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

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