Use consul/lib's RandomStagger

Removes four redundant copies of the method in the process.

command/agent/command.go

@@ -16,6 +16,7 @@ import (
 	"time"
 
 	"github.com/armon/go-metrics"
+	"github.com/hashicorp/consul/lib"
 	"github.com/hashicorp/go-checkpoint"
 	"github.com/hashicorp/go-syslog"
 	"github.com/hashicorp/logutils"
@@ -334,7 +335,7 @@ func (c *Command) setupAgent(config *Config, logOutput io.Writer) error {
 
 		// Do an immediate check within the next 30 seconds
 		go func() {
-			time.Sleep(randomStagger(30 * time.Second))
+			time.Sleep(lib.RandomStagger(30 * time.Second))
 			c.checkpointResults(checkpoint.Check(updateParams))
 		}()
 	}

command/agent/util.go

@@ -2,16 +2,9 @@ package agent
 
 import (
 	"fmt"
-	"math/rand"
 	"net"
-	"time"
 )
 
-// Returns a random stagger interval between 0 and the duration
-func randomStagger(intv time.Duration) time.Duration {
-	return time.Duration(uint64(rand.Int63()) % uint64(intv))
-}
-
 // IpOfDevice returns a routable ip addr of a device
 func ipOfDevice(name string) (net.IP, error) {
 	intf, err := net.InterfaceByName(name)

command/agent/util_test.go

@@ -1,16 +0,0 @@
-package agent
-
-import (
-	"testing"
-	"time"
-)
-
-func TestRandomStagger(t *testing.T) {
-	intv := time.Minute
-	for i := 0; i < 10; i++ {
-		stagger := randomStagger(intv)
-		if stagger < 0 || stagger >= intv {
-			t.Fatalf("Bad: %v", stagger)
-		}
-	}
-}