New option "--stats", to show a line of statistics about the transfer once it has ended (issue #49).

src/include/config.h.in

@@ -73,6 +73,9 @@
 /* Define to 1 if you have the <locale.h> header file. */
 #undef HAVE_LOCALE_H
 
+/* Define to 1 if you have the <math.h> header file. */
+#undef HAVE_MATH_H
+
 /* Define to 1 if you have the `memcpy' function. */
 #undef HAVE_MEMCPY
 
@@ -112,6 +115,9 @@
 /* Define to 1 if you have the `splice' function. */
 #undef HAVE_SPLICE
 
+/* Define to 1 if you have the `sqrtl' function. */
+#undef HAVE_SQRTL
+
 /* Define to 1 if stdbool.h conforms to C99. */
 #undef HAVE_STDBOOL_H
 

src/include/options.h

@@ -74,6 +74,7 @@ struct opts_s {
 	bool sync_after_write;         /* set if we sync after every write */
 	bool direct_io;                /* set if O_DIRECT is to be used */
 	bool discard_input;            /* set to write nothing to output */
+	bool show_stats;	       /* set to write statistics at the end */
 	bool width_set_manually;       /* width was set manually, not detected */
 	bool height_set_manually;      /* height was set manually, not detected */
 };

src/include/pv-internal.h

@@ -134,6 +134,7 @@ struct pvstate_s {
 		bool direct_io_changed;          /* set when direct_io is changed */
 		bool no_splice;                  /* never use splice() */
 		bool discard_input;              /* write nothing to stdout */
+		bool show_stats;		 /* show statistics on exit */
 		bool width_set_manually;	 /* width was set manually, not detected */
 		bool height_set_manually;	 /* height was set manually, not detected */
 	} control;
@@ -219,6 +220,12 @@ struct pvstate_s {
 		long double prev_trans;		 /* amount transferred since last rate calculation */
 		long double current_avg_rate;    /* current average rate over last history intervals */
 
+		long double rate_min;		 /* minimum measured transfer rate */
+		long double rate_max;		 /* maximum measured transfer rate */
+		long double rate_sum;		 /* sum of all measured transfer rates */
+		long double ratesquared_sum;	 /* sum of the squares of each transfer rate */
+		unsigned long measurements_taken; /* how many times the rate was measured */
+
 		/* Keep track of progress over last intervals to compute current average rate. */
 		/*@null@*/ struct {	 /* state at previous intervals (circular buffer) */
 			long double elapsed_sec;	/* time since start of transfer */

src/include/pv.h

@@ -172,6 +172,7 @@ extern void pv_state_set_format(pvstate_t state, bool progress,
  */
 extern void pv_state_force_set(pvstate_t, bool);
 extern void pv_state_cursor_set(pvstate_t, bool);
+extern void pv_state_show_stats_set(pvstate_t, bool);
 extern void pv_state_numeric_set(pvstate_t, bool);
 extern void pv_state_wait_set(pvstate_t, bool);
 extern void pv_state_delay_start_set(pvstate_t, double);

src/main/help.c

@@ -319,6 +319,9 @@ void display_help(void)
 		{ "-F", "--format", N_("FORMAT"),
 		 N_("set output format to FORMAT"),
 		 { 0, 0, 0, 0} },
+		{ "-v", "--stats", NULL,
+		 N_("output transfer statistics at the end"),
+		 { 0, 0, 0, 0} },
 		{ "-n", "--numeric", NULL,
 		 N_("output percentages, not visual information"),
 		 { 0, 0, 0, 0} },

src/main/main.c

@@ -306,6 +306,7 @@ int main(int argc, char **argv)
 	pv_state_no_display_set(state, opts->no_display);
 	pv_state_force_set(state, opts->force);
 	pv_state_cursor_set(state, opts->cursor);
+	pv_state_show_stats_set(state, opts->show_stats);
 	pv_state_numeric_set(state, opts->numeric);
 	pv_state_wait_set(state, opts->wait);
 	pv_state_delay_start_set(state, opts->delay_start);

