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, Encoding encoding)
  23         : url(url),
  24           encoding(encoding),
  25           data_fd(make_tempfile("")),
  26           backlog_size(backlog_size),
  27           bytes_received(0),
  28           last_suitable_starting_point(-1),
  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           pacing_rate(~0U),
  55           queued_data_last_starting_point(-1)
  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_bytes_received(bytes_received);
  75         serialized.set_last_suitable_starting_point(last_suitable_starting_point);
  76         serialized.set_url(url);
  77         data_fd = -1;
  78         return serialized;
  79 }
  80
  81 void Stream::set_backlog_size(size_t new_size)
  82 {
  83         if (backlog_size == new_size) {
  84                 return;
  85         }
  86
  87         string existing_data;
  88         if (!read_tempfile_and_close(data_fd, &existing_data)) {
  89                 exit(1);
  90         }
  91
  92         // Unwrap the data so it's no longer circular.
  93         if (bytes_received <= backlog_size) {
  94                 existing_data.resize(bytes_received);
  95         } else {
  96                 size_t pos = bytes_received % backlog_size;
  97                 existing_data = existing_data.substr(pos, string::npos) +
  98                         existing_data.substr(0, pos);
  99         }
 100
 101         // See if we need to discard data.
 102         if (new_size < existing_data.size()) {
 103                 size_t to_discard = existing_data.size() - new_size;
 104                 existing_data = existing_data.substr(to_discard, string::npos);
 105         }
 106
 107         // Create a new, empty data file.
 108         data_fd = make_tempfile("");
 109         if (data_fd == -1) {
 110                 exit(1);
 111         }
 112         backlog_size = new_size;
 113
 114         // Now cheat a bit by rewinding, and adding all the old data back.
 115         bytes_received -= existing_data.size();
 116         iovec iov;
 117         iov.iov_base = const_cast<char *>(existing_data.data());
 118         iov.iov_len = existing_data.size();
 119
 120         vector<iovec> iovs;
 121         iovs.push_back(iov);
 122         add_data_raw(iovs);
 123 }
 124
 125 void Stream::put_client_to_sleep(Client *client)
 126 {
 127         sleeping_clients.push_back(client);
 128 }
 129
 130 // Return a new set of iovecs that contains only the first <bytes_wanted> bytes of <data>.
 131 vector<iovec> collect_iovecs(const vector<iovec> &data, size_t bytes_wanted)
 132 {
 133         vector<iovec> ret;
 134         size_t max_iovecs = std::min<size_t>(data.size(), IOV_MAX);
 135         for (size_t i = 0; i < max_iovecs && bytes_wanted > 0; ++i) {
 136                 if (data[i].iov_len <= bytes_wanted) {
 137                         // Consume the entire iovec.
 138                         ret.push_back(data[i]);
 139                         bytes_wanted -= data[i].iov_len;
 140                 } else {
 141                         // Take only parts of this iovec.
 142                         iovec iov;
 143                         iov.iov_base = data[i].iov_base;
 144                         iov.iov_len = bytes_wanted;
 145                         ret.push_back(iov);
 146                         bytes_wanted = 0;
 147                 }
 148         }
 149         return ret;
 150 }
 151
 152 // Return a new set of iovecs that contains all of <data> except the first <bytes_wanted> bytes.
 153 vector<iovec> remove_iovecs(const vector<iovec> &data, size_t bytes_wanted)
 154 {
 155         vector<iovec> ret;
 156         size_t i;
 157         for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
 158                 if (data[i].iov_len <= bytes_wanted) {
 159                         // Consume the entire iovec.
 160                         bytes_wanted -= data[i].iov_len;
 161                 } else {
 162                         // Take only parts of this iovec.
 163                         iovec iov;
 164                         iov.iov_base = reinterpret_cast<char *>(data[i].iov_base) + bytes_wanted;
 165                         iov.iov_len = data[i].iov_len - bytes_wanted;
 166                         ret.push_back(iov);
 167                         bytes_wanted = 0;
 168                 }
 169         }
 170
 171         // Add the rest of the iovecs unchanged.
