concurrency design

cmd/main.go

@@ -16,7 +16,7 @@ func main() {
  fmt.Println("Result :", service.Result())
  }
  }()
- time.Sleep(10 * time.Second)
+ time.Sleep(time.Minute)
  service.Stop()
  fmt.Println("Result at the end :", service.Result())
 }

pi.go

@@ -33,6 +33,7 @@ var (
  one = big.NewFloat(1)
  oneInt = big.NewInt(1)
  two = big.NewInt(2)
+ four = big.NewInt(4)
 )
 
 // calculate next increment
@@ -43,43 +44,51 @@ func (s *Service) calculate(den *big.Int, cIncrement chan<- *big.Float) {
  cIncrement <- &next
 }
 
-// Prepare for next iteration
-func (s *Service) prepare(den *big.Int, minus *bool) {
- if (*minus && den.Sign() > 0) ||
- (!*minus && den.Sign() < 0) {
- den.Neg(den)
- }
-
- if den.Sign() > 0 {
- den.Add(den, two)
- } else {
- den.Sub(den, two)
- }
-
- *minus = !*minus
-}
-
 // Start pi-service
 func (s *Service) Start() {
- minus := false
- cIncrement := make(chan *big.Float)
- den := *big.NewInt(-3)
+ amountWorkers := 10
+ cIncrement := make(chan *big.Float, amountWorkers)
+ cDen := make(chan *big.Int, amountWorkers)
+
+ // denominator
+ den := big.NewInt(-3)
  go func() {
- defer close(cIncrement)
- // denominator
+ var wg sync.WaitGroup
+ for i := 0; i < amountWorkers; i++ {
+ wg.Add(1)
+ go func() {
+ for d := range cDen {
+ // Step : { 1/(-3) }
+ s.calculate(d, cIncrement)
+
+ // Step : { 1/(+5) }
+ d.Neg(d)
+ d.Add(d, two)
+ s.calculate(d, cIncrement)
+ }
+ wg.Done()
+ }()
+ }
+ go func() {
+ wg.Wait()
+ close(cIncrement)
+ }()
  for {
  select {
  case <-s.cStop:
+ close(cDen)
  return
  default:
  }
+ copy := new(big.Int).Set(den)
+ cDen <- den
 
- // calculation
- s.calculate(&den, cIncrement)
- // prepare for next iteration
- s.prepare(&den, &minus)
+ den = copy
+ den.Sub(den, four)
 
- s.iter.Add(s.iter, oneInt)
+ s.m.Lock()
+ s.iter.Add(s.iter, two)
+ s.m.Unlock()
  }
  }()