// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build ignore
package main
import (
"fmt"
"code.google.com/p/go-tour/tree"
)
func walkImpl(t *tree.Tree, ch chan int) {
if t == nil {
return
}
walkImpl(t.Left, ch)
ch <- t.Value
walkImpl(t.Right, ch)
}
// Walk walks the tree t sending all values
// from the tree to the channel ch.
func Walk(t *tree.Tree, ch chan int) {
walkImpl(t, ch)
// Need to close the channel here
close(ch)
}
// Same determines whether the trees
// t1 and t2 contain the same values.
// NOTE: The implementation leaks goroutines when trees are different.
// See binarytrees_quit.go for a better solution.
func Same(t1, t2 *tree.Tree) bool {
w1, w2 := make(chan int), make(chan int)
go Walk(t1, w1)
go Walk(t2, w2)
for {
v1, ok1 := <-w1
v2, ok2 := <-w2
if !ok1 || !ok2 {
return ok1 == ok2
}
if v1 != v2 {
return false
}
}
}
func main() {
fmt.Print("tree.New(1) == tree.New(1): ")
if Same(tree.New(1), tree.New(1)) {
fmt.Println("PASSED")
} else {
fmt.Println("FAILED")
}
fmt.Print("tree.New(1) != tree.New(2): ")
if !Same(tree.New(1), tree.New(2)) {
fmt.Println("PASSED")
} else {
fmt.Println("FAILED")
}
}
In this code, a solution for http://tour.golang.org/concurrency/8
Why is there a comment on Same() func Same(t1, t2 *tree.Tree) bool saying that it leaks goroutines? How so? It also mentions a second file that fixes this:
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build ignore
package main
import (
"fmt"
"code.google.com/p/go-tour/tree"
)
func walkImpl(t *tree.Tree, ch, quit chan int) {
if t == nil {
return
}
walkImpl(t.Left, ch, quit)
select {
case ch <- t.Value:
// Value successfully sent.
case <-quit:
return
}
walkImpl(t.Right, ch, quit)
}
// Walk walks the tree t sending all values
// from the tree to the channel ch.
func Walk(t *tree.Tree, ch, quit chan int) {
walkImpl(t, ch, quit)
close(ch)
}
// Same determines whether the trees
// t1 and t2 contain the same values.
func Same(t1, t2 *tree.Tree) bool {
w1, w2 := make(chan int), make(chan int)
quit := make(chan int)
defer close(quit)
go Walk(t1, w1, quit)
go Walk(t2, w2, quit)
for {
v1, ok1 := <-w1
v2, ok2 := <-w2
if !ok1 || !ok2 {
return ok1 == ok2
}
if v1 != v2 {
return false
}
}
}
func main() {
fmt.Print("tree.New(1) == tree.New(1): ")
if Same(tree.New(1), tree.New(1)) {
fmt.Println("PASSED")
} else {
fmt.Println("FAILED")
}
fmt.Print("tree.New(1) != tree.New(2): ")
if !Same(tree.New(1), tree.New(2)) {
fmt.Println("PASSED")
} else {
fmt.Println("FAILED")
}
}
How does it accomplish that? Where was this leak? (to test the code you will have to run it on http://tour.golang.org/concurrency/8). Very confused and would appreciate some help, thanks!
