[01/12] check: improve test list randomization

Commit Message

Darrick J. Wong March 20, 2019, 12:44 a.m. UTC

From: Darrick J. Wong <[e-mail]>

awk doesn't have a particularly good random number generator -- it seeds
from the Unix epoch time in seconds, which means that the run order
across a bunch of VMs started at exactly the same time are unsettlingly
predictable.  Therefore, at least try to seed it with bash's $RANDOM,
which is slightly less predictable.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 check         |   12 ++++++------
 randomize.awk |   12 ++++++++----
 2 files changed, 14 insertions(+), 10 deletions(-)

Patch

diff --git a/check b/check
index 20e95302..ecd1d39a 100755
--- a/check
+++ b/check
@@ -242,13 +242,13 @@  _prepare_test_list()
 	done
 
 	# sort the list of tests into numeric order
-	list=`sort -n $tmp.list | uniq`
-	rm -f $tmp.list
-
-	if $randomize
-	then
-		list=`echo $list | awk -f randomize.awk`
+	if $randomize; then
+		sorter="awk -v seed=$RANDOM -f randomize.awk"
+	else
+		sorter="cat"
 	fi
+	list=`sort -n $tmp.list | uniq | $sorter`
+	rm -f $tmp.list
 }
 
 # Process command arguments first.
diff --git a/randomize.awk b/randomize.awk
index 0a8ad71a..d979fb03 100644
--- a/randomize.awk
+++ b/randomize.awk
@@ -15,10 +15,14 @@  function randomize(array, N) {
 return
 }
 
+BEGIN {
+	srand(seed)
+}
 {
-    srand()
-    for (i = 0; i < NF; i++ ) array[i] = $(i+1)
-    randomize(array, NF)
-    for (i = 0; i < NF; i++) printf("%s ", array[i])
+	array[NR - 1] = $0
+}
+END {
+    randomize(array, NR)
+    for (i = 0; i < NR; i++) printf("%s ", array[i])
 }