add a new sessionstorage option to limit number of sessions per visitor

pkg/services/sessionstorage/config.go

@@ -8,14 +8,16 @@ import (
 
 // Session storage service configuration options.
 type Config struct {
-	gcInterval         time.Duration
-	sessionInactiveTtl time.Duration
+	gcInterval            time.Duration
+	sessionInactiveTtl    time.Duration
+	maxSessionsPerVisitor uint64
 }
 
 // ProvideConfig is a wire provider for session storage configuration.
 func ProvideConfig() Config {
 	return Config{
-		gcInterval:         config.ParseDurationEnvOrDefault("PRISME_SESSIONSTORAGE_GC_INTERVAL", 10*time.Minute),
-		sessionInactiveTtl: config.ParseDurationEnvOrDefault("PRISME_SESSIONSTORAGE_SESSION_INACTIVE_TTL", 24*time.Hour),
+		gcInterval:            config.ParseDurationEnvOrDefault("PRISME_SESSIONSTORAGE_GC_INTERVAL", 10*time.Minute),
+		sessionInactiveTtl:    config.ParseDurationEnvOrDefault("PRISME_SESSIONSTORAGE_SESSION_INACTIVE_TTL", 24*time.Hour),
+		maxSessionsPerVisitor: config.ParseUintEnvOrDefault("PRISME_SESSIONSTORAGE_MAX_SERSSIONS_PER_VISITOR", 64, 64),
 	}
 }

pkg/services/sessionstorage/service.go

@@ -11,15 +11,12 @@ import (
 	"github.com/rs/zerolog"
 )
 
-type AddPageviewResult struct {
-	Session           event.Session
-	DuplicatePageview bool
-}
-
 // Service define an in memory session storage.
 type Service interface {
-	// InsertSession stores given session.
-	InsertSession(deviceId uint64, session event.Session)
+	// InsertSession stores given session in memory. If number of visitor session
+	// exceed configured max session per visitor, this function returns false and
+	// session isn't stored.
+	InsertSession(deviceId uint64, session event.Session) bool
 	// AddPageview adds a pageview to a session with the given device id
 	// latest path (referrer). Session is returned along a true flag if it was
 	// found.
@@ -124,7 +121,7 @@ func (s *service) getValidSessionEntry(deviceId uint64, latestPath string) *entr
 }
 
 // InsertSession implements Service.
-func (s *service) InsertSession(deviceId uint64, session event.Session) {
+func (s *service) InsertSession(deviceId uint64, session event.Session) bool {
 	s.mu.Lock()
 	newEntry := entry{
 		Session:   session,
@@ -139,6 +136,10 @@ func (s *service) InsertSession(deviceId uint64, session event.Session) {
 		sessions = make([]entry, 1)
 		sessions[0] = newEntry
 		s.data[deviceId] = sessions
+	} else if len(sessions) >= int(s.cfg.maxSessionsPerVisitor) {
+		s.mu.Unlock()
+		// Prevent visitor from creating too many sessions.
+		return false
 	} else {
 		// New session only.
 
@@ -164,6 +165,8 @@ func (s *service) InsertSession(deviceId uint64, session event.Session) {
 	// Compute metrics.
 	s.metrics.sessionsCounter.With(prometheus.Labels{"type": "inserted"}).Inc()
 	s.metrics.activeSessions.Inc()
+
+	return true
 }
 
 // AddPageview implements Service.

pkg/services/sessionstorage/service_test.go

@@ -17,8 +17,9 @@ import (
 func TestService(t *testing.T) {
 	logger := log.NewLogger("sessionstorage_test", io.Discard, true)
 	cfg := Config{
-		gcInterval:         10 * time.Second,
-		sessionInactiveTtl: 24 * time.Hour,
+		gcInterval:            10 * time.Second,
+		sessionInactiveTtl:    24 * time.Hour,
+		maxSessionsPerVisitor: 64,
 	}
 
 	mustParseUri := testutils.Must(uri.Parse)
@@ -36,7 +37,8 @@ func TestService(t *testing.T) {
 				PageviewCount: 1,
 			}
 
-			service.InsertSession(deviceId, session)
+			ok := service.InsertSession(deviceId, session)
+			require.True(t, ok)
 
 			entry := service.getValidSessionEntry(deviceId, pageUri.Path())
 			require.NotNil(t, entry)
@@ -68,13 +70,15 @@ func TestService(t *testing.T) {
 				PageviewCount: 1,
 			}
 
