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           mark_pool(NULL),
  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           bytes_received(serialized.bytes_received()),
  55           mark_pool(NULL),
  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_bytes_received(bytes_received);
  77         serialized.set_last_suitable_starting_point(last_suitable_starting_point);
  78         serialized.set_url(url);
  79         data_fd = -1;
  80         return serialized;
  81 }
  82
  83 void Stream::set_backlog_size(size_t new_size)
  84 {
  85         if (backlog_size == new_size) {
  86                 return;
  87         }
  88
  89         string existing_data;
  90         if (!read_tempfile_and_close(data_fd, &existing_data)) {
  91                 exit(1);
  92         }
  93
  94         // Unwrap the data so it's no longer circular.
  95         if (bytes_received <= backlog_size) {
  96                 existing_data.resize(bytes_received);
  97         } else {
  98                 size_t pos = bytes_received % backlog_size;
  99                 existing_data = existing_data.substr(pos, string::npos) +
 100                         existing_data.substr(0, pos);
 101         }
 102
 103         // See if we need to discard data.
 104         if (new_size < existing_data.size()) {
 105                 size_t to_discard = existing_data.size() - new_size;
 106                 existing_data = existing_data.substr(to_discard, string::npos);
 107         }
 108
 109         // Create a new, empty data file.
 110         data_fd = make_tempfile("");
 111         if (data_fd == -1) {
 112                 exit(1);
 113         }
 114         backlog_size = new_size;
 115
 116         // Now cheat a bit by rewinding, and adding all the old data back.
 117         bytes_received -= existing_data.size();
 118         iovec iov;
 119         iov.iov_base = const_cast<char *>(existing_data.data());
 120         iov.iov_len = existing_data.size();
 121
 122         vector<iovec> iovs;
 123         iovs.push_back(iov);
 124         add_data_raw(iovs);
 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<iovec> &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].iov_len <= bytes_wanted) {
 139                         // Consume the entire iovec.
 140                         ret.push_back(data[i]);
 141                         bytes_wanted -= data[i].iov_len;
 142                 } else {
 143                         // Take only parts of this iovec.
 144                         iovec iov;
 145                         iov.iov_base = data[i].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<iovec> remove_iovecs(const vector<iovec> &data, size_t bytes_wanted)
 156 {
 157         vector<iovec> ret;
 158         size_t i;
 159         for (i = 0; i < data.size() && bytes_wanted > 0; ++i) {
 160                 if (data[i].iov_len <= bytes_wanted) {
 161                         // Consume the entire iovec.
 162                         bytes_wanted -= data[i].iov_len;
 163                 } else {
 164                         // Take only parts of this iovec.
 165                         iovec iov;
 166                         iov.iov_base = reinterpret_cast<char *>(data[i].iov_base) + bytes_wanted;
 167                         iov.iov_len = data[i].iov_len - bytes_wanted;
 168                         ret.push_back(iov);
 169                         bytes_wanted = 0;
 170                 }
 171         }
 172
 173         // Add the rest of the iovecs unchanged.
 174         ret.insert(ret.end(), data.begin() + i, data.end());
 175         return ret;
 176 }
 177
 178 void Stream::add_data_raw(const vector<iovec> &orig_data)
 179 {
 180         vector<iovec> data = orig_data;
 181         while (!data.empty()) {
 182                 size_t pos = bytes_received % backlog_size;
 183
 184                 // Collect as many iovecs as we can before we hit the point
 185                 // where the circular buffer wraps around.
 186                 vector<iovec> to_write = collect_iovecs(data, backlog_size - pos);
 187                 ssize_t ret;
 188                 do {
 189                         ret = pwritev(data_fd, to_write.data(), to_write.size(), pos);
 190                 } while (ret == -1 && errno == EINTR);
 191
 192                 if (ret == -1) {
 193                         log_perror("pwritev");
 194                         // Dazed and confused, but trying to continue...
