craigmj · June 13, 2013 01:07 · Jun 13, 2013
diff --git a/gomaps.go b/gomaps.go
@@ -0,0 +1,201 @@
+package main
+
+import (
+  "fmt"
+	"math/rand"
+	"runtime"
+	"strconv"
+	"sync"
+	"time"
+)
+
+type Map interface {
+	Get(key string) (interface{}, bool)
+	Set(key string, value interface{})
+}
+
+///////////////////////////////// GO ROUTINE BASED MAP ////////////////////////////////////////
+
+type mapResult struct {
+	value interface{}
+	ok    bool
+}
+type mapGet struct {
+	key string
+	out chan mapResult
+}
+type mapSet struct {
+	key   string
+	value interface{}
+}
+
+type GoMap struct {
+	get  chan mapGet
+	set  chan mapSet
+	done chan bool
+	m    map[string]interface{}
+}
+
+func NewGoMap() *GoMap {
+	g := &GoMap{
+		get:  make(chan mapGet),
+		set:  make(chan mapSet),
+		done: make(chan bool),
+		m:    make(map[string]interface{}),
+	}
+	go g.run()
+	return g
+}
+
+func (g *GoMap) run() {
+	defer func() { g.done <- true }()
+	for {
+		select {
+		case r, ok := <-g.get:
+			if !ok {
+				return
+			}
+			value, ok := g.m[r.key]
+			r.out <- mapResult{value, ok}
+		case r, ok := <-g.set:
+			if !ok {
+				return
+			}
+			g.m[r.key] = r.value
+		}
+	}
+}
+
+func (g *GoMap) Stop() {
+	close(g.get)
+	close(g.set)
+	<-g.done
+}
+
+func (g *GoMap) Get(key string) (interface{}, bool) {
+	c := make(chan mapResult)
+	g.get <- mapGet{key, c}
+	r := <-c
+	return r.value, r.ok
+}
+
+func (g *GoMap) Set(key string, value interface{}) {
+	g.set <- mapSet{key, value}
+}
+
+///////////////////////////////// SINGLE CHANNEL GO ROUTINE BASED MAP /////////////////////////
+type GoMap1Chan struct {
+	in   chan interface{}
+	done chan bool
+	m    map[string]interface{}
+}
+
+func NewGoMap1Chan() *GoMap1Chan {
+	g := &GoMap1Chan{in: make(chan interface{}), done: make(chan bool), m: make(map[string]interface{})}
+	go g.run()
+	return g
+}
+
+func (g *GoMap1Chan) run() {
+	defer func() { g.done <- true }()
+	for i := range g.in {
+		switch r := i.(type) {
+		case mapGet:
+			value, ok := g.m[r.key]
+			r.out <- mapResult{value, ok}
+		case mapSet:
+			g.m[r.key] = r.value
+		default:
+			panic("Unknown type on GoMap1Chan in")
+		}
+	}
+}
+
+func (g *GoMap1Chan) Stop() {
+	close(g.in)
+	<-g.done
+}
+
+func (g *GoMap1Chan) Get(key string) (interface{}, bool) {
+	c := make(chan mapResult)
+	g.in <- mapGet{key, c}
+	r := <-c
+	return r.value, r.ok
+}
+
+func (g *GoMap1Chan) Set(key string, value interface{}) {
+	g.in <- mapSet{key, value}
+}
+
+//////////////////////////////////// SYNC BASED MAP //////////////////////////////////
+
+type SyncMap struct {
+	lock sync.RWMutex
+	m    map[string]interface{}
+}
+
+func NewSyncMap() *SyncMap {
+	return &SyncMap{m: make(map[string]interface{})}
+}
+
+func (s *SyncMap) Get(key string) (interface{}, bool) {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
+	value, ok := s.m[key]
+	return value, ok
+}
+
+func (s *SyncMap) Set(key string, value interface{}) {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+	s.m[key] = value
+}
+
+//////////////////////////////////// THE TESTING CODE ////////////////////////////////
+
+func TheTest(g Map, rnd *rand.Rand) time.Duration {
+	start := time.Now()
+	var key string
+	var value string
+	var got interface{}
+	for i := 0; i < 100000; i++ {
+		key = strconv.Itoa(int(rnd.Int31n(500)))
+		value = "The value " + key
+		g.Set(key, value)
+		got, _ = g.Get(key)
+		if value != got {
+			panic(fmt.Sprintf("ERROR: expected %v, got %v", value, got))
+		}
+	}
+	return time.Now().Sub(start)
+}
+
+func TestInParallel(g Map, n int) time.Duration {
+	start := time.Now()
+	var wait sync.WaitGroup
+
+	for i := 0; i < n; i++ {
+		wait.Add(1)
+		go func() {
+			TheTest(g, rand.New(rand.NewSource(time.Now().Unix()+int64(i*500))))
+			wait.Done()
+		}()
+	}
+	wait.Wait()
+	return time.Now().Sub(start)
+}
+
+func main() {
+	runtime.GOMAXPROCS(runtime.NumCPU())
+	gm := NewGoMap()
+	gm1chan := NewGoMap1Chan()
+	sm := NewSyncMap()
+	nRoutines := 10
+	fmt.Println("In parallel on", runtime.NumCPU(), "CPUs with", nRoutines, "goroutines")
+	fmt.Println("GoMap:      ", TestInParallel(gm, nRoutines))
+	fmt.Println("GoMap1Chan: ", TestInParallel(gm1chan, nRoutines))
+	fmt.Println("SyncMap:    ", TestInParallel(sm, nRoutines))
+
+	gm.Stop()
+	gm1chan.Stop()
+}