golang channel example

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package main

import (
	"time"
	"math/rand"
	"fmt"
)

func longTimeRequest() <-chan int32 {
	r := make(chan int32)

	go func() {
		// Simulate a workload.
		time.Sleep(time.Second * 3)
		r <- rand.Int31n(100)
	}()

	return r
}

func sumSquares(a, b int32) int32 {
	return a*a + b*b
}

func main() {
	rand.Seed(time.Now().UnixNano())

	a, b := longTimeRequest(), longTimeRequest()
	fmt.Println(sumSquares(<-a, <-b))
}

Popularity 3/10 Helpfulness 1/10 Language go

Source: go101.org

Tags: channel go

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Contributed on Sep 25 2022

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

golang channel

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2

// When we send data into the channel using a GoRoutine, 
// it will be blocked until the data is consumed by another GoRoutine.

// When we receive data from channel using a GoRoutine, 
// it will be blocked until the data is available in the channel.

func main() {
	runIncrement()
}

func runIncrement() {
	channel := make(chan string)

	go increment(channel)
	time.Sleep(1 * time.Second)

	for msg := range channel {
		fmt.Println(msg)
	}
}

func increment(channel chan string) {
	for i := 0; i < 3; i++ {
		channel <- "Hello Wordl"
	}
	time.Sleep(1 * time.Second)
	close(channel)
}

func runCounter() {
	channel := make(chan string)
	wg := sync.WaitGroup{}

	wg.Add(1)
	go counter(channel, &wg)

	for msg := range channel {
		fmt.Println(msg)
	}
	wg.Wait()
}

func counter(channel chan string, wg *sync.WaitGroup) {
	for i := 0; i < 3; i++ {
		channel <- "Hello world"
	}
	wg.Done()
	close(channel)
}

Popularity 10/10 Helpfulness 3/10 Language go

Source: Grepper

Tags: channel

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Contributed on Apr 18 2022

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

golang channel

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0

package main

import (
	"fmt"
	"time"
)

func main() {
	channelImmutable()
}

// -> you use only allow one channel capacity, but you use 2 capacity, channel can be blocked
// for handle this issue, you must create channel to zero value, like this <- ch
func channelImmutable() {
	ch := make(chan string, 1)
	ch <- "marwan"
	<-ch
	ch <- "jajang"

	fmt.Println("channelOne", <-ch) // and i can print jajang not marwan and this can't be blocked
}

// channelOne print value, with declare to variable channel;
func channelOne() {
	ch := make(chan string, 2)
	ch <- "marwan"
	ch <- "jajang"

	fmt.Println("channelOne", <-ch)
	fmt.Println("channelOne", <-ch)
}

// channelTwo print value and wrapper with gorutine, because with you use loop range not using gorutine channel is blocked, because you print more channel
func channelTwo() {
	ch := make(chan string, 2)
	ch <- "marwan"
	ch <- "jajang"

	go func() {
		for v := range ch {
			fmt.Println(v)
		}
	}()
	time.Sleep(time.Second * 1)
}

// channelThree print value without gorutine, but with loop and length channel
func channelThree() {
	ch := make(chan string, 2)
	ch <- "marwan"
	ch <- "jajang"

	for i := 0; i <= len(ch); i++ {
		fmt.Println(<-ch)
	}
}

Popularity 6/10 Helpfulness 2/10 Language go

Source: Grepper

Tags: channel go

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Contributed on Mar 04 2024

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

golang channels example

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0

package main

import (
	"fmt"
)

func overwrite(n chan int) {
	<-n
	n <- 2021
	c := <-n
	fmt.Println(c)
}

func main() {
	ch := make(chan int, 1)
	ch <- 2022
	overwrite(ch)
}

Popularity 9/10 Helpfulness 2/10 Language go

Source: Grepper

Tags: channels channel

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Contributed on Sep 26 2022

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

golang channels example

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0

package main

import (
	"fmt"
	"time"
)

func main() {
	// channel with capacity of 2
	message := make(chan string, 2)

	go func() {
		message <- "ping 1"
		message <- "ping 2"
		message <- "ping 3"
	}()

	go func() {
		time.Sleep(time.Second)
		defer close(message)
	}()

	for msg := range message {
		fmt.Println(msg)
	}

}

Popularity 8/10 Helpfulness 2/10 Language go

Source: Grepper

Tags: channels channel

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Contributed on Sep 26 2022

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

golang channel

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0

package main

import (
	"errors"
	"fmt"
	"log"
	"time"
)

