doc/codewalk: update urlpoll to use time.Duration.

R=adg
CC=golang-dev
https://golang.org/cl/5545061

diff --git a/doc/codewalk/urlpoll.go b/doc/codewalk/urlpoll.go
index 1439e34218a54423f1288f93f290094594431711..e716c7e6c486cba8f8b696e9d522fb1c6f3769e3 100644 (file)
--- a/doc/codewalk/urlpoll.go
+++ b/doc/codewalk/urlpoll.go
@@ -11,11 +11,10 @@ import (
 )
 
 const (
-       numPollers     = 2           // number of Poller goroutines to launch
-       second         = 1e9         // one second is 1e9 nanoseconds
-       pollInterval   = 60 * second // how often to poll each URL
-       statusInterval = 10 * second // how often to log status to stdout
-       errTimeout     = 10 * second // back-off timeout on error
+       numPollers     = 2                // number of Poller goroutines to launch
+       pollInterval   = 60 * time.Second // how often to poll each URL
+       statusInterval = 10 * time.Second // how often to log status to stdout
+       errTimeout     = 10 * time.Second // back-off timeout on error
 )
 
 var urls = []string{
@@ -33,7 +32,7 @@ type State struct {
 // StateMonitor maintains a map that stores the state of the URLs being
 // polled, and prints the current state every updateInterval nanoseconds.
 // It returns a chan State to which resource state should be sent.
-func StateMonitor(updateInterval int64) chan<- State {
+func StateMonitor(updateInterval time.Duration) chan<- State {
        updates := make(chan State)
        urlStatus := make(map[string]string)
        ticker := time.NewTicker(updateInterval)
@@ -61,7 +60,7 @@ func logState(s map[string]string) {
 // Resource represents an HTTP URL to be polled by this program.
 type Resource struct {
        url      string
-       errCount int64
+       errCount int
 }
 
 // Poll executes an HTTP HEAD request for url
@@ -79,8 +78,8 @@ func (r *Resource) Poll() string {
 
 // Sleep sleeps for an appropriate interval (dependant on error state)
 // before sending the Resource to done.
-func (r *Resource) Sleep(done chan *Resource) {
-       time.Sleep(pollInterval + errTimeout*r.errCount)
+func (r *Resource) Sleep(done chan<- *Resource) {
+       time.Sleep(pollInterval + errTimeout*time.Duration(r.errCount))
        done <- r
 }
 
@@ -93,18 +92,18 @@ func Poller(in <-chan *Resource, out chan<- *Resource, status chan<- State) {
 }
 
 func main() {
-       // create our input and output channels
+       // Create our input and output channels.
        pending, complete := make(chan *Resource), make(chan *Resource)
 
-       // launch the StateMonitor
+       // Launch the StateMonitor.
        status := StateMonitor(statusInterval)
 
-       // launch some Poller goroutines
+       // Launch some Poller goroutines.
        for i := 0; i < numPollers; i++ {
                go Poller(pending, complete, status)
        }
 
-       // send some Resources to the pending queue
+       // Send some Resources to the pending queue.
        go func() {
                for _, url := range urls {
                        pending <- &Resource{url: url}