progress.c

Wget很好的处理了http和ftp的下载,很值得学习的经典代码

  log_set_flush (false);

  if (dp->dots == 0)
    logprintf (LOG_VERBOSE, "\n%6sK",
               number_to_static_string (dp->rows * ROW_BYTES / 1024));
  for (i = dp->dots; i < opt.dots_in_line; i++)
    {
      if (i % opt.dot_spacing == 0)
        logputs (LOG_VERBOSE, " ");
      logputs (LOG_VERBOSE, " ");
    }

  print_row_stats (dp, dltime, true);
  logputs (LOG_VERBOSE, "\n\n");
  log_set_flush (false);

  xfree (dp);
}

/* This function interprets the progress "parameters".  For example,
   if Wget is invoked with --progress=dot:mega, it will set the
   "dot-style" to "mega".  Valid styles are default, binary, mega, and
   giga.  */

static void
dot_set_params (const char *params)
{
  if (!params || !*params)
    params = opt.dot_style;

  if (!params)
    return;

  /* We use this to set the retrieval style.  */
  if (!strcasecmp (params, "default"))
    {
      /* Default style: 1K dots, 10 dots in a cluster, 50 dots in a
         line.  */
      opt.dot_bytes = 1024;
      opt.dot_spacing = 10;
      opt.dots_in_line = 50;
    }
  else if (!strcasecmp (params, "binary"))
    {
      /* "Binary" retrieval: 8K dots, 16 dots in a cluster, 48 dots
         (384K) in a line.  */
      opt.dot_bytes = 8192;
      opt.dot_spacing = 16;
      opt.dots_in_line = 48;
    }
  else if (!strcasecmp (params, "mega"))
    {
      /* "Mega" retrieval, for retrieving very long files; each dot is
         64K, 8 dots in a cluster, 6 clusters (3M) in a line.  */
      opt.dot_bytes = 65536L;
      opt.dot_spacing = 8;
      opt.dots_in_line = 48;
    }
  else if (!strcasecmp (params, "giga"))
    {
      /* "Giga" retrieval, for retrieving very very *very* long files;
         each dot is 1M, 8 dots in a cluster, 4 clusters (32M) in a
         line.  */
      opt.dot_bytes = (1L << 20);
      opt.dot_spacing = 8;
      opt.dots_in_line = 32;
    }
  else
    fprintf (stderr,
             _("Invalid dot style specification `%s'; leaving unchanged.\n"),
             params);
}

/* "Thermometer" (bar) progress. */

/* Assumed screen width if we can't find the real value.  */
#define DEFAULT_SCREEN_WIDTH 80

/* Minimum screen width we'll try to work with.  If this is too small,
   create_image will overflow the buffer.  */
#define MINIMUM_SCREEN_WIDTH 45

/* The last known screen width.  This can be updated by the code that
   detects that SIGWINCH was received (but it's never updated from the
   signal handler).  */
static int screen_width;

/* A flag that, when set, means SIGWINCH was received.  */
static volatile sig_atomic_t received_sigwinch;

/* Size of the download speed history ring. */
#define DLSPEED_HISTORY_SIZE 20

/* The minimum time length of a history sample.  By default, each
   sample is at least 150ms long, which means that, over the course of
   20 samples, "current" download speed spans at least 3s into the
   past.  */
#define DLSPEED_SAMPLE_MIN 0.15

/* The time after which the download starts to be considered
   "stalled", i.e. the current bandwidth is not printed and the recent
   download speeds are scratched.  */
#define STALL_START_TIME 5

/* Time between screen refreshes will not be shorter than this, so
   that Wget doesn't swamp the TTY with output.  */
#define REFRESH_INTERVAL 0.2

/* Don't refresh the ETA too often to avoid jerkiness in predictions.
   This allows ETA to change approximately once per second.  */
#define ETA_REFRESH_INTERVAL 0.99

struct bar_progress {
  wgint initial_length;         /* how many bytes have been downloaded
                                   previously. */
  wgint total_length;           /* expected total byte count when the
                                   download finishes */
  wgint count;                  /* bytes downloaded so far */

  double last_screen_update;    /* time of the last screen update,
                                   measured since the beginning of
                                   download. */

  int width;                    /* screen width we're using at the
                                   time the progress gauge was
                                   created.  this is different from
                                   the screen_width global variable in
                                   that the latter can be changed by a
                                   signal. */
  char *buffer;                 /* buffer where the bar "image" is
                                   stored. */
  int tick;                     /* counter used for drawing the
                                   progress bar where the total size
                                   is not known. */

