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

   1 #include <assert.h>
   2 #include <errno.h>
   3 #include <fcntl.h>
   4 #include <inttypes.h>
   5 #include <limits.h>
   6 #include <math.h>
   7 #include <netinet/in.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10 #include <string.h>
  11 #include <sys/types.h>
  12 #include <algorithm>
  13 #include <string>
  14 #include <queue>
  15 #include <vector>
  16
  17 #include "log.h"
  18 #include "metacube2.h"
  19 #include "state.pb.h"
  20 #include "stream.h"
  21 #include "util.h"
  22
  23 using namespace std;
  24
  25 Stream::Stream(const string &url,
  26                size_t backlog_size,
  27                uint64_t prebuffering_bytes,
  28                Encoding encoding,
  29                Encoding src_encoding,
  30                unsigned hls_frag_duration,
  31                size_t hls_backlog_margin,
  32                const std::string &allow_origin)
  33         : url(url),
  34           encoding(encoding),
  35           src_encoding(src_encoding),
  36           allow_origin(allow_origin),
  37           data_fd(make_tempfile("")),
  38           backlog_size(backlog_size),
  39           prebuffering_bytes(prebuffering_bytes),
  40           hls_frag_duration(hls_frag_duration),
  41           hls_backlog_margin(hls_backlog_margin)
  42 {
  43         if (data_fd == -1) {
  44                 exit(1);
  45         }
  46 }
  47
  48 Stream::~Stream()
  49 {
  50         if (data_fd != -1) {
  51                 safe_close(data_fd);
  52         }
  53 }
  54
  55 Stream::Stream(const StreamProto &serialized, int data_fd)
  56         : url(serialized.url()),
  57           unavailable(serialized.unavailable()),
  58           http_header(serialized.http_header()),
  59           stream_header(serialized.stream_header()),
  60           encoding(Stream::STREAM_ENCODING_RAW),  // Will be changed later.
  61           data_fd(data_fd),
  62           backlog_size(serialized.backlog_size()),
  63           bytes_received(serialized.bytes_received()),
  64           first_fragment_index(serialized.first_fragment_index()),
  65           discontinuity_counter(serialized.discontinuity_counter())
  66 {
  67         if (data_fd == -1) {
  68                 exit(1);
  69         }
  70
  71         // Set the close-on-exec parameter back on the backlog fd.
  72         fcntl(data_fd, F_SETFD, FD_CLOEXEC);
  73
  74         for (ssize_t point : serialized.suitable_starting_point()) {
  75                 if (point == -1) {
  76                         // Can happen when upgrading from before 1.1.3,
  77                         // where this was an optional field with -1 signifying
  78                         // "no such point".
  79                         continue;
  80                 }
  81                 suitable_starting_points.push_back(point);
  82         }
  83
  84         for (const FragmentStartProto &fragment : serialized.fragment()) {
  85                 fragments.push_back(FragmentStart { size_t(fragment.byte_position()), fragment.pts(), fragment.begins_header() });
  86         }
  87 }
  88
  89 StreamProto Stream::serialize()
  90 {
  91         StreamProto serialized;
  92         serialized.set_unavailable(unavailable);
  93         serialized.set_http_header(http_header);
  94         serialized.set_stream_header(stream_header);
  95         serialized.add_data_fds(data_fd);
  96         serialized.set_backlog_size(backlog_size);
  97         serialized.set_bytes_received(bytes_received);
  98         for (size_t point : suitable_starting_points) {
  99                 serialized.add_suitable_starting_point(point);
 100         }
 101         for (const FragmentStart &fragment : fragments) {
 102                 FragmentStartProto *proto = serialized.add_fragment();
 103                 proto->set_byte_position(fragment.byte_position);
 104                 proto->set_pts(fragment.pts);
 105                 proto->set_begins_header(fragment.begins_header);
 106         }
 107         serialized.set_first_fragment_index(first_fragment_index);
 108         serialized.set_discontinuity_counter(discontinuity_counter);
 109
 110         // Unset the close-on-exec flag for the backlog fd.
