git.sesse.net Git - cubemap/blob - server.cpp

   1 #include <assert.h>
   2 #include <errno.h>
   3 #include <netinet/in.h>
   4 #include <pthread.h>
   5 #include <stdint.h>
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <sys/epoll.h>
  10 #include <sys/sendfile.h>
  11 #include <sys/socket.h>
  12 #include <sys/types.h>
  13 #include <unistd.h>
  14 #include <algorithm>
  15 #include <map>
  16 #include <string>
  17 #include <utility>
  18 #include <vector>
  19
  20 #include "accesslog.h"
  21 #include "log.h"
  22 #include "metacube2.h"
  23 #include "mutexlock.h"
  24 #include "parse.h"
  25 #include "server.h"
  26 #include "state.pb.h"
  27 #include "stream.h"
  28 #include "util.h"
  29
  30 #ifndef SO_MAX_PACING_RATE
  31 #define SO_MAX_PACING_RATE 47
  32 #endif
  33
  34 using namespace std;
  35
  36 extern AccessLogThread *access_log;
  37
  38 namespace {
  39
  40 inline bool is_equal(timespec a, timespec b)
  41 {
  42         return a.tv_sec == b.tv_sec &&
  43                a.tv_nsec == b.tv_nsec;
  44 }
  45
  46 inline bool is_earlier(timespec a, timespec b)
  47 {
  48         if (a.tv_sec != b.tv_sec)
  49                 return a.tv_sec < b.tv_sec;
  50         return a.tv_nsec < b.tv_nsec;
  51 }
  52
  53 }  // namespace
  54
  55 Server::Server()
  56 {
  57         pthread_mutex_init(&mutex, NULL);
  58         pthread_mutex_init(&queued_clients_mutex, NULL);
  59
  60         epoll_fd = epoll_create(1024);  // Size argument is ignored.
  61         if (epoll_fd == -1) {
  62                 log_perror("epoll_fd");
  63                 exit(1);
  64         }
  65 }
  66
  67 Server::~Server()
  68 {
  69         for (size_t i = 0; i < streams.size(); ++i) {
  70                 delete streams[i];
  71         }
  72
  73         safe_close(epoll_fd);
  74 }
  75
  76 vector<ClientStats> Server::get_client_stats() const
  77 {
  78         vector<ClientStats> ret;
  79
  80         MutexLock lock(&mutex);
  81         for (map<int, Client>::const_iterator client_it = clients.begin();
  82              client_it != clients.end();
  83              ++client_it) {
  84                 ret.push_back(client_it->second.get_stats());
  85         }
  86         return ret;
  87 }
  88
  89 void Server::do_work()
  90 {
  91         while (!should_stop()) {
  92                 // Wait until there's activity on at least one of the fds,
  93                 // or 20 ms (about one frame at 50 fps) has elapsed.
  94                 //
  95                 // We could in theory wait forever and rely on wakeup()
  96                 // from add_client_deferred() and add_data_deferred(),
  97                 // but wakeup is a pretty expensive operation, and the
  98                 // two threads might end up fighting over a lock, so it's
  99                 // seemingly (much) more efficient to just have a timeout here.
 100                 int nfds = epoll_pwait(epoll_fd, events, EPOLL_MAX_EVENTS, EPOLL_TIMEOUT_MS, &sigset_without_usr1_block);
 101                 if (nfds == -1 && errno != EINTR) {
 102                         log_perror("epoll_wait");
 103                         exit(1);
 104                 }
 105
 106                 MutexLock lock(&mutex);  // We release the mutex between iterations.
 107
 108                 process_queued_data();
 109
 110                 // Process each client where we have socket activity.
 111                 for (int i = 0; i < nfds; ++i) {
 112                         Client *client = reinterpret_cast<Client *>(events[i].data.u64);
 113
 114                         if (events[i].events & (EPOLLERR | EPOLLRDHUP | EPOLLHUP)) {
 115                                 close_client(client);
 116                                 continue;
 117                         }
 118
 119                         process_client(client);
 120                 }
 121
 122                 // Process each client where its stream has new data,
 123                 // even if there was no socket activity.
