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 <vector>
  12
  13 #include "log.h"
  14 #include "metacube2.h"
  15 #include "mutexlock.h"
  16 #include "state.pb.h"
  17 #include "stream.h"
  18 #include "util.h"
  19
  20 using namespace std;
  21
  22 Stream::Stream(const string &url, size_t backlog_size, size_t prebuffering_bytes, Encoding encoding)
  23         : url(url),
  24           encoding(encoding),
  25           data_fd(make_tempfile("")),
  26           backlog_size(backlog_size),
  27           prebuffering_bytes(prebuffering_bytes),
  28           bytes_received(0),
  29           last_suitable_starting_point(-1),
  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         assert(serialized.has_last_suitable_starting_point());
  62         last_suitable_starting_point = serialized.last_suitable_starting_point();
  63
  64         pthread_mutex_init(&queued_data_mutex, NULL);
  65 }
  66
  67 StreamProto Stream::serialize()
  68 {
  69         StreamProto serialized;
  70         serialized.set_http_header(http_header);
  71         serialized.set_stream_header(stream_header);
  72         serialized.add_data_fds(data_fd);
  73         serialized.set_backlog_size(backlog_size);
  74         serialized.set_prebuffering_bytes(prebuffering_bytes);
  75         serialized.set_bytes_received(bytes_received);
  76         serialized.set_last_suitable_starting_point(last_suitable_starting_point);
  77         serialized.set_url(url);
  78         data_fd = -1;
  79         return serialized;
  80 }
  81
  82 void Stream::set_backlog_size(size_t new_size)
  83 {
  84         if (backlog_size == new_size) {
  85                 return;
  86         }
  87
  88         string existing_data;
  89         if (!read_tempfile_and_close(data_fd, &existing_data)) {
  90                 exit(1);
  91         }
  92
  93         // Unwrap the data so it's no longer circular.
  94         if (bytes_received <= backlog_size) {
  95                 existing_data.resize(bytes_received);
  96         } else {
  97                 size_t pos = bytes_received % backlog_size;
  98                 existing_data = existing_data.substr(pos, string::npos) +
  99                         existing_data.substr(0, pos);
 100         }
 101
 102         // See if we need to discard data.
 103         if (new_size < existing_data.size()) {
 104                 size_t to_discard = existing_data.size() - new_size;
 105                 existing_data = existing_data.substr(to_discard, string::npos);
 106         }
 107
 108         // Create a new, empty data file.
 109         data_fd = make_tempfile("");
 110         if (data_fd == -1) {
 111                 exit(1);
 112         }
 113         backlog_size = new_size;
 114
 115         // Now cheat a bit by rewinding, and adding all the old data back.
 116         bytes_received -= existing_data.size();
 117
 118         size_t bytes_before_suitable_starting_point;
 119         if (last_suitable_starting_point == -1) {
 120                 bytes_before_suitable_starting_point = existing_data.size();
 121         } else if (size_t(last_suitable_starting_point) < backlog_size) {
 122                 bytes_before_suitable_starting_point = 0;
 123         } else {
 124                 bytes_before_suitable_starting_point = last_suitable_starting_point - backlog_size;
 125         }
 126
 127         vector<DataElement> data_elements;
 128         if (bytes_before_suitable_starting_point > 0) {
 129                 // There's really no usable data here (except for ?backlog=1 users),
 130                 // but we need to get the accounting right anyway.
 131                 DataElement data_element;
 132                 data_element.data.iov_base = const_cast<char *>(existing_data.data());
 133                 data_element.data.iov_len = bytes_before_suitable_starting_point;
 134                 data_element.suitable_for_stream_start = NOT_SUITABLE_FOR_STREAM_START;
 135                 data_elements.push_back(data_element);
 136         }
 137         if (bytes_before_suitable_starting_point < existing_data.size()) {
 138                 DataElement data_element;
 139                 data_element.data.iov_base = const_cast<char *>(existing_data.data() + bytes_before_suitable_starting_point);
 140                 data_element.data.iov_len = existing_data.size() - bytes_before_suitable_starting_point;
 141                 data_element.suitable_for_stream_start = SUITABLE_FOR_STREAM_START;
 142                 data_elements.push_back(data_element);
 143         }
 144
 145         last_suitable_starting_point = -1;
 146         add_data_raw(data_elements);
 147 }
 148
 149 void Stream::put_client_to_sleep(Client *client)
 150 {
 151         sleeping_clients.push_back(client);
 152 }
 153
 154 // Return a new set of iovecs that contains only the first <bytes_wanted> bytes of <data>.
 155 vector<iovec> collect_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 156 {
 157         vector<iovec> ret;
 158         size_t max_iovecs = std::min<size_t>(data.size(), IOV_MAX);
 159         for (size_t i = 0; i < max_iovecs && bytes_wanted > 0; ++i) {
 160                 if (data[i].data.iov_len <= bytes_wanted) {
 161                         // Consume the entire iovec.
 162                         ret.push_back(data[i].data);
 163                         bytes_wanted -= data[i].data.iov_len;
 164                 } else {
 165                         // Take only parts of this iovec.
