Check if the destructor has been started when an event is triggered.

Whenever an event is triggered from a owned object, ex. from PersistentConnection to Repo, check if the destructor has been started using SafeReference.  If so, early out.  If not, lock the reference until the end of the event.

PiperOrigin-RevId: 265122249

Author: chkuang-g

app/src/safe_reference.h

@@ -77,6 +77,12 @@ class SafeReferenceLock {
   MutexLock lock_;
 };
 
+// A macro to check if the safe_reference is valid.  Early out if not.
+#define SAFE_REFERENCE_RETURN_VOID_IF_INVALID(lock_type, lock_name, \
+                                              safe_reference)       \
+  lock_type lock_name(&safe_reference);                             \
+  if (!lock_name.GetReference()) return;
+
 }  // namespace internal
 }  // namespace FIREBASE_NAMESPACE
 

database/src/desktop/connection/connection.cc

@@ -166,6 +166,8 @@ void Connection::Send(const Variant& message, bool is_sensitive) {
 }
 
 void Connection::OnOpen() {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ConnectionRefLock, lock, safe_this_);
+
   LogDebug("%s websocket opened", log_id_.c_str());
 
   scheduler_->Schedule(new callback::CallbackValue1<ConnectionRef>(
@@ -196,6 +198,8 @@ void Connection::OnOpen() {
 }
 
 void Connection::OnMessage(const char* msg) {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ConnectionRefLock, lock, safe_this_);
+
   LogDebug("%s websocket message received", log_id_.c_str());
   scheduler_->Schedule(new callback::CallbackValue1String1<ConnectionRef>(
       safe_this_, msg, [](ConnectionRef conn_ref, const char* msg) {
@@ -208,6 +212,8 @@ void Connection::OnMessage(const char* msg) {
 }
 
 void Connection::OnClose() {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ConnectionRefLock, lock, safe_this_);
+
   LogDebug("%s websocket closed", log_id_.c_str());
 
   scheduler_->Schedule(new callback::CallbackValue1<ConnectionRef>(
@@ -228,6 +234,8 @@ void Connection::OnClose() {
 }
 
 void Connection::OnError(const WebSocketClientErrorData& error_data) {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ConnectionRefLock, lock, safe_this_);
+
   LogDebug("%s websocket error occurred.  Uri: %s", log_id_.c_str(),
            error_data.GetUri().c_str());
 

database/src/desktop/connection/persistent_connection.cc

@@ -145,6 +145,8 @@ PersistentConnection::~PersistentConnection() {
 }
 
 void PersistentConnection::OnCacheHost(const std::string& host) {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ThisRefLock, lock, safe_this_);
+
   // TODO(chkuang): Ignore cache host for now.
 }
 
@@ -177,6 +179,8 @@ bool HasKey(const Variant& data, const char* key) {
 
 void PersistentConnection::OnReady(int64_t timestamp,
                                    const std::string& session_id) {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ThisRefLock, lock, safe_this_);
+
   LogDebug("%s OnReady", log_id_.c_str());
 
   // Trigger OnServerInfoUpdate based on timestamp delta
@@ -241,6 +245,8 @@ void PersistentConnection::HandleConnectStatsResponse(
 void PersistentConnection::OnDataMessage(const Variant& message) {
   assert(message.is_map());
 
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ThisRefLock, lock, safe_this_);
+
   if (HasKey(message, kRequestNumber)) {
     auto it_request_number = message.map().find(kRequestNumber);
     assert(it_request_number->second.is_numeric());
@@ -285,6 +291,8 @@ void PersistentConnection::OnDataMessage(const Variant& message) {
 }
 
 void PersistentConnection::OnDisconnect(Connection::DisconnectReason reason) {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ThisRefLock, lock, safe_this_);
+
   LogDebug("%s Got on disconnect due to %d", log_id_.c_str(),
            static_cast<int>(reason));
 
@@ -311,6 +319,8 @@ void PersistentConnection::OnDisconnect(Connection::DisconnectReason reason) {
 }
 
 void PersistentConnection::OnKill(const std::string& reason) {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ThisRefLock, lock, safe_this_);
+
   LogDebug(
       "%s Firebase Database connection was forcefully killed by the server. "
       "Will not attempt reconnect. Reason: %s",

database/src/desktop/core/repo.cc

@@ -487,9 +487,15 @@ static std::map<Path, Variant> VariantToPathMap(const Variant& data) {
   return path_map;
 }
 
-void Repo::OnConnect() { OnServerInfoUpdate(kDotInfoConnected, true); }
+void Repo::OnConnect() {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ThisRefLock, lock, safe_this_);
+
+  OnServerInfoUpdate(kDotInfoConnected, true);
+}
 
 void Repo::OnDisconnect() {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ThisRefLock, lock, safe_this_);
+
   OnServerInfoUpdate(kDotInfoConnected, false);
   RunOnDisconnectEvents();
 }
@@ -513,6 +519,8 @@ void Repo::RunOnDisconnectEvents() {
 }
 
 void Repo::OnAuthStatus(bool auth_ok) {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ThisRefLock, lock, safe_this_);
+
   OnServerInfoUpdate(kDotInfoAuthenticated, auth_ok);
 }
 
@@ -521,6 +529,8 @@ void Repo::OnServerInfoUpdate(const std::string& key, const Variant& value) {
 }
 
 void Repo::OnServerInfoUpdate(const std::map<Variant, Variant>& updates) {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ThisRefLock, lock, safe_this_);
+
   for (const std::pair<Variant, Variant> element : updates) {
     const Variant& key = element.first;
     const Variant& value = element.second;
@@ -530,6 +540,8 @@ void Repo::OnServerInfoUpdate(const std::map<Variant, Variant>& updates) {
 
 void Repo::OnDataUpdate(const Path& path, const Variant& data, bool is_merge,
                         const connection::PersistentConnection::Tag& tag) {
+  SAFE_REFERENCE_RETURN_VOID_IF_INVALID(ThisRefLock, lock, safe_this_);
+
   std::vector<Event> events;
   if (is_merge) {
     std::map<Path, Variant> changed_children = VariantToPathMap(data);