 111         // (This can't leak into a child, since there's only one thread left.)
 112         fcntl(data_fd, F_SETFD, 0);
 113
 114         serialized.set_url(url);
 115         data_fd = -1;
 116         return serialized;
 117 }
 118
 119 void Stream::set_backlog_size(size_t new_size)
 120 {
 121         if (backlog_size == new_size) {
 122                 return;
 123         }
 124
 125         string existing_data;
 126         if (!read_tempfile_and_close(data_fd, &existing_data)) {
 127                 exit(1);
 128         }
 129
 130         // Unwrap the data so it's no longer circular.
 131         if (bytes_received <= backlog_size) {
 132                 existing_data.resize(bytes_received);
 133         } else {
 134                 size_t pos = bytes_received % backlog_size;
 135                 existing_data = existing_data.substr(pos, string::npos) +
 136                         existing_data.substr(0, pos);
 137         }
 138
 139         // See if we need to discard data.
 140         if (new_size < existing_data.size()) {
 141                 size_t to_discard = existing_data.size() - new_size;
 142                 existing_data = existing_data.substr(to_discard, string::npos);
 143         }
 144
 145         // Create a new, empty data file.
 146         data_fd = make_tempfile("");
 147         if (data_fd == -1) {
 148                 exit(1);
 149         }
 150         backlog_size = new_size;
 151
 152         // Now cheat a bit by rewinding, and adding all the old data back.
 153         bytes_received -= existing_data.size();
 154         DataElement data_element;
 155         data_element.data.iov_base = const_cast<char *>(existing_data.data());
 156         data_element.data.iov_len = existing_data.size();
 157         data_element.metacube_flags = 0;  // Ignored by add_data_raw().
 158
 159         vector<DataElement> data_elements;
 160         data_elements.push_back(data_element);
 161         add_data_raw(data_elements);
 162         remove_obsolete_starting_points();
 163 }
 164
 165 void Stream::set_header(const std::string &new_http_header, const std::string &new_stream_header)
 166 {
 167         unavailable = false;
 168         http_header = new_http_header;
 169         if (new_stream_header == stream_header) {
 170                 return;
 171         }
 172
 173         // We cannot start at any of the older starting points anymore,
 174         // since they'd get the wrong header for the stream (not to mention
 175         // that a changed header probably means the stream restarted,
 176         // which means any client starting on the old one would probably
 177         // stop playing properly at the change point). Next block
 178         // should be a suitable starting point (if not, something is
 179         // pretty strange), so it will fill up again soon enough.
 180         suitable_starting_points.clear();
 181
 182         // HLS, on the other hand, can deal with discontinuities and multiple
 183         // headers. At least in theory (client support varies wildly).
 184         if (!fragments.empty()) {
 185                 // Commit the old header to the backlog, so that we can serve it
 186                 // for all the old fragments for as long as they exist.
 187                 if (!stream_header.empty()) {
 188                         // End the current fragment and make a new one for the header.
 189                         fragments.push_back(Stream::FragmentStart { bytes_received, 0.0, true });
 190                         process_queued_data();
 191                         Stream::DataElement elem;
 192                         elem.data.iov_base = (char *)stream_header.data();
 193                         elem.data.iov_len = stream_header.size();
 194                         add_data_raw({ elem });
 195                         remove_obsolete_starting_points();
 196
 197                         // The discontinuity counter will be increased when
 198                         // this header goes out of the backlog.
 199                 }
 200                 clear_hls_playlist_cache();
 201         }
 202         stream_header = new_stream_header;
 203 }
 204
 205 void Stream::put_client_to_sleep(Client *client)
 206 {
 207         sleeping_clients.push_back(client);
 208 }
 209
 210 // Return a new set of iovecs that contains only the first <bytes_wanted> bytes of <data>.
