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, Encoding src_encoding)
  24         : url(url),
  25           encoding(encoding),
  26           src_encoding(src_encoding),
  27           data_fd(make_tempfile("")),
  28           backlog_size(backlog_size),
  29           prebuffering_bytes(prebuffering_bytes),
  30           bytes_received(0),
  31           pacing_rate(~0U)
  32 {
  33         if (data_fd == -1) {
  34                 exit(1);
  35         }
  36
  37         pthread_mutex_init(&queued_data_mutex, NULL);
  38 }
  39
  40 Stream::~Stream()
  41 {
  42         if (data_fd != -1) {
  43                 safe_close(data_fd);
  44         }
  45 }
  46
  47 Stream::Stream(const StreamProto &serialized, int data_fd)
  48         : url(serialized.url()),
  49           http_header(serialized.http_header()),
  50           stream_header(serialized.stream_header()),
  51           encoding(Stream::STREAM_ENCODING_RAW),  // Will be changed later.
  52           data_fd(data_fd),
  53           backlog_size(serialized.backlog_size()),
  54           prebuffering_bytes(serialized.prebuffering_bytes()),
  55           bytes_received(serialized.bytes_received()),
  56           pacing_rate(~0U)
  57 {
  58         if (data_fd == -1) {
  59                 exit(1);
  60         }
  61
  62         for (int i = 0; i < serialized.suitable_starting_point_size(); ++i) {
  63                 ssize_t point = serialized.suitable_starting_point(i);
  64                 if (point == -1) {
  65                         // Can happen when upgrading from before 1.1.3,
  66                         // where this was an optional field with -1 signifying
  67                         // "no such point".
  68                         continue;
  69                 }
  70                 suitable_starting_points.push_back(point);
  71         }
  72
  73         pthread_mutex_init(&queued_data_mutex, NULL);
  74 }
  75
  76 StreamProto Stream::serialize()
  77 {
  78         StreamProto serialized;
  79         serialized.set_http_header(http_header);
  80         serialized.set_stream_header(stream_header);
  81         serialized.add_data_fds(data_fd);
  82         serialized.set_backlog_size(backlog_size);
  83         serialized.set_prebuffering_bytes(prebuffering_bytes);
  84         serialized.set_bytes_received(bytes_received);
  85         for (size_t i = 0; i < suitable_starting_points.size(); ++i) {
  86                 serialized.add_suitable_starting_point(suitable_starting_points[i]);
  87         }
  88         serialized.set_url(url);
  89         data_fd = -1;
  90         return serialized;
  91 }
  92
  93 void Stream::set_backlog_size(size_t new_size)
  94 {
  95         if (backlog_size == new_size) {
  96                 return;
  97         }
  98
  99         string existing_data;
 100         if (!read_tempfile_and_close(data_fd, &existing_data)) {
 101                 exit(1);
 102         }
 103
 104         // Unwrap the data so it's no longer circular.
 105         if (bytes_received <= backlog_size) {
 106                 existing_data.resize(bytes_received);
 107         } else {
 108                 size_t pos = bytes_received % backlog_size;
 109                 existing_data = existing_data.substr(pos, string::npos) +
 110                         existing_data.substr(0, pos);
 111         }
 112
 113         // See if we need to discard data.
 114         if (new_size < existing_data.size()) {
 115                 size_t to_discard = existing_data.size() - new_size;
 116                 existing_data = existing_data.substr(to_discard, string::npos);
 117         }
 118
 119         // Create a new, empty data file.
 120         data_fd = make_tempfile("");
 121         if (data_fd == -1) {
 122                 exit(1);
 123         }
 124         backlog_size = new_size;
 125
 126         // Now cheat a bit by rewinding, and adding all the old data back.
 127         bytes_received -= existing_data.size();
 128         DataElement data_element;
 129         data_element.data.iov_base = const_cast<char *>(existing_data.data());
 130         data_element.data.iov_len = existing_data.size();
 131         data_element.metacube_flags = 0;  // Ignored by add_data_raw().