  /* The following variables (kept in a struct for namespace reasons)
     keep track of recent download speeds.  See bar_update() for
     details.  */
  struct bar_progress_hist {
    int pos;
    double times[DLSPEED_HISTORY_SIZE];
    wgint bytes[DLSPEED_HISTORY_SIZE];

    /* The sum of times and bytes respectively, maintained for
       efficiency. */
    double total_time;
    wgint total_bytes;
  } hist;

  double recent_start;          /* timestamp of beginning of current
                                   position. */
  wgint recent_bytes;           /* bytes downloaded so far. */

  bool stalled;                 /* set when no data arrives for longer
                                   than STALL_START_TIME, then reset
                                   when new data arrives. */

  /* create_image() uses these to make sure that ETA information
     doesn't flicker. */
  double last_eta_time;         /* time of the last update to download
                                   speed and ETA, measured since the
                                   beginning of download. */
  int last_eta_value;
};

static void create_image (struct bar_progress *, double, bool);
static void display_image (char *);

static void *
bar_create (wgint initial, wgint total)
{
  struct bar_progress *bp = xnew0 (struct bar_progress);

  /* In theory, our callers should take care of this pathological
     case, but it can sometimes happen. */
  if (initial > total)
    total = initial;

  bp->initial_length = initial;
  bp->total_length   = total;

  /* Initialize screen_width if this hasn't been done or if it might
     have changed, as indicated by receiving SIGWINCH.  */
  if (!screen_width || received_sigwinch)
    {
      screen_width = determine_screen_width ();
      if (!screen_width)
        screen_width = DEFAULT_SCREEN_WIDTH;
      else if (screen_width < MINIMUM_SCREEN_WIDTH)
        screen_width = MINIMUM_SCREEN_WIDTH;
      received_sigwinch = 0;
    }

  /* - 1 because we don't want to use the last screen column. */
  bp->width = screen_width - 1;
  /* + enough space for the terminating zero, and hopefully enough room
   * for multibyte characters. */
  bp->buffer = xmalloc (bp->width + 100);

  logputs (LOG_VERBOSE, "\n");

  create_image (bp, 0, false);
  display_image (bp->buffer);

  return bp;
}

static void update_speed_ring (struct bar_progress *, wgint, double);

static void
bar_update (void *progress, wgint howmuch, double dltime)
{
  struct bar_progress *bp = progress;
  bool force_screen_update = false;

  bp->count += howmuch;
  if (bp->total_length > 0
      && bp->count + bp->initial_length > bp->total_length)
    /* We could be downloading more than total_length, e.g. when the
       server sends an incorrect Content-Length header.  In that case,
       adjust bp->total_length to the new reality, so that the code in
       create_image() that depends on total size being smaller or
       equal to the expected size doesn't abort.  */
    bp->total_length = bp->initial_length + bp->count;

  update_speed_ring (bp, howmuch, dltime);

  /* If SIGWINCH (the window size change signal) been received,
     determine the new screen size and update the screen.  */
  if (received_sigwinch)
    {
      int old_width = screen_width;
      screen_width = determine_screen_width ();
      if (!screen_width)
        screen_width = DEFAULT_SCREEN_WIDTH;
      else if (screen_width < MINIMUM_SCREEN_WIDTH)
        screen_width = MINIMUM_SCREEN_WIDTH;
      if (screen_width != old_width)
        {
          bp->width = screen_width - 1;
          bp->buffer = xrealloc (bp->buffer, bp->width + 100);
          force_screen_update = true;
        }
      received_sigwinch = 0;
    }

  if (dltime - bp->last_screen_update < REFRESH_INTERVAL && !force_screen_update)
    /* Don't update more often than five times per second. */
    return;

  create_image (bp, dltime, false);
  display_image (bp->buffer);
  bp->last_screen_update = dltime;
}

static void
bar_finish (void *progress, double dltime)
{
  struct bar_progress *bp = progress;

  if (bp->total_length > 0
      && bp->count + bp->initial_length > bp->total_length)
    /* See bar_update() for explanation. */
    bp->total_length = bp->initial_length + bp->count;

  create_image (bp, dltime, true);
  display_image (bp->buffer);

  logputs (LOG_VERBOSE, "\n\n");

  xfree (bp->buffer);
  xfree (bp);
}

/* This code attempts to maintain the notion of a "current" download
   speed, over the course of no less than 3s.  (Shorter intervals
   produce very erratic results.)

