Use consul/lib's RandomStagger

Removes four redundant copies of the method in the process.

client/client.go

@@ -13,8 +13,7 @@ import (
 	"time"
 
 	"github.com/armon/go-metrics"
-	"github.com/mitchellh/hashstructure"
-
+	"github.com/hashicorp/consul/lib"
 	"github.com/hashicorp/go-multierror"
 	"github.com/hashicorp/nomad/client/allocdir"
 	"github.com/hashicorp/nomad/client/config"
@@ -24,6 +23,7 @@ import (
 	"github.com/hashicorp/nomad/client/stats"
 	"github.com/hashicorp/nomad/nomad"
 	"github.com/hashicorp/nomad/nomad/structs"
+	"github.com/mitchellh/hashstructure"
 )
 
 const (
@@ -785,7 +785,7 @@ func (c *Client) retryIntv(base time.Duration) time.Duration {
 	if c.config.DevMode {
 		return devModeRetryIntv
 	}
-	return base + randomStagger(base)
+	return base + lib.RandomStagger(base)
 }
 
 // registerAndHeartbeat is a long lived goroutine used to register the client
@@ -804,7 +804,7 @@ func (c *Client) registerAndHeartbeat() {
 	if c.config.DevMode {
 		heartbeat = time.After(0)
 	} else {
-		heartbeat = time.After(randomStagger(initialHeartbeatStagger))
+		heartbeat = time.After(lib.RandomStagger(initialHeartbeatStagger))
 	}
 
 	for {

client/consul/check.go

@@ -2,10 +2,10 @@ package consul
 
 import (
 	"log"
-	"math/rand"
 	"sync"
 	"time"
 
+	"github.com/hashicorp/consul/lib"
 	cstructs "github.com/hashicorp/nomad/client/driver/structs"
 )
 
@@ -60,7 +60,7 @@ func (r *CheckRunner) Stop() {
 // run is invoked by a goroutine to run until Stop() is called
 func (r *CheckRunner) run() {
 	// Get the randomized initial pause time
-	initialPauseTime := randomStagger(r.check.Interval())
+	initialPauseTime := lib.RandomStagger(r.check.Interval())
 	r.logger.Printf("[DEBUG] agent: pausing %v before first invocation of %s", initialPauseTime, r.check.ID())
 	next := time.NewTimer(initialPauseTime)
 	for {
@@ -82,8 +82,3 @@ type Check interface {
 	Interval() time.Duration
 	Timeout() time.Duration
 }
-
-// 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))
-}

client/util.go

@@ -7,7 +7,6 @@ import (
 	"math/rand"
 	"os"
 	"path/filepath"
-	"time"
 
 	"github.com/hashicorp/nomad/nomad/structs"
 )
@@ -69,11 +68,6 @@ func diffAllocs(existing []*structs.Allocation, allocs *allocUpdates) *diffResul
 	return result
 }
 
-// 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))
-}
-
 // shuffleStrings randomly shuffles the list of strings
 func shuffleStrings(list []string) {
 	for i := range list {

client/util_test.go

@@ -6,7 +6,6 @@ import (
 	"path/filepath"
 	"reflect"
 	"testing"
-	"time"
 
 	"github.com/hashicorp/nomad/nomad/mock"
 	"github.com/hashicorp/nomad/nomad/structs"
@@ -56,17 +55,6 @@ func TestDiffAllocs(t *testing.T) {
 	}
 }
 
-func TestRandomStagger(t *testing.T) {
-	t.Parallel()
-	intv := time.Minute
-	for i := 0; i < 10; i++ {
-		stagger := randomStagger(intv)
-		if stagger < 0 || stagger >= intv {
-			t.Fatalf("Bad: %v", stagger)
-		}
-	}
-}
-
 func TestShuffleStrings(t *testing.T) {
 	t.Parallel()
 	// Generate input

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)
-		}
-	}
-}

nomad/heartbeat.go

@@ -51,7 +51,7 @@ func (s *Server) resetHeartbeatTimer(id string) (time.Duration, error) {
 	// Compute the target TTL value
 	n := len(s.heartbeatTimers)
 	ttl := lib.RateScaledInterval(s.config.MaxHeartbeatsPerSecond, s.config.MinHeartbeatTTL, n)
-	ttl += randomStagger(ttl)
+	ttl += lib.RandomStagger(ttl)
 
 	// Reset the TTL
 	s.resetHeartbeatTimerLocked(id, ttl+s.config.HeartbeatGrace)

nomad/rpc.go

@@ -11,6 +11,7 @@ import (
 	"time"
 
 	"github.com/armon/go-metrics"
+	"github.com/hashicorp/consul/lib"
 	"github.com/hashicorp/net-rpc-msgpackrpc"
 	"github.com/hashicorp/nomad/nomad/state"
 	"github.com/hashicorp/nomad/nomad/structs"
@@ -308,7 +309,7 @@ func (s *Server) blockingRPC(opts *blockingOptions) error {
 	}
 
 	// Apply a small amount of jitter to the request
-	opts.queryOpts.MaxQueryTime += randomStagger(opts.queryOpts.MaxQueryTime / jitterFraction)
+	opts.queryOpts.MaxQueryTime += lib.RandomStagger(opts.queryOpts.MaxQueryTime / jitterFraction)
 
 	// Setup a query timeout
 	timeout = time.NewTimer(opts.queryOpts.MaxQueryTime)

nomad/util.go

@@ -10,7 +10,6 @@ import (
 	"path/filepath"
 	"runtime"
 	"strconv"
-	"time"
 
 	crand "crypto/rand"
 
@@ -101,11 +100,6 @@ func isNomadServer(m serf.Member) (bool, *serverParts) {
 	return true, parts
 }
 
-// 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))
-}
-
 // shuffleStrings randomly shuffles the list of strings
 func shuffleStrings(list []string) {
 	for i := range list {

nomad/util_test.go

@@ -4,7 +4,6 @@ import (
 	"net"
 	"reflect"
 	"testing"
-	"time"
 
 	"github.com/hashicorp/nomad/nomad/structs"
 	"github.com/hashicorp/serf/serf"
@@ -57,16 +56,6 @@ func TestIsNomadServer(t *testing.T) {
 	}
 }
 
-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)
-		}
-	}
-}
-
 func TestShuffleStrings(t *testing.T) {
 	// Generate input
 	inp := make([]string, 10)