 211 vector<iovec> collect_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 212 {
 213         vector<iovec> ret;
 214         size_t max_iovecs = min<size_t>(data.size(), IOV_MAX);
 215         for (size_t i = 0; i < max_iovecs && bytes_wanted > 0; ++i) {
 216                 if (data[i].data.iov_len <= bytes_wanted) {
 217                         // Consume the entire iovec.
 218                         ret.push_back(data[i].data);
 219                         bytes_wanted -= data[i].data.iov_len;
 220                 } else {
 221                         // Take only parts of this iovec.
 222                         iovec iov;
 223                         iov.iov_base = data[i].data.iov_base;
 224                         iov.iov_len = bytes_wanted;
 225                         ret.push_back(iov);
 226                         bytes_wanted = 0;
 227                 }
 228         }
 229         return ret;
 230 }
 231
 232 // Return a new set of iovecs that contains all of <data> except the first <bytes_wanted> bytes.
 233 vector<Stream::DataElement> remove_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 234 {
 235         vector<Stream::DataElement> ret;
 236         size_t i;
 237         for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
 238                 if (data[i].data.iov_len <= bytes_wanted) {
 239                         // Consume the entire iovec.
 240                         bytes_wanted -= data[i].data.iov_len;
 241                 } else {
 242                         // Take only parts of this iovec.
 243                         Stream::DataElement data_element;
 244                         data_element.data.iov_base = reinterpret_cast<char *>(data[i].data.iov_base) + bytes_wanted;
 245                         data_element.data.iov_len = data[i].data.iov_len - bytes_wanted;
 246                         data_element.metacube_flags = METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START;
 247                         data_element.pts = RationalPTS();
 248                         ret.push_back(data_element);
 249                         bytes_wanted = 0;
 250                 }
 251         }
 252
 253         // Add the rest of the iovecs unchanged.
 254         ret.insert(ret.end(), data.begin() + i, data.end());
 255         return ret;
 256 }
 257
 258 void Stream::add_data_raw(const vector<DataElement> &orig_data)
 259 {
 260         vector<DataElement> data = orig_data;
 261         while (!data.empty()) {
 262                 size_t pos = bytes_received % backlog_size;
 263
 264                 // Collect as many iovecs as we can before we hit the point
 265                 // where the circular buffer wraps around.
 266                 vector<iovec> to_write = collect_iovecs(data, backlog_size - pos);
 267                 ssize_t ret;
 268                 do {
 269                         ret = pwritev(data_fd, to_write.data(), to_write.size(), pos);
 270                 } while (ret == -1 && errno == EINTR);
 271
 272                 if (ret == -1) {
 273                         log_perror("pwritev");
 274                         // Dazed and confused, but trying to continue...
 275                         return;
 276                 }
 277                 bytes_received += ret;
 278
 279                 // Remove the data that was actually written from the set of iovecs.
 280                 data = remove_iovecs(data, ret);
 281         }
 282 }
 283
 284 void Stream::remove_obsolete_starting_points()
 285 {
 286         // We could do a binary search here (std::lower_bound), but it seems
 287         // overkill for removing what's probably only a few points.
 288         while (!suitable_starting_points.empty() &&
 289                bytes_received - suitable_starting_points[0] > backlog_size) {
 290                 suitable_starting_points.pop_front();
 291         }
 292         assert(backlog_size >= hls_backlog_margin);
 293         while (!fragments.empty() &&
 294                bytes_received - fragments[0].byte_position > (backlog_size - hls_backlog_margin)) {
 295                 if (fragments[0].begins_header) {
 296                         ++discontinuity_counter;
 297                 } else {
 298                         ++first_fragment_index;
 299                 }
 300                 fragments.pop_front();
 301                 clear_hls_playlist_cache();
 302         }
 303 }
 304
 305 void Stream::add_data_deferred(const char *data, size_t bytes, uint16_t metacube_flags, const RationalPTS &pts)
 306 {
 307         // For regular output, we don't want to send the client twice
 308         // (it's already sent out together with the HTTP header).
 309         // However, for Metacube output, we need to send it so that
 310         // the Cubemap instance in the other end has a chance to update it.