 124                 for (size_t i = 0; i < streams.size(); ++i) {
 125                         vector<Client *> to_process;
 126                         swap(streams[i]->to_process, to_process);
 127                         for (size_t i = 0; i < to_process.size(); ++i) {
 128                                 process_client(to_process[i]);
 129                         }
 130                 }
 131
 132                 // Finally, go through each client to see if it's timed out
 133                 // in the READING_REQUEST state. (Seemingly there are clients
 134                 // that can hold sockets up for days at a time without sending
 135                 // anything at all.)
 136                 timespec timeout_time;
 137                 if (clock_gettime(CLOCK_MONOTONIC_COARSE, &timeout_time) == -1) {
 138                         log_perror("clock_gettime(CLOCK_MONOTONIC_COARSE)");
 139                         continue;
 140                 }
 141                 timeout_time.tv_sec -= REQUEST_READ_TIMEOUT_SEC;
 142                 while (!clients_ordered_by_connect_time.empty()) {
 143                         pair<timespec, int> &connect_time_and_fd = clients_ordered_by_connect_time.front();
 144
 145                         // See if we have reached the end of clients to process.
 146                         if (is_earlier(timeout_time, connect_time_and_fd.first)) {
 147                                 break;
 148                         }
 149
 150                         // If this client doesn't exist anymore, just ignore it
 151                         // (it was deleted earlier).
 152                         std::map<int, Client>::iterator client_it = clients.find(connect_time_and_fd.second);
 153                         if (client_it == clients.end()) {
 154                                 clients_ordered_by_connect_time.pop();
 155                                 continue;
 156                         }
 157                         Client *client = &client_it->second;
 158                         if (!is_equal(client->connect_time, connect_time_and_fd.first)) {
 159                                 // Another client has taken this fd in the meantime.
 160                                 clients_ordered_by_connect_time.pop();
 161                                 continue;
 162                         }
 163
 164                         if (client->state != Client::READING_REQUEST) {
 165                                 // Only READING_REQUEST can time out.
 166                                 clients_ordered_by_connect_time.pop();
 167                                 continue;
 168                         }
 169
 170                         // OK, it timed out.
 171                         close_client(client);
 172                         clients_ordered_by_connect_time.pop();
 173                 }
 174         }
 175 }
 176
 177 CubemapStateProto Server::serialize()
 178 {
 179         // We don't serialize anything queued, so empty the queues.
 180         process_queued_data();
 181
 182         // Set all clients in a consistent state before serializing
 183         // (ie., they have no remaining lost data). Otherwise, increasing
 184         // the backlog could take clients into a newly valid area of the backlog,
 185         // sending a stream of zeros instead of skipping the data as it should.
 186         //
 187         // TODO: Do this when clients are added back from serialized state instead;
 188         // it would probably be less wasteful.
 189         for (map<int, Client>::iterator client_it = clients.begin();
 190              client_it != clients.end();
 191              ++client_it) {
 192                 skip_lost_data(&client_it->second);
 193         }
 194
 195         CubemapStateProto serialized;
 196         for (map<int, Client>::const_iterator client_it = clients.begin();
 197              client_it != clients.end();
 198              ++client_it) {
 199                 serialized.add_clients()->MergeFrom(client_it->second.serialize());
 200         }
 201         for (size_t i = 0; i < streams.size(); ++i) {
 202                 serialized.add_streams()->MergeFrom(streams[i]->serialize());
 203         }
 204         return serialized;
 205 }
 206
 207 void Server::add_client_deferred(int sock)
 208 {
 209         MutexLock lock(&queued_clients_mutex);
 210         queued_add_clients.push_back(sock);
 211 }
 212
 213 void Server::add_client(int sock)
 214 {
 215         pair<map<int, Client>::iterator, bool> ret =
 216                 clients.insert(make_pair(sock, Client(sock)));
 217         assert(ret.second == true);  // Should not already exist.
