+#include "CongestionControl.hpp"
#include "Connection.hpp"
#include "ConnectionHandler.hpp"
#include "io.hpp"
#include "Packet.hpp"
#include "../app/init.hpp"
+#include "../geometry/const.hpp"
#include "../model/Model.hpp"
#include "../world/Entity.hpp"
#include "../world/EntityState.hpp"
constexpr size_t Packet::Message::MAX_LEN;
constexpr size_t Packet::Message::MAX_MESSAGE_LEN;
+
+CongestionControl::CongestionControl()
+// I know, I know, it's an estimate (about 20 for IPv4, 48 for IPv6)
+: packet_overhead(20)
+// only sample every eighth packet for measuring RTT
+, sample_skip(8)
+, packets_lost(0)
+, packets_received(0)
+, packet_loss(0.0f)
+, stamp_last(0)
+, rtt(64.0f)
+, next_sample(1000)
+, tx_bytes(0)
+, rx_bytes(0)
+, tx_kbps(0.0f)
+, rx_kbps(0.0f)
+, mode(GOOD)
+// rtt > 75ms or packet loss > 5% is BAD
+, bad_rtt(75.0f)
+, bad_loss(0.05f)
+// rtt > 150ms or packet loss > 15% is UGLY
+, ugly_rtt(150.0f)
+, ugly_loss(0.15f)
+, mode_keep_time(1000) {
+ Uint32 now = SDL_GetTicks();
+ for (Uint32 &s : stamps) {
+ s = now;
+ }
+ next_sample += now;
+ mode_entered = now;
+ mode_reset = now;
+ mode_step = now;
+}
+
+void CongestionControl::PacketSent(uint16_t seq) noexcept {
+ if (!SamplePacket(seq)) {
+ return;
+ }
+ stamps[SampleIndex(seq)] = SDL_GetTicks();
+ stamp_last = seq;
+}
+
+void CongestionControl::PacketLost(uint16_t seq) noexcept {
+ ++packets_lost;
+ UpdatePacketLoss();
+ UpdateRTT(seq);
+}
+
+void CongestionControl::PacketReceived(uint16_t seq) noexcept {
+ ++packets_received;
+ UpdatePacketLoss();
+ UpdateRTT(seq);
+}
+
+void CongestionControl::UpdatePacketLoss() noexcept {
+ unsigned int packets_total = packets_lost + packets_received;
+ if (packets_total >= 256) {
+ packet_loss = float(packets_lost) / float(packets_total);
+ packets_lost = 0;
+ packets_received = 0;
+ }
+}
+
+void CongestionControl::UpdateRTT(uint16_t seq) noexcept {
+ if (!SamplePacket(seq)) return;
+ int16_t diff = int16_t(stamp_last) - int16_t(seq);
+ if (diff < 0 || diff > int(15 * sample_skip)) {
+ // packet outside observed frame
+ return;
+ }
+ int cur_rtt = SDL_GetTicks() - stamps[SampleIndex(seq)];
+ rtt += (cur_rtt - rtt) * 0.1f;
+}
+
+bool CongestionControl::SamplePacket(uint16_t seq) const noexcept {
+ return seq % sample_skip == 0;
+}
+
+size_t CongestionControl::SampleIndex(uint16_t seq) const noexcept {
+ return (seq / sample_skip) % 16;
+}
+
+void CongestionControl::PacketIn(const UDPpacket &pack) noexcept {
+ rx_bytes += pack.len + packet_overhead;
+ UpdateStats();
+}
+
+void CongestionControl::PacketOut(const UDPpacket &pack) noexcept {
+ tx_bytes += pack.len + packet_overhead;
+ UpdateStats();
+}
+
+void CongestionControl::UpdateStats() noexcept {
+ Uint32 now = SDL_GetTicks();
+ if (now < next_sample) {
+ // not yet
+ return;
+ }
+ tx_kbps = float(tx_bytes) * (1.0f / 1024.0f);
+ rx_kbps = float(rx_bytes) * (1.0f / 1024.0f);
+ tx_bytes = 0;
+ rx_bytes = 0;
+ next_sample += 1000;
+ UpdateMode();
+}
+
+void CongestionControl::UpdateMode() noexcept {
+ Mode now_mode = Conditions();
+ if (now_mode > mode) {
+ ChangeMode(now_mode);
+ } else if (now_mode < mode) {
+ CheckUpgrade(now_mode);
+ } else {
+ KeepMode();
+ }
+}
+
+void CongestionControl::CheckUpgrade(Mode m) noexcept {
+ Uint32 now = SDL_GetTicks();
+ Uint32 time_in_mode = now - mode_entered;
+ if (time_in_mode < mode_keep_time) {
+ return;
+ }
+ ChangeMode(m);
+}
+
+void CongestionControl::ChangeMode(Mode m) noexcept {
+ Uint32 now = SDL_GetTicks();
+ if (m > mode) {
+ // changed to worse mode
+ // if we spent less than 10 seconds in better mode
+ // double keep time till up to 64 seconds
+ if (now - mode_entered < 10000) {