 166                         iovec iov;
 167                         iov.iov_base = data[i].data.iov_base;
 168                         iov.iov_len = bytes_wanted;
 169                         ret.push_back(iov);
 170                         bytes_wanted = 0;
 171                 }
 172         }
 173         return ret;
 174 }
 175
 176 // Return a new set of iovecs that contains all of <data> except the first <bytes_wanted> bytes.
 177 vector<Stream::DataElement> remove_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 178 {
 179         vector<Stream::DataElement> ret;
 180         size_t i;
 181         for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
 182                 if (data[i].data.iov_len <= bytes_wanted) {
 183                         // Consume the entire iovec.
 184                         bytes_wanted -= data[i].data.iov_len;
 185                 } else {
 186                         // Take only parts of this iovec.
 187                         Stream::DataElement data_element;
 188                         data_element.data.iov_base = reinterpret_cast<char *>(data[i].data.iov_base) + bytes_wanted;
 189                         data_element.data.iov_len = data[i].data.iov_len - bytes_wanted;
 190                         data_element.suitable_for_stream_start = NOT_SUITABLE_FOR_STREAM_START;
 191                         ret.push_back(data_element);
 192                         bytes_wanted = 0;
 193                 }
 194         }
 195
 196         // Add the rest of the iovecs unchanged.
 197         ret.insert(ret.end(), data.begin() + i, data.end());
 198         return ret;
 199 }
 200
 201 void Stream::add_data_raw(const vector<DataElement> &orig_data)
 202 {
 203         vector<DataElement> data = orig_data;
 204         while (!data.empty()) {
 205                 size_t pos = bytes_received % backlog_size;
 206
 207                 // Collect as many iovecs as we can before we hit the point
 208                 // where the circular buffer wraps around.
 209                 vector<iovec> to_write = collect_iovecs(data, backlog_size - pos);
 210                 ssize_t ret;
 211                 do {
 212                         ret = pwritev(data_fd, to_write.data(), to_write.size(), pos);
 213                 } while (ret == -1 && errno == EINTR);
 214
 215                 if (ret == -1) {
 216                         log_perror("pwritev");
 217                         // Dazed and confused, but trying to continue...
 218                         return;
 219                 }
 220                 bytes_received += ret;
 221
 222                 // Remove the data that was actually written from the set of iovecs.
 223                 data = remove_iovecs(data, ret);
 224         }
 225 }
 226
 227 void Stream::add_data_deferred(const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start)
 228 {
 229         MutexLock lock(&queued_data_mutex);
 230         assert(suitable_for_stream_start == SUITABLE_FOR_STREAM_START ||
 231                suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START);
 232
 233         DataElement data_element;
 234         data_element.suitable_for_stream_start = suitable_for_stream_start;
 235
 236         if (encoding == Stream::STREAM_ENCODING_METACUBE) {
 237                 // Add a Metacube block header before the data.
 238                 metacube2_block_header hdr;
 239                 memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
 240                 hdr.size = htonl(bytes);
 241                 hdr.flags = htons(0);
 242                 if (suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START) {
 243                         hdr.flags |= htons(METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START);
 244                 }
 245                 hdr.csum = htons(metacube2_compute_crc(&hdr));
 246
 247                 data_element.data.iov_base = new char[bytes + sizeof(hdr)];
 248                 data_element.data.iov_len = bytes + sizeof(hdr);
 249
 250                 memcpy(data_element.data.iov_base, &hdr, sizeof(hdr));
 251                 memcpy(reinterpret_cast<char *>(data_element.data.iov_base) + sizeof(hdr), data, bytes);
 252
 253                 queued_data.push_back(data_element);
 254         } else if (encoding == Stream::STREAM_ENCODING_RAW) {
 255                 // Just add the data itself.
 256                 data_element.data.iov_base = new char[bytes];
 257                 memcpy(data_element.data.iov_base, data, bytes);
 258                 data_element.data.iov_len = bytes;
 259
 260                 queued_data.push_back(data_element);
 261         } else {
 262                 assert(false);
 263         }
 264 }
 265
 266 void Stream::process_queued_data()
 267 {
 268         std::vector<DataElement> queued_data_copy;
 269
 270         // Hold the lock for as short as possible, since add_data_raw() can possibly
 271         // write to disk, which might disturb the input thread.
 272         {
 273                 MutexLock lock(&queued_data_mutex);
 274                 if (queued_data.empty()) {
 275                         return;
 276                 }
 277
 278                 swap(queued_data, queued_data_copy);
 279         }
 280
 281         // Update the last suitable starting point for the stream,
 282         // if the queued data contains such a starting point.
 283         size_t byte_position = bytes_received;
 284         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 285                 if (queued_data_copy[i].suitable_for_stream_start == SUITABLE_FOR_STREAM_START) {
 286                         last_suitable_starting_point = byte_position;
 287                 }
 288                 byte_position += queued_data_copy[i].data.iov_len;
 289         }
 290
 291         add_data_raw(queued_data_copy);
 292         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 293                 char *data = reinterpret_cast<char *>(queued_data_copy[i].data.iov_base);
 294                 delete[] data;
 295         }
 296
 297         // We have more data, so wake up all clients.
 298         if (to_process.empty()) {
 299                 swap(sleeping_clients, to_process);
 300         } else {
 301                 to_process.insert(to_process.end(), sleeping_clients.begin(), sleeping_clients.end());
 302                 sleeping_clients.clear();
 303         }
 304 }