365 lines
10 KiB
C++
365 lines
10 KiB
C++
// This file Copyright © 2008-2023 Mnemosyne LLC.
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// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
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// or any future license endorsed by Mnemosyne LLC.
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// License text can be found in the licenses/ folder.
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#include <algorithm>
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#include <utility> // for std::swap()
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#include <vector>
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#include <fmt/core.h>
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#include "transmission.h"
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#include "bandwidth.h"
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#include "crypto-utils.h"
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#include "log.h"
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#include "peer-io.h"
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#include "tr-assert.h"
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#include "utils.h" // tr_time_msec()
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tr_bytes_per_second_t tr_bandwidth::getSpeedBytesPerSecond(RateControl& r, unsigned int interval_msec, uint64_t now)
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{
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if (now == 0)
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{
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now = tr_time_msec();
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}
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if (now != r.cache_time_)
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{
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uint64_t bytes = 0;
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uint64_t const cutoff = now - interval_msec;
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for (int i = r.newest_; r.date_[i] > cutoff;)
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{
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bytes += r.size_[i];
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if (--i == -1)
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{
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i = HistorySize - 1; /* circular history */
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}
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if (i == r.newest_)
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{
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break; /* we've come all the way around */
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}
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}
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r.cache_val_ = static_cast<tr_bytes_per_second_t>(bytes * 1000U / interval_msec);
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r.cache_time_ = now;
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}
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return r.cache_val_;
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}
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void tr_bandwidth::notifyBandwidthConsumedBytes(uint64_t const now, RateControl* r, size_t size)
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{
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if (r->date_[r->newest_] + GranularityMSec >= now)
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{
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r->size_[r->newest_] += size;
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}
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else
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{
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if (++r->newest_ == HistorySize)
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{
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r->newest_ = 0;
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}
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r->date_[r->newest_] = now;
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r->size_[r->newest_] = size;
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}
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/* invalidate cache_val*/
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r->cache_time_ = 0;
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}
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// ---
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tr_bandwidth::tr_bandwidth(tr_bandwidth* parent)
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{
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this->setParent(parent);
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}
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// ---
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namespace
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{
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namespace deparent_helpers
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{
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void remove_child(std::vector<tr_bandwidth*>& v, tr_bandwidth* remove_me) noexcept
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{
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// the list isn't sorted -- so instead of erase()ing `it`,
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// do the cheaper option of overwriting it with the final item
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if (auto it = std::find(std::begin(v), std::end(v), remove_me); it != std::end(v))
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{
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*it = v.back();
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v.resize(v.size() - 1);
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}
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}
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} // namespace deparent_helpers
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} // namespace
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void tr_bandwidth::deparent() noexcept
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{
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using namespace deparent_helpers;
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if (parent_ == nullptr)
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{
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return;
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}
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remove_child(parent_->children_, this);
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parent_ = nullptr;
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}
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void tr_bandwidth::setParent(tr_bandwidth* new_parent)
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{
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TR_ASSERT(this != new_parent);
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deparent();
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if (new_parent != nullptr)
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{
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#ifdef TR_ENABLE_ASSERTS
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TR_ASSERT(new_parent->parent_ != this);
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auto& children = new_parent->children_;
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TR_ASSERT(std::find(std::begin(children), std::end(children), this) == std::end(children)); // not already there
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#endif
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new_parent->children_.push_back(this);
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this->parent_ = new_parent;
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}
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}
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// ---
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void tr_bandwidth::allocateBandwidth(
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tr_priority_t parent_priority,
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unsigned int period_msec,
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std::vector<std::shared_ptr<tr_peerIo>>& peer_pool)
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{
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auto const priority = std::max(parent_priority, this->priority_);
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// set the available bandwidth
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for (auto const dir : { TR_UP, TR_DOWN })
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{
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if (auto& bandwidth = band_[dir]; bandwidth.is_limited_)
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{
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auto const next_pulse_speed = bandwidth.desired_speed_bps_;
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bandwidth.bytes_left_ = next_pulse_speed * period_msec / 1000U;
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}
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}
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// add this bandwidth's peer, if any, to the peer pool
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if (auto shared = this->peer_.lock(); shared)
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{
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shared->set_priority(priority);
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peer_pool.push_back(std::move(shared));
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}
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// traverse & repeat for the subtree
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for (auto* child : this->children_)
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{
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child->allocateBandwidth(priority, period_msec, peer_pool);
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}
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}
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void tr_bandwidth::phaseOne(std::vector<tr_peerIo*>& peers, tr_direction dir)
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{
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// First phase of IO. Tries to distribute bandwidth fairly to keep faster
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// peers from starving the others.
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tr_logAddTrace(fmt::format("{} peers to go round-robin for {}", peers.size(), dir == TR_UP ? "upload" : "download"));
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// Shuffle the peers so they all have equal chance to be first in line.
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thread_local auto urbg = tr_urbg<size_t>{};
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std::shuffle(std::begin(peers), std::end(peers), urbg);
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// Give each peer `Increment` bandwidth bytes to use. Repeat this
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// process until we run out of bandwidth and/or peers that can use it.
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for (size_t n_unfinished = std::size(peers); n_unfinished > 0U;)
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{
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for (size_t i = 0; i < n_unfinished;)
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{
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// Value of 3000 bytes chosen so that when using µTP we'll send a full-size
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// frame right away and leave enough buffered data for the next frame to go
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// out in a timely manner.