 172         ret.insert(ret.end(), data.begin() + i, data.end());
 173         return ret;
 174 }
 175
 176 void Stream::add_data_raw(const vector<iovec> &orig_data)
 177 {
 178         vector<iovec> data = orig_data;
 179         while (!data.empty()) {
 180                 size_t pos = bytes_received % backlog_size;
 181
 182                 // Collect as many iovecs as we can before we hit the point
 183                 // where the circular buffer wraps around.
 184                 vector<iovec> to_write = collect_iovecs(data, backlog_size - pos);
 185                 ssize_t ret;
 186                 do {
 187                         ret = pwritev(data_fd, to_write.data(), to_write.size(), pos);
 188                 } while (ret == -1 && errno == EINTR);
 189
 190                 if (ret == -1) {
 191                         log_perror("pwritev");
 192                         // Dazed and confused, but trying to continue...
 193                         return;
 194                 }
 195                 bytes_received += ret;
 196
 197                 // Remove the data that was actually written from the set of iovecs.
 198                 data = remove_iovecs(data, ret);
 199         }
 200 }
 201
 202 void Stream::add_data_deferred(const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start)
 203 {
 204         MutexLock lock(&queued_data_mutex);
 205         assert(suitable_for_stream_start == SUITABLE_FOR_STREAM_START ||
 206                suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START);
 207         if (suitable_for_stream_start == SUITABLE_FOR_STREAM_START) {
 208                 queued_data_last_starting_point = queued_data.size();
 209         }
 210
 211         if (encoding == Stream::STREAM_ENCODING_METACUBE) {
 212                 // Add a Metacube block header before the data.
 213                 metacube2_block_header hdr;
 214                 memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
 215                 hdr.size = htonl(bytes);
 216                 hdr.flags = htons(0);
 217                 if (suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START) {
 218                         hdr.flags |= htons(METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START);
 219                 }
 220                 hdr.csum = htons(metacube2_compute_crc(&hdr));
 221
 222                 iovec iov;
 223                 iov.iov_base = new char[bytes + sizeof(hdr)];
 224                 iov.iov_len = bytes + sizeof(hdr);
 225
 226                 memcpy(iov.iov_base, &hdr, sizeof(hdr));
 227                 memcpy(reinterpret_cast<char *>(iov.iov_base) + sizeof(hdr), data, bytes);
 228
 229                 queued_data.push_back(iov);
 230         } else if (encoding == Stream::STREAM_ENCODING_RAW) {
 231                 // Just add the data itself.
 232                 iovec iov;
 233                 iov.iov_base = new char[bytes];
 234                 memcpy(iov.iov_base, data, bytes);
 235                 iov.iov_len = bytes;
 236
 237                 queued_data.push_back(iov);
 238         } else {
 239                 assert(false);
 240         }
 241 }
 242
 243 void Stream::process_queued_data()
 244 {
 245         std::vector<iovec> queued_data_copy;
 246         int queued_data_last_starting_point_copy = -1;
 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                 swap(queued_data_last_starting_point, queued_data_last_starting_point_copy);
 258         }
 259
 260         // Update the last suitable starting point for the stream,
 261         // if the queued data contains such a starting point.
 262         assert(queued_data_last_starting_point_copy < ssize_t(queued_data_copy.size()));
 263         if (queued_data_last_starting_point_copy >= 0) {
 264                 last_suitable_starting_point = bytes_received;
 265                 for (int i = 0; i < queued_data_last_starting_point_copy; ++i) {
 266                         last_suitable_starting_point += queued_data_copy[i].iov_len;
 267                 }
 268         }
 269
 270         add_data_raw(queued_data_copy);
 271         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 272                 char *data = reinterpret_cast<char *>(queued_data_copy[i].iov_base);
 273                 delete[] data;
 274         }
 275
 276         // We have more data, so wake up all clients.
 277         if (to_process.empty()) {
 278                 swap(sleeping_clients, to_process);
 279         } else {
 280                 to_process.insert(to_process.end(), sleeping_clients.begin(), sleeping_clients.end());
 281                 sleeping_clients.clear();
 282         }
 283 }