// anda dapat mencetak nilai setelah gorutine itu selesai process nya, ganti time.Sleep dengan sync.WaitGroup
func main() {
	SuccessOne()
}

func SuccessOne() {
	resChan := make(chan string, 1)
	errChan := make(chan error, 1)

	go func(chRes chan string, chErr chan error) {
		perkalian := 2 * 2

		if perkalian == 4 {
			chRes <- "Success"
		} else {
			chErr <- errors.New("Failed")
		}

	}(resChan, errChan)

	time.Sleep(time.Second * 1)

	select {
	case err := <-errChan:
		if err != nil {
			log.Fatal(err)
		}

	case res := <-resChan:
		if res != "" {
			fmt.Println(res)
		}

	default:
		fmt.Println("Not received channel")
	}
}

func SuccessTwo() {
	resChan := make(chan string, 1)
	errChan := make(chan error, 1)

	go func(chRes chan string, chErr chan error) {
		perkalian := 2 * 2

		if perkalian == 4 {
			defer close(chErr)
			chRes <- "Success"
		} else {
			defer close(chRes)
			chErr <- errors.New("Failed")
		}

	}(resChan, errChan)

	time.Sleep(time.Second * 1)

	if err := <-errChan; err != nil {
		log.Fatal(err)
	}

	fmt.Println(<-resChan)
}

func SuccessThree() {
	resChan := make(chan string, 1)
	errChan := make(chan error, 1)

	go func(chRes chan string, chErr chan error) {
		perkalian := 2 * 2

		if perkalian == 4 {
			chErr <- nil
			chRes <- "Success"
		} else {
			chRes <- ""
			chErr <- errors.New("Failed")
		}

	}(resChan, errChan)

	time.Sleep(time.Second * 1)

	if err := <-errChan; err != nil {
		log.Fatal(err)
	}

	fmt.Println(<-resChan)
}

// dikarenakan perkalian nilainya sama dengan 4 dan chRes menerima nilai success, 
// tetapi chErr tidak menerima nilai dan ini mengakibatkan chErr melakukan pemblokiran, karena channel nya selalu open dan nilainya kosong
// jadi dia harus di tutup atau di beri nilai atau menugnakan select untuk memilih channel mana yang memiliki nilai, untuk menghindari pemblokiran

func WrongCode() {
	resChan := make(chan string, 1)
	errChan := make(chan error, 1)

	go func(chRes chan string, chErr chan error) {
		perkalian := 2 * 2

		if perkalian == 4 {
			chRes <- "Success"
		} else {
			chErr <- errors.New("Failed")
		}

	}(resChan, errChan)

	time.Sleep(time.Second * 1)

	if err := <-errChan; err != nil {
		log.Fatal(err)
	}

	fmt.Println(<-resChan)
}

Popularity 6/10 Helpfulness 1/10 Language go

Source: Grepper

Tags: channel go

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Contributed on Mar 04 2024

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

golang channel

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0

package main

import (
	"fmt"
	"time"
)

func main() {
	ch := make(chan string, 1)

	go func(chStr chan string) {
		chStr <- "Fuck Israel"
	}(ch)

	go func(chStr chan string) {
		fmt.Println(<-chStr)
		chStr <- "Free Palestine"
	}(ch)

	time.Sleep(time.Second * 1)

	fmt.Println(<-ch)
}

Popularity 5/10 Helpfulness 1/10 Language go

Source: Grepper

Tags: channel go

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Contributed on Mar 04 2024

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

golang channel

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0

// if you use channel inside gorutine can't use defer in wg
// because this is deadlock, because channel is async process
// if you use channel, for better experience pass channel into params gorutine

package main

import (
	"fmt"
	"sync"
)

func main() {
	wg := sync.WaitGroup{}
	ch := make(chan int)

	wg1 := sync.WaitGroup{}
	slc := []int{}

	for i := 0; i < 5; i++ {
		wg.Add(1)
		go func(chInt chan int) {
			wg.Done()
			chInt <- i

		}(ch)

	}
	wg.Wait()

	for i := 0; i < 5; i++ {
		wg1.Add(1)
		go func() {
			defer wg1.Done()
			slc = append(slc, i)

		}()
	}
	wg1.Wait()

	fmt.Println(<-ch)
	fmt.Println(slc)
}

Popularity 5/10 Helpfulness 1/10 Language go

Source: Grepper

Tags: channel go

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Contributed on Mar 05 2024

Restu Wahyu Saputra

0 Answers Avg Quality 2/10

golang channel example

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