Fix a crash after joining broadcasts.

Telegram/SourceFiles/calls/group/calls_group_call.cpp

@@ -74,6 +74,11 @@ constexpr auto kMaxMediumQualities = 16; // 4 Fulls or 16 Mediums.
 	return msgId / double(1ULL << 32);
 }
 
+[[nodiscard]] int64 TimestampInMsFromMsgId(mtpMsgId msgId) {
+	// return (msgId * 1000) / (1ULL << 32); // Almost... But this overflows.
+	return ((msgId / (1ULL << 10)) * 1000) / (1ULL << 22);
+}
+
 [[nodiscard]] uint64 FindLocalRaisedHandRating(
 		const std::vector<Data::GroupCallParticipant> &list) {
 	const auto i = ranges::max_element(
@@ -95,6 +100,41 @@ using JoinClientFields = std::variant<
 	JoinVideoEndpoint,
 	JoinBroadcastStream>;
 
+class RequestCurrentTimeTask final : public tgcalls::BroadcastPartTask {
+public:
+	RequestCurrentTimeTask(
+		base::weak_ptr<GroupCall> call,
+		Fn<void(int64)> done);
+
+	void done(int64 value);
+	void cancel() override;
+
+private:
+	const base::weak_ptr<GroupCall> _call;
+	Fn<void(int64)> _done;
+	QMutex _mutex;
+
+};
+
+RequestCurrentTimeTask::RequestCurrentTimeTask(
+	base::weak_ptr<GroupCall> call,
+	Fn<void(int64)> done)
+: _call(call)
+, _done(std::move(done)) {
+}
+
+void RequestCurrentTimeTask::done(int64 value) {
+	QMutexLocker lock(&_mutex);
+	if (_done) {
+		base::take(_done)(value);
+	}
+}
+
+void RequestCurrentTimeTask::cancel() {
+	QMutexLocker lock(&_mutex);
+	_done = nullptr;
+}
+
 [[nodiscard]] JoinClientFields ParseJoinResponse(const QByteArray &json) {
 	auto error = QJsonParseError{ 0, QJsonParseError::NoError };
 	const auto document = QJsonDocument::fromJson(json, &error);
@@ -1273,7 +1313,12 @@ void GroupCall::rejoin(not_null<PeerData*> as) {
 				joinAs()->input,
 				MTP_string(_joinHash),
 				MTP_dataJSON(MTP_bytes(json))
-			)).done([=](const MTPUpdates &updates) {
+			)).done([=](
+					const MTPUpdates &updates,
+					const MTP::Response &response) {
+				_serverTimeMs = TimestampInMsFromMsgId(response.outerMsgId);
+				_serverTimeMsGotAt = crl::now();
+
 				_joinState.finish(ssrc);
 				_mySsrcs.emplace(ssrc);
 
@@ -2253,6 +2298,16 @@ bool GroupCall::tryCreateController() {
 		.createAudioDeviceModule = Webrtc::AudioDeviceModuleCreator(
 			settings.callAudioBackend()),
 		.videoCapture = _cameraCapture,
+		.requestCurrentTime = [=, call = base::make_weak(this)](
+				std::function<void(int64_t)> done) {
+			auto result = std::make_shared<RequestCurrentTimeTask>(
+				call,
+				std::move(done));
+			crl::on_main(weak, [=] {
+				result->done(approximateServerTimeInMs());
+			});
+			return result;
+		},
 		.requestAudioBroadcastPart = [=, call = base::make_weak(this)](
 				int64_t time,
 				int64_t period,
@@ -2499,6 +2554,12 @@ void GroupCall::mediaChannelDescriptionsCancel(
 	}
 }
 
+int64 GroupCall::approximateServerTimeInMs() const {
+	Expects(_serverTimeMs != 0);
+
+	return _serverTimeMs + (crl::now() - _serverTimeMsGotAt);
+}
+
 void GroupCall::updateRequestedVideoChannels() {
 	_requestedVideoChannelsUpdateScheduled = false;
 	const auto real = lookupReal();

Telegram/SourceFiles/calls/group/calls_group_call.h

@@ -406,16 +406,6 @@ public:
 private:
 	class LoadPartTask;
 	class MediaChannelDescriptionsTask;
-
-public:
-	void broadcastPartStart(std::shared_ptr<LoadPartTask> task);
-	void broadcastPartCancel(not_null<LoadPartTask*> task);
-	void mediaChannelDescriptionsStart(
-		std::shared_ptr<MediaChannelDescriptionsTask> task);
-	void mediaChannelDescriptionsCancel(
-		not_null<MediaChannelDescriptionsTask*> task);
-
-private:
 	using GlobalShortcutValue = base::GlobalShortcutValue;
 	using Error = Group::Error;
 	struct SinkPointer;
@@ -464,6 +454,14 @@ private:
 		return true;
 	}
 
+	void broadcastPartStart(std::shared_ptr<LoadPartTask> task);
+	void broadcastPartCancel(not_null<LoadPartTask*> task);
+	void mediaChannelDescriptionsStart(
+		std::shared_ptr<MediaChannelDescriptionsTask> task);
+	void mediaChannelDescriptionsCancel(
+		not_null<MediaChannelDescriptionsTask*> task);
+	[[nodiscard]] int64 approximateServerTimeInMs() const;
+
 	[[nodiscard]] bool mediaChannelDescriptionsFill(
 		not_null<MediaChannelDescriptionsTask*> task,
 		Fn<bool(uint32)> resolved = nullptr);
@@ -571,11 +569,14 @@ private:
 	base::flat_set<
 		std::shared_ptr<
 			MediaChannelDescriptionsTask>,
-		base::pointer_comparator<MediaChannelDescriptionsTask>> _mediaChannelDescriptionses;
+		base::pointer_comparator<
+			MediaChannelDescriptionsTask>> _mediaChannelDescriptionses;
 
 	rpl::variable<not_null<PeerData*>> _joinAs;
 	std::vector<not_null<PeerData*>> _possibleJoinAs;
 	QString _joinHash;
+	int64 _serverTimeMs = 0;
+	crl::time _serverTimeMsGotAt = 0;
 
 	rpl::variable<MuteState> _muted = MuteState::Muted;
 	rpl::variable<bool> _canManage = false;