NackModule2: Rename to NackRequester.
The alternative new name proposed, NackTracker, is already in
use in audio_coding.
Fixed: webrtc:11594
Change-Id: I6a05fafc05fa7ddb18ea4f64886a135e5ef59f7e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/226744
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Markus Handell <handellm@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34539}
diff --git a/modules/video_coding/nack_requester.h b/modules/video_coding/nack_requester.h
new file mode 100644
index 0000000..8b01237
--- /dev/null
+++ b/modules/video_coding/nack_requester.h
@@ -0,0 +1,168 @@
+/*
+ * Copyright (c) 2016 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.
+ */
+
+#ifndef MODULES_VIDEO_CODING_NACK_REQUESTER_H_
+#define MODULES_VIDEO_CODING_NACK_REQUESTER_H_
+
+#include <stdint.h>
+
+#include <map>
+#include <set>
+#include <vector>
+
+#include "api/sequence_checker.h"
+#include "api/units/time_delta.h"
+#include "modules/include/module_common_types.h"
+#include "modules/video_coding/histogram.h"
+#include "rtc_base/numerics/sequence_number_util.h"
+#include "rtc_base/task_queue.h"
+#include "rtc_base/task_utils/pending_task_safety_flag.h"
+#include "rtc_base/task_utils/repeating_task.h"
+#include "rtc_base/thread_annotations.h"
+#include "system_wrappers/include/clock.h"
+
+namespace webrtc {
+
+class NackRequesterBase {
+ public:
+ virtual ~NackRequesterBase() = default;
+ virtual void ProcessNacks() = 0;
+};
+
+class NackPeriodicProcessor {
+ public:
+ static constexpr TimeDelta kUpdateInterval = TimeDelta::Millis(20);
+ explicit NackPeriodicProcessor(TimeDelta update_interval = kUpdateInterval);
+ ~NackPeriodicProcessor();
+ void RegisterNackModule(NackRequesterBase* module);
+ void UnregisterNackModule(NackRequesterBase* module);
+
+ private:
+ void ProcessNackModules() RTC_RUN_ON(sequence_);
+
+ const TimeDelta update_interval_;
+ RepeatingTaskHandle repeating_task_ RTC_GUARDED_BY(sequence_);
+ std::vector<NackRequesterBase*> modules_ RTC_GUARDED_BY(sequence_);
+ RTC_NO_UNIQUE_ADDRESS SequenceChecker sequence_;
+};
+
+class ScopedNackPeriodicProcessorRegistration {
+ public:
+ ScopedNackPeriodicProcessorRegistration(NackRequesterBase* module,
+ NackPeriodicProcessor* processor);
+ ~ScopedNackPeriodicProcessorRegistration();
+
+ private:
+ NackRequesterBase* const module_;
+ NackPeriodicProcessor* const processor_;
+};
+
+class NackRequester final : public NackRequesterBase {
+ public:
+ NackRequester(TaskQueueBase* current_queue,
+ NackPeriodicProcessor* periodic_processor,
+ Clock* clock,
+ NackSender* nack_sender,
+ KeyFrameRequestSender* keyframe_request_sender);
+ ~NackRequester();
+
+ void ProcessNacks() override;
+
+ int OnReceivedPacket(uint16_t seq_num, bool is_keyframe);
+ int OnReceivedPacket(uint16_t seq_num, bool is_keyframe, bool is_recovered);
+
+ void ClearUpTo(uint16_t seq_num);
+ void UpdateRtt(int64_t rtt_ms);
+
+ private:
+ // Which fields to consider when deciding which packet to nack in
+ // GetNackBatch.
+ enum NackFilterOptions { kSeqNumOnly, kTimeOnly, kSeqNumAndTime };
+
+ // This class holds the sequence number of the packet that is in the nack list
+ // as well as the meta data about when it should be nacked and how many times
+ // we have tried to nack this packet.
+ struct NackInfo {
+ NackInfo();
+ NackInfo(uint16_t seq_num,
+ uint16_t send_at_seq_num,
+ int64_t created_at_time);
+
+ uint16_t seq_num;
+ uint16_t send_at_seq_num;
+ int64_t created_at_time;
+ int64_t sent_at_time;
+ int retries;
+ };
+
+ struct BackoffSettings {
+ BackoffSettings(TimeDelta min_retry, TimeDelta max_rtt, double base);
+ static absl::optional<BackoffSettings> ParseFromFieldTrials();
+
+ // Min time between nacks.
+ const TimeDelta min_retry_interval;
+ // Upper bound on link-delay considered for exponential backoff.
+ const TimeDelta max_rtt;
+ // Base for the exponential backoff.
+ const double base;
+ };
+
+ void AddPacketsToNack(uint16_t seq_num_start, uint16_t seq_num_end)
+ RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);
+
+ // Removes packets from the nack list until the next keyframe. Returns true
+ // if packets were removed.
+ bool RemovePacketsUntilKeyFrame()
+ RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);
+ std::vector<uint16_t> GetNackBatch(NackFilterOptions options)
+ RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);
+
+ // Update the reordering distribution.
+ void UpdateReorderingStatistics(uint16_t seq_num)
+ RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);
+
+ // Returns how many packets we have to wait in order to receive the packet
+ // with probability |probabilty| or higher.
+ int WaitNumberOfPackets(float probability) const
+ RTC_EXCLUSIVE_LOCKS_REQUIRED(worker_thread_);
+
+ TaskQueueBase* const worker_thread_;
+ Clock* const clock_;
+ NackSender* const nack_sender_;
+ KeyFrameRequestSender* const keyframe_request_sender_;
+
+ // TODO(philipel): Some of the variables below are consistently used on a
+ // known thread (e.g. see |initialized_|). Those probably do not need
+ // synchronized access.
+ std::map<uint16_t, NackInfo, DescendingSeqNumComp<uint16_t>> nack_list_
+ RTC_GUARDED_BY(worker_thread_);
+ std::set<uint16_t, DescendingSeqNumComp<uint16_t>> keyframe_list_
+ RTC_GUARDED_BY(worker_thread_);
+ std::set<uint16_t, DescendingSeqNumComp<uint16_t>> recovered_list_
+ RTC_GUARDED_BY(worker_thread_);
+ video_coding::Histogram reordering_histogram_ RTC_GUARDED_BY(worker_thread_);
+ bool initialized_ RTC_GUARDED_BY(worker_thread_);
+ int64_t rtt_ms_ RTC_GUARDED_BY(worker_thread_);
+ uint16_t newest_seq_num_ RTC_GUARDED_BY(worker_thread_);
+
+ // Adds a delay before send nack on packet received.
+ const int64_t send_nack_delay_ms_;
+
+ const absl::optional<BackoffSettings> backoff_settings_;
+
+ ScopedNackPeriodicProcessorRegistration processor_registration_;
+
+ // Used to signal destruction to potentially pending tasks.
+ ScopedTaskSafety task_safety_;
+};
+
+} // namespace webrtc
+
+#endif // MODULES_VIDEO_CODING_NACK_REQUESTER_H_