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           queued_data_last_starting_point(-1)
  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           queued_data_last_starting_point(-1)
  58 {
  59         if (data_fd == -1) {
  60                 exit(1);
  61         }
  62
  63         assert(serialized.has_last_suitable_starting_point());
  64         last_suitable_starting_point = serialized.last_suitable_starting_point();
  65
  66         pthread_mutex_init(&queued_data_mutex, NULL);
  67 }
  68
  69 StreamProto Stream::serialize()
  70 {
  71         StreamProto serialized;
  72         serialized.set_http_header(http_header);
  73         serialized.set_stream_header(stream_header);
  74         serialized.add_data_fds(data_fd);
  75         serialized.set_backlog_size(backlog_size);
  76         serialized.set_prebuffering_bytes(prebuffering_bytes);
  77         serialized.set_bytes_received(bytes_received);
  78         serialized.set_last_suitable_starting_point(last_suitable_starting_point);
  79         serialized.set_url(url);
  80         data_fd = -1;
  81         return serialized;
  82 }
  83
  84 void Stream::set_backlog_size(size_t new_size)
  85 {
  86         if (backlog_size == new_size) {
  87                 return;
  88         }
  89
  90         string existing_data;
  91         if (!read_tempfile_and_close(data_fd, &existing_data)) {
  92                 exit(1);
  93         }
  94
  95         // Unwrap the data so it's no longer circular.
  96         if (bytes_received <= backlog_size) {
  97                 existing_data.resize(bytes_received);
  98         } else {
  99                 size_t pos = bytes_received % backlog_size;
 100                 existing_data = existing_data.substr(pos, string::npos) +
 101                         existing_data.substr(0, pos);
 102         }
 103
 104         // See if we need to discard data.
 105         if (new_size < existing_data.size()) {
 106                 size_t to_discard = existing_data.size() - new_size;
 107                 existing_data = existing_data.substr(to_discard, string::npos);
 108         }
 109
 110         // Create a new, empty data file.
 111         data_fd = make_tempfile("");
 112         if (data_fd == -1) {
 113                 exit(1);
 114         }
 115         backlog_size = new_size;
 116
 117         // Now cheat a bit by rewinding, and adding all the old data back.
 118         bytes_received -= existing_data.size();
 119         iovec iov;
 120         iov.iov_base = const_cast<char *>(existing_data.data());
 121         iov.iov_len = existing_data.size();
 122
 123         vector<iovec> iovs;
 124         iovs.push_back(iov);
 125         add_data_raw(iovs);
 126 }
 127
 128 void Stream::put_client_to_sleep(Client *client)
 129 {
 130         sleeping_clients.push_back(client);
 131 }
 132
 133 // Return a new set of iovecs that contains only the first <bytes_wanted> bytes of <data>.
 134 vector<iovec> collect_iovecs(const vector<iovec> &data, size_t bytes_wanted)
 135 {
 136         vector<iovec> ret;
 137         size_t max_iovecs = std::min<size_t>(data.size(), IOV_MAX);
 138         for (size_t i = 0; i < max_iovecs && bytes_wanted > 0; ++i) {
 139                 if (data[i].iov_len <= bytes_wanted) {
 140                         // Consume the entire iovec.
 141                         ret.push_back(data[i]);
 142                         bytes_wanted -= data[i].iov_len;
 143                 } else {
 144                         // Take only parts of this iovec.
 145                         iovec iov;
 146                         iov.iov_base = data[i].iov_base;
 147                         iov.iov_len = bytes_wanted;
 148                         ret.push_back(iov);
 149                         bytes_wanted = 0;
 150                 }
 151         }
 152         return ret;
 153 }
 154
 155 // Return a new set of iovecs that contains all of <data> except the first <bytes_wanted> bytes.
 156 vector<iovec> remove_iovecs(const vector<iovec> &data, size_t bytes_wanted)
 157 {
 158         vector<iovec> ret;
 159         size_t i;
 160         for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
 161                 if (data[i].iov_len <= bytes_wanted) {
 162                         // Consume the entire iovec.
 163                         bytes_wanted -= data[i].iov_len;
 164                 } else {
 165                         // Take only parts of this iovec.
 166                         iovec iov;
 167                         iov.iov_base = reinterpret_cast<char *>(data[i].iov_base) + bytes_wanted;
 168                         iov.iov_len = data[i].iov_len - bytes_wanted;
 169                         ret.push_back(iov);
 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<iovec> &orig_data)
 180 {
 181         vector<iovec> 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         if (suitable_for_stream_start == SUITABLE_FOR_STREAM_START) {
 211                 queued_data_last_starting_point = queued_data.size();
 212         }
 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                 iovec iov;
 226                 iov.iov_base = new char[bytes + sizeof(hdr)];
 227                 iov.iov_len = bytes + sizeof(hdr);
 228
 229                 memcpy(iov.iov_base, &hdr, sizeof(hdr));
 230                 memcpy(reinterpret_cast<char *>(iov.iov_base) + sizeof(hdr), data, bytes);
 231
 232                 queued_data.push_back(iov);
 233         } else if (encoding == Stream::STREAM_ENCODING_RAW) {
 234                 // Just add the data itself.
 235                 iovec iov;
 236                 iov.iov_base = new char[bytes];
 237                 memcpy(iov.iov_base, data, bytes);
 238                 iov.iov_len = bytes;
 239
 240                 queued_data.push_back(iov);
 241         } else {
 242                 assert(false);
 243         }
 244 }
 245
 246 void Stream::process_queued_data()
 247 {
 248         std::vector<iovec> queued_data_copy;
 249         int queued_data_last_starting_point_copy = -1;
 250
 251         // Hold the lock for as short as possible, since add_data_raw() can possibly
 252         // write to disk, which might disturb the input thread.
 253         {
 254                 MutexLock lock(&queued_data_mutex);
 255                 if (queued_data.empty()) {
 256                         return;
 257                 }
 258
 259                 swap(queued_data, queued_data_copy);
 260                 swap(queued_data_last_starting_point, queued_data_last_starting_point_copy);
 261         }
 262
 263         // Update the last suitable starting point for the stream,
 264         // if the queued data contains such a starting point.
 265         assert(queued_data_last_starting_point_copy < ssize_t(queued_data_copy.size()));
 266         if (queued_data_last_starting_point_copy >= 0) {
 267                 last_suitable_starting_point = bytes_received;
 268                 for (int i = 0; i < queued_data_last_starting_point_copy; ++i) {
 269                         last_suitable_starting_point += queued_data_copy[i].iov_len;
 270                 }
 271         }
 272
 273         add_data_raw(queued_data_copy);
 274         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 275                 char *data = reinterpret_cast<char *>(queued_data_copy[i].iov_base);
 276                 delete[] data;
 277         }
 278
 279         // We have more data, so wake up all clients.
 280         if (to_process.empty()) {
 281                 swap(sleeping_clients, to_process);
 282         } else {
 283                 to_process.insert(to_process.end(), sleeping_clients.begin(), sleeping_clients.end());
 284                 sleeping_clients.clear();
 285         }
 286 }