src/main/options.c

@@ -290,6 +290,7 @@ opts_t opts_parse(unsigned int argc, char **argv)
 		{ "height", 1, NULL, (int) 'H' },
 		{ "name", 1, NULL, (int) 'N' },
 		{ "format", 1, NULL, (int) 'F' },
+		{ "stats", 0, NULL, (int) 'v' },
 		{ "rate-limit", 1, NULL, (int) 'L' },
 		{ "buffer-size", 1, NULL, (int) 'B' },
 		{ "no-splice", 0, NULL, (int) 'C' },
@@ -312,7 +313,7 @@ opts_t opts_parse(unsigned int argc, char **argv)
 	/*@+nullassign@ */
 	int option_index = 0;
 #endif				/* HAVE_GETOPT_LONG */
-	char *short_options = "hVpteIrab8kTA:fnqcWD:s:l0i:w:H:N:F:L:B:CEZ:SYKXR:P:d:m:o:"
+	char *short_options = "hVpteIrab8kTA:fvnqcWD:s:l0i:w:H:N:F:L:B:CEZ:SYKXR:P:d:m:o:"
 #ifdef ENABLE_DEBUGGING
 	    "!:"
 #endif
@@ -512,6 +513,9 @@ opts_t opts_parse(unsigned int argc, char **argv)
 		case 'f':
 			opts->force = true;
 			break;
+		case 'v':
+			opts->show_stats = true;
+			break;
 		case 'n':
 			opts->numeric = true;
 			numopts++;

src/pv/display.c

@@ -694,6 +694,24 @@ void pv_calculate_transfer_rate(pvstate_t state, bool final)
 		transfer_rate = ((long double) bytes_since_last + state->calc.prev_trans) / time_since_last;
 		state->calc.prev_elapsed_sec = state->transfer.elapsed_seconds;
 		state->calc.prev_trans = 0;
+
+		/* Maintain information for statistics. */
+		if (state->control.show_stats) {
+			long double measured_rate = transfer_rate;
+
+			if (state->control.bits)
+				measured_rate = 8.0 * measured_rate;
+
+			if ((state->calc.measurements_taken < 1) || (measured_rate < state->calc.rate_min)) {
+				state->calc.rate_min = measured_rate;
+			}
+			if (measured_rate > state->calc.rate_max) {
+				state->calc.rate_max = measured_rate;
+			}
+			state->calc.rate_sum += measured_rate;
+			state->calc.ratesquared_sum += (measured_rate * measured_rate);
+			state->calc.measurements_taken++;
+		}
 	}
 	state->calc.prev_rate = transfer_rate;
 

src/pv/loop.c

@@ -24,6 +24,32 @@
 #include <sys/ioctl.h>
 #include <sys/stat.h>
 
+#if HAVE_MATH_H
+#include <math.h>
+#endif
+
+
+#if HAVE_SQRTL
+#else
+/*
+ * Square root of a long double.  Adapted from iputils ping/ping_common.c.
+ */
+static long ldsqrt(long double value)
+{
+	long double previous = (long double) LLONG_MAX;
+	long double result = value;
+
+	if (result > 0) {
+		while (result < previous) {
+			previous = result;
+			result = (result + (value / result)) / 2;
+		}
+	}
+
+	return result;
+}
+#endif
+
 
 /*
  * Pipe data from a list of files to standard output, giving information
@@ -243,8 +269,11 @@ int pv_main_loop(pvstate_t state)
 			}
 		}
 
-		/* Just go round the loop again if there's no display. */
-		if (state->control.no_display)
+		/*
+		 * Just go round the loop again if there's no display and
+		 * we're not reporting statistics.
+		 */
+		if (state->control.no_display && !state->control.show_stats)
 			continue;
 
 		/*
@@ -331,7 +360,13 @@ int pv_main_loop(pvstate_t state)
 				state->control.height = new_height;
 		}
 
-		pv_display(state, final_update);
+		if (state->control.no_display) {
+			/* If there's no display, calculate rate for the statistics. */
+			pv_calculate_transfer_rate(state, final_update);
+		} else {
+			/* Produce the display. */
+			pv_display(state, final_update);
+		}
 	}
 
 	debug("%s: %s=%s, %s=%s", "loop ended", "eof_in", eof_in ? "true" : "false", "eof_out",
@@ -351,6 +386,52 @@ int pv_main_loop(pvstate_t state)
 	if (fd >= 0)
 		(void) close(fd);
 
