git.sesse.net Git - nageru/blob - futatabi/frame_on_disk.cpp

   1 #include "frame_on_disk.h"
   2
   3 #include "shared/metrics.h"
   4
   5 #include <atomic>
   6 #include <chrono>
   7 #include <fcntl.h>
   8 #include <mutex>
   9 #include <unistd.h>
  10
  11 using namespace std;
  12 using namespace std::chrono;
  13
  14 namespace {
  15
  16 // There can be multiple FrameReader classes, so make all the metrics static.
  17 once_flag frame_metrics_inited;
  18
  19 atomic<int64_t> metric_frame_opened_files{ 0 };
  20 atomic<int64_t> metric_frame_closed_files{ 0 };
  21 atomic<int64_t> metric_frame_read_bytes{ 0 };
  22 atomic<int64_t> metric_frame_read_frames{ 0 };
  23
  24 Summary metric_frame_read_time_seconds;
  25
  26 }  // namespace
  27
  28 FrameReader::FrameReader()
  29 {
  30         call_once(frame_metrics_inited, [] {
  31                 global_metrics.add("frame_opened_files", &metric_frame_opened_files);
  32                 global_metrics.add("frame_closed_files", &metric_frame_closed_files);
  33                 global_metrics.add("frame_read_bytes", &metric_frame_read_bytes);
  34                 global_metrics.add("frame_read_frames", &metric_frame_read_frames);
  35
  36                 vector<double> quantiles{ 0.01, 0.1, 0.25, 0.5, 0.75, 0.9, 0.99 };
  37                 metric_frame_read_time_seconds.init(quantiles, 60.0);
  38                 global_metrics.add("frame_read_time_seconds", &metric_frame_read_time_seconds);
  39         });
  40 }
  41
  42 FrameReader::~FrameReader()
  43 {
  44         if (fd != -1) {
  45                 close(fd);
  46                 ++metric_frame_closed_files;
  47         }
  48 }
  49
  50 namespace {
  51
  52 string read_string(int fd, size_t size, off_t offset)
  53 {
  54         string str;
  55         str.resize(size);
  56         size_t str_offset = 0;
  57         while (str_offset < size) {
  58                 int ret = pread(fd, &str[str_offset], size - str_offset, offset + str_offset);
  59                 if (ret <= 0) {
  60                         perror("pread");
  61                         abort();
  62                 }
  63
  64                 str_offset += ret;
  65         }
  66         return str;
  67 }
  68
  69 }  // namespace
  70
  71 FrameReader::Frame FrameReader::read_frame(FrameOnDisk frame, bool read_audio)
  72 {
  73         steady_clock::time_point start = steady_clock::now();
  74
  75         if (int(frame.filename_idx) != last_filename_idx) {
  76                 if (fd != -1) {
  77                         close(fd);  // Ignore errors.
  78                         ++metric_frame_closed_files;
  79                 }
  80
  81                 string filename;
  82                 {
  83                         lock_guard<mutex> lock(frame_mu);
  84                         filename = frame_filenames[frame.filename_idx];
  85                 }
  86
  87                 fd = open(filename.c_str(), O_RDONLY);
  88                 if (fd == -1) {
  89                         perror(filename.c_str());
  90                         abort();
  91                 }
  92
  93                 // We want readahead. (Ignore errors.)
  94                 posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL);
  95
  96                 last_filename_idx = frame.filename_idx;
  97                 ++metric_frame_opened_files;
  98         }
  99
 100         Frame ret;
 101         ret.video = read_string(fd, frame.size, frame.offset);
 102         if (read_audio) {
 103                 ret.audio = read_string(fd, frame.audio_size, frame.offset + frame.size);
 104         }
 105
 106         steady_clock::time_point stop = steady_clock::now();
 107         metric_frame_read_time_seconds.count_event(duration<double>(stop - start).count());
 108
 109         metric_frame_read_bytes += frame.size;
 110         ++metric_frame_read_frames;
 111
 112         return ret;
 113 }