 311         // It may come twice in its stream, but Cubemap doesn't care.
 312         if (encoding == Stream::STREAM_ENCODING_RAW &&
 313             (metacube_flags & METACUBE_FLAGS_HEADER) != 0) {
 314                 return;
 315         }
 316
 317         lock_guard<mutex> lock(queued_data_mutex);
 318
 319         DataElement data_element;
 320         data_element.metacube_flags = metacube_flags;
 321         data_element.pts = pts;
 322
 323         if (encoding == Stream::STREAM_ENCODING_METACUBE) {
 324                 // Construct a PTS metadata block. (We'll avoid sending it out
 325                 // if we don't have a valid PTS.)
 326                 metacube2_pts_packet pts_packet;
 327                 pts_packet.type = htobe64(METACUBE_METADATA_TYPE_NEXT_BLOCK_PTS);
 328                 pts_packet.pts = htobe64(pts.pts);
 329                 pts_packet.timebase_num = htobe64(pts.timebase_num);
 330                 pts_packet.timebase_den = htobe64(pts.timebase_den);
 331
 332                 metacube2_block_header pts_hdr;
 333                 memcpy(pts_hdr.sync, METACUBE2_SYNC, sizeof(pts_hdr.sync));
 334                 pts_hdr.size = htonl(sizeof(pts_packet));
 335                 pts_hdr.flags = htons(METACUBE_FLAGS_METADATA);
 336                 pts_hdr.csum = htons(metacube2_compute_crc(&pts_hdr));
 337
 338                 // Add a Metacube block header before the data.
 339                 metacube2_block_header hdr;
 340                 memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
 341                 hdr.size = htonl(bytes);
 342                 hdr.flags = htons(metacube_flags);
 343                 hdr.csum = htons(metacube2_compute_crc(&hdr));
 344
 345                 data_element.data.iov_len = bytes + sizeof(hdr);
 346                 if (pts.timebase_num != 0) {
 347                         data_element.data.iov_len += sizeof(pts_hdr) + sizeof(pts_packet);
 348                 }
 349                 data_element.data.iov_base = new char[data_element.data.iov_len];
 350
 351                 char *ptr = reinterpret_cast<char *>(data_element.data.iov_base);
 352                 if (pts.timebase_num != 0) {
 353                         memcpy(ptr, &pts_hdr, sizeof(pts_hdr));
 354                         ptr += sizeof(pts_hdr);
 355                         memcpy(ptr, &pts_packet, sizeof(pts_packet));
 356                         ptr += sizeof(pts_packet);
 357                 }
 358
 359                 memcpy(ptr, &hdr, sizeof(hdr));
 360                 ptr += sizeof(hdr);
 361                 memcpy(ptr, data, bytes);
 362
 363                 queued_data.push_back(data_element);
 364         } else if (encoding == Stream::STREAM_ENCODING_RAW) {
 365                 // Just add the data itself.
 366                 data_element.data.iov_base = new char[bytes];
 367                 memcpy(data_element.data.iov_base, data, bytes);
 368                 data_element.data.iov_len = bytes;
 369
 370                 queued_data.push_back(data_element);
 371         } else {
 372                 assert(false);
 373         }
 374 }
 375
 376 void Stream::process_queued_data()
 377 {
 378         vector<DataElement> queued_data_copy;
 379
 380         // Hold the lock for as short as possible, since add_data_raw() can possibly
 381         // write to disk, which might disturb the input thread.
 382         {
 383                 lock_guard<mutex> lock(queued_data_mutex);
 384                 if (queued_data.empty()) {
 385                         return;
 386                 }
 387
 388                 swap(queued_data, queued_data_copy);
 389         }
 390
 391         // Add suitable starting points for the stream, if the queued data
 392         // contains such starting points. Note that we drop starting points
 393         // if they're less than 10 kB apart, so that we don't get a huge
 394         // amount of them for e.g. each and every MPEG-TS 188-byte cell.
