Use session_modified_on instead of session_wait_started_on to gate timeout updates

Author: rowanseymour

Diff for: backends/rapidpro/backend.go

@@ -515,8 +515,8 @@ func (b *backend) OnSendComplete(ctx context.Context, msg courier.MsgOut, status
 
 	// if message was successfully sent, and we have a session timeout, update it
 	wasSuccess := status.Status() == courier.MsgStatusWired || status.Status() == courier.MsgStatusSent || status.Status() == courier.MsgStatusDelivered || status.Status() == courier.MsgStatusRead
-	if wasSuccess && dbMsg.SessionWaitStartedOn_ != nil {
-		if err := updateSessionTimeout(ctx, b, dbMsg.SessionID_, *dbMsg.SessionWaitStartedOn_, dbMsg.SessionTimeout_); err != nil {
+	if wasSuccess && dbMsg.SessionTimeout_ != 0 {
+		if err := updateSessionTimeout(ctx, b, dbMsg.SessionID_, *dbMsg.SessionModifiedOn_, dbMsg.SessionTimeout_); err != nil {
 			slog.Error("unable to update session timeout", "error", err, "session_id", dbMsg.SessionID_)
 		}
 	}

Diff for: backends/rapidpro/backend_test.go

@@ -1338,7 +1338,7 @@ func (ts *BackendTestSuite) TestSessionTimeout() {
 	ctx := context.Background()
 
 	// parse from an iso date
-	t, err := time.Parse("2006-01-02 15:04:05.000000-07", "2018-12-04 11:52:20.958955-08")
+	t, err := time.Parse("2006-01-02 15:04:05.000000-07", "2018-12-04 11:52:20.900234-08")
 	ts.NoError(err)
 
 	err = updateSessionTimeout(ctx, ts.b, SessionID(1), t, 300)

Diff for: backends/rapidpro/msg.go

@@ -87,10 +87,10 @@ type Msg struct {
 	ContactLastSeenOn_    *time.Time              `json:"contact_last_seen_on"`
 
 	// extra fields used to allow courier to update a session's timeout to *after* the message has been sent
-	SessionID_            SessionID  `json:"session_id"`
-	SessionTimeout_       int        `json:"session_timeout"`
-	SessionWaitStartedOn_ *time.Time `json:"session_wait_started_on"`
-	SessionStatus_        string     `json:"session_status"`
+	SessionID_         SessionID  `json:"session_id"`
+	SessionTimeout_    int        `json:"session_timeout"`
+	SessionStatus_     string     `json:"session_status"`
+	SessionModifiedOn_ *time.Time `json:"session_modified_on"`
 
 	ContactName_   string            `json:"contact_name"`
 	URNAuthTokens_ map[string]string `json:"auth_tokens"`

Diff for: backends/rapidpro/schema.sql

@@ -132,6 +132,7 @@ DROP TABLE IF EXISTS flows_flowsession CASCADE;
 CREATE TABLE flows_flowsession (
     id serial primary key,
     status character varying(1) NOT NULL,
+    modified_on timestamp with time zone NOT NULL,
     timeout_on timestamp with time zone NULL,
     wait_started_on timestamp with time zone
 );

Diff for: backends/rapidpro/sessions.go

@@ -15,12 +15,12 @@ const updateSessionTimeoutSQL = `
 		timeout_on = NOW() + $3 * interval '1 second'
 	WHERE
 		id = $1 AND
-		extract(epoch from wait_started_on) = extract(epoch from $2::timestamp with time zone) AND
+		extract(epoch from modified_on) = extract(epoch from $2::timestamptz) AND
 		status = 'W'
 `
 
 // updateSessionTimeout updates the timeout_on value on a db session if our session's wait on hasn't changed
-func updateSessionTimeout(ctx context.Context, b *backend, sessionID SessionID, waitStartedOn time.Time, timeoutSeconds int) error {
-	_, err := b.db.ExecContext(ctx, updateSessionTimeoutSQL, sessionID, waitStartedOn.In(time.UTC), timeoutSeconds)
+func updateSessionTimeout(ctx context.Context, b *backend, sessionID SessionID, sessionModifiedOn time.Time, timeoutSeconds int) error {
+	_, err := b.db.ExecContext(ctx, updateSessionTimeoutSQL, sessionID, sessionModifiedOn.In(time.UTC), timeoutSeconds)
 	return err
 }

Diff for: backends/rapidpro/testdata.sql

@@ -68,6 +68,6 @@ INSERT INTO msgs_media("id", "uuid", "org_id", "content_type", "url", "path", "s
 
 /** Simple session */
 DELETE from flows_flowsession;
-INSERT INTO flows_flowsession("id", "status", "wait_started_on")
-                       VALUES(1, 'W', '2018-12-04 11:52:20.958955-08'),
-                             (2, 'C', '2018-12-04 11:52:20.958955-08');
+INSERT INTO flows_flowsession("id", "status", "modified_on", "wait_started_on")
+                       VALUES(1, 'W', '2018-12-04 11:52:20.900234-08', '2018-12-04 11:52:20.900123-08'),
+                             (2, 'C', '2018-12-04 11:52:20.900456-08', '2018-12-04 11:52:20.900345-08');