   To do so, it samples the speed in 150ms intervals and stores the
   recorded samples in a FIFO history ring.  The ring stores no more
   than 20 intervals, hence the history covers the period of at least
   three seconds and at most 20 reads into the past.  This method
   should produce reasonable results for downloads ranging from very
   slow to very fast.

   The idea is that for fast downloads, we get the speed over exactly
   the last three seconds.  For slow downloads (where a network read
   takes more than 150ms to complete), we get the speed over a larger
   time period, as large as it takes to complete thirty reads.  This
   is good because slow downloads tend to fluctuate more and a
   3-second average would be too erratic.  */

static void
update_speed_ring (struct bar_progress *bp, wgint howmuch, double dltime)
{
  struct bar_progress_hist *hist = &bp->hist;
  double recent_age = dltime - bp->recent_start;

  /* Update the download count. */
  bp->recent_bytes += howmuch;

  /* For very small time intervals, we return after having updated the
     "recent" download count.  When its age reaches or exceeds minimum
     sample time, it will be recorded in the history ring.  */
  if (recent_age < DLSPEED_SAMPLE_MIN)
    return;

  if (howmuch == 0)
    {
      /* If we're not downloading anything, we might be stalling,
         i.e. not downloading anything for an extended period of time.
         Since 0-reads do not enter the history ring, recent_age
         effectively measures the time since last read.  */
      if (recent_age >= STALL_START_TIME)
        {
          /* If we're stalling, reset the ring contents because it's
             stale and because it will make bar_update stop printing
             the (bogus) current bandwidth.  */
          bp->stalled = true;
          xzero (*hist);
          bp->recent_bytes = 0;
        }
      return;
    }

  /* We now have a non-zero amount of to store to the speed ring.  */

  /* If the stall status was acquired, reset it. */
  if (bp->stalled)
    {
      bp->stalled = false;
      /* "recent_age" includes the the entired stalled period, which
         could be very long.  Don't update the speed ring with that
         value because the current bandwidth would start too small.
         Start with an arbitrary (but more reasonable) time value and
         let it level out.  */
      recent_age = 1;
    }

  /* Store "recent" bytes and download time to history ring at the
     position POS.  */

  /* To correctly maintain the totals, first invalidate existing data
     (least recent in time) at this position. */
  hist->total_time  -= hist->times[hist->pos];
  hist->total_bytes -= hist->bytes[hist->pos];

  /* Now store the new data and update the totals. */
  hist->times[hist->pos] = recent_age;
  hist->bytes[hist->pos] = bp->recent_bytes;
  hist->total_time  += recent_age;
  hist->total_bytes += bp->recent_bytes;

  /* Start a new "recent" period. */
  bp->recent_start = dltime;
  bp->recent_bytes = 0;

  /* Advance the current ring position. */
  if (++hist->pos == DLSPEED_HISTORY_SIZE)
    hist->pos = 0;

#if 0
  /* Sledgehammer check to verify that the totals are accurate. */
  {
    int i;
    double sumt = 0, sumb = 0;
    for (i = 0; i < DLSPEED_HISTORY_SIZE; i++)
      {
        sumt += hist->times[i];
        sumb += hist->bytes[i];
      }
    assert (sumb == hist->total_bytes);
    /* We can't use assert(sumt==hist->total_time) because some
       precision is lost by adding and subtracting floating-point
       numbers.  But during a download this precision should not be
       detectable, i.e. no larger than 1ns.  */
    double diff = sumt - hist->total_time;
    if (diff < 0) diff = -diff;
    assert (diff < 1e-9);
  }
#endif
}

#if USE_NLS_PROGRESS_BAR
int