From d04c755cb2852cb088990d94dc7ae88b4e5ef656 Mon Sep 17 00:00:00 2001
From: Maxim Kuvyrkov <maxim.kuvyrkov@linaro.org>
Date: Tue, 5 Jan 2021 19:30:18 +0000
Subject: round-robin-bisect.sh: Make logic of handling successful bisects more
 robust

Now on successful bisects we always have either a confirmed
regression or a restarted bisect.

Change-Id: Ic8600fa85c7b511063ddf5bbbbff31021a8b9535
---
 round-robin-bisect.sh | 57 ++++++++++++++++++++++++++-------------------------
 1 file changed, 29 insertions(+), 28 deletions(-)

diff --git a/round-robin-bisect.sh b/round-robin-bisect.sh
index 8a49e0c0..016d0883 100755
--- a/round-robin-bisect.sh
+++ b/round-robin-bisect.sh
@@ -343,6 +343,8 @@ touch ../interesting-commits/$current_project
 # Generate list of commits inside the bisection range.
 commits_to_test=$artifacts/git-logs/commits_to_test
 git bisect view --pretty=%H > $commits_to_test
+orig_commits_to_test=$artifacts/git-logs/orig_commits_to_test
+cp $commits_to_test $orig_commits_to_test
 # This loop can generate lots of console noise.
 set +x
 while [ x"$(get_first_bad </dev/null)" = x"" ] && read -a arr; do
@@ -396,8 +398,13 @@ notify_devs=true
 if [ x"$first_bad" != x"" ]; then
     # "git bisect run" succeeded.  Check whether this is an actual regression
     # or bisection artifact.
-    res=0
-    for last_good in $(git rev-parse $first_bad^@); do
+    last_good=""
+    bad_last_good=""
+    for sha1 in $(git rev-parse $first_bad^@); do
+	# Ignore commits outside of original bisection range.
+	if ! grep -q "^$sha1\$" $orig_commits_to_test; then
+	    continue
+	fi
 	# It seems that git-bisect assumes parent commit as "good" on
 	# the basis of one of its children being "good".  Therefore we
 	# can have a situation when we have parent P with children C1 and C2,
@@ -411,41 +418,35 @@ if [ x"$first_bad" != x"" ]; then
 	$artifacts/test.sh &
 	res=0 && wait $! || res=$?
 	if [ x"$res" = x"0" ]; then
+	    last_good=$sha1
 	    break
 	fi
+	bad_last_good=$sha1
     done
-    # Add both $last_good and $first_bad to interesting commits.
-    push_interesting_commit $last_good "last-good"
-    push_interesting_commit $first_bad "regression"
-    if [ x"$push_interesting_commit_result" = x"125" ]; then
-	notify_devs=false
-    fi
-    if [ x"$res" = x"0" ]; then
+
+    if [ x"$last_good" != x"" ]; then
 	# Success!  Touch $artifacts/first-bad as a marker of successful bisect.
 	echo $first_bad > $artifacts/first-bad
+	# Add both $last_good and $first_bad to interesting commits.
+	push_interesting_commit $last_good "last-good"
+	push_interesting_commit $first_bad "regression"
+	if [ x"$push_interesting_commit_result" = x"125" ]; then
+	    notify_devs=false
+	fi
     else
-	# It seems $last_good was on a path that tested good, even though
-	# it itself is bad.
-	#
-	# We need to be careful to avoid re-trigger loops
-	assert_with_msg "Last good is not an ancestor of bad rev!" \
-	  git merge-base --is-ancestor $last_good $bad_rev
-	if git merge-base --is-ancestor $baseline_rev $last_good; then
-	    # $last_good is a child of $baseline_rev, so we can re-trigger
-	    # bisection with reduced bisection range.
-	    cat > $artifacts/trigger-bisect <<EOF
+	assert_with_msg "Broken bisection range" [ x"$bad_last_good" != x"" ]
+	# All parents of $first_bad tested bad, so retrigger bisection with
+	# a reduced bisection range.
+	cat > $artifacts/trigger-bisect <<EOF
 current_project=$current_project
 bad_url=$bad_url
-bad_branch=$last_good
+bad_branch=$bad_last_good
 EOF
-	    sed -i -e "s/\$/-last_good-bad/" $artifacts/jenkins/build-name
-	    # Don't send any emails.
-	    echo > $artifacts/jenkins/mail-recipients.txt
-	    trap "" EXIT
-	    exit 0
-	fi
-	# This case will be handled similar to "git bisect run" failure below.
-	# We are going to reset baseline to $first_bad.
+	sed -i -e "s/\$/-retry-bisect/" $artifacts/jenkins/build-name
+	# Don't send any emails.
+	echo > $artifacts/jenkins/mail-recipients.txt
+	trap "" EXIT
+	exit 0
     fi
 else
     # When "git bisect run" fails, e.g., due to merge-base of $baseline_rev and
-- 
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