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           http_header(serialized.http_header()),
  57           stream_header(serialized.stream_header()),
  58           encoding(Stream::STREAM_ENCODING_RAW),  // Will be changed later.
  59           data_fd(data_fd),
  60           backlog_size(serialized.backlog_size()),
  61           bytes_received(serialized.bytes_received()),
  62           first_fragment_index(serialized.first_fragment_index()),
  63           discontinuity_counter(serialized.discontinuity_counter())
  64 {
  65         if (data_fd == -1) {
  66                 exit(1);
  67         }
  68
  69         for (ssize_t point : serialized.suitable_starting_point()) {
  70                 if (point == -1) {
  71                         // Can happen when upgrading from before 1.1.3,
  72                         // where this was an optional field with -1 signifying
  73                         // "no such point".
  74                         continue;
  75                 }
  76                 suitable_starting_points.push_back(point);
  77         }
  78
  79         for (const FragmentStartProto &fragment : serialized.fragment()) {
  80                 fragments.push_back(FragmentStart { size_t(fragment.byte_position()), fragment.pts() });
  81         }
  82 }
  83
  84 StreamProto Stream::serialize()
  85 {
  86         StreamProto serialized;
  87         serialized.set_http_header(http_header);
  88         serialized.set_stream_header(stream_header);
  89         serialized.add_data_fds(data_fd);
  90         serialized.set_backlog_size(backlog_size);
  91         serialized.set_bytes_received(bytes_received);
  92         for (size_t point : suitable_starting_points) {
  93                 serialized.add_suitable_starting_point(point);
  94         }
  95         for (const FragmentStart &fragment : fragments) {
  96                 FragmentStartProto *proto = serialized.add_fragment();
  97                 proto->set_byte_position(fragment.byte_position);
  98                 proto->set_pts(fragment.pts);
  99         }
 100         serialized.set_first_fragment_index(first_fragment_index);
 101         serialized.set_discontinuity_counter(discontinuity_counter);
 102
 103         serialized.set_url(url);
 104         data_fd = -1;
 105         return serialized;
 106 }
 107
 108 void Stream::set_backlog_size(size_t new_size)
 109 {
 110         if (backlog_size == new_size) {
 111                 return;
 112         }
 113
 114         string existing_data;
 115         if (!read_tempfile_and_close(data_fd, &existing_data)) {
 116                 exit(1);
 117         }
 118
 119         // Unwrap the data so it's no longer circular.
 120         if (bytes_received <= backlog_size) {
 121                 existing_data.resize(bytes_received);
 122         } else {
 123                 size_t pos = bytes_received % backlog_size;
 124                 existing_data = existing_data.substr(pos, string::npos) +
 125                         existing_data.substr(0, pos);
 126         }
 127
 128         // See if we need to discard data.
 129         if (new_size < existing_data.size()) {
 130                 size_t to_discard = existing_data.size() - new_size;
 131                 existing_data = existing_data.substr(to_discard, string::npos);
 132         }
 133
 134         // Create a new, empty data file.
 135         data_fd = make_tempfile("");
 136         if (data_fd == -1) {
 137                 exit(1);
 138         }
 139         backlog_size = new_size;
 140
 141         // Now cheat a bit by rewinding, and adding all the old data back.
 142         bytes_received -= existing_data.size();
 143         DataElement data_element;
 144         data_element.data.iov_base = const_cast<char *>(existing_data.data());
 145         data_element.data.iov_len = existing_data.size();
 146         data_element.metacube_flags = 0;  // Ignored by add_data_raw().
 147
 148         vector<DataElement> data_elements;
 149         data_elements.push_back(data_element);
 150         add_data_raw(data_elements);
 151         remove_obsolete_starting_points();
 152 }
 153
 154 void Stream::put_client_to_sleep(Client *client)
 155 {
 156         sleeping_clients.push_back(client);
 157 }
 158
 159 // Return a new set of iovecs that contains only the first <bytes_wanted> bytes of <data>.
 160 vector<iovec> collect_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 161 {
 162         vector<iovec> ret;
 163         size_t max_iovecs = min<size_t>(data.size(), IOV_MAX);
 164         for (size_t i = 0; i < max_iovecs && bytes_wanted > 0; ++i) {
 165                 if (data[i].data.iov_len <= bytes_wanted) {
 166                         // Consume the entire iovec.
 167                         ret.push_back(data[i].data);
 168                         bytes_wanted -= data[i].data.iov_len;
 169                 } else {
 170                         // Take only parts of this iovec.