+	/* Calculate and display the transfer statistics. */
+	if (state->control.show_stats && state->calc.measurements_taken > 0) {
+		char stats_buf[256];	 /* flawfinder: ignore */
+		long double rate_mean, rate_variance, rate_deviation;
+		int stats_size;
+
+		/* flawfinder: made safe by use of pv_snprintf() */
+
+		rate_mean = state->calc.rate_sum / ((long double) (state->calc.measurements_taken));
+		rate_variance =
+		    (state->calc.ratesquared_sum / ((long double) (state->calc.measurements_taken))) -
+		    (rate_mean * rate_mean);
+#if HAVE_SQRTL
+		rate_deviation = sqrtl(rate_variance);
+#else
+		rate_deviation = ldsqrt(rate_variance);
+#endif
+
+		debug("%s: %ld", "measurements taken", state->calc.measurements_taken);
+		debug("%s: %.3Lf", "rate_sum", state->calc.rate_sum);
+		debug("%s: %.3Lf", "ratesquared_sum", state->calc.ratesquared_sum);
+		debug("%s: %.3Lf", "rate_mean", rate_mean);
+		debug("%s: %.3Lf", "rate_variance", rate_variance);
+		debug("%s: %.3Lf", "rate_deviation", rate_deviation);
+
+		memset(stats_buf, 0, sizeof(stats_buf));
+		stats_size =
+		    pv_snprintf(stats_buf, sizeof(stats_buf), "%s = %.3Lf/%.3Lf/%.3Lf/%.3Lf %s\n",
+				_("rate min/avg/max/mdev"), state->calc.rate_min, rate_mean, state->calc.rate_max,
+				rate_deviation, state->control.bits ? _("b/s") : _("B/s"));
+
+		if (stats_size > 0 && stats_size < (int) (sizeof(stats_buf)))
+			pv_tty_write(state, stats_buf, (size_t) stats_size);
+	} else if (state->control.show_stats && state->calc.measurements_taken < 1) {
+		char msg_buf[256];	 /* flawfinder: ignore */
+		int msg_size;
+
+		/* flawfinder: made safe by use of pv_snprintf() */
+
+		memset(msg_buf, 0, sizeof(msg_buf));
+		msg_size = pv_snprintf(msg_buf, sizeof(msg_buf), "%s\n", _("rate not measured"));
+
+		if (msg_size > 0 && msg_size < (int) (sizeof(msg_buf)))
+			pv_tty_write(state, msg_buf, (size_t) msg_size);
+	}
+
 	return state->status.exit_status;
 }
 

src/pv/state.c

@@ -85,6 +85,22 @@ pvstate_t pv_state_alloc(const char *program_name)
 #endif				/* HAVE_SPLICE */
 	state->display.display_visible = false;
 
+	/*
+	 * Explicitly set important floating point values to 0, as memset()
+	 * is not recommended for this.
+	 */
+	state->calc.transfer_rate = 0.0;
+	state->calc.average_rate = 0.0;
+	state->calc.prev_elapsed_sec = 0.0;
+	state->calc.prev_rate = 0.0;
+	state->calc.prev_trans = 0.0;
+	state->calc.current_avg_rate = 0.0;
+	state->calc.rate_min = 0.0;
+	state->calc.rate_max = 0.0;
+	state->calc.rate_sum = 0.0;
+	state->calc.ratesquared_sum = 0.0;
+	state->transfer.elapsed_seconds = 0.0;
+
 	/*
 	 * Get the current working directory, if possible, as a base for
 	 * showing relative filenames with --watchfd.
@@ -234,6 +250,11 @@ void pv_state_cursor_set(pvstate_t state, bool val)
 	state->control.cursor = val;
 }
 
+void pv_state_show_stats_set(pvstate_t state, bool val)
+{
+	state->control.show_stats = val;
+}
+
 void pv_state_numeric_set(pvstate_t state, bool val)
 {
 	state->control.numeric = val;