BACKEND-200: Allow retransmit packets on ratelimit (#1)

Author: chernikovdmitry

include/steam/isteamnetworkingsockets.h

@@ -299,6 +299,11 @@ class ISteamNetworkingSockets
 	/// -k_EResultInvalidState if the connection was in an invalid state.
 	/// See ISteamNetworkingSockets::SendMessageToConnection for possible
 	/// failure codes.
+	/// NOTE: @LowKick
+	/// Fixed, don't skip any messages.
+	/// if it get k_EResultLimitExceeded for some message it will stop sending to this overloaded
+	/// connection and mark all subsequent messages to this connection as k_EResultLimitExceeded
+	/// allowing caller to retransmit it later
 	virtual void SendMessages( int nMessages, SteamNetworkingMessage_t *const *pMessages, int64 *pOutMessageNumberOrResult ) = 0;
 
 	/// Flush any messages waiting on the Nagle timer and send them

src/steamnetworkingsockets/clientlib/csteamnetworkingsockets.cpp

@@ -1333,6 +1333,28 @@ void CSteamNetworkingSockets::SendMessages( int nMessages, SteamNetworkingMessag
 		// Return result for this message if they asked for it
 		if ( pOutMessageNumberOrResult )
 			pOutMessageNumberOrResult[pSort->m_idx] = result;
+
+		// Have too many pending bytes on this connection
+		if ( result == -k_EResultLimitExceeded )
+		{
+			// If caller wants to know - mark all next messages as k_EResultLimitExceeded so caller could
+			// attempt to resend them later
+			if ( pOutMessageNumberOrResult ) {
+				++pSort; // Already done
+				for ( ; pSort < pSortEnd ; ++pSort )
+				{
+					if ( pSort->m_hConn != hConn )
+						break;
+
+					pOutMessageNumberOrResult[pSort->m_idx] = -k_EResultLimitExceeded;
+				}
+			}
+			else
+			{
+				// Caller doesn't care - just skip this one
+				pMsg->Release();
+			}
+		}
 	}
 
 	// Flush out last connection, if any

src/steamnetworkingsockets/clientlib/steamnetworkingsockets_snp.cpp

@@ -317,7 +317,8 @@ int64 CSteamNetworkConnectionBase::SNP_SendMessage( CSteamNetworkingMessage *pSe
 	if ( m_senderState.PendingBytesTotal() + cbData > m_connectionConfig.m_SendBufferSize.Get() )
 	{
 		SpewWarningRateLimited( usecNow, "Connection already has %u bytes pending, cannot queue any more messages\n", m_senderState.PendingBytesTotal() );
-		pSendMessage->Release();
+		// NOTE: @LowKick: we should keep the message around, but not send it, so caller can retry later
+		// pSendMessage->Release();
 		return -k_EResultLimitExceeded;
 	}
 

tests/test_connection.cpp

@@ -1103,6 +1103,7 @@ void Test_netloopback_throughput()
 					SteamNetworkingSockets()->SendMessages( 1, &pSendMsg, &nMsgNumberOrResult );
 					if ( nMsgNumberOrResult == -k_EResultLimitExceeded )
 					{
+						pSendMsg->Release();
 						TEST_Printf( "SendMessage returned limit exceeded trying to queue %d + %d = %d\n", serverStatus.m_cbPendingReliable, cbSendMsg, serverStatus.m_cbPendingReliable + cbSendMsg );
 						break;
 					}