feat(bisect): introduce scripts for VPP bisecting

+ Parsing common with per-patch job is moved to a library.

Ticket: CSIT-1618

Change-Id: I185bea084a29e6a37ef94e9da42b192a6a81fc17
Signed-off-by: Vratko Polak <vrpolak@cisco.com>

2 files changed, 78 insertions, 1 deletions

diff --git a/resources/libraries/bash/function/common.sh b/resources/libraries/bash/function/common.sh
index 44149ca6e1..c2b169f550 100644
--- a/resources/libraries/bash/function/common.sh
+++ b/resources/libraries/bash/function/common.sh
@@ -290,7 +290,7 @@ function compose_robot_arguments () {
         *"device"*)
             ROBOT_ARGS+=("--suite" "tests.${DUT}.device")
             ;;
-        *"perf"*)
+        *"perf"* | *"bisect"*)
             ROBOT_ARGS+=("--suite" "tests.${DUT}.perf")
             ;;
         *)
@@ -557,6 +557,8 @@ function get_test_tag_string () {
     # Variables set:
     # - TEST_TAG_STRING - The string following trigger word in gerrit comment.
     #   May be empty, or even not set on event types not adding comment.
+    # - GIT_BISECT_FROM - If bisecttest, the commit hash to bisect from.
+    #   Else not set.
     # Variables exported optionally:
     # - GRAPH_NODE_VARIANT - Node variant to test with, set if found in trigger.
 
@@ -566,6 +568,10 @@ function get_test_tag_string () {
 
     if [[ "${GERRIT_EVENT_TYPE-}" == "comment-added" ]]; then
         case "${TEST_CODE}" in
+            # Order matters, bisect job contains "perf" in its name.
+            *"bisect"*)
+                trigger="bisecttest"
+                ;;
             *"device"*)
                 trigger="devicetest"
                 ;;
@@ -591,6 +597,18 @@ function get_test_tag_string () {
             comment=$(fgrep "${trigger}" <<< "${comment}" || true)
             TEST_TAG_STRING=$("${cmd[@]}" <<< "${comment}" || true)
         fi
+        if [[ "${trigger}" == "bisecttest" ]]; then
+            # Intentionally without quotes, so spaces delimit elements.
+            test_tag_array=(${TEST_TAG_STRING}) || die "How could this fail?"
+            # First "argument" of bisecttest is a commit hash.
+            GIT_BISECT_FROM="${test_tag_array[0]}" || {
+                die "Bisect job requires commit hash."
+            }
+            # Update the tag string (tag expressions only, no commit hash).
+            TEST_TAG_STRING="${test_tag_array[@]:1}" || {
+                die "Bisect job needs a single test, no default."
+            }
+        fi
         if [[ -n "${TEST_TAG_STRING-}" ]]; then
             test_tag_array=(${TEST_TAG_STRING})
             if [[ "${test_tag_array[0]}" == "icl" ]]; then
diff --git a/resources/libraries/bash/function/per_patch.sh b/resources/libraries/bash/function/per_patch.sh
index b9680a1560..44bd57da80 100644
--- a/resources/libraries/bash/function/per_patch.sh
+++ b/resources/libraries/bash/function/per_patch.sh
@@ -110,6 +110,65 @@ function initialize_csit_dirs () {
 }
 
 
+function main_bisect_loop () {
+
+    # Perform the iterative part of bisect entry script.
+    #
+    # The logic is too complex to remain in the entry script.
+    #
+    # At the start, the loop assumes git bisect old/new has just been executed,
+    # and verified more iterations are needed.
+    # The iteration cleans the build directory and builds the new mid commit.
+    # Then, testbed is reserved, tests run, and testbed unreserved.
+    # Results are moved from default to archive location
+    # (indexed by iteration number) and analyzed.
+    # The new adjective ("old" or "new") is selected,
+    # and git bisect with the adjective is executed.
+    # The symlinks csit_early and csit_late are updated to tightest bounds.
+    # The git.log file is examined and if the bisect is finished, loop ends.
+
+    iteration=0
+    while true
+    do
+        let iteration+=1
+        git clean -dffx "build"/ "build-root"/ || die
+        build_vpp_ubuntu "MIDDLE" || die
+        select_build "build-root" || die
+        check_download_dir || die
+        reserve_and_cleanup_testbed || die
+        run_robot || die
+        move_test_results "csit_middle/${iteration}" || die
+        untrap_and_unreserve_testbed || die
+        rm -vf "csit_mid" || die
+        ln -s -T "csit_middle/${iteration}" "csit_mid" || die
+        set +e
+        python3 "${TOOLS_DIR}/integrated/compare_bisect.py"
+        bisect_rc="${?}"
+        set -e
+        if [[ "${bisect_rc}" == "3" ]]; then
+            adjective="new"
+            rm -v "csit_late" || die
+            ln -s -T "csit_middle/${iteration}" "csit_late" || die
+        elif [[ "${bisect_rc}" == "0" ]]; then
+            adjective="old"
+            rm -v "csit_early" || die
+            ln -s -T "csit_middle/${iteration}" "csit_early" || die
+        else
+            die "Unexpected return code: ${bisect_rc}"
+        fi
+        git bisect "${adjective}" | tee "git.log" || die
+        git describe || die
+        git status || die
+        if head -n 1 "git.log" | cut -b -11 | fgrep -q "Bisecting:"; then
+            echo "Still bisecting..."
+        else
+            echo "Bisecting done."
+            break
+        fi
+    done
+}
+
+
 function move_test_results () {
 
     # Arguments: