more examples

.vscode/extensions.json

@@ -2,6 +2,7 @@
   "recommendations": [
     "streetsidesoftware.code-spell-checker",
     "esbenp.prettier-vscode",
+    "humao.rest-client",
     "firsttris.vscode-jest-runner",
     "dbaeumer.vscode-eslint",
     "EditorConfig.EditorConfig",

go-lang/digital-ocean-multifunc/go.mod

@@ -0,0 +1,3 @@
+module github/vanduc1102/digital-ocean-multifunc
+
+go 1.20

go-lang/digital-ocean-multifunc/main.go

@@ -0,0 +1,42 @@
+package main
+
+import (
+	"fmt"
+	"sync"
+	"time"
+)
+
+func generateNumbers(total int, wg *sync.WaitGroup, ch chan<- int) {
+	defer wg.Done()
+	for i := 1; i <= total; i++ {
+		fmt.Printf("sending %d to channel time=%v\n", i, time.Now())
+		time.Sleep(time.Second * 2)
+		ch <- i
+	}
+}
+
+func printNumbers(wg *sync.WaitGroup, ch <-chan int) {
+	defer wg.Done()
+	for value := range ch {
+		time.Sleep(time.Second)
+		fmt.Printf("reading %d from channel time=%v\n", value, time.Now())
+	}
+}
+
+func main() {
+	var wg sync.WaitGroup
+
+	numberChannel := make(chan int)
+	for i := 0; i < 12; i++ {
+		wg.Add(1)
+		go printNumbers(&wg, numberChannel)
+	}
+
+	generateNumbers(3, &wg, numberChannel)
+
+	close(numberChannel)
+
+	fmt.Printf("Waiting for goroutines to finish... time=%v\n", time.Now())
+	wg.Wait()
+	fmt.Printf("Done at time=%v\n", time.Now())
+}

go-lang/hello/go.mod

@@ -0,0 +1,10 @@
+module example/hello
+
+go 1.20
+
+require rsc.io/quote v1.5.2
+
+require (
+	golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c // indirect
+	rsc.io/sampler v1.3.0 // indirect
+)

go-lang/hello/go.sum

@@ -0,0 +1,6 @@
+golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c h1:qgOY6WgZOaTkIIMiVjBQcw93ERBE4m30iBm00nkL0i8=
+golang.org/x/text v0.0.0-20170915032832-14c0d48ead0c/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+rsc.io/quote v1.5.2 h1:w5fcysjrx7yqtD/aO+QwRjYZOKnaM9Uh2b40tElTs3Y=
+rsc.io/quote v1.5.2/go.mod h1:LzX7hefJvL54yjefDEDHNONDjII0t9xZLPXsUe+TKr0=
+rsc.io/sampler v1.3.0 h1:7uVkIFmeBqHfdjD+gZwtXXI+RODJ2Wc4O7MPEh/QiW4=
+rsc.io/sampler v1.3.0/go.mod h1:T1hPZKmBbMNahiBKFy5HrXp6adAjACjK9JXDnKaTXpA=

go-lang/hello/hello.go

@@ -0,0 +1,13 @@
+// https://go.dev/doc/tutorial/getting-started
+
+package main
+
+import (
+	"fmt"
+
+	"rsc.io/quote"
+)
+
+func main() {
+	fmt.Println("Hello, World: ", quote.Go())
+}

go-lang/learn-go-in-y-minutes/go.mod

@@ -0,0 +1,3 @@
+module example/learn-go-in-y-minutes
+
+go 1.20

go-lang/learn-go-in-y-minutes/main.go

@@ -0,0 +1,94 @@
+// https://learnxinyminutes.com/docs/go/
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"time"
+)
+
+func main() {
+	fmt.Println("Hello , World! from Learn GoLang in Y minutes")
+	fmt.Println("The time is ", time.Now())
+	beyondHello()
+}
+
+func beyondHello() {
+	var x int
+	x = 3
+	y := 4
+
+	sum, prod := learnMultiple(x, y)
+	fmt.Println("sum: ", sum, "prod: ", prod)
+	learnTypes()
+}
+
+func learnMultiple(x, y int) (sum, prod int) {
+	return x + y, x * y
+}
+
+func learnTypes() {
+	str := "Learn Go!"
+
+	s2 := `A \"raw\" string literal
+
+    can include line breaks.`
+
+	g := 'Σ'
+
+	f := 3.1419
+	c := 3 + 4i
+
+	var u uint = 7
+	var pi float32 = 22. / 7
+
+	n := byte('\n')
+
+	var a4 [4]int
+	a5 := [...]int{3, 1, 5, 10, 100}
+
+	a4_cpy := a4
+	a4_cpy[0] = 25
+
+	fmt.Println(a4_cpy[0] == a4[0])
+
+	s3 := []int{4, 5, 9}
+	s4 := make([]int, 4)
+	var d2 [][]float64
+	bs := []byte("a slide")
+
+	s3_cpy := s3
+	s3_cpy[0] = 0
+	fmt.Println(s3_cpy[0] == s3[0])
+
+	s := []int{1, 2, 3}
+	s = append(s, 4, 5, 6)
+	fmt.Println(s)
+
+	s = append(s, []int{7, 8, 9}...)
+	fmt.Println(s)
+
+	p, q := learnMemory()
+	fmt.Println(*p, *q)
+
+	m := map[string]int{"three": 3, "four": 4}
+	m["one"] = 1
+
+	_, _, _, _, _, _, _, _, _, _, _, _, _ = str, s2, g, f, c, pi, n, a5, a4, s4, d2, bs, u
+
+	file, _ := os.Create("output.txt")
+	fmt.Fprint(file, "This is how you write to a file, by the way")
+	file.Close()
+
+	fmt.Println(s, c, a4, s3, d2, m)
+}
+
+func learnMemory() (p, q *int) {
+	p = new(int)
+
+	s := make([]int, 20)
+	s[3] = 7
+	r := -2
+	return &s[3], &r
+}

