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

   1 #include <assert.h>
   2 #include <errno.h>
   3 #include <limits.h>
   4 #include <netinet/in.h>
   5 #include <stdio.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <sys/types.h>
   9 #include <algorithm>
  10 #include <string>
  11 #include <queue>
  12 #include <vector>
  13
  14 #include "log.h"
  15 #include "metacube2.h"
  16 #include "mutexlock.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, size_t backlog_size, size_t prebuffering_bytes, Encoding encoding)
  24         : url(url),
  25           encoding(encoding),
  26           data_fd(make_tempfile("")),
  27           backlog_size(backlog_size),
  28           prebuffering_bytes(prebuffering_bytes),
  29           bytes_received(0),
  30           pacing_rate(~0U)
  31 {
  32         if (data_fd == -1) {
  33                 exit(1);
  34         }
  35
  36         pthread_mutex_init(&queued_data_mutex, NULL);
  37 }
  38
  39 Stream::~Stream()
  40 {
  41         if (data_fd != -1) {
  42                 safe_close(data_fd);
  43         }
  44 }
  45
  46 Stream::Stream(const StreamProto &serialized, int data_fd)
  47         : url(serialized.url()),
  48           http_header(serialized.http_header()),
  49           stream_header(serialized.stream_header()),
  50           encoding(Stream::STREAM_ENCODING_RAW),  // Will be changed later.
  51           data_fd(data_fd),
  52           backlog_size(serialized.backlog_size()),
  53           prebuffering_bytes(serialized.prebuffering_bytes()),
  54           bytes_received(serialized.bytes_received()),
  55           pacing_rate(~0U)
  56 {
  57         if (data_fd == -1) {
  58                 exit(1);
  59         }
  60
  61         for (int i = 0; i < serialized.suitable_starting_point_size(); ++i) {
  62                 ssize_t point = serialized.suitable_starting_point(i);
  63                 if (point == -1) {
  64                         // Can happen when upgrading from before 1.1.3,
  65                         // where this was an optional field with -1 signifying
  66                         // "no such point".
  67                         continue;
  68                 }
  69                 suitable_starting_points.push_back(point);
  70         }
  71
  72         pthread_mutex_init(&queued_data_mutex, NULL);
  73 }
  74
  75 StreamProto Stream::serialize()
  76 {
  77         StreamProto serialized;
  78         serialized.set_http_header(http_header);
  79         serialized.set_stream_header(stream_header);
  80         serialized.add_data_fds(data_fd);
  81         serialized.set_backlog_size(backlog_size);
  82         serialized.set_prebuffering_bytes(prebuffering_bytes);
  83         serialized.set_bytes_received(bytes_received);
  84         for (size_t i = 0; i < suitable_starting_points.size(); ++i) {
  85                 serialized.add_suitable_starting_point(suitable_starting_points[i]);
  86         }
  87         serialized.set_url(url);
  88         data_fd = -1;
  89         return serialized;
  90 }
  91
  92 void Stream::set_backlog_size(size_t new_size)
  93 {
  94         if (backlog_size == new_size) {
  95                 return;
  96         }
  97
  98         string existing_data;
  99         if (!read_tempfile_and_close(data_fd, &existing_data)) {
 100                 exit(1);
 101         }
 102
 103         // Unwrap the data so it's no longer circular.
 104         if (bytes_received <= backlog_size) {
 105                 existing_data.resize(bytes_received);
 106         } else {
 107                 size_t pos = bytes_received % backlog_size;
 108                 existing_data = existing_data.substr(pos, string::npos) +
 109                         existing_data.substr(0, pos);
 110         }
 111
 112         // See if we need to discard data.
 113         if (new_size < existing_data.size()) {
 114                 size_t to_discard = existing_data.size() - new_size;
 115                 existing_data = existing_data.substr(to_discard, string::npos);
 116         }
 117
 118         // Create a new, empty data file.
 119         data_fd = make_tempfile("");
 120         if (data_fd == -1) {
 121                 exit(1);
 122         }
 123         backlog_size = new_size;
 124
 125         // Now cheat a bit by rewinding, and adding all the old data back.
