Find the nearest common commit id to the MERGE_POINT

nearest_common_commit_to_merge_point.sh

#
# Checks if differences occur between two branches.
#
# Usage:
#     source ./build_utils.sh
#     DIRECTORY="idbc"
#     #before merge
#     COMMON_COMMITS_ID=`common_branch_commit_id ur_branch_1 trunk/master`
#     #after merge
#     RES=`diferences_check $COMMON_COMMITS_ID HEAD $DIRECTORY`
#

# Gets the nearest common parent commit_id of two branches.
# before merge
function common_branch_commit_id(){
  CURRENT_BRANCH_COMMIT_ID=$1
  REMOTE_BRANCH_COMMIT_ID=$2
  COMMON_COMMIT_ID=`git merge-base $CURRENT_BRANCH_COMMIT_ID $REMOTE_BRANCH_COMMIT_ID`
  echo $COMMON_COMMIT_ID
}

# Checks differences between two commits.
#
# If any file of DIRECTORY has been changed from commit_a to commit_b, returns Y.
# otherwise, returns N.
function differences_check(){
  FIRST_COMMIT_ID=$1
  SECOND_COMMIT_ID=$2
  DIRECTORY=$3
  git diff --exit-code --name-only $FIRST_COMMIT_ID $SECOND_COMMIT_ID $DIRECTORY > /dev/null
  if [[ $? == 1 ]]; then
    echo "Y"
  else
    echo "N"
  fi
}

#
# Gets latest commit id of last successful pipeline.
# INPUTS:
# TOKEN, PRIVATE-TOKEN of gitlab by curl.
# PRJ_NAME, project name. If project under some namespace, use ${NAMESPACE}%2F${PROJECT_NAME}.
# BRANCH_NAME, default is master.
#
function get_last_successed_pipeline_commit_id(){
  set +e
  TOKEN=$1
  PRJ_NAME=$2
  BRANCH_NAME=$3
  if [[ $BRANCH_NAME == "" ]]; then BRANCH_NAME="master"; fi
  PIPELINE_INFO=`curl --header "PRIVATE-TOKEN: ${TOKEN}" "http://172.16.1.41:10080/api/v4/projects/${PRJ_NAME}/pipelines?scope=finished&status=success&ref=${BRANCH_NAME}&per_page=1&page=1"`
  COMMIT_ID=`awk -F '"' '{print $6}' ${PIPELINE_INFO}`
  set -e
  echo ${COMMIT_ID}
}


# Find the nearest common commit id to the MERGE_POINT.
# Assume the following history exists and the current branch is "master":
#           5  branch_2
#        /     \
#       3---6---M1---7   branch_1
#      /              \
# 1---2---4------------M2---8 master
#
# Usages and explanations:

#  nearest_common_commit_to_merge_point M1 returns 3,
#  nearest_common_commit_to_merge_point M2 returns 2.
#
function nearest_common_commit_to_merge_point(){
  MERGE_POINT=$1
  # Current on the master branch.
  # get all parents from merged commit id(HEAD).
  parents_commits=`git rev-list --parents -n 1 ${MERGE_POINT}`
  #Commits on master branch
  common_commit[0]=`git log --pretty=format:"%h" --first-parent ${parents_commits[0]}`
  common_commit_arr_1st=(${common_commit[0]//\n/ })
  #Find all common commits from HEAD(Merged point).
  for first_parents in ${parents_commits}
  do
    common_commit[1]=`git log --pretty=format:"%h" --first-parent ${first_parents}`
    common_commit_arr_2nd=(${common_commit[1]//\n/ })
    common_commit_arr_1st=($(comm -12 <(printf '%s\n' "${common_commit_arr_1st[@]}" | LC_ALL=C sort) <(printf '%s\n' "${common_commit_arr_2nd[@]}" | LC_ALL=C sort)))
  done
  #All we need is the top commit id in common commits.
  common_id=${common_commit_arr_1st[0]}
  echo ${common_id}
}


#初始化build history环境
#默认在 ~/ 目录下建立 .build_history 文件夹
function init_history(){
  cd ~
  export history_root="`pwd`/.build_history"
  cd -
  if [[ ! -d "$history_root" ]]; then
     mkdir ${history_root}
  fi
}
#写入当前build的commit id戳
# write_path: 历史记录文件路径
# branch_name: 分支名
# commit_id: 要写入的commit id
function write_build_history(){
   write_path=$1
   branch_name=$2
   commit_id=$3
   BUILT=`check_if_built ${write_path} ${branch_name}`

   contents=${branch_name}:${commit_id}

   if [[ ${BUILT} == "Y" ]]; then
     sed -i "s/${branch_name}:.*/${contents}/g" ${file_path}
   else
     echo "${contents}" >> ${write_path}
   fi
}
#获取或创建built历史记录
#write_path: 历史记录存放路径
function mk_or_get_file_path(){
  write_path=$1
  if [[ ! -d "$write_path" ]]; then
    mkdir -p $write_path
  fi 
  file_path="${write_path}/last_build"
  touch ${file_path}
  echo ${file_path}
}
# 检查是否已被buid过
# file_path: 历史记录存放文件路径
# branch_name: 分支名
function check_if_built(){
   file_path=$1
   branch_name=$2
   BUILT="N"
   grep ${branch_name} ${file_path} > /dev/null
   if [[ $? == 0 ]]; then
     BUILT="Y"
   fi
   echo $BUILT
}

#获取上一次build的commit id
#write_path: 历史记录存放文件夹
#branch_name: 分支名 
function get_last_built_commit(){
  write_path=$1
  branch_name=$2
  file_path="`mk_or_get_file_path ${write_path} ${branch_name}`"
  last_built_commit_id=`grep -w "${branch_name}" ${file_path} | awk -F ":" '{print $2}'`
  #if [[ -z last_built_commit_id ]]; then
  #  last_built_commit_id="HEAD"
  #fi
  echo ${last_built_commit_id}
}

#检查目录当前commit是否已经build过，未build返回‘Y’
#module_dir: 目录路径， 该路径会转换为md5值.
function check_if_need_build(){
  module_dir=$1
  module_dir=`echo -n ${module_dir} | md5sum | cut -d ' ' -f1`
  echo ${module_dir}
  branch_name=$2
  #1. init
  init_history
  #2. check history
  module_history=`mk_or_get_file_path "${history_root}/${module_dir}"`
  built=`check_if_built ${module_history} ${branch_name}`
  last_built_commit="HEAD"
  changed="Y" #default "Y"
  if [[ ${built} == "Y" ]]; then
    last_built_commit=`get_last_built_commit ${module_history} ${branch_name}`
    changed=`differences_check ${last_built_commit} "HEAD" ${module_dir}`
  fi
  #3. check changed or not
  if [[ ${changed} == "Y" ]]; then
    echo "Y"
  else
    echo "N"
  fi
}
#将当前的commit id写入历史记录
# module_dir: 目录路径
# branch_name: 分支名
function post_build(){
  module_dir=$1
  branch_name=$2
  commit_id=`git log --pretty=format:"%h" -n 1 ${module_dir}`
  module_dir=`echo -n ${module_dir} | md5sum | cut -d ' ' -f1`
  module_history=`mk_or_get_file_path ${history_root}/${module_dir}`
  write_build_history ${module_history} ${branch_name} ${commit_id}
}