 132
 133         vector<DataElement> data_elements;
 134         data_elements.push_back(data_element);
 135         add_data_raw(data_elements);
 136         remove_obsolete_starting_points();
 137 }
 138
 139 void Stream::put_client_to_sleep(Client *client)
 140 {
 141         sleeping_clients.push_back(client);
 142 }
 143
 144 // Return a new set of iovecs that contains only the first <bytes_wanted> bytes of <data>.
 145 vector<iovec> collect_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 146 {
 147         vector<iovec> ret;
 148         size_t max_iovecs = min<size_t>(data.size(), IOV_MAX);
 149         for (size_t i = 0; i < max_iovecs && bytes_wanted > 0; ++i) {
 150                 if (data[i].data.iov_len <= bytes_wanted) {
 151                         // Consume the entire iovec.
 152                         ret.push_back(data[i].data);
 153                         bytes_wanted -= data[i].data.iov_len;
 154                 } else {
 155                         // Take only parts of this iovec.
 156                         iovec iov;
 157                         iov.iov_base = data[i].data.iov_base;
 158                         iov.iov_len = bytes_wanted;
 159                         ret.push_back(iov);
 160                         bytes_wanted = 0;
 161                 }
 162         }
 163         return ret;
 164 }
 165
 166 // Return a new set of iovecs that contains all of <data> except the first <bytes_wanted> bytes.
 167 vector<Stream::DataElement> remove_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 168 {
 169         vector<Stream::DataElement> ret;
 170         size_t i;
 171         for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
 172                 if (data[i].data.iov_len <= bytes_wanted) {
 173                         // Consume the entire iovec.
 174                         bytes_wanted -= data[i].data.iov_len;
 175                 } else {
 176                         // Take only parts of this iovec.
 177                         Stream::DataElement data_element;
 178                         data_element.data.iov_base = reinterpret_cast<char *>(data[i].data.iov_base) + bytes_wanted;
 179                         data_element.data.iov_len = data[i].data.iov_len - bytes_wanted;
 180                         data_element.metacube_flags = METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START;
 181                         ret.push_back(data_element);
 182                         bytes_wanted = 0;
 183                 }
 184         }
 185
 186         // Add the rest of the iovecs unchanged.
 187         ret.insert(ret.end(), data.begin() + i, data.end());
 188         return ret;
 189 }
 190
 191 void Stream::add_data_raw(const vector<DataElement> &orig_data)
 192 {
 193         vector<DataElement> data = orig_data;
 194         while (!data.empty()) {
 195                 size_t pos = bytes_received % backlog_size;
 196
 197                 // Collect as many iovecs as we can before we hit the point
 198                 // where the circular buffer wraps around.
 199                 vector<iovec> to_write = collect_iovecs(data, backlog_size - pos);
 200                 ssize_t ret;
 201                 do {
 202                         ret = pwritev(data_fd, to_write.data(), to_write.size(), pos);
 203                 } while (ret == -1 && errno == EINTR);
 204
 205                 if (ret == -1) {
 206                         log_perror("pwritev");
 207                         // Dazed and confused, but trying to continue...
 208                         return;
 209                 }
 210                 bytes_received += ret;
 211
 212                 // Remove the data that was actually written from the set of iovecs.
 213                 data = remove_iovecs(data, ret);
 214         }
 215 }
 216
 217 void Stream::remove_obsolete_starting_points()
 218 {
 219         // We could do a binary search here (std::lower_bound), but it seems
 220         // overkill for removing what's probably only a few points.
 221         while (!suitable_starting_points.empty() &&
 222                bytes_received - suitable_starting_points[0] > backlog_size) {
 223                 suitable_starting_points.pop_front();
 224         }
 225 }
 226
 227 void Stream::add_data_deferred(const char *data, size_t bytes, uint16_t metacube_flags)
 228 {
 229         // For regular output, we don't want to send the client twice
 230         // (it's already sent out together with the HTTP header).