go-lang/learn-go-in-y-minutes/output.txt

@@ -0,0 +1 @@
+This is how you write to a file, by the way

go-lang/read-big-file/go.mod

@@ -0,0 +1,3 @@
+module github/vanduc1102/read-big-file
+
+go 1.20

go-lang/read-big-file/main.go

@@ -0,0 +1,135 @@
+package main
+
+import (
+	"encoding/csv"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strconv"
+	"sync"
+	"time"
+)
+
+type MovieLink struct {
+	Id     int
+	ImdbId string
+	TmdbId string
+}
+
+const (
+	Odd  string = "odd"
+	Even string = "even"
+)
+
+func main() {
+	var wg sync.WaitGroup
+
+	startTime := time.Now()
+	file, err := os.Open("ml-latest/links.csv")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	defer file.Close()
+
+	items := 10000
+	itemsPerWorker := 100
+	kind := Odd
+	numberWorkers := 1
+	if items > itemsPerWorker {
+		numberWorkers := items / itemsPerWorker
+		if items%itemsPerWorker != 0 {
+			numberWorkers++
+		}
+	}
+
+	jobQueue := make(chan []string, numberWorkers)
+
+	wg.Add(1)
+	go func() {
+		csvReader := csv.NewReader(file)
+
+		if _, err := csvReader.Read(); err != nil {
+			log.Fatal(err)
+		}
+
+		for {
+			row, err := csvReader.Read()
+			if err == io.EOF {
+				break
+			}
+			if err != nil {
+				log.Fatal(err)
+			}
+			jobQueue <- row
+		}
+		defer wg.Done()
+	}()
+
+	outputChannel := make(chan []MovieLink, numberWorkers)
+	for i := 0; i < numberWorkers; i++ {
+		wg.Add(1)
+		go func() {
+			worker(jobQueue, outputChannel, itemsPerWorker, kind)
+			wg.Done()
+		}()
+	}
+
+	movies := make([]MovieLink, items)
+	for chunk := range outputChannel {
+		fmt.Printf("== lines : %d\n", len(movies))
+		movies = append(movies, chunk...)
+		if len(movies) >= items {
+			close(outputChannel)
+			break
+		}
+	}
+
+	// wg.Wait()
+	fmt.Printf("lines : %d\n", len(movies))
+	fmt.Printf("The seconds difference is: %fs\n", time.Since(startTime).Seconds())
+}
+
+func worker(jobChannel <-chan []string, output chan<- []MovieLink, itemsPerWorker int, kind string) {
+	movies := make([]MovieLink, itemsPerWorker)
+	for line := range jobChannel {
+		item, err := marshal(line)
+		if err == nil {
+			if kind == Odd && item.Id%2 == 1 {
+				// fmt.Printf("Add odd %s\n", line)
+				movies = append(movies, *item)
+			}
+			if kind == Even && item.Id%2 == 0 {
+				// fmt.Printf("Add even %s\n", line)
+				movies = append(movies, *item)
+			}
+			fmt.Printf("collected size %d\n", len(movies))
+			if len(movies) == itemsPerWorker {
+				output <- movies
+				break
+			}
+		} else {
+			log.Fatal(err)
+		}
+	}
+}
+
+func marshal(row []string) (*MovieLink, error) {
+	var movie MovieLink
+	for j, field := range row {
+		if j == 0 {
+			id, err := strconv.Atoi(field)
+			if err != nil {
+				return nil, err
+			}
+			movie.Id = id
+		} else if j == 1 {
+			movie.ImdbId = field
+		} else if j == 2 {
+			movie.TmdbId = field
+		}
+	}
+
+	return &movie, nil
+}