massive: move a lot of things

x-tba/slicing-allocs-gotcha/main.go

@@ -0,0 +1,71 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// Before running this program:
+//
+//     RUN: `go run nums/main.go`
+//     It will create a 12 MB long nums.txt file.
+
+import (
+	"fmt"
+	"io/ioutil"
+	"runtime"
+
+	s "github.com/inancgumus/prettyslice"
+)
+
+const (
+	loops = 1000
+	file  = "nums.txt"
+)
+
+var buf []byte
+
+func main() {
+	{
+		b, _ := ioutil.ReadFile(file)
+		buf = b[:1]
+
+		s.Show("sliced buf", buf)
+	}
+	report()
+
+	{
+		var nilBuf []byte
+
+		b, _ := ioutil.ReadFile(file)
+		buf = append(nilBuf, b[:1]...)
+
+		s.Show("copied buf", buf)
+	}
+	report()
+}
+
+func report() {
+	const KB = 1024
+
+	var m runtime.MemStats
+	r := func() {
+		runtime.ReadMemStats(&m)
+		fmt.Printf("%v KB\n", m.Alloc/KB)
+	}
+
+	fmt.Print(" > Before Garbage Collection: ")
+	r()
+
+	runtime.GC()
+	fmt.Print(" > After Garbage Colletion  : ")
+	r()
+}
+
+func init() {
+	s.Width = 50
+	s.PrintBacking = true
+	s.MaxElements = 10
+}

x-tba/slicing-allocs-gotcha/nums/main.go

@@ -0,0 +1,32 @@
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+)
+
+func main() {
+	const path = "nums.txt"
+
+	_ = os.Remove(path)
+
+	f, _ := os.OpenFile(path,
+		os.O_CREATE|os.O_WRONLY,
+		0644)
+	defer f.Close()
+
+	const size = 1000000
+	w := bufio.NewWriterSize(f, 1<<16)
+	for i := 1; i <= size; i++ {
+		fmt.Fprintf(w, "num: %d\n", i)
+	}
+	w.Flush()
+}