 126         bytes_received -= existing_data.size();
 127         DataElement data_element;
 128         data_element.data.iov_base = const_cast<char *>(existing_data.data());
 129         data_element.data.iov_len = existing_data.size();
 130         data_element.suitable_for_stream_start = NOT_SUITABLE_FOR_STREAM_START;  // Ignored by add_data_raw().
 131
 132         vector<DataElement> data_elements;
 133         data_elements.push_back(data_element);
 134         add_data_raw(data_elements);
 135         remove_obsolete_starting_points();
 136 }
 137
 138 void Stream::put_client_to_sleep(Client *client)
 139 {
 140         sleeping_clients.push_back(client);
 141 }
 142
 143 // Return a new set of iovecs that contains only the first <bytes_wanted> bytes of <data>.
 144 vector<iovec> collect_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 145 {
 146         vector<iovec> ret;
 147         size_t max_iovecs = min<size_t>(data.size(), IOV_MAX);
 148         for (size_t i = 0; i < max_iovecs && bytes_wanted > 0; ++i) {
 149                 if (data[i].data.iov_len <= bytes_wanted) {
 150                         // Consume the entire iovec.
 151                         ret.push_back(data[i].data);
 152                         bytes_wanted -= data[i].data.iov_len;
 153                 } else {
 154                         // Take only parts of this iovec.
 155                         iovec iov;
 156                         iov.iov_base = data[i].data.iov_base;
 157                         iov.iov_len = bytes_wanted;
 158                         ret.push_back(iov);
 159                         bytes_wanted = 0;
 160                 }
 161         }
 162         return ret;
 163 }
 164
 165 // Return a new set of iovecs that contains all of <data> except the first <bytes_wanted> bytes.
 166 vector<Stream::DataElement> remove_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 167 {
 168         vector<Stream::DataElement> ret;
 169         size_t i;
 170         for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
 171                 if (data[i].data.iov_len <= bytes_wanted) {
 172                         // Consume the entire iovec.
 173                         bytes_wanted -= data[i].data.iov_len;
 174                 } else {
 175                         // Take only parts of this iovec.
 176                         Stream::DataElement data_element;
 177                         data_element.data.iov_base = reinterpret_cast<char *>(data[i].data.iov_base) + bytes_wanted;
 178                         data_element.data.iov_len = data[i].data.iov_len - bytes_wanted;
 179                         data_element.suitable_for_stream_start = NOT_SUITABLE_FOR_STREAM_START;
 180                         ret.push_back(data_element);
 181                         bytes_wanted = 0;
 182                 }
 183         }
 184
 185         // Add the rest of the iovecs unchanged.
 186         ret.insert(ret.end(), data.begin() + i, data.end());
 187         return ret;
 188 }
 189
 190 void Stream::add_data_raw(const vector<DataElement> &orig_data)
 191 {
 192         vector<DataElement> data = orig_data;
 193         while (!data.empty()) {
 194                 size_t pos = bytes_received % backlog_size;
 195
 196                 // Collect as many iovecs as we can before we hit the point
 197                 // where the circular buffer wraps around.
 198                 vector<iovec> to_write = collect_iovecs(data, backlog_size - pos);
 199                 ssize_t ret;
 200                 do {
 201                         ret = pwritev(data_fd, to_write.data(), to_write.size(), pos);
 202                 } while (ret == -1 && errno == EINTR);
 203
 204                 if (ret == -1) {
 205                         log_perror("pwritev");
 206                         // Dazed and confused, but trying to continue...
 207                         return;
 208                 }
 209                 bytes_received += ret;
 210
 211                 // Remove the data that was actually written from the set of iovecs.
 212                 data = remove_iovecs(data, ret);
 213         }
 214 }
 215
 216 void Stream::remove_obsolete_starting_points()
 217 {
 218         // We could do a binary search here (std::lower_bound), but it seems
 219         // overkill for removing what's probably only a few points.