 218         Client *client_ptr = &ret.first->second;
 219
 220         // Connection timestamps must be nondecreasing. I can't find any guarantee
 221         // that even the monotonic clock can't go backwards by a small amount
 222         // (think switching between CPUs with non-synchronized TSCs), so if
 223         // this actually should happen, we hack around it by fudging
 224         // connect_time.
 225         if (!clients_ordered_by_connect_time.empty() &&
 226             is_earlier(client_ptr->connect_time, clients_ordered_by_connect_time.back().first)) {
 227                 client_ptr->connect_time = clients_ordered_by_connect_time.back().first;
 228         }
 229         clients_ordered_by_connect_time.push(make_pair(client_ptr->connect_time, sock));
 230
 231         // Start listening on data from this socket.
 232         epoll_event ev;
 233         ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
 234         ev.data.u64 = reinterpret_cast<uint64_t>(client_ptr);
 235         if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, sock, &ev) == -1) {
 236                 log_perror("epoll_ctl(EPOLL_CTL_ADD)");
 237                 exit(1);
 238         }
 239
 240         process_client(client_ptr);
 241 }
 242
 243 void Server::add_client_from_serialized(const ClientProto &client)
 244 {
 245         MutexLock lock(&mutex);
 246         Stream *stream;
 247         int stream_index = lookup_stream_by_url(client.url());
 248         if (stream_index == -1) {
 249                 assert(client.state() != Client::SENDING_DATA);
 250                 stream = NULL;
 251         } else {
 252                 stream = streams[stream_index];
 253         }
 254         pair<map<int, Client>::iterator, bool> ret =
 255                 clients.insert(make_pair(client.sock(), Client(client, stream)));
 256         assert(ret.second == true);  // Should not already exist.
 257         Client *client_ptr = &ret.first->second;
 258
 259         // Connection timestamps must be nondecreasing.
 260         assert(clients_ordered_by_connect_time.empty() ||
 261                !is_earlier(client_ptr->connect_time, clients_ordered_by_connect_time.back().first));
 262         clients_ordered_by_connect_time.push(make_pair(client_ptr->connect_time, client.sock()));
 263
 264         // Start listening on data from this socket.
 265         epoll_event ev;
 266         if (client.state() == Client::READING_REQUEST) {
 267                 ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
 268         } else {
 269                 // If we don't have more data for this client, we'll be putting it into
 270                 // the sleeping array again soon.
 271                 ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
 272         }
 273         ev.data.u64 = reinterpret_cast<uint64_t>(client_ptr);
 274         if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, client.sock(), &ev) == -1) {
 275                 log_perror("epoll_ctl(EPOLL_CTL_ADD)");
 276                 exit(1);
 277         }
 278
 279         if (client_ptr->state == Client::WAITING_FOR_KEYFRAME ||
 280             client_ptr->state == Client::PREBUFFERING ||
 281             (client_ptr->state == Client::SENDING_DATA &&
 282              client_ptr->stream_pos == client_ptr->stream->bytes_received)) {
 283                 client_ptr->stream->put_client_to_sleep(client_ptr);
 284         } else {
 285                 process_client(client_ptr);
 286         }
 287 }
 288
 289 int Server::lookup_stream_by_url(const std::string &url) const
 290 {
 291         map<string, int>::const_iterator url_it = url_map.find(url);
 292         if (url_it == url_map.end()) {
 293                 return -1;
 294         }
 295         return url_it->second;
 296 }
 297
 298 int Server::add_stream(const string &url, size_t backlog_size, size_t prebuffering_bytes, Stream::Encoding encoding)
 299 {
 300         MutexLock lock(&mutex);
 301         url_map.insert(make_pair(url, streams.size()));
 302         streams.push_back(new Stream(url, backlog_size, prebuffering_bytes, encoding));
 303         return streams.size() - 1;
 304 }
 305
 306 int Server::add_stream_from_serialized(const StreamProto &stream, int data_fd)
 307 {
 308         MutexLock lock(&mutex);
 309         url_map.insert(make_pair(stream.url(), streams.size()));
 310         streams.push_back(new Stream(stream, data_fd));
 311         return streams.size() - 1;
 312 }
 313
 314 void Server::set_backlog_size(int stream_index, size_t new_size)
 315 {
 316         MutexLock lock(&mutex);
 317         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 318         streams[stream_index]->set_backlog_size(new_size);
 319 }
 320
 321 void Server::set_prebuffering_bytes(int stream_index, size_t new_amount)
 322 {
 323         MutexLock lock(&mutex);
 324         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 325         streams[stream_index]->prebuffering_bytes = new_amount;
 326 }
 327
 328 void Server::set_encoding(int stream_index, Stream::Encoding encoding)
 329 {
 330         MutexLock lock(&mutex);
 331         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 332         streams[stream_index]->encoding = encoding;
 333 }
 334
 335 void Server::set_header(int stream_index, const string &http_header, const string &stream_header)
 336 {
 337         MutexLock lock(&mutex);
 338         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 339         streams[stream_index]->http_header = http_header;
 340         streams[stream_index]->stream_header = stream_header;
 341         // FIXME: We should reset last_suitable_starting_point at this point.
