-/* Reads the contents of file descriptor FD, until it is closed, or a
- read error occurs. The data is read in 8K chunks, and stored to
- stream fp, which should have been open for writing. If BUF is
- non-NULL and its file descriptor is equal to FD, flush RBUF first.
- This function will *not* use the rbuf_* functions!
+ /* Calculate the amount of time we expect downloading the chunk
+ should take. If in reality it took less time, sleep to
+ compensate for the difference. */
+ expected = 1000.0 * limit_data.chunk_bytes / opt.limit_rate;
+
+ if (expected > delta_t)
+ {
+ double slp = expected - delta_t + limit_data.sleep_adjust;
+ double t0, t1;
+ if (slp < 200)
+ {
+ DEBUGP (("deferring a %.2f ms sleep (%s/%.2f).\n",
+ slp, number_to_static_string (limit_data.chunk_bytes),
+ delta_t));
+ return;
+ }
+ DEBUGP (("\nsleeping %.2f ms for %s bytes, adjust %.2f ms\n",
+ slp, number_to_static_string (limit_data.chunk_bytes),
+ limit_data.sleep_adjust));
+
+ t0 = ptimer_read (timer);
+ xsleep (slp / 1000);
+ t1 = ptimer_measure (timer);
+
+ /* Due to scheduling, we probably slept slightly longer (or
+ shorter) than desired. Calculate the difference between the
+ desired and the actual sleep, and adjust the next sleep by
+ that amount. */
+ limit_data.sleep_adjust = slp - (t1 - t0);
+ }
+
+ limit_data.chunk_bytes = 0;
+ limit_data.chunk_start = ptimer_read (timer);
+}
+
+#ifndef MIN
+# define MIN(i, j) ((i) <= (j) ? (i) : (j))
+#endif
+
+/* Write data in BUF to OUT. However, if *SKIP is non-zero, skip that
+ amount of data and decrease SKIP. Increment *TOTAL by the amount
+ of data written. */
+
+static int
+write_data (FILE *out, const char *buf, int bufsize, wgint *skip,
+ wgint *written)
+{
+ if (!out)
+ return 1;
+ if (*skip > bufsize)
+ {
+ *skip -= bufsize;
+ return 1;
+ }
+ if (*skip)
+ {
+ buf += *skip;
+ bufsize -= *skip;
+ *skip = 0;
+ if (bufsize == 0)
+ return 1;
+ }
+
+ fwrite (buf, 1, bufsize, out);
+ *written += bufsize;
+
+ /* Immediately flush the downloaded data. This should not hinder
+ performance: fast downloads will arrive in large 16K chunks
+ (which stdio would write out immediately anyway), and slow
+ downloads wouldn't be limited by disk speed. */
+ fflush (out);
+ return !ferror (out);
+}