-			service.InsertSession(deviceId, sessionA)
+			ok := service.InsertSession(deviceId, sessionA)
+			require.True(t, ok)
 
 			sessionB := sessionA
 			sessionB.VisitorId = "prisme_YYY"
 
 			// Add another session on same path.
-			service.InsertSession(deviceId, sessionB)
+			ok = service.InsertSession(deviceId, sessionB)
+			require.True(t, ok)
 
 			// get session returns first matching session, here it is session A.
 			entry := service.getValidSessionEntry(deviceId, pageUri.Path())
@@ -94,6 +98,31 @@ func TestService(t *testing.T) {
 			require.Equal(t, float64(0),
 				testutils.HistogramSumValue(t, promRegistry, "sessionstorage_sessions_pageviews", nil))
 		})
+
+		t.Run("TooManySession", func(t *testing.T) {
+			testCfg := cfg
+			testCfg.maxSessionsPerVisitor = 1
+
+			promRegistry := prometheus.NewRegistry()
+			service := ProvideService(logger, testCfg, promRegistry).(*service)
+
+			deviceId := rand.Uint64()
+			pageUri := mustParseUri("https://example.com")
+			sessionA := event.Session{
+				PageUri:       pageUri,
+				VisitorId:     "prisme_XXX",
+				PageviewCount: 1,
+			}
+
+			ok := service.InsertSession(deviceId, sessionA)
+			require.True(t, ok)
+
+			sessionB := sessionA
+			sessionB.VisitorId = "prisme_YYY"
+
+			ok = service.InsertSession(deviceId, sessionB)
+			require.False(t, ok)
+		})
 	})
 
 	t.Run("AddPageview", func(t *testing.T) {
@@ -109,7 +138,8 @@ func TestService(t *testing.T) {
 				PageviewCount: 1,
 			}
 
-			service.InsertSession(deviceId, sessionV1)
+			ok := service.InsertSession(deviceId, sessionV1)
+			require.True(t, ok)
 
 			// Referrer doesn't match page uri of created session.
 			referrer := event.ReferrerUri{Uri: mustParseUri("https://example.com/bar")}
@@ -148,7 +178,8 @@ func TestService(t *testing.T) {
 				PageviewCount: 1,
 			}
 
-			service.InsertSession(deviceId, sessionV1)
+			ok := service.InsertSession(deviceId, sessionV1)
+			require.True(t, ok)
 
 			referrer := event.ReferrerUri{Uri: pageUri}
 			pageUri = mustParseUri("https://example.com/foo")
@@ -190,7 +221,8 @@ func TestService(t *testing.T) {
 				PageviewCount: 1,
 			}
 
-			service.InsertSession(deviceId, session)
+			ok := service.InsertSession(deviceId, session)
+			require.True(t, ok)
 
 			identifiedSession, ok := service.IdentifySession(deviceId, session.PageUri, "prisme_YYY")
 			require.True(t, ok)
@@ -210,7 +242,8 @@ func TestService(t *testing.T) {
 				PageviewCount: 1,
 			}
 
-			service.InsertSession(deviceId, session)
+			ok := service.InsertSession(deviceId, session)
+			require.True(t, ok)
 
 			identifiedSession, ok := service.IdentifySession(deviceId, mustParseUri("https://example.com/foo"), "prisme_YYY")
 			require.False(t, ok)
@@ -305,7 +338,8 @@ func TestService(t *testing.T) {
 					require.Equal(t, float64(1),
 						testutils.GaugeValue(t, promRegistry, "sessionstorage_sessions_wait", nil))
 
-					service.InsertSession(deviceId, session)
+					ok := service.InsertSession(deviceId, session)
+					require.True(t, ok)
 				}()
 
 				// Wait for session.
@@ -371,7 +405,8 @@ func TestService(t *testing.T) {
 					require.Equal(t, float64(1),
 						testutils.GaugeValue(t, promRegistry, "sessionstorage_sessions_wait", nil))
 
-					service.InsertSession(deviceId, session)
+					ok := service.InsertSession(deviceId, session)
+					require.True(t, ok)
 				}()
 
 				// Wait for session with /foo path.
@@ -413,7 +448,8 @@ func TestService(t *testing.T) {
 			}
 
 			// Insert session.
-			service.InsertSession(deviceId, session)
+			ok := service.InsertSession(deviceId, session)
+			require.True(t, ok)
 
 			now := time.Now()
 			actualSession, found := service.WaitSession(deviceId, pageUri, 10*time.Millisecond)