timers

src/timers/timers.go

@@ -1,24 +1,43 @@
 // ## Timers
 
+// We often want to execute Go code at some point in the
+// future, or repeatedly at some interval. Go's built-in
+// timer and ticker features make both of these tasks
+// easy. First we'll look at timers.
+
 package main
 
 import "time"
 import "fmt"
 
 func main() {
-    timer1 := time.NewTimer(time.Second)
+
+    // Timers represent a single event in the future. You
+    // tell the timer how long you want to wait, and it
+    // provides a channel that will be notified at that
+    // time. This timer will wait 2 seconds.
+    timer1 := time.NewTimer(time.Second * 2)
+
+    // The `<-timer1.C` blocks on the timer's channel `C`
+    // until it sends a value indicating that the timer
+    // expired.
     <-timer1.C
     fmt.Println("Timer 1 expired")
-    stop1 := timer1.Stop()
-    fmt.Println("Timer 2 stopped:", stop1)
 
+    // If you just wanted to wait, you could have used
+    // `time.Sleep`. One reason a timer may be useful is
+    // that you can cancel the timer before it expires.
     timer2 := time.NewTimer(time.Second)
     go func() {
         <-timer2.C
         fmt.Println("Timer 2 expired")
     }()
-    stop2 := timer2.Stop()
-    fmt.Println("Timer 2 stopped:", stop2)
-}
 
-// todo: pull from blog post
+    // In this case we'll cancel the timer before it has a
+    // change to expire (`.Stop()` would return `false` if
+    // we tried to cancel it after it expired).
+    stop2 := timer2.Stop()
+    if stop2 {
+        fmt.Println("Timer 2 stopped")
+    }
+}

src/timers/timers.sh

@@ -0,0 +1,3 @@
+$ go run timers.go
+Timer 1 expired
+Timer 2 stopped

src/timers/tiners.sh

@@ -1,4 +0,0 @@
-$ go run timers.go
-Timer 1 expired
-Timer 2 stopped: false
-Timer 2 stopped: true