Correct the Session.Renew{,Periodic} to handle session expiration better

api/session.go

@@ -1,6 +1,7 @@
 package api
 
 import (
+	"errors"
 	"fmt"
 	"time"
 )
@@ -16,6 +17,8 @@ const (
 	SessionBehaviorDelete = "delete"
 )
 
+var ErrSessionExpired = errors.New("session expired")
+
 // SessionEntry represents a session in consul
 type SessionEntry struct {
 	CreateIndex uint64
@@ -113,11 +116,26 @@ func (s *Session) Destroy(id string, q *WriteOptions) (*WriteMeta, error) {
 
 // Renew renews the TTL on a given session
 func (s *Session) Renew(id string, q *WriteOptions) (*SessionEntry, *WriteMeta, error) {
-	var entries []*SessionEntry
-	wm, err := s.c.write("/v1/session/renew/"+id, nil, &entries, q)
+	r := s.c.newRequest("PUT", "/v1/session/renew/"+id)
+	r.setWriteOptions(q)
+	rtt, resp, err := s.c.doRequest(r)
 	if err != nil {
 		return nil, nil, err
 	}
+	defer resp.Body.Close()
+
+	wm := &WriteMeta{RequestTime: rtt}
+
+	if resp.StatusCode == 404 {
+		return nil, wm, nil
+	} else if resp.StatusCode != 200 {
+		return nil, nil, fmt.Errorf("Unexpected response code: %d", resp.StatusCode)
+	}
+
+	var entries []*SessionEntry
+	if err := decodeBody(resp, &entries); err != nil {
+		return nil, nil, fmt.Errorf("Failed to read response: %v", err)
+	}
 	if len(entries) > 0 {
 		return entries[0], wm, nil
 	}
@@ -149,9 +167,7 @@ func (s *Session) RenewPeriodic(initialTTL string, id string, q *WriteOptions, d
 				continue
 			}
 			if entry == nil {
-				waitDur = time.Second
-				lastErr = fmt.Errorf("No SessionEntry returned")
-				continue
+				return ErrSessionExpired
 			}
 
 			// Handle the server updating the TTL

api/session_test.go

@@ -2,6 +2,7 @@ package api
 
 import (
 	"testing"
+	"time"
 )
 
 func TestSession_CreateDestroy(t *testing.T) {
@@ -85,6 +86,114 @@ func TestSession_CreateRenewDestroy(t *testing.T) {
 	}
 }
 
+func TestSession_CreateRenewDestroyRenew(t *testing.T) {
+	t.Parallel()
+	c, s := makeClient(t)
+	defer s.Stop()
+
+	session := c.Session()
+
+	entry := &SessionEntry{
+		Behavior: SessionBehaviorDelete,
+		TTL:      "500s", // disable ttl
+	}
+
+	id, meta, err := session.Create(entry, nil)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	if meta.RequestTime == 0 {
+		t.Fatalf("bad: %v", meta)
+	}
+
+	if id == "" {
+		t.Fatalf("invalid: %v", id)
+	}
+
+	// Extend right after create. Everything should be fine.
+	entry, _, err = session.Renew(id, nil)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if entry == nil {
+		t.Fatal("session unexpectedly vanished")
+	}
+
+	// Simulate TTL loss by manually destroying the session.
+	meta, err = session.Destroy(id, nil)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	if meta.RequestTime == 0 {
+		t.Fatalf("bad: %v", meta)
+	}
+
+	// Extend right after delete. The 404 should proxy as a nil.
+	entry, _, err = session.Renew(id, nil)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+	if entry != nil {
+		t.Fatal("session still exists")
+	}
+}
+
+func TestSession_CreateDestroyRenewPeriodic(t *testing.T) {
+	t.Parallel()
+	c, s := makeClient(t)
+	defer s.Stop()
+
+	session := c.Session()
+
+	entry := &SessionEntry{
+		Behavior: SessionBehaviorDelete,
+		TTL:      "500s", // disable ttl
+	}
+
+	id, meta, err := session.Create(entry, nil)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	if meta.RequestTime == 0 {
+		t.Fatalf("bad: %v", meta)
+	}
+
+	if id == "" {
+		t.Fatalf("invalid: %v", id)
+	}
+
+	// This only tests Create/Destroy/RenewPeriodic to avoid the more
+	// difficult case of testing all of the timing code.
+
+	// Simulate TTL loss by manually destroying the session.
+	meta, err = session.Destroy(id, nil)
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	if meta.RequestTime == 0 {
+		t.Fatalf("bad: %v", meta)
+	}
+
+	// Extend right after delete. The 404 should terminate the loop quickly and return ErrSessionExpired.
+	errCh := make(chan error, 1)
+	doneCh := make(chan struct{})
+	go func() { errCh <- session.RenewPeriodic("1s", id, nil, doneCh) }()
+	defer close(doneCh)
+
+	select {
+	case <-time.After(1 * time.Second):
+		t.Fatal("timedout: missing session did not terminate renewal loop")
+	case err = <-errCh:
+		if err != ErrSessionExpired {
+			t.Fatalf("err: %v", err)
+		}
+	}
+}
+
 func TestSession_Info(t *testing.T) {
 	t.Parallel()
 	c, s := makeClient(t)