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/*
* 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 "modules/remote_bitrate_estimator/packet_arrival_map.h"
#include <algorithm>
#include <cstdint>
#include "api/units/timestamp.h"
#include "rtc_base/checks.h"
namespace webrtc {
void PacketArrivalTimeMap::AddPacket(int64_t sequence_number,
Timestamp arrival_time) {
RTC_DCHECK_GE(arrival_time, Timestamp::Zero());
if (!has_seen_packet()) {
// First packet.
Reallocate(kMinCapacity);
begin_sequence_number_ = sequence_number;
end_sequence_number_ = sequence_number + 1;
arrival_times_[Index(sequence_number)] = arrival_time;
return;
}
if (sequence_number >= begin_sequence_number() &&
sequence_number < end_sequence_number()) {
// The packet is within the buffer - no need to expand it.
arrival_times_[Index(sequence_number)] = arrival_time;
return;
}
if (sequence_number < begin_sequence_number()) {
// The packet goes before the current buffer. Expand to add packet, but only
// if it fits within kMaxNumberOfPackets.
int64_t new_size = end_sequence_number() - sequence_number;
if (new_size > kMaxNumberOfPackets) {
// Don't expand the buffer further, as that would remove newly received
// packets.
return;
}
AdjustToSize(new_size);
arrival_times_[Index(sequence_number)] = arrival_time;
SetNotReceived(sequence_number + 1, begin_sequence_number_);
begin_sequence_number_ = sequence_number;
return;
}
// The packet goes after the buffer.
RTC_DCHECK_GE(sequence_number, end_sequence_number_);
int64_t new_end_sequence_number = sequence_number + 1;
if (new_end_sequence_number >= end_sequence_number_ + kMaxNumberOfPackets) {
// All old packets have to be removed.
begin_sequence_number_ = sequence_number;
end_sequence_number_ = new_end_sequence_number;
arrival_times_[Index(sequence_number)] = arrival_time;
return;
}
if (begin_sequence_number_ < new_end_sequence_number - kMaxNumberOfPackets) {
// Remove oldest entries
begin_sequence_number_ = new_end_sequence_number - kMaxNumberOfPackets;
RTC_DCHECK_GT(end_sequence_number_, begin_sequence_number_);
}
AdjustToSize(new_end_sequence_number - begin_sequence_number_);
// Packets can be received out-of-order. If this isn't the next expected
// packet, add enough placeholders to fill the gap.
SetNotReceived(end_sequence_number_, sequence_number);
end_sequence_number_ = new_end_sequence_number;
arrival_times_[Index(sequence_number)] = arrival_time;
}
void PacketArrivalTimeMap::SetNotReceived(
int64_t begin_sequence_number_inclusive,
int64_t end_sequence_number_exclusive) {
static constexpr Timestamp value = Timestamp::MinusInfinity();
int begin_index = Index(begin_sequence_number_inclusive);
int end_index = Index(end_sequence_number_exclusive);
if (begin_index <= end_index) {
// Entries to clear are in single block:
// [......{-----}....]
std::fill(arrival_times_.get() + begin_index,
arrival_times_.get() + end_index, value);
} else {
// Entries to clear span across arrival_times_ border:
// [--}..........{---]
std::fill(arrival_times_.get() + begin_index,
arrival_times_.get() + capacity(), value);
std::fill(arrival_times_.get(), arrival_times_.get() + end_index, value);
}
}
void PacketArrivalTimeMap::RemoveOldPackets(int64_t sequence_number,
Timestamp arrival_time_limit) {
int64_t check_to = std::min(sequence_number, end_sequence_number_);
while (begin_sequence_number_ < check_to &&
arrival_times_[Index(begin_sequence_number_)] <= arrival_time_limit) {
++begin_sequence_number_;
}
AdjustToSize(end_sequence_number_ - begin_sequence_number_);
}
void PacketArrivalTimeMap::EraseTo(int64_t sequence_number) {
if (sequence_number < begin_sequence_number_) {
return;
}
if (sequence_number >= end_sequence_number_) {
// Erase all.
begin_sequence_number_ = end_sequence_number_;
return;
}
// Remove some.
begin_sequence_number_ = sequence_number;
AdjustToSize(end_sequence_number_ - begin_sequence_number_);
}
void PacketArrivalTimeMap::AdjustToSize(int new_size) {
if (new_size > capacity()) {
int new_capacity = capacity();
while (new_capacity < new_size)
new_capacity *= 2;
Reallocate(new_capacity);
}
if (capacity() > std::max(kMinCapacity, 4 * new_size)) {
int new_capacity = capacity();
while (new_capacity > 2 * std::max(new_size, kMinCapacity)) {
new_capacity /= 2;
}
Reallocate(new_capacity);
}
RTC_DCHECK_LE(new_size, capacity());
}
void PacketArrivalTimeMap::Reallocate(int new_capacity) {
int new_capacity_minus_1 = new_capacity - 1;
// Check capacity is a power of 2.
RTC_DCHECK_EQ(new_capacity & new_capacity_minus_1, 0);
// Create uninitialized memory.
// All valid entries should be set by `AddPacket` before use.
void* raw = operator new[](new_capacity * sizeof(Timestamp));
Timestamp* new_buffer = static_cast<Timestamp*>(raw);
for (int64_t sequence_number = begin_sequence_number_;
sequence_number < end_sequence_number_; ++sequence_number) {
new_buffer[sequence_number & new_capacity_minus_1] =
arrival_times_[sequence_number & capacity_minus_1_];
}
arrival_times_.reset(new_buffer);
capacity_minus_1_ = new_capacity_minus_1;
}
} // namespace webrtc
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