 342 }
 343
 344 void Server::set_pacing_rate(int stream_index, uint32_t pacing_rate)
 345 {
 346         MutexLock lock(&mutex);
 347         assert(clients.empty());
 348         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 349         streams[stream_index]->pacing_rate = pacing_rate;
 350 }
 351
 352 void Server::add_data_deferred(int stream_index, const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start)
 353 {
 354         assert(stream_index >= 0 && stream_index < ssize_t(streams.size()));
 355         streams[stream_index]->add_data_deferred(data, bytes, suitable_for_stream_start);
 356 }
 357
 358 // See the .h file for postconditions after this function.
 359 void Server::process_client(Client *client)
 360 {
 361         switch (client->state) {
 362         case Client::READING_REQUEST: {
 363 read_request_again:
 364                 // Try to read more of the request.
 365                 char buf[1024];
 366                 int ret;
 367                 do {
 368                         ret = read(client->sock, buf, sizeof(buf));
 369                 } while (ret == -1 && errno == EINTR);
 370
 371                 if (ret == -1 && errno == EAGAIN) {
 372                         // No more data right now. Nothing to do.
 373                         // This is postcondition #2.
 374                         return;
 375                 }
 376                 if (ret == -1) {
 377                         log_perror("read");
 378                         close_client(client);
 379                         return;
 380                 }
 381                 if (ret == 0) {
 382                         // OK, the socket is closed.
 383                         close_client(client);
 384                         return;
 385                 }
 386
 387                 RequestParseStatus status = wait_for_double_newline(&client->request, buf, ret);
 388
 389                 switch (status) {
 390                 case RP_OUT_OF_SPACE:
 391                         log(WARNING, "[%s] Client sent overlong request!", client->remote_addr.c_str());
 392                         close_client(client);
 393                         return;
 394                 case RP_NOT_FINISHED_YET:
 395                         // OK, we don't have the entire header yet. Fine; we'll get it later.
 396                         // See if there's more data for us.
 397                         goto read_request_again;
 398                 case RP_EXTRA_DATA:
 399                         log(WARNING, "[%s] Junk data after request!", client->remote_addr.c_str());
 400                         close_client(client);
 401                         return;
 402                 case RP_FINISHED:
 403                         break;
 404                 }
 405
 406                 assert(status == RP_FINISHED);
 407
 408                 int error_code = parse_request(client);
 409                 if (error_code == 200) {
 410                         construct_header(client);
 411                 } else {
 412                         construct_error(client, error_code);
 413                 }
 414
 415                 // We've changed states, so fall through.
 416                 assert(client->state == Client::SENDING_ERROR ||
 417                        client->state == Client::SENDING_HEADER);
 418         }
 419         case Client::SENDING_ERROR:
 420         case Client::SENDING_HEADER: {
 421 sending_header_or_error_again:
 422                 int ret;
 423                 do {
 424                         ret = write(client->sock,
 425                                     client->header_or_error.data() + client->header_or_error_bytes_sent,
 426                                     client->header_or_error.size() - client->header_or_error_bytes_sent);
 427                 } while (ret == -1 && errno == EINTR);
 428
 429                 if (ret == -1 && errno == EAGAIN) {
 430                         // We're out of socket space, so now we're at the “low edge” of epoll's
 431                         // edge triggering. epoll will tell us when there is more room, so for now,
 432                         // just return.
