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         DataElement data_element;
 118         data_element.data.iov_base = const_cast<char *>(existing_data.data());
 119         data_element.data.iov_len = existing_data.size();
 120         data_element.suitable_for_stream_start = NOT_SUITABLE_FOR_STREAM_START;  // Ignored by add_data_raw().
 121
 122         vector<DataElement> data_elements;
 123         data_elements.push_back(data_element);
 124         add_data_raw(data_elements);
 125 }
 126
 127 void Stream::put_client_to_sleep(Client *client)
 128 {
 129         sleeping_clients.push_back(client);
 130 }
 131
 132 // Return a new set of iovecs that contains only the first <bytes_wanted> bytes of <data>.
 133 vector<iovec> collect_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 134 {
 135         vector<iovec> ret;
 136         size_t max_iovecs = std::min<size_t>(data.size(), IOV_MAX);
 137         for (size_t i = 0; i < max_iovecs && bytes_wanted > 0; ++i) {
 138                 if (data[i].data.iov_len <= bytes_wanted) {
 139                         // Consume the entire iovec.
 140                         ret.push_back(data[i].data);
 141                         bytes_wanted -= data[i].data.iov_len;
 142                 } else {
 143                         // Take only parts of this iovec.
 144                         iovec iov;
 145                         iov.iov_base = data[i].data.iov_base;
 146                         iov.iov_len = bytes_wanted;
 147                         ret.push_back(iov);
 148                         bytes_wanted = 0;
 149                 }
 150         }
 151         return ret;
 152 }
 153
 154 // Return a new set of iovecs that contains all of <data> except the first <bytes_wanted> bytes.
 155 vector<Stream::DataElement> remove_iovecs(const vector<Stream::DataElement> &data, size_t bytes_wanted)
 156 {
 157         vector<Stream::DataElement> ret;
 158         size_t i;
 159         for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
 160                 if (data[i].data.iov_len <= bytes_wanted) {
 161                         // Consume the entire iovec.
 162                         bytes_wanted -= data[i].data.iov_len;
 163                 } else {
 164                         // Take only parts of this iovec.
 165                         Stream::DataElement data_element;
 166                         data_element.data.iov_base = reinterpret_cast<char *>(data[i].data.iov_base) + bytes_wanted;
 167                         data_element.data.iov_len = data[i].data.iov_len - bytes_wanted;
 168                         data_element.suitable_for_stream_start = NOT_SUITABLE_FOR_STREAM_START;
 169                         ret.push_back(data_element);
 170                         bytes_wanted = 0;
 171                 }
 172         }
 173
 174         // Add the rest of the iovecs unchanged.
 175         ret.insert(ret.end(), data.begin() + i, data.end());
 176         return ret;
 177 }
 178
 179 void Stream::add_data_raw(const vector<DataElement> &orig_data)
 180 {
 181         vector<DataElement> data = orig_data;
 182         while (!data.empty()) {
 183                 size_t pos = bytes_received % backlog_size;
 184
 185                 // Collect as many iovecs as we can before we hit the point
 186                 // where the circular buffer wraps around.
 187                 vector<iovec> to_write = collect_iovecs(data, backlog_size - pos);
 188                 ssize_t ret;
 189                 do {
 190                         ret = pwritev(data_fd, to_write.data(), to_write.size(), pos);
 191                 } while (ret == -1 && errno == EINTR);
 192
 193                 if (ret == -1) {
 194                         log_perror("pwritev");
 195                         // Dazed and confused, but trying to continue...
 196                         return;
 197                 }
 198                 bytes_received += ret;
 199
 200                 // Remove the data that was actually written from the set of iovecs.
 201                 data = remove_iovecs(data, ret);
 202         }
 203 }
 204
 205 void Stream::add_data_deferred(const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start)
 206 {
 207         MutexLock lock(&queued_data_mutex);
 208         assert(suitable_for_stream_start == SUITABLE_FOR_STREAM_START ||
 209                suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START);
 210
 211         DataElement data_element;
 212         data_element.suitable_for_stream_start = suitable_for_stream_start;
 213
 214         if (encoding == Stream::STREAM_ENCODING_METACUBE) {
 215                 // Add a Metacube block header before the data.
 216                 metacube2_block_header hdr;
 217                 memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
 218                 hdr.size = htonl(bytes);
 219                 hdr.flags = htons(0);
 220                 if (suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START) {
 221                         hdr.flags |= htons(METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START);
 222                 }
 223                 hdr.csum = htons(metacube2_compute_crc(&hdr));
 224
 225                 data_element.data.iov_base = new char[bytes + sizeof(hdr)];
 226                 data_element.data.iov_len = bytes + sizeof(hdr);
 227
 228                 memcpy(data_element.data.iov_base, &hdr, sizeof(hdr));
 229                 memcpy(reinterpret_cast<char *>(data_element.data.iov_base) + sizeof(hdr), data, bytes);
 230
 231                 queued_data.push_back(data_element);
 232         } else if (encoding == Stream::STREAM_ENCODING_RAW) {
 233                 // Just add the data itself.
 234                 data_element.data.iov_base = new char[bytes];
 235                 memcpy(data_element.data.iov_base, data, bytes);
 236                 data_element.data.iov_len = bytes;
 237
 238                 queued_data.push_back(data_element);
 239         } else {
 240                 assert(false);
 241         }
 242 }
 243
 244 void Stream::process_queued_data()
 245 {
 246         std::vector<DataElement> queued_data_copy;
 247
 248         // Hold the lock for as short as possible, since add_data_raw() can possibly
 249         // write to disk, which might disturb the input thread.
 250         {
 251                 MutexLock lock(&queued_data_mutex);
 252                 if (queued_data.empty()) {
 253                         return;
 254                 }
 255
 256                 swap(queued_data, queued_data_copy);
 257         }
 258
 259         // Update the last suitable starting point for the stream,
 260         // if the queued data contains such a starting point.
 261         size_t byte_position = bytes_received;
 262         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 263                 if (queued_data_copy[i].suitable_for_stream_start == SUITABLE_FOR_STREAM_START) {
 264                         last_suitable_starting_point = byte_position;
 265                 }
 266                 byte_position += queued_data_copy[i].data.iov_len;
 267         }
 268
 269         add_data_raw(queued_data_copy);
 270         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 271                 char *data = reinterpret_cast<char *>(queued_data_copy[i].data.iov_base);
 272                 delete[] data;
 273         }
 274
 275         // We have more data, so wake up all clients.
 276         if (to_process.empty()) {
 277                 swap(sleeping_clients, to_process);
 278         } else {
 279                 to_process.insert(to_process.end(), sleeping_clients.begin(), sleeping_clients.end());
 280                 sleeping_clients.clear();
 281         }
 282 }