ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/deliantra/server/socket/loop.C
Revision: 1.65
Committed: Sun Jul 29 02:24:34 2007 UTC (16 years, 10 months ago) by root
Content type: text/plain
Branch: MAIN
Changes since 1.64: +78 -94 lines
Log Message:
implement the most elaborate rate limit system to date, from the errors before:

- output-rate is now an upper bound only. its purpose is to give the user
  some control over bandwith use. it should be set too high rather than too low.
- the server will (on linux only, or systems that support tcpi), guess
  how much the kernel is willing to send without delay (this is imperfect as
  we do not know the remote receive window, but we assume its "large enough").
- we accuretyl measure mss and ensure that preferably mss-sized packets
  leave the server, by sending less in some cases and more in others
  to reacht eh desired bandwidth goal
  (e.g. 15000 == http://ue.tst.eu/545350740128735b13aaf541c88bfaf2.txt)

the net effect is that the server will never send (much) more data than the kernel
thinks the network is able to handle. that is, when the connection was idle for a time
and the congestion window is small, we will only start sending small amounts of
data, prompting the kernel to accuratly model the bandwidth.

in essence, this creates a tcp stream that never has more data buffered
than neccessary for in-flight data, ensuring that we can get low-latency
map updates through to the client whole using all excess bandwidth the
network can handle.

I mostly tested with netem, e.g.

   ifconfig lo mtu 1500
   tc qdisc change dev lo root netem delay 190ms 10ms drop 0.1

gave me roughtly 20kb/s throughput even though output-rate was 100kb/s,
without stalling the conenction even when downloading backgorund music and
other large chunks of data.

