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/*
* 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.
*/
#include <glog/logging.h>
#include <hicn/transport/core/global_object_pool.h>
#include <protocols/fec/rely.h>
#include <rely/packet.hpp>
namespace transport {
namespace protocol {
namespace fec {
RelyEncoder::RelyEncoder(uint32_t k, uint32_t n, uint32_t /* seq_offset */)
: RelyBase(k, n) {
configure(kmtu, ktimeout, kmax_stream_size);
set_repair_trigger(k_, n_ - k_, n_ - k_);
}
void RelyEncoder::onPacketProduced(core::ContentObject &content_object,
uint32_t offset, uint32_t metadata) {
// Get pointer to payload, leaving space to insert FEC header.
// TODO Check if this additional header is really needed.
auto data = content_object.writableData() + offset - sizeof(fec_metadata);
auto length = content_object.length() - offset + sizeof(fec_metadata);
// Check packet length does not exceed maximum length supported by the
// encoder (otherwise segmentation would take place).
DCHECK(length < max_packet_bytes());
DLOG_IF(INFO, VLOG_IS_ON(4))
<< "Encoding packet of length " << length - sizeof(fec_metadata);
// Get the suffix. With rely we need to write it in the fec_metadata in order
// to be able to recognize the seq number upon recovery.
auto suffix = content_object.getName().getSuffix();
DLOG_IF(INFO, VLOG_IS_ON(4)) << "Producing packet " << suffix
<< " (index == " << current_index_ << ")";
// Consume payload. Add fec_metadata in front before feeding payload to
// encoder, and copy original content of packet
fec_metadata *h = reinterpret_cast<fec_metadata *>(data);
fec_metadata copy = *h;
h->setSeqNumberBase(suffix);
h->setMetadataBase(metadata);
auto packets = consume(data, length, getCurrentTime());
DCHECK(packets == 1);
// Update packet counter
current_index_ += packets;
// Restore original packet content and increment data pointer to the correct
// position
*h = copy;
data += sizeof(fec_metadata);
// Check position of this packet inside N size block
auto i = current_index_ % n_;
// encoder will produce a source packet
if (i <= k_) {
// Rely modifies the payload of the packet. We replace the packet with the
// one returned by rely.
// TODO Optimize it by copying only the RELY header
// Be sure encoder can produce
DCHECK(can_produce());
// Check new payload size and make sure it fits in packet buffer
auto new_payload_size = produce_bytes();
int difference = (int)(new_payload_size - length);
DCHECK(difference > 0);
DCHECK(content_object.ensureCapacity(difference));
// Update length
DLOG_IF(INFO, VLOG_IS_ON(4)) << "The packet length will be incremented by "
<< difference + sizeof(fec_metadata);
content_object.append(difference + sizeof(fec_metadata));
content_object.updateLength();
// Make sure we got a source packet, otherwise we would put a repair symbol
// in a source packet
DCHECK(rely::packet_is_systematic(produce_data()));
// Copy rely packet replacing old source packet.
std::memcpy(data, produce_data(), new_payload_size);
// Advance the encoder to next symbol.
produce_next();
}
#if 0
if (i == k_) {
// Ensure repair are generated after k source packets
flush_repair();
}
#endif
// Here we should produce all the repair packets
while (can_produce()) {
// The current index MUST be k_, because we enforce n - k repair to be
// produced after k sources
DCHECK(current_index_ == k_);
buffer packet;
if (!buffer_callback_) {
// If no callback is installed, let's allocate a buffer from global pool
packet = core::PacketManager<>::getInstance().getMemBuf();
packet->append(produce_bytes());
} else {
// Otherwise let's ask a buffer to the caller.
packet = buffer_callback_(produce_bytes());
}
DLOG_IF(INFO, VLOG_IS_ON(4))
<< "Producing symbol of size " << produce_bytes();
// Copy symbol to packet buffer
std::memcpy(packet->writableData(), produce_data(), produce_bytes());
// Push symbol in repair_packets
packets_.emplace_back(0, metadata, std::move(packet));
// Advance the encoder
produce_next();
}
// Print number of unprotected symbols
DLOG_IF(INFO, VLOG_IS_ON(4))
<< "Number of unprotected symbols: " << unprotected_symbols();
// If we have generated repair symbols, let's notify caller via the installed
// callback
if (packets_.size()) {
DCHECK(packets_.size() == n_ - k_);
fec_callback_(packets_);
packets_.clear();
current_index_ = 0;
}
}
RelyDecoder::RelyDecoder(uint32_t k, uint32_t n, uint32_t seq_offset)
: RelyBase(k, n, seq_offset) {
configure(kmtu, ktimeout, kmax_stream_size);
}
void RelyDecoder::onDataPacket(core::ContentObject &content_object,
uint32_t offset, uint32_t metadata) {
// Adjust pointers to point to packet payload
auto data = content_object.writableData() + offset;
auto size = content_object.length() - offset;
// Pass payload to decoder
consume(data, size, getCurrentTime());
producePackets();
}
void RelyDecoder::producePackets() {
// Drain decoder if possible
while (can_produce()) {
auto fec_header_size = sizeof(fec_metadata);
auto payload_size = produce_bytes() - sizeof(fec_metadata);
buffer packet;
if (!buffer_callback_) {
packet = core::PacketManager<>::getInstance().getMemBuf();
packet->append(payload_size);
} else {
packet = buffer_callback_(payload_size);
}
// Read seq number
const fec_metadata *h =
reinterpret_cast<const fec_metadata *>(produce_data());
uint32_t index = h->getSeqNumberBase();
uint32_t metadata = h->getMetadataBase();
DLOG_IF(INFO, VLOG_IS_ON(4))
<< "The index written in the packet is " << index;
// Copy payload
std::memcpy(packet->writableData(), produce_data() + fec_header_size,
payload_size);
// Save packet in buffer
packets_.emplace_back(index, metadata, std::move(packet));
// Advance to next packet
produce_next();
}
// If we produced packets, lets notify the caller via the callback
if (packets_.size() > 0) {
fec_callback_(packets_);
packets_.clear();
}
flushOutOfOrder();
}
void RelyDecoder::flushOutOfOrder() {
if (flush_timer_ == nullptr) return;
flush_timer_->cancel();
if (has_upcoming_flush()) {
flush_timer_->expires_from_now(std::chrono::milliseconds(
std::max((int64_t)0, upcoming_flush(getCurrentTime()))));
flush_timer_->async_wait([this](const std::error_code &ec) {
if (ec) return;
if (has_upcoming_flush()) {
flush(getCurrentTime());
producePackets();
}
});
}
}
} // namespace fec
} // namespace protocol
} // namespace transport
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