Use precise sync of the server unixtime.

Telegram/SourceFiles/mtproto/session_private.cpp

@@ -40,6 +40,7 @@ constexpr auto kTestModeDcIdShift = 10000;
 constexpr auto kCheckSentRequestsEach = 1 * crl::time(1000);
 constexpr auto kKeyOldEnoughForDestroy = 60 * crl::time(1000);
 constexpr auto kSentContainerLives = 600 * crl::time(1000);
+constexpr auto kFastRequestDuration = crl::time(500);
 
 // If we can't connect for this time we will ask _instance to update config.
 constexpr auto kRequestConfigTimeout = 8 * crl::time(1000);
@@ -57,6 +58,8 @@ constexpr auto kSendStateRequestWaiting = crl::time(1000);
 // How much time to wait for some more requests, when sending msg acks.
 constexpr auto kAckSendWaiting = 10 * crl::time(1000);
 
+auto SyncTimeRequestDuration = kFastRequestDuration;
+
 using namespace details;
 
 [[nodiscard]] QString LogIdsVector(const QVector<MTPlong> &ids) {
@@ -1467,8 +1470,12 @@ SessionPrivate::HandleResult SessionPrivate::handleOneReceived(
 			return badTime ? HandleResult::Ignored : HandleResult::Success;
 		}
 
-		if (badTime && !requestsFixTimeSalt(ids, serverTime, serverSalt)) {
-			return HandleResult::Ignored;
+		if (badTime) {
+			if (!requestsFixTimeSalt(ids, serverTime, serverSalt)) {
+				return HandleResult::Ignored;
+			}
+		} else {
+			correctUnixtimeByFastRequest(ids, serverTime);
 		}
 		requestsAcked(ids);
 	} return HandleResult::Success;
@@ -1520,7 +1527,8 @@ SessionPrivate::HandleResult SessionPrivate::handleOneReceived(
 				if (serverSalt) {
 					_sessionSalt = serverSalt;
 				}
-				base::unixtime::update(serverTime, true);
+
+				correctUnixtimeWithBadLocal(serverTime);
 
 				DEBUG_LOG(("Message Info: unixtime updated, now %1, resending in container...").arg(serverTime));
 
@@ -1530,7 +1538,7 @@ SessionPrivate::HandleResult SessionPrivate::handleOneReceived(
 					if (serverSalt) {
 						_sessionSalt = serverSalt;
 					}
-					base::unixtime::update(serverTime, true);
+					correctUnixtimeWithBadLocal(serverTime);
 					badTime = false;
 				}
 				LOG(("Message Info: bad message notification received, msgId %1, error_code %2").arg(data.vbad_msg_id().v).arg(errorCode));
@@ -1580,7 +1588,7 @@ SessionPrivate::HandleResult SessionPrivate::handleOneReceived(
 		}
 
 		_sessionSalt = data.vnew_server_salt().v;
-		base::unixtime::update(serverTime);
+		correctUnixtimeWithBadLocal(serverTime);
 
 		if (setState(ConnectedState, ConnectingState)) {
 			resendAll();
@@ -1612,7 +1620,7 @@ SessionPrivate::HandleResult SessionPrivate::handleOneReceived(
 			if (serverSalt) {
 				_sessionSalt = serverSalt; // requestsFixTimeSalt with no lookup
 			}
-			base::unixtime::update(serverTime, true);
+			correctUnixtimeWithBadLocal(serverTime);
 
 			DEBUG_LOG(("Message Info: unixtime updated from mtpc_msgs_state_info, now %1").arg(serverTime));
 
@@ -1956,20 +1964,48 @@ mtpBuffer SessionPrivate::ungzip(const mtpPrime *from, const mtpPrime *end) cons
 }
 
 bool SessionPrivate::requestsFixTimeSalt(const QVector<MTPlong> &ids, int32 serverTime, uint64 serverSalt) {
-	uint32 idsCount = ids.size();
-
-	for (uint32 i = 0; i < idsCount; ++i) {
-		if (wasSent(ids[i].v)) {// found such msg_id in recent acked requests or in recent sent requests
+	for (const auto &id : ids) {
+		if (wasSent(id.v)) {
+			// Found such msg_id in recent acked or in recent sent requests.
 			if (serverSalt) {
 				_sessionSalt = serverSalt;
 			}
-			base::unixtime::update(serverTime, true);
+			correctUnixtimeWithBadLocal(serverTime);
 			return true;
 		}
 	}
 	return false;
 }
 
+void SessionPrivate::correctUnixtimeByFastRequest(
+		const QVector<MTPlong> &ids,
+		TimeId serverTime) {
+	const auto now = crl::now();
+
+	QReadLocker locker(_sessionData->haveSentMutex());
+	const auto &haveSent = _sessionData->haveSentMap();
+	for (const auto &id : ids) {
+		const auto i = haveSent.find(id.v);
+		if (i == haveSent.end()) {
+			continue;
+		}
+		const auto duration = (now - i->second->lastSentTime);
+		if (duration < 0 || duration > SyncTimeRequestDuration) {
+			continue;
+		}
+		locker.unlock();
+
+		SyncTimeRequestDuration = duration;
+		base::unixtime::update(serverTime, true);
+		return;
+	}
+}
+
+void SessionPrivate::correctUnixtimeWithBadLocal(TimeId serverTime) {
+	SyncTimeRequestDuration = kFastRequestDuration;
+	base::unixtime::update(serverTime, true);
+}
+
 void SessionPrivate::requestsAcked(const QVector<MTPlong> &ids, bool byResponse) {
 	uint32 idsCount = ids.size();
 

Telegram/SourceFiles/mtproto/session_private.h

@@ -139,6 +139,12 @@ private:
 	// if badTime received - search for ids in sessionData->haveSent and sessionData->wereAcked and sync time/salt, return true if found
 	bool requestsFixTimeSalt(const QVector<MTPlong> &ids, int32 serverTime, uint64 serverSalt);
 
+	// if we had a confirmed fast request use its unixtime as a correct one.
+	void correctUnixtimeByFastRequest(
+		const QVector<MTPlong> &ids,
+		TimeId serverTime);
+	void correctUnixtimeWithBadLocal(TimeId serverTime);
+
 	// remove msgs with such ids from sessionData->haveSent, add to sessionData->wereAcked
 	void requestsAcked(const QVector<MTPlong> &ids, bool byResponse = false);
 

Telegram/lib_base

@@ -1 +1 @@
-Subproject commit 9e01ede6661e2a74697283c7836d4fae433f50ce
+Subproject commit b376282b656b13c54cd892e3c2742bb26acf42fe