validate parent chain only once

hooks/validate.sh

@@ -44,6 +44,7 @@ if [[ ! -d "$DIR" ]]; then DIR="$PWD"; fi
 declare -i MINVERSION=$TIMESTAMPING_VERSION
 declare -i MAX_COMMITS_TO_CHECK=0
 declare -A PROCESSED_COMMIT
+declare -A PROCESSED_PARENT
 declare -A COMMITS
 declare -A COMMIT_TIMES
 
@@ -323,12 +324,19 @@ validate_commit_and_parents() {
   local COMMIT_HASH="$1"
   log "validate_commit_and_parents for $COMMIT_HASH"
 
+  if [[ ${PROCESSED_PARENT[$COMMIT_HASH]} ]]; then
+    log "parents for $COMMIT_HASH have already been validated"
+    return 0;
+  else
+    PROCESSED_PARENT[$COMMIT_HASH]=1
+  fi
   local ALL_PASSED=true
   if ! validate_commit "$COMMIT_HASH"; then
     ALL_PASSED=false
   fi
   NUM_COMMITS_CHECKED=${#PROCESSED_COMMIT[@]}
   local PARENTS=$(git cat-file -p "$COMMIT_HASH" | awk '/^$/{exit} /parent/ {print}' | sed 's/parent //')
+
   #iterate over all parents of commit
   if [ ! -z "$PARENTS" ]; then
     while read PARENT_HASH; do
@@ -337,6 +345,7 @@ validate_commit_and_parents() {
       fi
     done <<< $(printf "%s" "$PARENTS")
   fi
+
   if [ "$ALL_PASSED" = true ]; then
     return 0
   fi