 171                         iovec iov;
 172                         iov.iov_base = data[i].data.iov_base;
 173                         iov.iov_len = bytes_wanted;
 174                         ret.push_back(iov);
 175                         bytes_wanted = 0;
 176                 }
 177         }
 178         return ret;
 179 }
 180
 181 // Return a new set of iovecs that contains all of <data> except the first <bytes_wanted> bytes.
 182 vector<Stream::DataElement> remove_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 183 {
 184         vector<Stream::DataElement> ret;
 185         size_t i;
 186         for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
 187                 if (data[i].data.iov_len <= bytes_wanted) {
 188                         // Consume the entire iovec.
 189                         bytes_wanted -= data[i].data.iov_len;
 190                 } else {
 191                         // Take only parts of this iovec.
 192                         Stream::DataElement data_element;
 193                         data_element.data.iov_base = reinterpret_cast<char *>(data[i].data.iov_base) + bytes_wanted;
 194                         data_element.data.iov_len = data[i].data.iov_len - bytes_wanted;
 195                         data_element.metacube_flags = METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START;
 196                         data_element.pts = RationalPTS();
 197                         ret.push_back(data_element);
 198                         bytes_wanted = 0;
 199                 }
 200         }
 201
 202         // Add the rest of the iovecs unchanged.
 203         ret.insert(ret.end(), data.begin() + i, data.end());
 204         return ret;
 205 }
 206
 207 void Stream::add_data_raw(const vector<DataElement> &orig_data)
 208 {
 209         vector<DataElement> data = orig_data;
 210         while (!data.empty()) {
 211                 size_t pos = bytes_received % backlog_size;
 212
 213                 // Collect as many iovecs as we can before we hit the point
 214                 // where the circular buffer wraps around.
 215                 vector<iovec> to_write = collect_iovecs(data, backlog_size - pos);
 216                 ssize_t ret;
 217                 do {
 218                         ret = pwritev(data_fd, to_write.data(), to_write.size(), pos);
 219                 } while (ret == -1 && errno == EINTR);
 220
 221                 if (ret == -1) {
 222                         log_perror("pwritev");
 223                         // Dazed and confused, but trying to continue...
 224                         return;
 225                 }
 226                 bytes_received += ret;
 227
 228                 // Remove the data that was actually written from the set of iovecs.
 229                 data = remove_iovecs(data, ret);
 230         }
 231 }
 232
 233 void Stream::remove_obsolete_starting_points()
 234 {
 235         // We could do a binary search here (std::lower_bound), but it seems
 236         // overkill for removing what's probably only a few points.
 237         while (!suitable_starting_points.empty() &&
 238                bytes_received - suitable_starting_points[0] > backlog_size) {
 239                 suitable_starting_points.pop_front();
 240         }
 241         assert(backlog_size >= hls_backlog_margin);
 242         while (!fragments.empty() &&
 243                bytes_received - fragments[0].byte_position > (backlog_size - hls_backlog_margin)) {
 244                 fragments.pop_front();
 245                 ++first_fragment_index;
 246                 clear_hls_playlist_cache();
 247         }
 248 }
 249
 250 void Stream::add_data_deferred(const char *data, size_t bytes, uint16_t metacube_flags, const RationalPTS &pts)
 251 {
 252         // For regular output, we don't want to send the client twice
 253         // (it's already sent out together with the HTTP header).
 254         // However, for Metacube output, we need to send it so that
 255         // the Cubemap instance in the other end has a chance to update it.
 256         // It may come twice in its stream, but Cubemap doesn't care.
 257         if (encoding == Stream::STREAM_ENCODING_RAW &&
 258             (metacube_flags & METACUBE_FLAGS_HEADER) != 0) {
 259                 return;
 260         }
 261
 262         lock_guard<mutex> lock(queued_data_mutex);
 263
 264         DataElement data_element;
 265         data_element.metacube_flags = metacube_flags;
 266         data_element.pts = pts;
 267
 268         if (encoding == Stream::STREAM_ENCODING_METACUBE) {
 269                 // Construct a PTS metadata block. (We'll avoid sending it out
 270                 // if we don't have a valid PTS.)
