Update to go mod and parameterize check time and randomize time

selfupdate/selfupdate.go

@@ -83,6 +83,8 @@ type Updater struct {
 	DiffURL        string    // Base URL for diff downloads.
 	Dir            string    // Directory to store selfupdate state.
 	ForceCheck     bool      // Check for update regardless of cktime timestamp
+	CheckTime      int       // Time in hours before next check
+	RandomizeTime  int       // Time in hours to randomize with CheckTime
 	Requester      Requester //Optional parameter to override existing http request handler
 	Info           struct {
 		Version string
@@ -102,34 +104,62 @@ func (u *Updater) BackgroundRun() error {
 		// fail
 		return err
 	}
-	if u.wantUpdate() {
+	if u.WantUpdate() {
 		if err := up.CanUpdate(); err != nil {
 			// fail
 			return err
 		}
+
+		u.SetUpdateTime()
+
 		//self, err := osext.Executable()
 		//if err != nil {
 		// fail update, couldn't figure out path to self
 		//return
 		//}
 		// TODO(bgentry): logger isn't on Windows. Replace w/ proper error reports.
-		if err := u.update(); err != nil {
+		if err := u.Update(); err != nil {
 			return err
 		}
 	}
 	return nil
 }
 
-func (u *Updater) wantUpdate() bool {
-	path := u.getExecRelativeDir(u.Dir + upcktimePath)
-	if u.CurrentVersion == "dev" || (!u.ForceCheck && readTime(path).After(time.Now())) {
+// WantUpdate returns boolean designating if an update is desired
+func (u *Updater) WantUpdate() bool {
+	if u.CurrentVersion == "dev" || (!u.ForceCheck && u.NextUpdate().After(time.Now())) {
 		return false
 	}
-	wait := 24*time.Hour + randDuration(24*time.Hour)
-	return writeTime(path, time.Now().Add(wait))
+
+	return true
 }
 
-func (u *Updater) update() error {
+// NextUpdate returns the next time update should be checked
+func (u *Updater) NextUpdate() time.Time {
+	path := u.getExecRelativeDir(u.Dir + upcktimePath)
+	nextTime := readTime(path)
+
+	return nextTime
+}
+
+// SetUpdateTime writes the next update time to the state file
+func (u *Updater) SetUpdateTime() bool {
+	path := u.getExecRelativeDir(u.Dir + upcktimePath)
+	wait := time.Duration(u.CheckTime) * time.Hour
+	// Add 1 to random time since max is not included
+	waitrand := time.Duration(rand.Intn(u.RandomizeTime+1)) * time.Hour
+
+	return writeTime(path, time.Now().Add(wait+waitrand))
+}
+
+// ClearUpdateState writes current time to state file
+func (u *Updater) ClearUpdateState() {
+	path := u.getExecRelativeDir(u.Dir + upcktimePath)
+	os.Remove(path)
+}
+
+// Update initiates the self update process
+func (u *Updater) Update() error {
 	path, err := osext.Executable()
 	if err != nil {
 		return err
@@ -250,11 +280,6 @@ func (u *Updater) fetchBin() ([]byte, error) {
 	return buf.Bytes(), nil
 }
 
-// returns a random duration in [0,n).
-func randDuration(n time.Duration) time.Duration {
-	return time.Duration(rand.Int63n(int64(n)))
-}
-
 func (u *Updater) fetch(url string) (io.ReadCloser, error) {
 	if u.Requester == nil {
 		return defaultHTTPRequester.Fetch(url)

selfupdate/selfupdate_test.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"testing"
+	"time"
 )
 
 var testHash = sha256.New()
@@ -17,7 +18,11 @@ func TestUpdaterFetchMustReturnNonNilReaderCloser(t *testing.T) {
 			return nil, nil
 		})
 	updater := createUpdater(mr)
+	updater.CheckTime = 24
+	updater.RandomizeTime = 24
+
 	err := updater.BackgroundRun()
+
 	if err != nil {
 		equals(t, "Fetch was expected to return non-nil ReadCloser", err.Error())
 	} else {
@@ -34,6 +39,8 @@ func TestUpdaterWithEmptyPayloadNoErrorNoUpdate(t *testing.T) {
 			return newTestReaderCloser("{}"), nil
 		})
 	updater := createUpdater(mr)
+	updater.CheckTime = 24
+	updater.RandomizeTime = 24
 
 	err := updater.BackgroundRun()
 	if err != nil {
@@ -41,6 +48,46 @@ func TestUpdaterWithEmptyPayloadNoErrorNoUpdate(t *testing.T) {
 	}
 }
 
+func TestUpdaterCheckTime(t *testing.T) {
+	mr := &mockRequester{}
+	mr.handleRequest(
+		func(url string) (io.ReadCloser, error) {
+			equals(t, "http://updates.yourdomain.com/myapp/darwin-amd64.json", url)
+			return newTestReaderCloser("{}"), nil
+		})
+
+	// Run test with various time
+	runTestTimeChecks(t, mr, 0, 0, false)
+	runTestTimeChecks(t, mr, 0, 5, true)
+	runTestTimeChecks(t, mr, 1, 0, true)
+	runTestTimeChecks(t, mr, 100, 100, true)
+}
+
+// Helper function to run check time tests
+func runTestTimeChecks(t *testing.T, mr *mockRequester, checkTime int, randomizeTime int, expectUpdate bool) {
+	updater := createUpdater(mr)
+	updater.ClearUpdateState()
+	updater.CheckTime = checkTime
+	updater.RandomizeTime = randomizeTime
+
+	updater.BackgroundRun()
+
+	if updater.WantUpdate() == expectUpdate {
+		t.Errorf("WantUpdate returned %v; want %v", updater.WantUpdate(), expectUpdate)
+	}
+
+	maxHrs := time.Duration(updater.CheckTime+updater.RandomizeTime) * time.Hour
+	maxTime := time.Now().Add(maxHrs)
+
+	if !updater.NextUpdate().Before(maxTime) {
+		t.Errorf("NextUpdate should less than %s hrs (CheckTime + RandomizeTime) from now; now %s; next update %s", maxHrs, time.Now(), updater.NextUpdate())
+	}
+
+	if maxHrs > 0 && !updater.NextUpdate().After(time.Now()) {
+		t.Errorf("NextUpdate should be after now")
+	}
+}
+
 func TestUpdaterWithEmptyPayloadNoErrorNoUpdateEscapedPath(t *testing.T) {
 	mr := &mockRequester{}
 	mr.handleRequest(

selfupdate/update/cktime

@@ -0,0 +1 @@
+2020-12-08T21:11:49-07:00