+ if (mode_keep_time < 64000) {
+ mode_keep_time *= 2;
+ }
+ }
+ }
+ mode = m;
+ mode_entered = now;
+ mode_reset = mode_entered;
+}
+
+void CongestionControl::KeepMode() noexcept {
+ mode_reset = SDL_GetTicks();
+ // if in good mode for 10 seconds, halve keep time till down to one second
+ if (mode == GOOD && mode_keep_time > 1000 && mode_step - mode_reset > 10000) {
+ mode_keep_time /= 2;
+ mode_step = mode_reset;
+ }
+}
+
+CongestionControl::Mode CongestionControl::Conditions() const noexcept {
+ if (rtt > ugly_rtt || packet_loss > ugly_loss) {
+ return UGLY;
+ } else if (rtt > bad_rtt || packet_loss > bad_loss) {
+ return BAD;
+ } else {
+ return GOOD;
+ }
+}
+
+
Connection::Connection(const IPaddress &addr)
: handler(nullptr)
, addr(addr)
-, send_timer(500)
+// make sure a packet is sent at least every 50ms since packets contains
+// acks that the remote end will use to measure RTT
+, send_timer(50)
, recv_timer(10000)
, ctrl_out{ 0, 0xFFFF, 0xFFFFFFFF }
, ctrl_in{ 0, 0xFFFF, 0xFFFFFFFF }
}
if (HasHandler()) {
+ Handler().PacketOut(udp_pack);
Handler().PacketSent(seq);
}
}
Packet::TControl ctrl_new = pack.header.ctrl;
+ Handler().PacketIn(udp_pack);
Handler().Handle(udp_pack);
if (diff > 0) {
ConnectionHandler::ConnectionHandler()
-: packets_lost(0)
-, packets_received(0)
-, packet_loss(0.0f)
-, stamp_cursor(15)
-, stamp_last(0)
-, rtt(64.0f) {
- Uint32 now = SDL_GetTicks();
- for (Uint32 &s : stamps) {
- s = now;
- }
+: cc() {
+
}
-void ConnectionHandler::PacketSent(uint16_t seq) {
- if (!SamplePacket(seq)) {
- return;
- }
- stamp_cursor = (stamp_cursor + 1) % 16;
- stamps[stamp_cursor] = SDL_GetTicks();
- stamp_last = seq;
+void ConnectionHandler::PacketSent(uint16_t seq) noexcept {
+ cc.PacketSent(seq);
}
void ConnectionHandler::PacketLost(uint16_t seq) {
OnPacketLost(seq);
- ++packets_lost;
- UpdatePacketLoss();
- UpdateRTT(seq);
+ cc.PacketLost(seq);
}
void ConnectionHandler::PacketReceived(uint16_t seq) {
OnPacketReceived(seq);
- ++packets_received;
- UpdatePacketLoss();
- UpdateRTT(seq);
+ cc.PacketReceived(seq);
}
-void ConnectionHandler::UpdatePacketLoss() noexcept {
- unsigned int packets_total = packets_lost + packets_received;
- if (packets_total >= 256) {
- packet_loss = float(packets_lost) / float(packets_total);
- packets_lost = 0;
- packets_received = 0;
- }
+void ConnectionHandler::PacketIn(const UDPpacket &pack) noexcept {
+ cc.PacketIn(pack);
}
-void ConnectionHandler::UpdateRTT(std::uint16_t seq) noexcept {
- if (!SamplePacket(seq)) return;
- int diff = HeadDiff(seq);
- if (diff > 0 || diff < -15) {
- // packet outside observed time frame
- return;
- }
- int cur_rtt = SDL_GetTicks() - stamps[(stamp_cursor + diff + 16) % 16];
- rtt += (cur_rtt - rtt) * 0.1f;
-}
-
-bool ConnectionHandler::SamplePacket(std::uint16_t seq) const noexcept {
- // only sample every eighth packet
- return seq % 8 == 0;
-}
-
-int ConnectionHandler::HeadDiff(std::uint16_t seq) const noexcept {
- int16_t diff = int16_t(seq) - int16_t(stamp_last);
- return diff / 8;
+void ConnectionHandler::PacketOut(const UDPpacket &pack) noexcept {
+ cc.PacketOut(pack);
}
}
void Packet::Payload::Write(const glm::quat &val, size_t off) noexcept {
- WritePackN(val.w, off);
- WritePackN(val.x, off + 2);
- WritePackN(val.y, off + 4);
- WritePackN(val.z, off + 6);
+ // find the largest component
+ float largest = 0.0f;
+ int largest_index = -1;
+ for (int i = 0; i < 4; ++i) {
+ float iabs = abs(val[i]);
+ if (iabs > largest) {
+ largest = iabs;
+ largest_index = i;
+ }
+ }
+ // make sure it's positive
+ const glm::quat q(val[largest_index] < 0.0f ? -val : val);
+ // move index to the two most significant bits