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static auto constexpr Increment = size_t{ 3000 };
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auto const bytes_used = peers[i]->flush(dir, Increment);
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tr_logAddTrace(fmt::format("peer #{} of {} used {} bytes in this pass", i, n_unfinished, bytes_used));
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if (bytes_used != Increment)
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{
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// peer is done writing for now; move it to the end of the list
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std::swap(peers[i], peers[n_unfinished - 1]);
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--n_unfinished;
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}
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else
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{
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++i;
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}
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}
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}
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}
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void tr_bandwidth::allocate(unsigned int period_msec)
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{
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// keep these peers alive for the scope of this function
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auto refs = std::vector<std::shared_ptr<tr_peerIo>>{};
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auto peer_arrays = std::array<std::vector<tr_peerIo*>, 3>{};
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auto& high = peer_arrays[0];
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auto& normal = peer_arrays[1];
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auto& low = peer_arrays[2];
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// allocateBandwidth () is a helper function with two purposes:
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// 1. allocate bandwidth to b and its subtree
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// 2. accumulate an array of all the peerIos from b and its subtree.
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this->allocateBandwidth(TR_PRI_LOW, period_msec, refs);
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for (auto const& io : refs)
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{
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io->flush_outgoing_protocol_msgs();
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switch (io->priority())
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{
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case TR_PRI_HIGH:
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high.push_back(io.get());
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[[fallthrough]];
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case TR_PRI_NORMAL:
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normal.push_back(io.get());
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[[fallthrough]];
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default:
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low.push_back(io.get());
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}
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}
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// First phase of IO. Tries to distribute bandwidth fairly to keep faster
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// peers from starving the others. Loop through the peers, giving each a
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// small chunk of bandwidth. Keep looping until we run out of bandwidth
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// and/or peers that can use it
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for (auto& peers : peer_arrays)
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{
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phaseOne(peers, TR_UP);
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phaseOne(peers, TR_DOWN);
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}
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// Second phase of IO. To help us scale in high bandwidth situations,
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// enable on-demand IO for peers with bandwidth left to burn.
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// This on-demand IO is enabled until (1) the peer runs out of bandwidth,
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// or (2) the next tr_bandwidth::allocate () call, when we start over again.
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for (auto const& io : refs)
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{
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io->set_enabled(TR_UP, io->has_bandwidth_left(TR_UP));
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io->set_enabled(TR_DOWN, io->has_bandwidth_left(TR_DOWN));
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}
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}
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// ---
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size_t tr_bandwidth::clamp(uint64_t now, tr_direction dir, size_t byte_count) const
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{
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TR_ASSERT(tr_isDirection(dir));
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if (this->band_[dir].is_limited_)
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{
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byte_count = std::min(byte_count, this->band_[dir].bytes_left_);
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/* if we're getting close to exceeding the speed limit,
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* clamp down harder on the bytes available */
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if (byte_count > 0)
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{
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if (now == 0)
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{
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now = tr_time_msec();
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}
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auto const current = this->getRawSpeedBytesPerSecond(now, TR_DOWN);
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auto const desired = this->getDesiredSpeedBytesPerSecond(TR_DOWN);
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auto const r = desired >= 1 ? static_cast<double>(current) / desired : 0.0;
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if (r > 1.0)
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{
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byte_count = 0; // none left
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}
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else if (r > 0.9)
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{
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byte_count -= (byte_count / 5U); // cap at 80%
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}
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else if (r > 0.8)
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{
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byte_count -= (byte_count / 10U); // cap at 90%
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}
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}
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}
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if (this->parent_ != nullptr && this->band_[dir].honor_parent_limits_ && byte_count > 0)
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{
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byte_count = this->parent_->clamp(now, dir, byte_count);
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}
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return byte_count;
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}
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void tr_bandwidth::notifyBandwidthConsumed(tr_direction dir, size_t byte_count, bool is_piece_data, uint64_t now)
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{
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TR_ASSERT(tr_isDirection(dir));
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Band* band = &this->band_[dir];
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if (band->is_limited_ && is_piece_data)
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{
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band->bytes_left_ -= std::min(size_t{ band->bytes_left_ }, byte_count);
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}
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#ifdef DEBUG_DIRECTION
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if (dir == DEBUG_DIRECTION && band_->isLimited)
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{
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fprintf(
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stderr,
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"%p consumed %5zu bytes of %5s data... was %6zu, now %6zu left\n",
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this,
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byte_count,
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is_piece_data ? "piece" : "raw",
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oldBytesLeft,
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band_->bytesLeft);
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}
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#endif
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notifyBandwidthConsumedBytes(now, &band->raw_, byte_count);
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if (is_piece_data)
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{
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notifyBandwidthConsumedBytes(now, &band->piece_, byte_count);
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}
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if (this->parent_ != nullptr)
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{
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this->parent_->notifyBandwidthConsumed(dir, byte_count, is_piece_data, now);
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}
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}
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// ---
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tr_bandwidth_limits tr_bandwidth::getLimits() const
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{
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tr_bandwidth_limits limits;
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limits.up_limit_KBps = tr_toSpeedKBps(this->getDesiredSpeedBytesPerSecond(TR_UP));
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limits.down_limit_KBps = tr_toSpeedKBps(this->getDesiredSpeedBytesPerSecond(TR_DOWN));
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limits.up_limited = this->isLimited(TR_UP);
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limits.down_limited = this->isLimited(TR_DOWN);
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return limits;
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}
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void tr_bandwidth::setLimits(tr_bandwidth_limits const* limits)
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{
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this->setDesiredSpeedBytesPerSecond(TR_UP, tr_toSpeedBytes(limits->up_limit_KBps));
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this->setDesiredSpeedBytesPerSecond(TR_DOWN, tr_toSpeedBytes(limits->down_limit_KBps));
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this->setLimited(TR_UP, limits->up_limited);
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this->setLimited(TR_DOWN, limits->down_limited);
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}
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