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

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