Refactor some of the histogram printing

* runtime/stat-common.c (reprint_buf): Removed.
  (_stp_stat_print_histogram_buf): Use a local HIST_PRINTF macro to
  abstract the buffer management.  Also convert reprint_buf calls to
  either %* formats or simple for-loops.

1 files changed, 29 insertions, 56 deletions

diff --git a/runtime/stat-common.c b/runtime/stat-common.c
index db85c35b..e6fd3a11 100644
--- a/runtime/stat-common.c
+++ b/runtime/stat-common.c
@@ -53,17 +53,6 @@ static int needed_space(int64_t v)
 	return space;
 }
 
-static int reprint_buf(char *buf, size_t size, int num, char *s)
-{
-	char *cur_buf = buf, *fake = buf;
-	char **ptr = (buf == NULL ? &fake : &cur_buf);
-	while (num > 0) {
-		*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, s);
-		num--;
-	}
-	return *ptr - buf;
-}
-
 /* Given a bucket number for a log histogram, return the value. */
 static int64_t _stp_bucket_to_val(int num)
 {
@@ -145,10 +134,13 @@ static void _stp_stat_print_histogram_buf(char *buf, size_t size, Hist st, stat
 {
 	int scale, i, j, val_space, cnt_space;
 	int low_bucket = -1, high_bucket = 0, over = 0, under = 0;
-	int64_t val, v, max = 0;
+	int64_t val, v, valmax = 0;
 	int eliding = 0;
 	char *cur_buf = buf, *fake = buf;
-	char **ptr = (buf == NULL ? &fake : &cur_buf);
+	char **bufptr = (buf == NULL ? &fake : &cur_buf);
+
+#define HIST_PRINTF(fmt, args...) \
+	(*bufptr += _stp_snprintf(cur_buf, buf + size - cur_buf, fmt, ## args))
 
 	if (st->type != HIST_LOG && st->type != HIST_LINEAR)
 		return;
@@ -160,8 +152,8 @@ static void _stp_stat_print_histogram_buf(char *buf, size_t size, Hist st, stat
 			low_bucket = i;
 		if (sd->histogram[i] > 0)
 			high_bucket = i;
-		if (sd->histogram[i] > max)
-			max = sd->histogram[i];
+		if (sd->histogram[i] > valmax)
+			valmax = sd->histogram[i];
 	}
 
 	/* Touch up the bucket margin to show up to two zero-slots on
@@ -191,45 +183,37 @@ static void _stp_stat_print_histogram_buf(char *buf, size_t size, Hist st, stat
 			over = 1;
 	}
 
-	if (max <= HIST_WIDTH)
+	if (valmax <= HIST_WIDTH)
 		scale = 1;
 	else {
-		int64_t tmp = max;
+		int64_t tmp = valmax;
 		int rem = do_div(tmp, HIST_WIDTH);
 		scale = tmp;
 		if (rem) scale++;
 	}
 
 	/* count space */
-	cnt_space = needed_space(max);
+	cnt_space = needed_space(valmax);
 
 	/* Compute value space */
 	if (st->type == HIST_LINEAR) {
-		i = needed_space(st->start) + under;
-		val_space = needed_space(st->start +  st->interval * high_bucket) + over;
+		val_space = max(needed_space(st->start) + under,
+				needed_space(st->start +  st->interval * high_bucket) + over);
 	} else {
-		i = needed_space(_stp_bucket_to_val(high_bucket));
-		val_space = needed_space(_stp_bucket_to_val(low_bucket));
+		val_space = max(needed_space(_stp_bucket_to_val(high_bucket)),
+				needed_space(_stp_bucket_to_val(low_bucket)));
 	}
-	if (i > val_space)
-		val_space = i;
-
+	val_space = max(val_space, 5 /* = sizeof("value") */);
 
 	/* print header */
-	j = 0;
-	if (val_space > 5)		/* 5 = sizeof("value") */
-		j = val_space - 5;
-	else
-		val_space = 5;
-	for ( i = 0; i < j; i++)
-		*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, " ");
-	*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, "value |");
-	*ptr += reprint_buf(cur_buf, buf + size - cur_buf, HIST_WIDTH, "-");
-	*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, " count\n");
+	HIST_PRINTF("%*s |", val_space, "value");
+	for (j = 0; j < HIST_WIDTH; ++j)
+		HIST_PRINTF("-");
+	HIST_PRINTF(" count\n");
 
 	eliding = 0;
 	for (i = low_bucket; i <= high_bucket; i++) {
-		int over_under = 0;
+		const char *val_prefix = "";
 
 		/* Elide consecutive zero buckets.  Specifically, skip
 		   this row if it is zero and some of its nearest
@@ -259,8 +243,7 @@ static void _stp_stat_print_histogram_buf(char *buf, size_t size, Hist st, stat
 			   about to print a new one.  So let's print a mark on
 			   the vertical axis to represent the missing rows. */
 			if (eliding) {
-				*ptr += reprint_buf(cur_buf, buf + size - cur_buf, val_space, " ");
-				*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, " ~\n");
+				HIST_PRINTF("%*s ~\n", val_space, "");
 				eliding = 0;
 			}
 		}
@@ -269,38 +252,28 @@ static void _stp_stat_print_histogram_buf(char *buf, size_t size, Hist st, stat
 			if (i == 0) {
 				/* underflow */
 				val = st->start;
-				over_under = 1;
+				val_prefix = "<";
 			} else if (i == st->buckets-1) {
 				/* overflow */
 				val = st->start + (i - 2) * st->interval;
-				over_under = 1;
+				val_prefix = ">";
 			} else
 				val = st->start + (i - 1) * st->interval;
 		} else
 			val = _stp_bucket_to_val(i);
 
-		*ptr += reprint_buf(cur_buf, buf + size - cur_buf, val_space - needed_space(val) - over_under, " ");
-
-		if (over_under) {
-			if (i == 0)
-				*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, "<%lld", val);
-			else if (i == st->buckets-1)
-				*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, ">%lld", val);
-			else
-				*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, "%lld", val);
-		} else
-			*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, "%lld", val);
-		*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, " |");
+		HIST_PRINTF("%*s%lld |", val_space - needed_space(val), val_prefix, val);
 
 		/* v = s->histogram[i] / scale; */
 		v = sd->histogram[i];
 		do_div(v, scale);
 
-		*ptr += reprint_buf(cur_buf, buf + size - cur_buf, v, "@");
-		*ptr += reprint_buf(cur_buf, buf + size - cur_buf, HIST_WIDTH - v + 1 + cnt_space - needed_space(sd->histogram[i]), " ");
-		*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, "%lld\n", sd->histogram[i]);
+		for (j = 0; j < v; ++j)
+			HIST_PRINTF("@");
+		HIST_PRINTF("%*lld\n", HIST_WIDTH - v + 1 + cnt_space, sd->histogram[i]);
 	}
-	*ptr += _stp_snprintf(cur_buf, buf + size - cur_buf, "\n");
+	HIST_PRINTF("\n");
+#undef HIST_PRINTF
 }
 
 static void _stp_stat_print_histogram(Hist st, stat *sd)