 433                         // This is postcondition #4.
 434                         return;
 435                 }
 436
 437                 if (ret == -1) {
 438                         // Error! Postcondition #1.
 439                         log_perror("write");
 440                         close_client(client);
 441                         return;
 442                 }
 443
 444                 client->header_or_error_bytes_sent += ret;
 445                 assert(client->header_or_error_bytes_sent <= client->header_or_error.size());
 446
 447                 if (client->header_or_error_bytes_sent < client->header_or_error.size()) {
 448                         // We haven't sent all yet. Fine; go another round.
 449                         goto sending_header_or_error_again;
 450                 }
 451
 452                 // We're done sending the header or error! Clear it to release some memory.
 453                 client->header_or_error.clear();
 454
 455                 if (client->state == Client::SENDING_ERROR) {
 456                         // We're done sending the error, so now close.
 457                         // This is postcondition #1.
 458                         close_client(client);
 459                         return;
 460                 }
 461
 462                 // Start sending from the first keyframe we get. In other
 463                 // words, we won't send any of the backlog, but we'll start
 464                 // sending immediately as we get the next keyframe block.
 465                 // This is postcondition #3.
 466                 if (client->stream_pos == size_t(-2)) {
 467                         client->stream_pos = std::min<size_t>(
 468                             client->stream->bytes_received - client->stream->backlog_size,
 469                             0);
 470                         client->state = Client::SENDING_DATA;
 471                 } else {
 472                         // client->stream_pos should be -1, but it might not be,
 473                         // if we have clients from an older version.
 474                         client->stream_pos = client->stream->bytes_received;
 475                         client->state = Client::WAITING_FOR_KEYFRAME;
 476                 }
 477                 client->stream->put_client_to_sleep(client);
 478                 return;
 479         }
 480         case Client::WAITING_FOR_KEYFRAME: {
 481                 Stream *stream = client->stream;
 482                 if (stream->suitable_starting_points.empty() ||
 483                     client->stream_pos > stream->suitable_starting_points.back()) {
 484                         // We haven't received a keyframe since this stream started waiting,
 485                         // so keep on waiting for one.
 486                         // This is postcondition #3.
 487                         stream->put_client_to_sleep(client);
 488                         return;
 489                 }
 490                 client->stream_pos = stream->suitable_starting_points.back();
 491                 client->state = Client::PREBUFFERING;
 492                 // Fall through.
 493         }
 494         case Client::PREBUFFERING: {
 495                 Stream *stream = client->stream;
 496                 size_t bytes_to_send = stream->bytes_received - client->stream_pos;
 497                 assert(bytes_to_send <= stream->backlog_size);
 498                 if (bytes_to_send < stream->prebuffering_bytes) {
 499                         // We don't have enough bytes buffered to start this client yet.
 500                         // This is postcondition #3.
 501                         stream->put_client_to_sleep(client);
 502                         return;
 503                 }
 504                 client->state = Client::SENDING_DATA;
 505                 // Fall through.
 506         }
 507         case Client::SENDING_DATA: {
 508                 skip_lost_data(client);
 509                 Stream *stream = client->stream;
 510
 511 sending_data_again:
 512                 size_t bytes_to_send = stream->bytes_received - client->stream_pos;
 513                 assert(bytes_to_send <= stream->backlog_size);
 514                 if (bytes_to_send == 0) {
 515                         return;
 516                 }
 517
 518                 // See if we need to split across the circular buffer.