 271                 metacube2_pts_packet pts_packet;
 272                 pts_packet.type = htobe64(METACUBE_METADATA_TYPE_NEXT_BLOCK_PTS);
 273                 pts_packet.pts = htobe64(pts.pts);
 274                 pts_packet.timebase_num = htobe64(pts.timebase_num);
 275                 pts_packet.timebase_den = htobe64(pts.timebase_den);
 276
 277                 metacube2_block_header pts_hdr;
 278                 memcpy(pts_hdr.sync, METACUBE2_SYNC, sizeof(pts_hdr.sync));
 279                 pts_hdr.size = htonl(sizeof(pts_packet));
 280                 pts_hdr.flags = htons(METACUBE_FLAGS_METADATA);
 281                 pts_hdr.csum = htons(metacube2_compute_crc(&pts_hdr));
 282
 283                 // Add a Metacube block header before the data.
 284                 metacube2_block_header hdr;
 285                 memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
 286                 hdr.size = htonl(bytes);
 287                 hdr.flags = htons(metacube_flags);
 288                 hdr.csum = htons(metacube2_compute_crc(&hdr));
 289
 290                 data_element.data.iov_len = bytes + sizeof(hdr);
 291                 if (pts.timebase_num != 0) {
 292                         data_element.data.iov_len += sizeof(pts_hdr) + sizeof(pts_packet);
 293                 }
 294                 data_element.data.iov_base = new char[data_element.data.iov_len];
 295
 296                 char *ptr = reinterpret_cast<char *>(data_element.data.iov_base);
 297                 if (pts.timebase_num != 0) {
 298                         memcpy(ptr, &pts_hdr, sizeof(pts_hdr));
 299                         ptr += sizeof(pts_hdr);
 300                         memcpy(ptr, &pts_packet, sizeof(pts_packet));
 301                         ptr += sizeof(pts_packet);
 302                 }
 303
 304                 memcpy(ptr, &hdr, sizeof(hdr));
 305                 ptr += sizeof(hdr);
 306                 memcpy(ptr, data, bytes);
 307
 308                 queued_data.push_back(data_element);
 309         } else if (encoding == Stream::STREAM_ENCODING_RAW) {
 310                 // Just add the data itself.
 311                 data_element.data.iov_base = new char[bytes];
 312                 memcpy(data_element.data.iov_base, data, bytes);
 313                 data_element.data.iov_len = bytes;
 314
 315                 queued_data.push_back(data_element);
 316         } else {
 317                 assert(false);
 318         }
 319 }
 320
 321 void Stream::process_queued_data()
 322 {
 323         vector<DataElement> queued_data_copy;
 324
 325         // Hold the lock for as short as possible, since add_data_raw() can possibly
 326         // write to disk, which might disturb the input thread.
 327         {
 328                 lock_guard<mutex> lock(queued_data_mutex);
 329                 if (queued_data.empty()) {
 330                         return;
 331                 }
 332
 333                 swap(queued_data, queued_data_copy);
 334         }
 335
 336         // Add suitable starting points for the stream, if the queued data
 337         // contains such starting points. Note that we drop starting points
 338         // if they're less than 10 kB apart, so that we don't get a huge
 339         // amount of them for e.g. each and every MPEG-TS 188-byte cell.
 340         // The 10 kB value is somewhat arbitrary, but at least it should make
 341         // the RAM cost of saving the position ~0.1% (or less) of the actual
 342         // data, and 10 kB is a very fine granularity in most streams.
 343         static const int minimum_start_point_distance = 10240;
 344         size_t byte_position = bytes_received;
 345         bool need_hls_clear = false;
 346         for (const DataElement &elem : queued_data_copy) {
 347                 if ((elem.metacube_flags & METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START) == 0) {
 348                         size_t num_points = suitable_starting_points.size();
 349                         if (num_points >= 2 &&
 350                             suitable_starting_points[num_points - 1] - suitable_starting_points[num_points - 2] < minimum_start_point_distance) {
 351                                 // p[n-1] - p[n-2] < 10 kB, so drop p[n-1].
 352                                 suitable_starting_points.pop_back();
 353                         }
 354                         suitable_starting_points.push_back(byte_position);
 355
 356                         if (elem.pts.timebase_num != 0) {
 357                                 need_hls_clear |= add_fragment_boundary(byte_position, elem.pts);
 358                         }
 359                 }
 360                 byte_position += elem.data.iov_len;
 361         }
 362         if (need_hls_clear) {
 363                 clear_hls_playlist_cache();
 364         }
 365
 366         add_data_raw(queued_data_copy);
 367         remove_obsolete_starting_points();
 368         for (const DataElement &elem : queued_data_copy) {
 369                 char *data = reinterpret_cast<char *>(elem.data.iov_base);
 370                 delete[] data;
 371         }
 372
 373         // We have more data, so wake up all clients.
