        value: result(piCalculus(value: parameter()))
    })
    : done(|value| {
      value: end(System.currentTimeMillis())
      println(
        "Pi = " + value: result() +
        " Duration = " + (value: end() - value: start()) +
        " ms Iterations = " + value: parameter()
      )
    })
    : submit(value()
      : parameter(10000)
      : start(System.currentTimeMillis()
    ))

  let p2 = Promise(executor)
    : task(|value| {
        value: result(piCalculus(value: parameter()))
    })
    : done(|value| {
      value: end(System.currentTimeMillis())
      println(
        "Pi = " + value: result() +
        " Duration = " + (value: end() - value: start()) +
        " ms Iterations = " + value: parameter()
      )
    })
    : submit(value()
      : parameter(1500)
      : start(System.currentTimeMillis()
    ))

  executor: shutdown()
}