+/* 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 = 1000;
+ }
+
+ /* 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 (sumt == hist->total_time);
+ assert (sumb == hist->total_bytes);
+ }
+#endif
+}
+
+static const char *eta_to_human (int);
+
projects / wget / blobdiff