1 files changed, 71 insertions, 0 deletions
diff --git a/libtransport/src/protocols/rtc/rtc_rs_low_rate.h b/libtransport/src/protocols/rtc/rtc_rs_low_rate.h
new file mode 100644
index 000000000..0e76efaca
--- /dev/null
+++ b/libtransport/src/protocols/rtc/rtc_rs_low_rate.h
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2021 Cisco and/or its affiliates.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+#include <protocols/rtc/rtc_recovery_strategy.h>
+
+#include <vector>
+
+namespace transport {
+
+namespace protocol {
+
+namespace rtc {
+
+struct thresholds_t {
+  uint32_t rtt;
+  uint32_t loss_rtx_to_fec;  // loss rate used to move from rtx to fec
+  uint32_t loss_fec_to_rtx;  // loss rate used to move from fec to rtx
+};
+
+class RecoveryStrategyLowRate : public RecoveryStrategy {
+ public:
+  RecoveryStrategyLowRate(Indexer *indexer, SendRtxCallback &&callback,
+                          asio::io_service &io_service,
+                          interface::RtcTransportRecoveryStrategies rs_type,
+                          interface::StrategyCallback &&external_callback);
+
+  RecoveryStrategyLowRate(RecoveryStrategy &&rs);
+
+  ~RecoveryStrategyLowRate();
+
+  void turnOnRecovery();
+  void onNewRound(bool in_sync);
+  void newPacketLoss(uint32_t seq);
+  void receivedPacket(uint32_t seq);
+
+ private:
+  void initSwitchVector();
+  void setRecoveryParameters(bool use_rtx, bool use_fec, uint32_t fec_to_ask);
+  void selectRecoveryStrategy(bool in_sync);
+
+  uint32_t fec_consecutive_rounds_;
+  uint32_t rtx_allowed_consecutive_rounds_;
+
+  // this table contains the thresholds that indicates when to switch from RTX
+  // to FEC and viceversa. values in the vector are detected with a set of
+  // experiments. the vector is used in the following way: if rtt and loss rate
+  // are less than one of the values in the in the vector, losses are
+  // recovered using RTX. otherwive losses are recovered using FEC. as for FEC
+  // only and delay based strategy, the swith from RTX to FEC is smooth,
+  // meaning that FEC and RTX are used together for some rounds
+  std::vector<thresholds_t> switch_vector;
+};
+
+}  // end namespace rtc
+
+}  // end namespace protocol
+
+}  // end namespace transport