 220         while (!suitable_starting_points.empty() &&
 221                bytes_received - suitable_starting_points[0] > backlog_size) {
 222                 suitable_starting_points.pop_front();
 223         }
 224 }
 225
 226 void Stream::add_data_deferred(const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start)
 227 {
 228         MutexLock lock(&queued_data_mutex);
 229         assert(suitable_for_stream_start == SUITABLE_FOR_STREAM_START ||
 230                suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START);
 231
 232         DataElement data_element;
 233         data_element.suitable_for_stream_start = suitable_for_stream_start;
 234
 235         if (encoding == Stream::STREAM_ENCODING_METACUBE) {
 236                 // Add a Metacube block header before the data.
 237                 metacube2_block_header hdr;
 238                 memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
 239                 hdr.size = htonl(bytes);
 240                 hdr.flags = htons(0);
 241                 if (suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START) {
 242                         hdr.flags |= htons(METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START);
 243                 }
 244                 hdr.csum = htons(metacube2_compute_crc(&hdr));
 245
 246                 data_element.data.iov_base = new char[bytes + sizeof(hdr)];
 247                 data_element.data.iov_len = bytes + sizeof(hdr);
 248
 249                 memcpy(data_element.data.iov_base, &hdr, sizeof(hdr));
 250                 memcpy(reinterpret_cast<char *>(data_element.data.iov_base) + sizeof(hdr), data, bytes);
 251
 252                 queued_data.push_back(data_element);
 253         } else if (encoding == Stream::STREAM_ENCODING_RAW) {
 254                 // Just add the data itself.
 255                 data_element.data.iov_base = new char[bytes];
 256                 memcpy(data_element.data.iov_base, data, bytes);
 257                 data_element.data.iov_len = bytes;
 258
 259                 queued_data.push_back(data_element);
 260         } else {
 261                 assert(false);
 262         }
 263 }
 264
 265 void Stream::process_queued_data()
 266 {
 267         vector<DataElement> queued_data_copy;
 268
 269         // Hold the lock for as short as possible, since add_data_raw() can possibly
 270         // write to disk, which might disturb the input thread.
 271         {
 272                 MutexLock lock(&queued_data_mutex);
 273                 if (queued_data.empty()) {
 274                         return;
 275                 }
 276
 277                 swap(queued_data, queued_data_copy);
 278         }
 279
 280         // Add suitable starting points for the stream, if the queued data
 281         // contains such starting points. Note that we drop starting points
 282         // if they're less than 10 kB apart, so that we don't get a huge
 283         // amount of them for e.g. each and every MPEG-TS 188-byte cell.
 284         // The 10 kB value is somewhat arbitrary, but at least it should make
 285         // the RAM cost of saving the position ~0.1% (or less) of the actual
 286         // data, and 10 kB is a very fine granularity in most streams.
 287         static const int minimum_start_point_distance = 10240;
 288         size_t byte_position = bytes_received;
 289         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 290                 if (queued_data_copy[i].suitable_for_stream_start == SUITABLE_FOR_STREAM_START) {
 291                         size_t num_points = suitable_starting_points.size();
 292                         if (num_points >= 2 &&
 293                             suitable_starting_points[num_points - 1] - suitable_starting_points[num_points - 2] < minimum_start_point_distance) {
 294                                 // p[n-1] - p[n-2] < 10 kB, so drop p[n-1].
 295                                 suitable_starting_points.pop_back();
 296                         }
 297                         suitable_starting_points.push_back(byte_position);
 298                 }
 299                 byte_position += queued_data_copy[i].data.iov_len;
 300         }
 301
 302         add_data_raw(queued_data_copy);
 303         remove_obsolete_starting_points();
 304         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 305                 char *data = reinterpret_cast<char *>(queued_data_copy[i].data.iov_base);
 306                 delete[] data;
 307         }
 308
 309         // We have more data, so wake up all clients.
 310         if (to_process.empty()) {
 311                 swap(sleeping_clients, to_process);
 312         } else {
 313                 to_process.insert(to_process.end(), sleeping_clients.begin(), sleeping_clients.end());
 314                 sleeping_clients.clear();
 315         }
 316 }