1 files changed, 154 insertions, 0 deletions
diff --git a/libtransport/src/protocols/rtc/rtc_recovery_strategy.h b/libtransport/src/protocols/rtc/rtc_recovery_strategy.h
new file mode 100644
index 000000000..9ffc69a1b
--- /dev/null
+++ b/libtransport/src/protocols/rtc/rtc_recovery_strategy.h
@@ -0,0 +1,154 @@
+/*
+ * 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 <hicn/transport/interfaces/callbacks.h>
+#include <hicn/transport/utils/chrono_typedefs.h>
+#include <protocols/indexer.h>
+#include <protocols/rtc/rtc_rc.h>
+#include <protocols/rtc/rtc_state.h>
+
+#include <map>
+#include <unordered_map>
+
+namespace transport {
+
+namespace protocol {
+
+namespace rtc {
+
+class RecoveryStrategy : public std::enable_shared_from_this<RecoveryStrategy> {
+ protected:
+  struct rtx_state_ {
+    uint64_t first_send_;
+    uint64_t next_send_;
+    uint32_t rtx_count_;
+  };
+
+  using rtxState = struct rtx_state_;
+
+ public:
+  using SendRtxCallback = std::function<void(uint32_t)>;
+
+  RecoveryStrategy(Indexer *indexer, SendRtxCallback &&callback,
+                   asio::io_service &io_service, bool use_rtx, bool use_fec,
+                   interface::StrategyCallback *external_callback);
+
+  RecoveryStrategy(RecoveryStrategy &&rs);
+
+  virtual ~RecoveryStrategy();
+
+  void setRtxFec(std::optional<bool> rtx_on = {},
+                 std::optional<bool> fec_on = {});
+  void setState(RTCState *state) { state_ = state; }
+  void setRateControl(RTCRateControl *rateControl) { rc_ = rateControl; }
+  void setFecParams(uint32_t n, uint32_t k);
+
+  void tunrOnRecovery() { recovery_on_ = true; }
+
+  bool isRtx(uint32_t seq) {
+    if (rtx_state_.find(seq) != rtx_state_.end()) return true;
+    return false;
+  }
+
+  bool isPossibleLossWithNoRtx(uint32_t seq) {
+    if (recover_with_fec_.find(seq) != recover_with_fec_.end()) return true;
+    return false;
+  }
+
+  bool isRtxOn() { return rtx_on_; }
+
+  RTCState *getState() { return state_; }
+  bool lossDetected(uint32_t seq);
+  void clear();
+
+  virtual void onNewRound(bool in_sync) = 0;
+  virtual void newPacketLoss(uint32_t seq) = 0;
+  virtual void receivedPacket(uint32_t seq) = 0;
+  void onLostTimeout(uint32_t seq);
+
+  void incRoundId() { round_id_++; }
+
+  // utils
+  uint64_t getNow() {
+    uint64_t now = utils::SteadyTime::nowMs().count();
+    return now;
+  }
+
+ protected:
+  // rtx functions
+  void addNewRtx(uint32_t seq, bool force);
+  uint64_t computeNextSend(uint32_t seq, bool new_rtx);
+  void retransmit();
+  void scheduleNextRtx();
+  void deleteRtx(uint32_t seq);
+
+  // fec functions
+  uint32_t computeFecPacketsToAsk(bool in_sync);
+
+  // common functons
+  void removePacketState(uint32_t seq);
+
+  bool recovery_on_;
+  bool rtx_on_;
+  bool fec_on_;
+
+  // this map keeps track of the retransmitted interest, ordered from the oldest
+  // to the newest one. the state contains the timer of the first send of the
+  // interest (from pendingIntetests_), the timer of the next send (key of the
+  // multimap) and the number of rtx
+  std::map<uint32_t, rtxState> rtx_state_;
+  // this map stored the rtx by timer. The key is the time at which the rtx
+  // should be sent, and the val is the interest seq number
+  std::multimap<uint64_t, uint32_t> rtx_timers_;
+
+  // lost packets that will be recovered with fec
+  std::unordered_set<uint32_t> recover_with_fec_;
+
+  // rtx vars
+  std::unique_ptr<asio::steady_timer> timer_;
+  uint64_t next_rtx_timer_;
+  SendRtxCallback send_rtx_callback_;
+
+  // fec vars
+  uint32_t n_;
+  uint32_t k_;
+  Indexer *indexer_;
+
+  RTCState *state_;
+  RTCRateControl *rc_;
+
+ private:
+  struct fec_state_ {
+    uint32_t fec_to_ask;
+    uint32_t last_update;      // round id of the last update
+                               // (wait 10 ruonds (2sec) between updates)
+    uint32_t consecutive_use;  // consecutive ruonds where this fec was used
+    double avg_residual_losses;
+  };
+
+  void reduceFec();
+
+  uint32_t round_id_;  // number of rounds
+  uint32_t last_fec_used_;
+  std::vector<fec_state_> fec_per_loss_rate_;
+  interface::StrategyCallback *callback_;
+};
+
+}  // end namespace rtc
+
+}  // end namespace protocol
+
+}  // end namespace transport