 231         // However, for Metacube output, we need to send it so that
 232         // the Cubemap instance in the other end has a chance to update it.
 233         // It may come twice in its stream, but Cubemap doesn't care.
 234         if (encoding == Stream::STREAM_ENCODING_RAW &&
 235             (metacube_flags & METACUBE_FLAGS_HEADER) != 0) {
 236                 return;
 237         }
 238
 239         MutexLock lock(&queued_data_mutex);
 240
 241         DataElement data_element;
 242         data_element.metacube_flags = metacube_flags;
 243
 244         if (encoding == Stream::STREAM_ENCODING_METACUBE) {
 245                 // Add a Metacube block header before the data.
 246                 metacube2_block_header hdr;
 247                 memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
 248                 hdr.size = htonl(bytes);
 249                 hdr.flags = htons(metacube_flags);
 250                 hdr.csum = htons(metacube2_compute_crc(&hdr));
 251
 252                 data_element.data.iov_base = new char[bytes + sizeof(hdr)];
 253                 data_element.data.iov_len = bytes + sizeof(hdr);
 254
 255                 memcpy(data_element.data.iov_base, &hdr, sizeof(hdr));
 256                 memcpy(reinterpret_cast<char *>(data_element.data.iov_base) + sizeof(hdr), data, bytes);
 257
 258                 queued_data.push_back(data_element);
 259         } else if (encoding == Stream::STREAM_ENCODING_RAW) {
 260                 // Just add the data itself.
 261                 data_element.data.iov_base = new char[bytes];
 262                 memcpy(data_element.data.iov_base, data, bytes);
 263                 data_element.data.iov_len = bytes;
 264
 265                 queued_data.push_back(data_element);
 266         } else {
 267                 assert(false);
 268         }
 269 }
 270
 271 void Stream::process_queued_data()
 272 {
 273         vector<DataElement> queued_data_copy;
 274
 275         // Hold the lock for as short as possible, since add_data_raw() can possibly
 276         // write to disk, which might disturb the input thread.
 277         {
 278                 MutexLock lock(&queued_data_mutex);
 279                 if (queued_data.empty()) {
 280                         return;
 281                 }
 282
 283                 swap(queued_data, queued_data_copy);
 284         }
 285
 286         // Add suitable starting points for the stream, if the queued data
 287         // contains such starting points. Note that we drop starting points
 288         // if they're less than 10 kB apart, so that we don't get a huge
 289         // amount of them for e.g. each and every MPEG-TS 188-byte cell.
 290         // The 10 kB value is somewhat arbitrary, but at least it should make
 291         // the RAM cost of saving the position ~0.1% (or less) of the actual
 292         // data, and 10 kB is a very fine granularity in most streams.
 293         static const int minimum_start_point_distance = 10240;
 294         size_t byte_position = bytes_received;
 295         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 296                 if ((queued_data_copy[i].metacube_flags & METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START) == 0) {
 297                         size_t num_points = suitable_starting_points.size();
 298                         if (num_points >= 2 &&
 299                             suitable_starting_points[num_points - 1] - suitable_starting_points[num_points - 2] < minimum_start_point_distance) {
 300                                 // p[n-1] - p[n-2] < 10 kB, so drop p[n-1].
 301                                 suitable_starting_points.pop_back();
 302                         }
 303                         suitable_starting_points.push_back(byte_position);
 304                 }
 305                 byte_position += queued_data_copy[i].data.iov_len;
 306         }
 307
 308         add_data_raw(queued_data_copy);
 309         remove_obsolete_starting_points();
 310         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 311                 char *data = reinterpret_cast<char *>(queued_data_copy[i].data.iov_base);
 312                 delete[] data;
 313         }
 314
 315         // We have more data, so wake up all clients.
 316         if (to_process.empty()) {
 317                 swap(sleeping_clients, to_process);
 318         } else {
 319                 to_process.insert(to_process.end(), sleeping_clients.begin(), sleeping_clients.end());
 320                 sleeping_clients.clear();
 321         }
 322 }