 374         if (to_process.empty()) {
 375                 swap(sleeping_clients, to_process);
 376         } else {
 377                 to_process.insert(to_process.end(), sleeping_clients.begin(), sleeping_clients.end());
 378                 sleeping_clients.clear();
 379         }
 380 }
 381
 382 bool Stream::add_fragment_boundary(size_t byte_position, const RationalPTS &pts)
 383 {
 384         double pts_double = double(pts.pts) * pts.timebase_den / pts.timebase_num;
 385
 386         if (fragments.size() <= 1) {
 387                 // Just starting up, so try to establish the first in-progress fragment.
 388                 fragments.push_back(FragmentStart{ byte_position, pts_double });
 389                 return false;
 390         }
 391
 392         // Keep extending the in-progress fragment as long as we do not
 393         // exceed the target duration by more than half a second
 394         // (RFC 8216 4.3.3.1) and we get closer to the target by doing so.
 395         // Note that in particular, this means we'll always extend
 396         // as long as we don't exceed the target duration.
 397         double current_duration = fragments[fragments.size() - 1].pts;
 398         double candidate_duration = pts_double - fragments[fragments.size() - 2].pts;
 399         if (lrintf(candidate_duration) <= hls_frag_duration &&
 400             fabs(candidate_duration - hls_frag_duration) < fabs(current_duration - hls_frag_duration)) {
 401                 fragments.back() = FragmentStart{ byte_position, pts_double };
 402                 return false;
 403         } else {
 404                 // Extending the in-progress fragment would make it too long,
 405                 // so finalize it and start a new in-progress fragment.
 406                 fragments.push_back(FragmentStart{ byte_position, pts_double });
 407                 return true;
 408         }
 409 }
 410
 411 void Stream::clear_hls_playlist_cache()
 412 {
 413         hls_playlist_http10.reset();
 414         hls_playlist_http11_close.reset();
 415         hls_playlist_http11_persistent.reset();
 416 }
 417
 418 shared_ptr<const string> Stream::generate_hls_playlist(bool http_11, bool close_after_response)
 419 {
 420         char buf[256];
 421         snprintf(buf, sizeof(buf),
 422                 "#EXTM3U\r\n"
 423                 "#EXT-X-VERSION:7\r\n"
 424                 "#EXT-X-TARGETDURATION:%u\r\n"
 425                 "#EXT-X-MEDIA-SEQUENCE:%" PRIu64 "\r\n"
 426                 "#EXT-X-DISCONTINUITY-SEQUENCE:%" PRIu64 "\r\n",
 427                 hls_frag_duration,
 428                 first_fragment_index,
 429                 discontinuity_counter);
 430
 431         string playlist = buf;
 432
 433         if (!stream_header.empty()) {
 434                 snprintf(buf, sizeof(buf), "#EXT-X-MAP:URI=\"%s?frag=header\"\r\n", url.c_str());
 435                 playlist += buf;
 436         }
 437
 438         playlist += "\r\n";
 439         if (fragments.size() >= 3) {
 440                 for (size_t i = 0; i < fragments.size() - 2; ++i) {
 441                         char buf[256];
 442                         snprintf(buf, sizeof(buf), "#EXTINF:%f,\r\n%s?frag=%" PRIu64 "-%" PRIu64 "\r\n",
 443                                 fragments[i + 1].pts - fragments[i].pts,
 444                                 url.c_str(),
 445                                 fragments[i].byte_position,
 446                                 fragments[i + 1].byte_position);
 447                         playlist += buf;
 448                 }
 449         }
 450
 451         string response;
 452         if (http_11) {
 453                 response = "HTTP/1.1 200 OK\r\n";
 454                 if (close_after_response) {
 455                         response.append("Connection: close\r\n");
 456                 }
 457         } else {
 458                 assert(close_after_response);
 459                 response = "HTTP/1.0 200 OK\r\n";
 460         }
 461         snprintf(buf, sizeof(buf), "Content-Length: %zu\r\n", playlist.size());
 462         response.append(buf);
 463         response.append("Content-Type: application/x-mpegURL\r\n");
 464         if (!allow_origin.empty()) {
 465                 response.append("Access-Control-Allow-Origin: ");
 466                 response.append(allow_origin);
 467                 response.append("\r\n");
 468         }
 469         response.append("\r\n");
 470         response.append(move(playlist));
 471
 472         return shared_ptr<const string>(new string(move(response)));
 473 }