+ uint64_t packed = uint64_t(largest_index) << 62;
+ // we have to map from [-0.7072,0.7072] to [-524287,524287] and move into positive range
+ constexpr float conv = 524287.0f / 0.7072f;
+ // if largest is 1, the other three are 0
+ // precision of comparison is the interval of our mapping
+ if (abs(1.0 - largest) < (1.0f / conv)) {
+ packed |= 0x7FFFF7FFFF7FFFF;
+ } else {
+ // pack the three smaller components into 20bit ints each
+ int shift = 40;
+ for (int i = 0; i < 4; ++i) {
+ if (i != largest_index) {
+ packed |= uint64_t(int(q[i] * conv) + 524287) << shift;
+ shift -= 20;
+ }
+ }
+ }
+ // and write it out
+ Write(packed, off);
}
void Packet::Payload::Read(glm::quat &val, size_t off) const noexcept {
- ReadPackN(val.w, off);
- ReadPackN(val.x, off + 2);
- ReadPackN(val.y, off + 4);
- ReadPackN(val.z, off + 6);
- val = normalize(val);
+ // extract the 8 byte packed value
+ uint64_t packed = 0;
+ Read(packed, off);
+ // two most significant bits are the index of the largest (omitted) component
+ int largest_index = packed >> 62;
+ // if all other three are 0, largest is 1 and we can omit the conversion
+ if ((packed & 0xFFFFFFFFFFFFFFF) == 0x7FFFF7FFFF7FFFF) {
+ val = { 0.0f, 0.0f, 0.0f, 0.0f };
+ val[largest_index] = 1.0f;
+ return;
+ }
+ // we have to map from [-524287,524287] to [-0.7072,0.7072]
+ constexpr float conv = 0.7072f / 524287.0f;
+ int shift = 40;
+ for (int i = 0; i < 4; ++i) {
+ if (i != largest_index) {
+ val[i] = float(int((packed >> shift) & 0xFFFFF) - 524287) * conv;
+ shift -= 20;
+ } else {
+ // set to zero so the length of the other three can be determined
+ val[i] = 0.0f;
+ }
+ }
+ // omitted component squared is 1 - length squared of others
+ val[largest_index] = sqrt(1.0f - glm::length2(val));
+ // and already normalized
}
void Packet::Payload::Write(const EntityState &state, size_t off) noexcept {
- Write(state.chunk_pos, off);
- WritePackU(state.block_pos * (1.0f / 16.0f), off + 12);
+ Write(state.pos.chunk, off);
+ WritePackU(state.pos.block * (1.0f / ExactLocation::fscale), off + 12);
Write(state.velocity, off + 18);
Write(state.orient, off + 30);
WritePackN(state.pitch * PI_0p5_inv, off + 38);
}
void Packet::Payload::Read(EntityState &state, size_t off) const noexcept {
- Read(state.chunk_pos, off);
- ReadPackU(state.block_pos, off + 12);
+ Read(state.pos.chunk, off);
+ ReadPackU(state.pos.block, off + 12);
Read(state.velocity, off + 18);
Read(state.orient, off + 30);
ReadPackN(state.pitch, off + 38);
ReadPackN(state.yaw, off + 40);
- state.block_pos *= 16.0f;
+ state.pos.block *= ExactLocation::fscale;
state.pitch *= PI_0p5;
state.yaw *= PI;
}
void Packet::Payload::Write(const EntityState &state, const glm::ivec3 &base, size_t off) noexcept {
- WritePackB(state.chunk_pos - base, off);
- WritePackU(state.block_pos * (1.0f / 16.0f), off + 3);
+ WritePackB(state.pos.chunk - base, off);
+ WritePackU(state.pos.block * (1.0f / ExactLocation::fscale), off + 3);
Write(state.velocity, off + 9);
Write(state.orient, off + 21);
WritePackN(state.pitch * PI_0p5_inv, off + 29);
}
void Packet::Payload::Read(EntityState &state, const glm::ivec3 &base, size_t off) const noexcept {
- ReadPackB(state.chunk_pos, off);
- ReadPackU(state.block_pos, off + 3);
+ ReadPackB(state.pos.chunk, off);
+ ReadPackU(state.pos.block, off + 3);
Read(state.velocity, off + 9);
Read(state.orient, off + 21);
ReadPackN(state.pitch, off + 29);
ReadPackN(state.yaw, off + 31);
- state.chunk_pos += base;
- state.block_pos *= 16.0f;
+ state.pos.chunk += base;
+ state.pos.block *= ExactLocation::fscale;
state.pitch *= PI_0p5;
state.yaw *= PI;
}
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