 195                         return;
 196                 }
 197                 bytes_received += ret;
 198
 199                 // Remove the data that was actually written from the set of iovecs.
 200                 data = remove_iovecs(data, ret);
 201         }
 202 }
 203
 204 void Stream::add_data_deferred(const char *data, size_t bytes, StreamStartSuitability suitable_for_stream_start)
 205 {
 206         MutexLock lock(&queued_data_mutex);
 207         assert(suitable_for_stream_start == SUITABLE_FOR_STREAM_START ||
 208                suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START);
 209         if (suitable_for_stream_start == SUITABLE_FOR_STREAM_START) {
 210                 queued_data_last_starting_point = queued_data.size();
 211         }
 212
 213         if (encoding == Stream::STREAM_ENCODING_METACUBE) {
 214                 // Add a Metacube block header before the data.
 215                 metacube2_block_header hdr;
 216                 memcpy(hdr.sync, METACUBE2_SYNC, sizeof(hdr.sync));
 217                 hdr.size = htonl(bytes);
 218                 hdr.flags = htons(0);
 219                 if (suitable_for_stream_start == NOT_SUITABLE_FOR_STREAM_START) {
 220                         hdr.flags |= htons(METACUBE_FLAGS_NOT_SUITABLE_FOR_STREAM_START);
 221                 }
 222                 hdr.csum = htons(metacube2_compute_crc(&hdr));
 223
 224                 iovec iov;
 225                 iov.iov_base = new char[bytes + sizeof(hdr)];
 226                 iov.iov_len = bytes + sizeof(hdr);
 227
 228                 memcpy(iov.iov_base, &hdr, sizeof(hdr));
 229                 memcpy(reinterpret_cast<char *>(iov.iov_base) + sizeof(hdr), data, bytes);
 230
 231                 queued_data.push_back(iov);
 232         } else if (encoding == Stream::STREAM_ENCODING_RAW) {
 233                 // Just add the data itself.
 234                 iovec iov;
 235                 iov.iov_base = new char[bytes];
 236                 memcpy(iov.iov_base, data, bytes);
 237                 iov.iov_len = bytes;
 238
 239                 queued_data.push_back(iov);
 240         } else {
 241                 assert(false);
 242         }
 243 }
 244
 245 void Stream::process_queued_data()
 246 {
 247         std::vector<iovec> queued_data_copy;
 248         int queued_data_last_starting_point_copy = -1;
 249
 250         // Hold the lock for as short as possible, since add_data_raw() can possibly
 251         // write to disk, which might disturb the input thread.
 252         {
 253                 MutexLock lock(&queued_data_mutex);
 254                 if (queued_data.empty()) {
 255                         return;
 256                 }
 257
 258                 swap(queued_data, queued_data_copy);
 259                 swap(queued_data_last_starting_point, queued_data_last_starting_point_copy);
 260         }
 261
 262         // Update the last suitable starting point for the stream,
 263         // if the queued data contains such a starting point.
 264         assert(queued_data_last_starting_point_copy < ssize_t(queued_data_copy.size()));
 265         if (queued_data_last_starting_point_copy >= 0) {
 266                 last_suitable_starting_point = bytes_received;
 267                 for (int i = 0; i < queued_data_last_starting_point_copy; ++i) {
 268                         last_suitable_starting_point += queued_data_copy[i].iov_len;
 269                 }
 270         }
 271
 272         add_data_raw(queued_data_copy);
 273         for (size_t i = 0; i < queued_data_copy.size(); ++i) {
 274                 char *data = reinterpret_cast<char *>(queued_data_copy[i].iov_base);
 275                 delete[] data;
 276         }
 277
 278         // We have more data, so wake up all clients.
 279         if (to_process.empty()) {
 280                 swap(sleeping_clients, to_process);
 281         } else {
 282                 to_process.insert(to_process.end(), sleeping_clients.begin(), sleeping_clients.end());
 283                 sleeping_clients.clear();
 284         }
 285 }