From 2e420b099775ca52d261b72092ce7e615a7a5847 Mon Sep 17 00:00:00 2001
From: Silvan Jegen <s.jegen@gmail.com>
Date: Tue, 29 Nov 2016 21:32:22 +0100
Subject: Run one Work load in one Goroutine

---
 manager.go | 101 +++++++++++++++++++++++++++++++------------------------------
 1 file changed, 52 insertions(+), 49 deletions(-)

diff --git a/manager.go b/manager.go
index b6b41fb..3253129 100644
--- a/manager.go
+++ b/manager.go
@@ -8,6 +8,7 @@ import (
 	"io"
 	"os"
 	"strings"
+	"sync"
 )
 
 type Manager struct {
@@ -25,7 +26,7 @@ type StdinInput struct {
 }
 
 type Filter interface {
-	Filter(chan *Work) chan *Work
+	Filter(*Work) *Work
 }
 
 type StringFilter struct {
@@ -34,7 +35,7 @@ type StringFilter struct {
 }
 
 type Output interface {
-	Output(chan *Work)
+	Output(*Work)
 }
 
 type StdoutOutput struct {
@@ -67,67 +68,69 @@ func (i *StdinInput) Start() chan *Work {
 	return i.retchan
 }
 
-func (f *StringFilter) Filter(ic chan *Work) chan *Work {
-	f.retchan = make(chan *Work, 100)
+func (f *StringFilter) Filter(w *Work) *Work {
 	if f.FilterFuncMap == nil {
 		f.FilterFuncMap = make(map[string]func(string) string, 10)
 		f.FilterFuncMap["F"] = func(s string) string { return strings.ToUpper(s) }
 	}
 
-	go func() {
-		for w := range ic {
-			dec := json.NewDecoder(bytes.NewReader(w.data))
-			jm := make(map[string]string, 10)
-
-			err := dec.Decode(&jm)
-			if err == io.EOF {
-				fmt.Printf("EOF jm: %v\n", jm)
-				f.retchan <- w
-				continue
-			}
-			if err != nil {
-				fmt.Printf("Error when decoding JSON: %q\n", err)
-				w.err = err
-			}
+	dec := json.NewDecoder(bytes.NewReader(w.data))
+	jm := make(map[string]string, 10)
 
-			changed := false
-			for k, v := range jm {
-				ff, ok := f.FilterFuncMap[k]
-				if !ok {
-					continue
-				}
+	err := dec.Decode(&jm)
+	if err == io.EOF {
+		fmt.Printf("EOF jm: %v\n", jm)
+		return w
+	}
+	if err != nil {
+		fmt.Printf("Error when decoding JSON: %q\n", err)
+		w.err = err
+		return w
+	}
 
-				jm[k] = ff(v)
-				changed = true
-			}
-			if changed {
-				bs, err := json.Marshal(jm)
-				if err != nil {
-					fmt.Printf("Error when marshalling JSON: %q\n", err)
-					w.err = err
-				} else {
-					w.data = bs
-				}
-			}
+	changed := false
+	for k, v := range jm {
+		ff, ok := f.FilterFuncMap[k]
+		if !ok {
+			continue
+		}
 
-			f.retchan <- w
+		jm[k] = ff(v)
+		changed = true
+	}
+	if changed {
+		bs, err := json.Marshal(jm)
+		if err != nil {
+			fmt.Printf("Error when marshalling JSON: %q\n", err)
+			w.err = err
+		} else {
+			w.data = bs
 		}
-		close(f.retchan)
-	}()
+	}
 
-	return f.retchan
+	return w
 }
 
-func (o *StdoutOutput) Output(wc chan *Work) {
-	for w := range wc {
-		fmt.Printf("%s\n", w.data)
-	}
+func (o *StdoutOutput) Output(w *Work) {
+	fmt.Printf("%s\n", w.data)
 }
 
-func (m *Manager) Go() {
+func (m *Manager) Run() {
+	var wg sync.WaitGroup
+
 	ic := m.Input.Start()
-	fc := m.Filter.Filter(ic)
-	m.Output.Output(fc)
+	for w := range ic {
+		wg.Add(1)
+
+		go func(w *Work) {
+			nw := m.Filter.Filter(w)
+			m.Output.Output(nw)
+
+			wg.Done()
+		}(w)
+	}
+
+	wg.Wait()
 }
 
 func main() {
@@ -137,5 +140,5 @@ func main() {
 		Output: &StdoutOutput{},
 	}
 
-	m.Go()
+	m.Run()
 }
-- 
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