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

   1 #include <assert.h>
   2 #include <errno.h>
   3 #include <netinet/in.h>
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <string.h>
   7 #include <sys/types.h>
   8 #include <algorithm>
   9 #include <string>
  10 #include <vector>
  11
  12 #include "log.h"
  13 #include "metacube2.h"
  14 #include "mutexlock.h"
  15 #include "state.pb.h"
  16 #include "stream.h"
  17 #include "util.h"
  18
  19 using namespace std;
  20
  21 Stream::Stream(const string &url, size_t backlog_size, Encoding encoding)
  22         : url(url),
  23           encoding(encoding),
  24           data_fd(make_tempfile("")),
  25           backlog_size(backlog_size),
  26           bytes_received(0),
  27           last_suitable_starting_point(-1),
  28           mark_pool(NULL),
  29           pacing_rate(~0U),
  30           queued_data_last_starting_point(-1)
  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           bytes_received(serialized.bytes_received()),
  54           mark_pool(NULL),
  55           pacing_rate(~0U),
  56           queued_data_last_starting_point(-1)
  57 {
  58         if (data_fd == -1) {
  59                 exit(1);
  60         }
  61
  62         assert(serialized.has_last_suitable_starting_point());
  63         last_suitable_starting_point = serialized.last_suitable_starting_point();
  64
  65         pthread_mutex_init(&queued_data_mutex, NULL);
  66 }
  67
  68 StreamProto Stream::serialize()
  69 {
  70         StreamProto serialized;
  71         serialized.set_http_header(http_header);
  72         serialized.set_stream_header(stream_header);
  73         serialized.add_data_fds(data_fd);
  74         serialized.set_backlog_size(backlog_size);
  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         iovec iov;
 118         iov.iov_base = const_cast<char *>(existing_data.data());
 119         iov.iov_len = existing_data.size();
 120
 121         vector<iovec> iovs;
 122         iovs.push_back(iov);
 123         add_data_raw(iovs);
 124 }
 125
 126 void Stream::put_client_to_sleep(Client *client)
 127 {
 128         sleeping_clients.push_back(client);
 129 }
 130
 131 // Return a new set of iovecs that contains only the first <bytes_wanted> bytes of <data>.
 132 vector<iovec> collect_iovecs(const vector<iovec> &data, size_t bytes_wanted)
 133 {
 134         vector<iovec> ret;
 135         size_t max_iovecs = std::min<size_t>(data.size(), IOV_MAX);
 136         for (size_t i = 0; i < max_iovecs && bytes_wanted > 0; ++i) {
 137                 if (data[i].iov_len <= bytes_wanted) {
 138                         // Consume the entire iovec.
 139                         ret.push_back(data[i]);
 140                         bytes_wanted -= data[i].iov_len;
 141                 } else {
 142                         // Take only parts of this iovec.
 143                         iovec iov;
 144                         iov.iov_base = data[i].iov_base;
 145                         iov.iov_len = bytes_wanted;
 146                         ret.push_back(iov);
 147                         bytes_wanted = 0;
 148                 }
 149         }
 150         return ret;
 151 }
 152
 153 // Return a new set of iovecs that contains all of <data> except the first <bytes_wanted> bytes.
 154 vector<iovec> remove_iovecs(const vector<iovec> &data, size_t bytes_wanted)
 155 {
 156         vector<iovec> ret;
 157         size_t i;
 158         for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
 159                 if (data[i].iov_len <= bytes_wanted) {
 160                         // Consume the entire iovec.
 161                         bytes_wanted -= data[i].iov_len;
 162                 } else {
 163                         // Take only parts of this iovec.
 164                         iovec iov;
 165                         iov.iov_base = reinterpret_cast<char *>(data[i].iov_base) + bytes_wanted;
 166                         iov.iov_len = data[i].iov_len - bytes_wanted;
 167                         ret.push_back(iov);
 168                         bytes_wanted = 0;
 169                 }
 170         }
 171
 172         // Add the rest of the iovecs unchanged.
 173         ret.insert(ret.end(), data.begin() + i, data.end());
 174         return ret;
 175 }
 176
 177 void Stream::add_data_raw(const vector<iovec> &orig_data)
 178 {
 179         vector<iovec> data = orig_data;
 180         while (!data.empty()) {
 181                 size_t pos = bytes_received % backlog_size;
 182
 183                 // Collect as many iovecs as we can before we hit the point
 184                 // where the circular buffer wraps around.