 519                 bool more_data = false;
 520                 if ((client->stream_pos % stream->backlog_size) + bytes_to_send > stream->backlog_size) {
 521                         bytes_to_send = stream->backlog_size - (client->stream_pos % stream->backlog_size);
 522                         more_data = true;
 523                 }
 524
 525                 ssize_t ret;
 526                 do {
 527                         off_t offset = client->stream_pos % stream->backlog_size;
 528                         ret = sendfile(client->sock, stream->data_fd, &offset, bytes_to_send);
 529                 } while (ret == -1 && errno == EINTR);
 530
 531                 if (ret == -1 && errno == EAGAIN) {
 532                         // We're out of socket space, so return; epoll will wake us up
 533                         // when there is more room.
 534                         // This is postcondition #4.
 535                         return;
 536                 }
 537                 if (ret == -1) {
 538                         // Error, close; postcondition #1.
 539                         log_perror("sendfile");
 540                         close_client(client);
 541                         return;
 542                 }
 543                 client->stream_pos += ret;
 544                 client->bytes_sent += ret;
 545
 546                 if (client->stream_pos == stream->bytes_received) {
 547                         // We don't have any more data for this client, so put it to sleep.
 548                         // This is postcondition #3.
 549                         stream->put_client_to_sleep(client);
 550                 } else if (more_data && size_t(ret) == bytes_to_send) {
 551                         goto sending_data_again;
 552                 }
 553                 break;
 554         }
 555         default:
 556                 assert(false);
 557         }
 558 }
 559
 560 // See if there's some data we've lost. Ideally, we should drop to a block boundary,
 561 // but resync will be the mux's problem.
 562 void Server::skip_lost_data(Client *client)
 563 {
 564         Stream *stream = client->stream;
 565         if (stream == NULL) {
 566                 return;
 567         }
 568         size_t bytes_to_send = stream->bytes_received - client->stream_pos;
 569         if (bytes_to_send > stream->backlog_size) {
 570                 size_t bytes_lost = bytes_to_send - stream->backlog_size;
 571                 client->stream_pos = stream->bytes_received - stream->backlog_size;
 572                 client->bytes_lost += bytes_lost;
 573                 ++client->num_loss_events;
 574         }
 575 }
 576
 577 int Server::parse_request(Client *client)
 578 {
 579         vector<string> lines = split_lines(client->request);
 580         if (lines.empty()) {
 581                 return 400;  // Bad request (empty).
 582         }
 583
 584         // Parse the headers, for logging purposes.
 585         // TODO: Case-insensitivity.
 586         multimap<string, string> headers = extract_headers(lines, client->remote_addr);
 587         multimap<string, string>::const_iterator referer_it = headers.find("Referer");
 588         if (referer_it != headers.end()) {
 589                 client->referer = referer_it->second;
 590         }
 591         multimap<string, string>::const_iterator user_agent_it = headers.find("User-Agent");
 592         if (user_agent_it != headers.end()) {
 593                 client->user_agent = user_agent_it->second;
 594         }
 595
 596         vector<string> request_tokens = split_tokens(lines[0]);
 597         if (request_tokens.size() < 2) {
 598                 return 400;  // Bad request (empty).
 599         }
 600         if (request_tokens[0] != "GET") {
 601                 return 400;  // Should maybe be 405 instead?
 602         }
 603
 604         string url = request_tokens[1];
 605         if (url.find("?backlog") == url.size() - 8) {
 606                 client->stream_pos = -2;
 607                 url = url.substr(0, url.size() - 8);
 608         } else {
 609                 client->stream_pos = -1;
 610         }
 611
 612         map<string, int>::const_iterator url_map_it = url_map.find(url);
 613         if (url_map_it == url_map.end()) {
 614                 return 404;  // Not found.
 615         }
 616
 617         Stream *stream = streams[url_map_it->second];
 618         if (stream->http_header.empty()) {
 619                 return 503;  // Service unavailable.
 620         }
 621
 622         client->url = request_tokens[1];
 623
 624         client->stream = stream;
 625         if (setsockopt(client->sock, SOL_SOCKET, SO_MAX_PACING_RATE, &client->stream->pacing_rate, sizeof(client->stream->pacing_rate)) == -1) {
 626                 if (client->stream->pacing_rate != ~0U) {
 627                         log_perror("setsockopt(SO_MAX_PACING_RATE)");
 628                 }
 629         }
 630         client->request.clear();
 631
 632         return 200;  // OK!
