refactor: slice exercises 22 and 24

16-slices/exercises/24-fix-the-memory-leak/solution/main.go

@@ -18,39 +18,35 @@ func main() {
 	// reports the initial memory usage
 	api.Report()
 
-	// reads 65 MB of temperature data into the memory!
-	temps := api.Read()
+	// returns a slice with 10 million elements.
+	// it allocates 65 MB of memory space.
+	millions := api.Read()
 
 	// ------------------------------------------------------
+
 	// SOLUTION #1:
-	// ------------------------------------------------------
+	// Copy the last 10 elements of the returned slice
+	// to a new slice. This will create a new backing array
+	// only with 10 elements.
+	last10 := make([]int, 10)
+	copy(last10, millions[len(millions)-10:])
 
-	//
-	// Copy the last 10 elements of the returned temperatures
-	// to a new slice.
-	//
-	// This will create a new backing array.
-	//
-	need := make([]int, 10)
-	copy(need, temps[len(temps)-10:])
+	// Make the millions slice lose reference to its backing array
+	// so that its backing array can be cleaned up from memory.
+	millions = last10
 
-	//
-	// Make the temp slice lose reference to its backing array
-	// so that its backing array can be cleaned from the memory.
-	//
-	temps = need
-
-	// ------------------------------------------------------
 	// SOLUTION #2:
-	// ------------------------------------------------------
-
 	// Similar to the 1st solution. It does the same thing.
 	// But this code is more concise. Use this one.
 
-	// temps = append([]int(nil), temps[len(temps)-10:]...)
+	// millions = append([]int(nil), millions[len(millions)-10:]...)
+
+	fmt.Printf("\nLast 10 elements: %d\n\n", last10)
 
 	// ------------------------------------------------------
-	// don't worry about this code yet.
+
 	api.Report()
-	fmt.Fprintln(ioutil.Discard, temps[0])
+
+	// don't worry about this code yet.
+	fmt.Fprintln(ioutil.Discard, millions[0])
 }