File Contents

# Content
1 /*
2 * This file is part of Crossfire TRT, the Roguelike Realtime MORPG.
3 *
4 * Copyright (©) 2005,2006,2007 Marc Alexander Lehmann / Robin Redeker / the Crossfire TRT team
5 * Copyright (©) 2002-2003,2007 Mark Wedel & The Crossfire Development Team
6 * Copyright (©) 1992,2007 Frank Tore Johansen
7 *
8 * Crossfire TRT is free software: you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation, either version 3 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program. If not, see <http://www.gnu.org/licenses/>.
20 *
21 * The authors can be reached via e-mail to <crossfire@schmorp.de>
22 */
23
24 /**
25 * \file
26 * Main client/server loops.
27 *
28 * \date 2003-12-02
29 *
30 * loop.c mainly deals with initialization and higher level socket
31 * maintanance (checking for lost connections and if data has arrived.)
32 */
33
34 #include <global.h>
35 #include <sproto.h>
36 #include <sockproto.h>
37
38 #include <sys/types.h>
39 #include <sys/time.h>
40 #include <sys/socket.h>
41 #include <netinet/in.h>
42 #include <netdb.h>
43
44 #include <unistd.h>
45 #include <arpa/inet.h>
46
47 #include <loader.h>
48
49 #define BG_SCRUB_RATE 4 // how often to send a face in the background
50
51 #define MAX_QUEUE_DEPTH 50
52 #define MAX_QUEUE_BACKLOG 3.
53
54 void
55 client::reset_state ()
56 {
57 if (!pl)
58 return;
59
60 pl->run_on = 0;
61 pl->fire_on = 0;
62 }
63
64 void
65 client::queue_command (packet_type *handler, char *data, int datalen)
66 {
67 tstamp stamp = NOW;
68
69 if (cmd_queue.size () >= MAX_QUEUE_DEPTH)
70 {
71 //TODO: just disconnect here?
72 reset_state ();
73 send_packet_printf ("drawinfo %d command queue overflow, ignoring.", NDI_RED);
74 }
75 else
76 {
77 cmd_queue.push_back (command ());
78 command &cmd = cmd_queue.back ();
79 cmd.stamp = stamp;
80 cmd.handler = handler;
81 cmd.data = salloc<char> (datalen + 1, data);
82 cmd.datalen = datalen;
83 }
84 }
85
86 bool
87 client::handle_command ()
88 {
89 if (!cmd_queue.empty ()
90 && state == ST_PLAYING
91 && pl->ob->speed_left > 0.f)
92 {
93 command &cmd = cmd_queue.front ();
94
95 if (cmd.stamp + MAX_QUEUE_BACKLOG < NOW)
96 {
97 reset_state ();
98 send_packet_printf ("drawinfo %d ignoring delayed commands.", NDI_RED);
99 }
100 else
101 execute (cmd.handler, cmd.data, cmd.datalen);
102
103 cmd_queue.pop_front ();
104 return true;
105 }
106 else
107 return false;
108 }
109
110 void
111 flush_sockets (void)
112 {
113 for (sockvec::iterator i = clients.begin (); i != clients.end (); ++i)
114 (*i)->flush ();
115 }
116
117 /**
118 * This checks the sockets for input, does the right thing.
119 *
120 * A bit of this code is grabbed out of socket.c
121 * There are 2 lists we need to look through - init_sockets is a list
122 *
123 */
124 void
125 doeric_server (void)
126 {
127 //TODO: should not be done here, either
128 for (unsigned i = 0; i < clients.size (); ++i)
129 {
130 client *ns = clients [i];
131
132 ns->tick ();
133 ns->refcnt_chk ();
134 }
135 }
136
137 void
138 client::tick ()
139 {
140 if (!pl || destroyed ())
141 return;
142
143 /* Update the players stats once per tick. More efficient than
144 * sending them whenever they change, and probably just as useful
145 */
146 esrv_update_stats (pl);
147
148 if (last_weight != -1 && last_weight != WEIGHT (pl->ob))
149 {
150 esrv_update_item (UPD_WEIGHT, pl->ob, pl->ob);
151 if (last_weight != WEIGHT (pl->ob))
152 LOG (llevError, "esrv_update_item(UPD_WEIGHT) did not set player weight: is %lu, should be %lu\n",
153 (unsigned long) last_weight, WEIGHT (pl->ob));
154 }
155
156 draw_client_map (pl);
157
158 if (update_look)
159 esrv_draw_look (pl);
160
161 if (ixface.empty ())
162 {
163 // regularly send a new face when queue is empty
164 if (bg_scrub && !--bg_scrub && enable_bg_scrub)
165 while (scrub_idx < faces.size () - 1)
166 {
167 ++scrub_idx;
168
169 if (!faces_sent [scrub_idx])
170 if (faceinfo *f = face_info (scrub_idx))
171 if (f->type == FT_FACE) // only scrub faces for now
172 {
173 send_face (scrub_idx, -120);
174 flush_fx ();
175
176 bg_scrub = 1; // send up to one face per tick, unless an image was requested
177 break;
178 }
179 }
180
181 rate_avail = max_rate - outputbuffer_len ();
182 }
183 else
184 {
185 int ol = outputbuffer_len ();
186
187 rate_avail = min (max_rate + mss, rate_avail + max_rate);
188
189 int avail = rate_avail;
190
191 // if we can split images, round to next-lowest mss
192 if (fxix) avail -= avail % mss;
193
194 rate_avail -= ol;
195 avail -= ol;
196
197 #if HAVE_TCP_INFO
198 // further restrict the available bandwidth by the excess bandwidth available
199 avail = max (0, min (avail, (tcpi.tcpi_snd_cwnd - tcpi.tcpi_unacked + tcpi.tcpi_sacked) * mss));
200 #endif
201
202 bg_scrub = BG_SCRUB_RATE;
203
204 while (avail > 0)
205 {
206 ixsend &ix = ixface.back ();
207
208 if (facedata *d = face_data (ix.idx, faceset))
209 {
210 if (fxix)
211 {
212 // estimate the packet header overhead "ix " + idx + (new)ofs
213 int pktlen = 3 + ber32::encoded_size (ix.idx) + ber32::encoded_size (ix.ofs);
214 int chunk = min (avail - packet::hdrlen, MAXSOCKBUF) - pktlen;
215
216 // only transfer something if the amount of data transferred
217 // has a healthy relation to the header overhead
218 if (chunk < 64)
219 break;
220
221 chunk = min (chunk, (int)ix.ofs);
222
223 ix.ofs -= chunk;
224
225 //fprintf (stderr, "i%dx %6d: %5d+%4d (%4d)\n", fxix, ix.idx,ix.ofs,chunk, ixface.size());//D
226
227 packet sl ("ix");
228
229 sl << ber32 (ix.idx)
230 << ber32 (ix.ofs)
231 << data (d->data.data () + ix.ofs, chunk);
232
233 send_packet (sl);
234 }
235 else
236 {
237 send_image (ix.idx);
238 ix.ofs = 0;
239 }
240 }
241 else
242 ix.ofs = 0;
243
244 int consumed = outputbuffer_len () - ol;
245
246 avail -= consumed;
247 rate_avail -= consumed;
248
249 ol = outputbuffer_len ();
250
251 if (!ix.ofs)
252 {
253 ixface.pop_back ();
254
255 if (ixface.empty ())
256 break;
257 }
258 }
259 }
260 }
261