 395         // The 10 kB value is somewhat arbitrary, but at least it should make
 396         // the RAM cost of saving the position ~0.1% (or less) of the actual
 397         // data, and 10 kB is a very fine granularity in most streams.
 398         static const int minimum_start_point_distance = 10240;
 399         size_t byte_position = bytes_received;
 400         bool need_hls_clear = false;
 401         for (const DataElement &elem : queued_data_copy) {
 402                 if ((elem.metacube_flags & METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START) == 0) {
 403                         size_t num_points = suitable_starting_points.size();
 404                         if (num_points >= 2 &&
 405                             suitable_starting_points[num_points - 1] - suitable_starting_points[num_points - 2] < minimum_start_point_distance) {
 406                                 // p[n-1] - p[n-2] < 10 kB, so drop p[n-1].
 407                                 suitable_starting_points.pop_back();
 408                         }
 409                         suitable_starting_points.push_back(byte_position);
 410
 411                         if (elem.pts.timebase_num != 0) {
 412                                 need_hls_clear |= add_fragment_boundary(byte_position, elem.pts);
 413                         }
 414                 }
 415                 byte_position += elem.data.iov_len;
 416         }
 417         if (need_hls_clear) {
 418                 clear_hls_playlist_cache();
 419         }
 420
 421         add_data_raw(queued_data_copy);
 422         remove_obsolete_starting_points();
 423         for (const DataElement &elem : queued_data_copy) {
 424                 char *data = reinterpret_cast<char *>(elem.data.iov_base);
 425                 delete[] data;
 426         }
 427
 428         // We have more data, so wake up all clients.
 429         if (to_process.empty()) {
 430                 swap(sleeping_clients, to_process);
 431         } else {
 432                 to_process.insert(to_process.end(), sleeping_clients.begin(), sleeping_clients.end());
 433                 sleeping_clients.clear();
 434         }
 435 }
 436
 437 bool Stream::add_fragment_boundary(size_t byte_position, const RationalPTS &pts)
 438 {
 439         double pts_double = double(pts.pts) * pts.timebase_den / pts.timebase_num;
 440
 441         if (fragments.size() <= 1 ||
 442             fragments[fragments.size() - 1].begins_header ||
 443             fragments[fragments.size() - 2].begins_header) {
 444                 // Just starting up, so try to establish the first in-progress fragment.
 445                 fragments.push_back(FragmentStart{ byte_position, pts_double, false });
 446                 return false;
 447         }
 448
 449         // Keep extending the in-progress fragment as long as we do not
 450         // exceed the target duration by more than half a second
 451         // (RFC 8216 4.3.3.1) and we get closer to the target by doing so.
 452         // Note that in particular, this means we'll always extend
 453         // as long as we don't exceed the target duration.
 454         double current_duration = pts_double - fragments[fragments.size() - 1].pts;
 455         double candidate_duration = pts_double - fragments[fragments.size() - 2].pts;
 456         if (lrintf(candidate_duration) <= hls_frag_duration &&
 457             fabs(candidate_duration - hls_frag_duration) < fabs(current_duration - hls_frag_duration)) {
 458                 fragments.back() = FragmentStart{ byte_position, pts_double, false };
 459                 return false;
 460         } else {
 461                 // Extending the in-progress fragment would make it too long,
 462                 // so finalize it and start a new in-progress fragment.
 463                 fragments.push_back(FragmentStart{ byte_position, pts_double, false });
 464                 return true;
 465         }
 466 }
 467
 468 void Stream::clear_hls_playlist_cache()
 469 {
 470         hls_playlist_http10.reset();
 471         hls_playlist_http11_close.reset();
 472         hls_playlist_http11_persistent.reset();
 473 }
 474
 475 shared_ptr<const string> Stream::generate_hls_playlist(bool http_11, bool close_after_response)
 476 {
 477         char buf[256];
 478         snprintf(buf, sizeof(buf),
 479                 "#EXTM3U\r\n"
 480                 "#EXT-X-VERSION:7\r\n"
 481                 "#EXT-X-TARGETDURATION:%u\r\n"
 482                 "#EXT-X-MEDIA-SEQUENCE:%" PRIu64 "\r\n"
 483                 "#EXT-X-DISCONTINUITY-SEQUENCE:%" PRIu64 "\r\n",
 484                 hls_frag_duration,
 485                 first_fragment_index,
 486                 discontinuity_counter);
 487
 488         string playlist = buf;
 489
 490         if (fragments.size() >= 3) {
 491                 bool printed_header_for_this_group = false;
 492                 bool printed_first_header = false;
 493                 for (size_t i = 0; i < fragments.size() - 2; ++i) {
 494                         char buf[256];
 495
 496                         if (fragments[i].begins_header) {
 497                                 // End of this group. (We've already printed the header
 498                                 // as part of the previous group.)
