PR 5057: histogram zero elision

2007-09-22  Frank Ch. Eigler  <fche@elastic.org>

	PR 5057.
	* stat-common.c (_stp_stat_print_histogram): Elide consecutive
	zero rows beyond 2*STAT_ELISION+1.
	(STAT_ELISION): New parameter, default 2.

2007-09-22  Frank Ch. Eigler  <fche@elastic.org>

	PR 5057.
	* systemtap.maps/linear_nearlyempty.*: New test for
	histogram printing elision.

5 files changed, 92 insertions, 0 deletions

diff --git a/runtime/ChangeLog b/runtime/ChangeLog
index 48787132..54a3554e 100644
--- a/runtime/ChangeLog
+++ b/runtime/ChangeLog
@@ -1,3 +1,10 @@
+2007-09-22  Frank Ch. Eigler  <fche@elastic.org>
+
+	PR 5057.
+	* stat-common.c (_stp_stat_print_histogram): Elide consecutive
+	zero rows beyond 2*STAT_ELISION+1.
+	(STAT_ELISION): New parameter, default 2.
+
 2007-09-21  Martin Hunt  <hunt@redhat.com>
 	PR 5024
 	* stat-common.c (_stp_stat_print_histogram): Change
diff --git a/runtime/stat-common.c b/runtime/stat-common.c
index 7a6f439b..8b2f3cf3 100644
--- a/runtime/stat-common.c
+++ b/runtime/stat-common.c
@@ -133,11 +133,17 @@ static int _stp_val_to_bucket(int64_t val)
 #define HIST_WIDTH 50
 #endif
 
+#ifndef HIST_ELISION
+#define HIST_ELISION 2 /* zeroes before and after */
+#endif
+
+
 static void _stp_stat_print_histogram (Hist st, stat *sd)
 {
 	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;
+        int eliding = 0;
 
 	if (st->type != HIST_LOG && st->type != HIST_LINEAR)
 		return;
@@ -215,8 +221,38 @@ static void _stp_stat_print_histogram (Hist st, stat *sd)
 	_stp_print("value |");
 	reprint (HIST_WIDTH, "-");
 	_stp_print(" count\n");
+
+        eliding=0;
 	for (i = low_bucket;  i <= high_bucket; i++) {
 		int over_under = 0;
+
+                /* Elide consecutive zero buckets.  Specifically, skip
+                   this row if it is zero and some of its nearest
+                   neighbours are also zero.  */
+                int k;
+                int elide=1;
+                for (k=i-HIST_ELISION; k<=i+HIST_ELISION; k++)
+                  {
+                    if (k >= 0 && k < st->buckets && sd->histogram[k] != 0)
+                      elide = 0;
+                  }
+                if (elide)
+                  { 
+                    eliding = 1;
+                    continue;
+                  }
+
+                /* State change: we have elided some rows, but now are about
+                   to print a new one.  So let's print a mark on the vertical
+                   axis to represent the missing rows.  */
+                if (eliding)
+                  {
+                    reprint (val_space, " ");
+                    _stp_print(" ~\n");
+                    eliding = 0;
+                  }
+
+
 		if (st->type == HIST_LINEAR) {
 			if (i == 0) {
 				/* underflow */
diff --git a/testsuite/ChangeLog b/testsuite/ChangeLog
index 4c5d811b..a2317b5f 100644
--- a/testsuite/ChangeLog
+++ b/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2007-09-22  Frank Ch. Eigler  <fche@elastic.org>
+
+	PR 5057.
+	* systemtap.maps/linear_nearlyempty.*: New test for
+	histogram printing elision.
+
 2007-09-21  Martin Hunt  <hunt@redhat.com>
 
 	* systemtap.maps/linear*: Updated linear histogram tests.
diff --git a/testsuite/systemtap.maps/linear_nearlyempty.exp b/testsuite/systemtap.maps/linear_nearlyempty.exp
new file mode 100644
index 00000000..dfb5e9ef
--- /dev/null
+++ b/testsuite/systemtap.maps/linear_nearlyempty.exp
@@ -0,0 +1,25 @@
+# Test nearly empty linear histogram
+
+set test "linear_nearlyempty"
+set ::result_string {count=2
+sum=1443
+min=444
+max=999
+avg=721
+value |-------------------------------------------------- count
+  300 |                                                   0
+  350 |                                                   0
+  400 |@                                                  1
+  450 |                                                   0
+  500 |                                                   0
+      ~
+  850 |                                                   0
+  900 |                                                   0
+  950 |@                                                  1
+ 1000 |                                                   0
+ 1050 |                                                   0
+}
+
+stap_run2 $srcdir/$subdir/$test.stp
+
+
diff --git a/testsuite/systemtap.maps/linear_nearlyempty.stp b/testsuite/systemtap.maps/linear_nearlyempty.stp
new file mode 100644
index 00000000..f0b70607
--- /dev/null
+++ b/testsuite/systemtap.maps/linear_nearlyempty.stp
@@ -0,0 +1,18 @@
+# test that we can check the count of an empty array
+
+global agg
+
+probe begin
+{
+	agg <<< 444
+	agg <<< 999
+	printf("count=%d\n", @count(agg))
+	if (@count(agg) > 0) {
+		printf("sum=%d\n", @sum(agg))
+        	printf("min=%d\n", @min(agg))
+	        printf("max=%d\n", @max(agg))
+        	printf("avg=%d\n", @avg(agg))
+	        print(@hist_linear(agg, 0, 1500, 50))
+	}
+	exit()
+}