add reflect-operate-channel

Author: bigwhite

reflect-operate-channel/select-benchmark/benchmark_test.go

@@ -0,0 +1,83 @@
+package main
+
+import (
+	"reflect"
+	"testing"
+)
+
+func createCases(rchs []chan int) []reflect.SelectCase {
+	var cases []reflect.SelectCase
+
+	// 创建recv case
+	for _, ch := range rchs {
+		cases = append(cases, reflect.SelectCase{
+			Dir:  reflect.SelectRecv,
+			Chan: reflect.ValueOf(ch),
+		})
+	}
+	return cases
+}
+
+func BenchmarkSelect(b *testing.B) {
+	var c1 = make(chan int)
+	var c2 = make(chan int)
+	var c3 = make(chan int)
+
+	go func() {
+		for {
+			c1 <- 1
+		}
+	}()
+	go func() {
+		for {
+			c2 <- 2
+		}
+	}()
+	go func() {
+		for {
+			c3 <- 3
+		}
+	}()
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		select {
+		case <-c1:
+		case <-c2:
+		case <-c3:
+		}
+	}
+}
+
+func BenchmarkReflectSelect(b *testing.B) {
+	var c1 = make(chan int)
+	var c2 = make(chan int)
+	var c3 = make(chan int)
+
+	go func() {
+		for {
+			c1 <- 1
+		}
+	}()
+	go func() {
+		for {
+			c2 <- 2
+		}
+	}()
+	go func() {
+		for {
+			c3 <- 3
+		}
+	}()
+
+	chs := createCases([]chan int{c1, c2, c3})
+
+	b.ReportAllocs()
+	b.ResetTimer()
+
+	for i := 0; i < b.N; i++ {
+		_, _, _ = reflect.Select(chs)
+	}
+}

reflect-operate-channel/select-recv-with-default/go.mod

@@ -0,0 +1,3 @@
+module demo
+
+go 1.19

reflect-operate-channel/select-recv-with-default/main.go

@@ -0,0 +1,77 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"reflect"
+	"sync"
+	"time"
+)
+
+func main() {
+	var wg sync.WaitGroup
+	wg.Add(2)
+	var rchs []chan int
+	for i := 0; i < 10; i++ {
+		rchs = append(rchs, make(chan int))
+	}
+
+	// 创建SelectCase
+	var cases = createRecvCases(rchs, true)
+
+	// 消费者goroutine
+	go func() {
+		defer wg.Done()
+		for {
+			chosen, recv, ok := reflect.Select(cases)
+			if cases[chosen].Dir == reflect.SelectDefault {
+				fmt.Println("choose the default")
+				continue
+			}
+			if ok {
+				fmt.Printf("recv from channel [%d], val=%v\n", chosen, recv)
+				continue
+			}
+			// one of the channels is closed, exit the goroutine
+			fmt.Printf("channel [%d] closed, select goroutine exit\n", chosen)
+			return
+		}
+	}()
+
+	// 生产者goroutine
+	go func() {
+		defer wg.Done()
+		var n int
+		s := rand.NewSource(time.Now().Unix())
+		r := rand.New(s)
+		for i := 0; i < 10; i++ {
+			n = r.Intn(10)
+			rchs[n] <- n
+		}
+		close(rchs[n])
+	}()
+
+	wg.Wait()
+}
+
+func createRecvCases(rchs []chan int, withDefault bool) []reflect.SelectCase {
+	var cases []reflect.SelectCase
+
+	// 创建recv case
+	for _, ch := range rchs {
+		cases = append(cases, reflect.SelectCase{
+			Dir:  reflect.SelectRecv,
+			Chan: reflect.ValueOf(ch),
+		})
+	}
+
+	if withDefault {
+		cases = append(cases, reflect.SelectCase{
+			Dir:  reflect.SelectDefault,
+			Chan: reflect.Value{},
+			Send: reflect.Value{},
+		})
+	}
+
+	return cases
+}

reflect-operate-channel/select-recv/go.mod

@@ -0,0 +1,3 @@
+module demo
+
+go 1.19

reflect-operate-channel/select-recv/main.go

@@ -0,0 +1,64 @@
+package main
+
+import (
+	"fmt"
+	"math/rand"
+	"reflect"
+	"sync"
+	"time"
+)
+
+func main() {
+	var wg sync.WaitGroup
+	wg.Add(2)
+	var rchs []chan int
+	for i := 0; i < 10; i++ {
+		rchs = append(rchs, make(chan int))
+	}
+
+	// 创建SelectCase
+	var cases = createRecvCases(rchs)
+
+	// 消费者goroutine
+	go func() {
+		defer wg.Done()
+		for {
+			chosen, recv, ok := reflect.Select(cases)
+			if ok {
+				fmt.Printf("recv from channel [%d], val=%v\n", chosen, recv)
+				continue
+			}
+			// one of the channels is closed, exit the goroutine
+			fmt.Printf("channel [%d] closed, select goroutine exit\n", chosen)
+			return
+		}
+	}()
+
+	// 生产者goroutine
+	go func() {
+		defer wg.Done()
+		var n int
+		s := rand.NewSource(time.Now().Unix())
+		r := rand.New(s)
+		for i := 0; i < 10; i++ {
+			n = r.Intn(10)
+			rchs[n] <- n
+		}
+		close(rchs[n])
+	}()
+
+	wg.Wait()
+}
+
+func createRecvCases(rchs []chan int) []reflect.SelectCase {
+	var cases []reflect.SelectCase
+
+	// 创建recv case
+	for _, ch := range rchs {
+		cases = append(cases, reflect.SelectCase{
+			Dir:  reflect.SelectRecv,
+			Chan: reflect.ValueOf(ch),
+		})
+	}
+	return cases
+}

reflect-operate-channel/select-send/go.mod

@@ -0,0 +1,3 @@
+module demo
+
+go 1.19

reflect-operate-channel/select-send/main.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"fmt"
+	"reflect"
+	"sync"
+)
+
+func main() {
+	var wg sync.WaitGroup
+	wg.Add(2)
+	ch0, ch1, ch2 := make(chan int), make(chan int), make(chan int)
+	var schs = []chan int{ch0, ch1, ch2}
+
+	// 创建SelectCase
+	var cases = createCases(schs)
+
+	// 生产者goroutine
+	go func() {
+		defer wg.Done()
+		for range cases {
+			chosen, _, _ := reflect.Select(cases)
+			fmt.Printf("send to channel [%d], val=%v\n", chosen, cases[chosen].Send)
+			cases[chosen].Chan = reflect.Value{}
+		}
+		fmt.Println("select goroutine exit")
+		return
+	}()
+
+	// 消费者goroutine
+	go func() {
+		defer wg.Done()
+		for range schs {
+			var v int
+			select {
+			case v = <-ch0:
+				fmt.Printf("recv %d from ch0\n", v)
+			case v = <-ch1:
+				fmt.Printf("recv %d from ch1\n", v)
+			case v = <-ch2:
+				fmt.Printf("recv %d from ch2\n", v)
+			}
+		}
+	}()
+
+	wg.Wait()
+}
+
+func createCases(schs []chan int) []reflect.SelectCase {
+	var cases []reflect.SelectCase
+
+	// 创建send case
+	for i, ch := range schs {
+		n := i + 100
+		cases = append(cases, reflect.SelectCase{
+			Dir:  reflect.SelectSend,
+			Chan: reflect.ValueOf(ch),
+			Send: reflect.ValueOf(n),
+		})
+	}
+
+	return cases
+}