 499                                 printed_header_for_this_group = false;
 500                                 continue;
 501                         }
 502                         if (!printed_header_for_this_group) {
 503                                 // Look forward until we find the header for this group (if any).
 504                                 for (size_t j = i + 1; j < fragments.size() - 1; ++j) {
 505                                         if (fragments[j].begins_header) {
 506                                                 if (printed_first_header) {
 507                                                         playlist += "#EXT-X-DISCONTINUITY\r\n";
 508                                                 }
 509                                                 snprintf(buf, sizeof(buf),
 510                                                         "#EXT-X-MAP:URI=\"%s?frag=%" PRIu64 "-%" PRIu64 "\"\r\n",
 511                                                         url.c_str(), fragments[j].byte_position,
 512                                                         fragments[j + 1].byte_position);
 513                                                 playlist += buf;
 514                                                 printed_first_header = true;
 515                                                 printed_header_for_this_group = true;
 516                                                 break;
 517                                         }
 518                                 }
 519
 520                                 if (!printed_header_for_this_group && !stream_header.empty()) {
 521                                         if (printed_first_header) {
 522                                                 playlist += "#EXT-X-DISCONTINUITY\r\n";
 523                                         }
 524                                         snprintf(buf, sizeof(buf), "#EXT-X-MAP:URI=\"%s?frag=header\"\r\n", url.c_str());
 525                                         playlist += buf;
 526                                 }
 527
 528                                 // Even if we didn't find anything, we don't want to search again for each fragment.
 529                                 printed_first_header = true;
 530                                 printed_header_for_this_group = true;
 531                         }
 532
 533                         if (fragments[i + 1].begins_header) {
 534                                 // Since we only have start pts for each block and not duration,
 535                                 // we have no idea how long this fragment is; the encoder restarted
 536                                 // before it got to output the next pts. However, it's likely
 537                                 // to be very short, so instead of trying to guess, we just skip it.
 538                                 continue;
 539                         }
 540
 541                         snprintf(buf, sizeof(buf), "#EXTINF:%f,\r\n%s?frag=%" PRIu64 "-%" PRIu64 "\r\n",
 542                                 fragments[i + 1].pts - fragments[i].pts,
 543                                 url.c_str(),
 544                                 fragments[i].byte_position,
 545                                 fragments[i + 1].byte_position);
 546                         playlist += buf;
 547                 }
 548         }
 549
 550         string response;
 551         if (http_11) {
 552                 response = "HTTP/1.1 200 OK\r\n";
 553                 if (close_after_response) {
 554                         response.append("Connection: close\r\n");
 555                 }
 556         } else {
 557                 assert(close_after_response);
 558                 response = "HTTP/1.0 200 OK\r\n";
 559         }
 560         snprintf(buf, sizeof(buf), "Content-Length: %zu\r\n", playlist.size());
 561         response.append(buf);
 562         response.append("Content-Type: application/x-mpegURL\r\n");
 563         if (!allow_origin.empty()) {
 564                 response.append("Access-Control-Allow-Origin: ");
 565                 response.append(allow_origin);
 566                 response.append("\r\n");
 567         }
 568         response.append("\r\n");
 569         response.append(move(playlist));
 570
 571         return shared_ptr<const string>(new string(move(response)));
 572 }