1 files changed, 107 insertions, 0 deletions
diff --git a/libtransport/src/protocols/rtc/probe_handler.cc b/libtransport/src/protocols/rtc/probe_handler.cc
new file mode 100644
index 000000000..efba362d4
--- /dev/null
+++ b/libtransport/src/protocols/rtc/probe_handler.cc
@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2017-2021 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.
+ */
+
+#include <protocols/rtc/probe_handler.h>
+#include <protocols/rtc/rtc_consts.h>
+
+namespace transport {
+
+namespace protocol {
+
+namespace rtc {
+
+ProbeHandler::ProbeHandler(SendProbeCallback &&send_callback,
+                           asio::io_service &io_service)
+    : probe_interval_(0),
+      max_probes_(0),
+      sent_probes_(0),
+      probe_timer_(std::make_unique<asio::steady_timer>(io_service)),
+      rand_eng_((std::random_device())()),
+      distr_(MIN_RTT_PROBE_SEQ, MAX_RTT_PROBE_SEQ),
+      send_probe_callback_(std::move(send_callback)) {}
+
+ProbeHandler::~ProbeHandler() {}
+
+uint64_t ProbeHandler::getRtt(uint32_t seq) {
+  auto it = pending_probes_.find(seq);
+
+  if (it == pending_probes_.end()) return 0;
+
+  uint64_t now = std::chrono::duration_cast<std::chrono::milliseconds>(
+                     std::chrono::steady_clock::now().time_since_epoch())
+                     .count();
+  uint64_t rtt = now - it->second;
+  if(rtt < 1) rtt = 1;
+
+  pending_probes_.erase(it);
+
+  return rtt;
+}
+
+void ProbeHandler::setProbes(uint32_t probe_interval, uint32_t max_probes) {
+  stopProbes();
+  probe_interval_ = probe_interval;
+  max_probes_ = max_probes;
+}
+
+void ProbeHandler::stopProbes() {
+  probe_interval_ = 0;
+  max_probes_ = 0;
+  sent_probes_ = 0;
+  probe_timer_->cancel();
+}
+
+void ProbeHandler::sendProbes() {
+  if (probe_interval_ == 0) return;
+  if (max_probes_ != 0 && sent_probes_ >= max_probes_) return;
+
+  uint64_t now = std::chrono::duration_cast<std::chrono::milliseconds>(
+                     std::chrono::steady_clock::now().time_since_epoch())
+                     .count();
+
+  uint32_t seq = distr_(rand_eng_);
+  pending_probes_.insert(std::pair<uint32_t, uint64_t>(seq, now));
+  send_probe_callback_(seq);
+  sent_probes_++;
+
+  // clean up
+  // a probe may get lost. if the pending_probes_ size becomes bigger than
+  // MAX_PENDING_PROBES remove all the probes older than a seconds
+  if (pending_probes_.size() > MAX_PENDING_PROBES) {
+    for (auto it = pending_probes_.begin(); it != pending_probes_.end();) {
+      if ((now - it->second) > 1000)
+        it = pending_probes_.erase(it);
+      else
+        it++;
+    }
+  }
+
+  if (probe_interval_ == 0) return;
+
+  std::weak_ptr<ProbeHandler> self(shared_from_this());
+  probe_timer_->expires_from_now(std::chrono::microseconds(probe_interval_));
+  probe_timer_->async_wait([self](std::error_code ec) {
+    if (ec) return;
+    if (auto s = self.lock()) {
+      s->sendProbes();
+    }
+  });
+}
+
+}  // namespace rtc
+
+}  // namespace protocol
+
+}  // namespace transport