more practice

buffered-channels.go

@@ -0,0 +1,11 @@
+package main
+
+import "fmt"
+
+func main() {
+    ch := make(chan int, 2)
+    ch <- 1
+    ch <- 2
+    fmt.Println(<-ch)
+    fmt.Println(<-ch)
+}

channels.go

@@ -0,0 +1,21 @@
+package main
+
+import "fmt"
+
+func sum(s []int, c chan int) {
+    sum := 0
+    for _, v := range s {
+        sum += v
+    }
+    c <- sum // send sum to c
+}
+
+func main() {
+    s := []int{7, 2, 8, -9, 4, 0}
+    c := make(chan int)
+    go sum(s[:len(s) / 2], c)
+    go sum(s[len(s) / 2:], c)
+    x, y := <-c, <-c // receive from c
+
+    fmt.Println(x, y, x + y)
+}

default-selection.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+    "fmt"
+    "time"
+)
+
+func main() {
+    tick := time.Tick(100 * time.Millisecond)
+    boom := time.After(500 * time.Millisecond)
+    for {
+        select {
+        case <-tick:
+            fmt.Println("tick.")
+        case <-boom:
+            fmt.Println("BOOM!")
+            return
+        default:
+            fmt.Println("    .")
+            time.Sleep(50 * time.Millisecond)
+        }
+    }
+}

goroutines.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+    "fmt"
+    "time"
+)
+
+func say(s string) {
+    for i := 0; i < 5; i++ {
+        time.Sleep(100 * time.Millisecond)
+        fmt.Println(s)
+    }
+}
+
+func main() {
+    go say("world")
+    say("hello")
+}

range-and-close.go

@@ -0,0 +1,22 @@
+package main
+
+import (
+    "fmt"
+)
+
+func fibonacci(n int, c chan int) {
+    x, y := 0, 1
+    for i := 0; i < n; i++ {
+        c <- x
+        x, y = y, x + y
+    }
+    close(c)
+}
+
+func main() {
+    c := make(chan int, 10)
+    go fibonacci(cap(c), c)
+    for i := range c {
+        fmt.Println(i)
+    }
+}

select.go

@@ -0,0 +1,28 @@
+package main
+
+import "fmt"
+
+func fibonacci(c, quit chan int) {
+    x, y := 0, 1
+    for {
+        select {
+        case c <- x:
+            x, y = y, x+y
+        case <-quit:
+            fmt.Println("quit")
+            return
+        }
+    }
+}
+
+func main() {
+    c := make(chan int)
+    quit := make(chan int)
+    go func() {
+        for i := 0; i < 10; i++ {
+            fmt.Println(<-c)
+        }
+        quit <- 0
+    }()
+    fibonacci(c, quit)
+}