 633 }
 634
 635 void Server::construct_header(Client *client)
 636 {
 637         Stream *stream = client->stream;
 638         if (stream->encoding == Stream::STREAM_ENCODING_RAW) {
 639                 client->header_or_error = stream->http_header +
 640                         "\r\n" +
 641                         stream->stream_header;
 642         } else if (stream->encoding == Stream::STREAM_ENCODING_METACUBE) {
 643                 client->header_or_error = stream->http_header +
 644                         "Content-encoding: metacube\r\n" +
 645                         "\r\n";
 646                 if (!stream->stream_header.empty()) {
 647                         metacube2_block_header hdr;
 648                         memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
 649                         hdr.size = htonl(stream->stream_header.size());
 650                         hdr.flags = htons(METACUBE_FLAGS_HEADER);
 651                         hdr.csum = htons(metacube2_compute_crc(&hdr));
 652                         client->header_or_error.append(
 653                                 string(reinterpret_cast<char *>(&hdr), sizeof(hdr)));
 654                 }
 655                 client->header_or_error.append(stream->stream_header);
 656         } else {
 657                 assert(false);
 658         }
 659
 660         // Switch states.
 661         client->state = Client::SENDING_HEADER;
 662
 663         epoll_event ev;
 664         ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
 665         ev.data.u64 = reinterpret_cast<uint64_t>(client);
 666
 667         if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, client->sock, &ev) == -1) {
 668                 log_perror("epoll_ctl(EPOLL_CTL_MOD)");
 669                 exit(1);
 670         }
 671 }
 672
 673 void Server::construct_error(Client *client, int error_code)
 674 {
 675         char error[256];
 676         snprintf(error, 256, "HTTP/1.0 %d Error\r\nContent-type: text/plain\r\n\r\nSomething went wrong. Sorry.\r\n",
 677                 error_code);
 678         client->header_or_error = error;
 679
 680         // Switch states.
 681         client->state = Client::SENDING_ERROR;
 682
 683         epoll_event ev;
 684         ev.events = EPOLLOUT | EPOLLET | EPOLLRDHUP;
 685         ev.data.u64 = reinterpret_cast<uint64_t>(client);
 686
 687         if (epoll_ctl(epoll_fd, EPOLL_CTL_MOD, client->sock, &ev) == -1) {
 688                 log_perror("epoll_ctl(EPOLL_CTL_MOD)");
 689                 exit(1);
 690         }
 691 }
 692
 693 template<class T>
 694 void delete_from(vector<T> *v, T elem)
 695 {
 696         typename vector<T>::iterator new_end = remove(v->begin(), v->end(), elem);
 697         v->erase(new_end, v->end());
 698 }
 699
 700 void Server::close_client(Client *client)
 701 {
 702         if (epoll_ctl(epoll_fd, EPOLL_CTL_DEL, client->sock, NULL) == -1) {
 703                 log_perror("epoll_ctl(EPOLL_CTL_DEL)");
 704                 exit(1);
 705         }
 706
 707         // This client could be sleeping, so we'll need to fix that. (Argh, O(n).)
 708         if (client->stream != NULL) {
 709                 delete_from(&client->stream->sleeping_clients, client);
 710                 delete_from(&client->stream->to_process, client);
 711         }
 712
 713         // Log to access_log.
 714         access_log->write(client->get_stats());
 715
 716         // Bye-bye!
 717         safe_close(client->sock);
 718
 719         clients.erase(client->sock);
 720 }
 721
 722 void Server::process_queued_data()
 723 {
 724         {
 725                 MutexLock lock(&queued_clients_mutex);
 726
 727                 for (size_t i = 0; i < queued_add_clients.size(); ++i) {
 728                         add_client(queued_add_clients[i]);
 729                 }
 730                 queued_add_clients.clear();
 731         }
 732
 733         for (size_t i = 0; i < streams.size(); ++i) {
 734                 streams[i]->process_queued_data();
 735         }
 736 }