 185                 vector<iovec> to_write = collect_iovecs(data, backlog_size - pos);
 186                 ssize_t ret;
 187                 do {
 188                         ret = pwritev(data_fd, to_write.data(), to_write.size(), pos);
 189                 } while (ret == -1 && errno == EINTR);
 190
 191                 if (ret == -1) {
 192                         log_perror("pwritev");
 193                         // Dazed and confused, but trying to continue...
 194                         return;
 195                 }
 196                 bytes_received += ret;
 197
 198                 // Remove the data that was actually written from the set of iovecs.
 199                 data = remove_iovecs(data, ret);
 200         }
 201 }
 202
 203 void Stream::add_data_deferred(const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start)
 204 {
 205         MutexLock lock(&queued_data_mutex);
 206         assert(suitable_for_stream_start == SUITABLE_FOR_STREAM_START ||
 207                suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START);
 208         if (suitable_for_stream_start == SUITABLE_FOR_STREAM_START) {
 209                 queued_data_last_starting_point = queued_data.size();
 210         }
 211
 212         if (encoding == Stream::STREAM_ENCODING_METACUBE) {
 213                 // Add a Metacube block header before the data.
 214                 metacube2_block_header hdr;
 215                 memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
 216                 hdr.size = htonl(bytes);
 217                 hdr.flags = htons(0);
 218                 if (suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START) {
 219                         hdr.flags |= htons(METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START);
 220                 }
 221                 hdr.csum = htons(metacube2_compute_crc(&hdr));
 222
 223                 iovec iov;
 224                 iov.iov_base = new char[bytes + sizeof(hdr)];
 225                 iov.iov_len = bytes + sizeof(hdr);
 226
 227                 memcpy(iov.iov_base, &hdr, sizeof(hdr));
 228                 memcpy(reinterpret_cast<char *>(iov.iov_base) + sizeof(hdr), data, bytes);
 229
 230                 queued_data.push_back(iov);
 231         } else if (encoding == Stream::STREAM_ENCODING_RAW) {
 232                 // Just add the data itself.
 233                 iovec iov;
 234                 iov.iov_base = new char[bytes];
 235                 memcpy(iov.iov_base, data, bytes);
 236                 iov.iov_len = bytes;
 237
 238                 queued_data.push_back(iov);
 239         } else {
 240                 assert(false);
 241         }
 242 }
 243
 244 void Stream::process_queued_data()
 245 {
 246         std::vector<iovec> queued_data_copy;
 247         int queued_data_last_starting_point_copy = -1;
 248
 249         // Hold the lock for as short as possible, since add_data_raw() can possibly
 250         // write to disk, which might disturb the input thread.
 251         {
 252                 MutexLock lock(&queued_data_mutex);
 253                 if (queued_data.empty()) {
 254                         return;
 255                 }
 256
 257                 swap(queued_data, queued_data_copy);
 258                 swap(queued_data_last_starting_point, queued_data_last_starting_point_copy);
 259         }
 260
 261         // Update the last suitable starting point for the stream,
 262         // if the queued data contains such a starting point.
 263         assert(queued_data_last_starting_point_copy < ssize_t(queued_data_copy.size()));
 264         if (queued_data_last_starting_point_copy >= 0) {
 265                 last_suitable_starting_point = bytes_received;
 266                 for (int i = 0; i < queued_data_last_starting_point_copy; ++i) {
 267                         last_suitable_starting_point += queued_data_copy[i].iov_len;
 268                 }
 269         }
 270
 271         add_data_raw(queued_data_copy);
 272         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 273                 char *data = reinterpret_cast<char *>(queued_data_copy[i].iov_base);
 274                 delete[] data;
 275         }
 276
 277         // We have more data, so wake up all clients.
 278         if (to_process.empty()) {
 279                 swap(sleeping_clients, to_process);
 280         } else {
 281                 to_process.insert(to_process.end(), sleeping_clients.begin(), sleeping_clients.end());
 282                 sleeping_clients.clear();
 283         }
 284 }