1 files changed, 156 insertions, 0 deletions
diff --git a/third_party/libwebrtc/net/dcsctp/timer/timer.cc b/third_party/libwebrtc/net/dcsctp/timer/timer.cc
new file mode 100644
index 0000000000..bde07638a5
--- /dev/null
+++ b/third_party/libwebrtc/net/dcsctp/timer/timer.cc
@@ -0,0 +1,156 @@
+/*
+ *  Copyright (c) 2021 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+#include "net/dcsctp/timer/timer.h"
+
+#include <algorithm>
+#include <cstdint>
+#include <limits>
+#include <memory>
+#include <utility>
+
+#include "absl/memory/memory.h"
+#include "absl/strings/string_view.h"
+#include "net/dcsctp/public/timeout.h"
+#include "rtc_base/checks.h"
+
+namespace dcsctp {
+namespace {
+TimeoutID MakeTimeoutId(TimerID timer_id, TimerGeneration generation) {
+  return TimeoutID(static_cast<uint64_t>(*timer_id) << 32 | *generation);
+}
+
+DurationMs GetBackoffDuration(const TimerOptions& options,
+                              DurationMs base_duration,
+                              int expiration_count) {
+  switch (options.backoff_algorithm) {
+    case TimerBackoffAlgorithm::kFixed:
+      return base_duration;
+    case TimerBackoffAlgorithm::kExponential: {
+      int32_t duration_ms = *base_duration;
+
+      while (expiration_count > 0 && duration_ms < *Timer::kMaxTimerDuration) {
+        duration_ms *= 2;
+        --expiration_count;
+
+        if (options.max_backoff_duration.has_value() &&
+            duration_ms > **options.max_backoff_duration) {
+          return *options.max_backoff_duration;
+        }
+      }
+
+      return DurationMs(std::min(duration_ms, *Timer::kMaxTimerDuration));
+    }
+  }
+}
+}  // namespace
+
+constexpr DurationMs Timer::kMaxTimerDuration;
+
+Timer::Timer(TimerID id,
+             absl::string_view name,
+             OnExpired on_expired,
+             UnregisterHandler unregister_handler,
+             std::unique_ptr<Timeout> timeout,
+             const TimerOptions& options)
+    : id_(id),
+      name_(name),
+      options_(options),
+      on_expired_(std::move(on_expired)),
+      unregister_handler_(std::move(unregister_handler)),
+      timeout_(std::move(timeout)),
+      duration_(options.duration) {}
+
+Timer::~Timer() {
+  Stop();
+  unregister_handler_();
+}
+
+void Timer::Start() {
+  expiration_count_ = 0;
+  if (!is_running()) {
+    is_running_ = true;
+    generation_ = TimerGeneration(*generation_ + 1);
+    timeout_->Start(duration_, MakeTimeoutId(id_, generation_));
+  } else {
+    // Timer was running - stop and restart it, to make it expire in `duration_`
+    // from now.
+    generation_ = TimerGeneration(*generation_ + 1);
+    timeout_->Restart(duration_, MakeTimeoutId(id_, generation_));
+  }
+}
+
+void Timer::Stop() {
+  if (is_running()) {
+    timeout_->Stop();
+    expiration_count_ = 0;
+    is_running_ = false;
+  }
+}
+
+void Timer::Trigger(TimerGeneration generation) {
+  if (is_running_ && generation == generation_) {
+    ++expiration_count_;
+    is_running_ = false;
+    if (!options_.max_restarts.has_value() ||
+        expiration_count_ <= *options_.max_restarts) {
+      // The timer should still be running after this triggers. Start a new
+      // timer. Note that it might be very quickly restarted again, if the
+      // `on_expired_` callback returns a new duration.
+      is_running_ = true;
+      DurationMs duration =
+          GetBackoffDuration(options_, duration_, expiration_count_);
+      generation_ = TimerGeneration(*generation_ + 1);
+      timeout_->Start(duration, MakeTimeoutId(id_, generation_));
+    }
+
+    absl::optional<DurationMs> new_duration = on_expired_();
+    if (new_duration.has_value() && new_duration != duration_) {
+      duration_ = new_duration.value();
+      if (is_running_) {
+        // Restart it with new duration.
+        timeout_->Stop();
+
+        DurationMs duration =
+            GetBackoffDuration(options_, duration_, expiration_count_);
+        generation_ = TimerGeneration(*generation_ + 1);
+        timeout_->Start(duration, MakeTimeoutId(id_, generation_));
+      }
+    }
+  }
+}
+
+void TimerManager::HandleTimeout(TimeoutID timeout_id) {
+  TimerID timer_id(*timeout_id >> 32);
+  TimerGeneration generation(*timeout_id);
+  auto it = timers_.find(timer_id);
+  if (it != timers_.end()) {
+    it->second->Trigger(generation);
+  }
+}
+
+std::unique_ptr<Timer> TimerManager::CreateTimer(absl::string_view name,
+                                                 Timer::OnExpired on_expired,
+                                                 const TimerOptions& options) {
+  next_id_ = TimerID(*next_id_ + 1);
+  TimerID id = next_id_;
+  // This would overflow after 4 billion timers created, which in SCTP would be
+  // after 800 million reconnections on a single socket. Ensure this will never
+  // happen.
+  RTC_CHECK_NE(*id, std::numeric_limits<uint32_t>::max());
+  std::unique_ptr<Timeout> timeout = create_timeout_(options.precision);
+  RTC_CHECK(timeout != nullptr);
+  auto timer = absl::WrapUnique(new Timer(
+      id, name, std::move(on_expired), [this, id]() { timers_.erase(id); },
+      std::move(timeout), options));
+  timers_[id] = timer.get();
+  return timer;
+}
+
+}  // namespace dcsctp