server/update-stable

   1 #!/bin/sh
   2
   3 #
   4 # This enforces stable/candidate/topic patterns.
   5 #
   6 # Specifically:
   7 #
   8 # * stable must be moved 1 merge commit at a time (see below)
   9 # * candidates/topics are frozen once merged into stable
  10 # * topics are frozen once merged into candidates
  11 #
  12 # For DAG aesthetics, we prefer stable only moving in the approved way,
  13 # which is via empty (no change) merge commits. The rationale is that
  14 # in the DAG we want a simple, one-commit move from each release to the
  15 # next.
  16 #
  17 # We started out with:
  18 #
  19 # * -- A                stable
  20 #  \    \
  21 #   \    * -- * -- B    topic1
  22 #    \           /
  23 #     * -- * -- *       topic2
  24 #
  25 # And then publishing stable was a matter of fast-forwarding
  26 # from A to B.
  27 #
  28 # In a complicated (non-rebased) DAG, this becomes hard to follow,
  29 # so want we want instead is:
  30 #
  31 # * -- A ----------- C  stable
  32 #  \    \           /
  33 #   \    * -- * -- B    topic1
  34 #    \           /
  35 #     * -- * -- *       topic2
  36 #
  37 # Where commit C lists as it's first parent the prior stable
  38 # commit and as it's second parent the release candidate. No
  39 # other parents are allowed (e.g. no octopus merges here, which
  40 # would insinuate qa didn't happen on the merged result).
  41 #
  42 # Also, we want to enforce that C does not actually introduce
  43 # any diffs to the files between B and C--otherwise this changes
  44 # would not have appeared in QA.
  45 #
  46
  47 refname="$1"
  48 oldrev="$2"
  49 newrev="$3"
  50
  51 . $(dirname $0)/functions
  52 set_change_type
  53
  54 case "$refname" in
  55         refs/heads/*)
  56                 short_refname=${refname##refs/heads/}
  57                 ;;
  58         *)
  59                 exit 0
  60                 ;;
  61 esac
  62
  63 if [ "$change_type" == "delete" ] ; then
  64         exit 0
  65 fi
  66
  67 if [ "$change_type" == "create" -a "$short_refname" != "stable" ] ; then
  68         not_on_stable=$(git rev-list stable..$newrev)
  69         if [ "$not_on_stable" == "" ] ; then
  70                 echo "----------------------------------------------------"
  71                 echo
  72                 echo "Creating a branch must include new commits"
  73                 echo
  74                 echo "----------------------------------------------------"
  75                 exit 1
  76         fi
  77 fi
  78
  79 # create/delete is okay
  80 if [ "$change_type" != "update" ] ; then
  81         exit 0
  82 fi
  83
  84 # # The tip must always be new
  85 # already=$(git branch --contains "$newrev")
  86 # if [ "$already" != "" ] ; then
  87 #       already=${already##  }
  88 #       echo "----------------------------------------------------"
  89 #       echo
  90 #       echo "$short_refname is already referred to by $already"
  91 #       echo
  92 #       echo "----------------------------------------------------"
  93 #       exit 1
  94 #fi
  95
  96 if [ "$short_refname" == "stable" ] ; then
  97         # Stable enforcement
  98
  99         # read backwards:
 100         # - all commits from old..new
 101         # - unless they were already pointed to by a branch
 102         # = all new commits on stable
 103         count=$(git rev-parse --not --branches | git rev-list --stdin $oldrev..$newrev | wc -l)
 104         if [ "$count" -ne "1" ] ; then
 105                 echo "----------------------------------------------------"
 106                 echo
 107                 echo "Moving stable must entail a single commit"
 108                 echo
 109                 echo "----------------------------------------------------"
 110                 exit 1
 111         fi
 112
 113         number_of_parents=$(git rev-list --no-walk --parents $newrev | sed 's/ /\n/g' | grep -v $newrev | wc -l)
 114         if [ "$number_of_parents" -ne "2" ] ; then
 115                 echo "----------------------------------------------------"
 116                 echo
 117                 echo "Moving stable must entail a merge commit"
 118                 echo
 119                 echo "----------------------------------------------------"
 120                 exit 1
 121         fi
 122
 123         first_parent=$(git rev-list --no-walk --parents $newrev | sed 's/ /\n/g' | grep -v $newrev | head --lines=1)
 124         if [ "$first_parent" != "$oldrev" ] ; then
 125                 echo "----------------------------------------------------"
 126                 echo
 127                 echo "Moving stable must have the previous stable as the first parent"
 128                 echo
 129                 echo "----------------------------------------------------"
 130                 exit 1
 131         fi
 132
 133         second_parent=$(git rev-list --no-walk --parents $newrev | sed 's/ /\n/g' | grep -v $newrev | tail --lines=1)
 134         changed_lines=$(git diff $second_parent..$newrev | wc -l)
 135         if [ "$changed_lines" -ne "0" ] ; then
 136                 echo "----------------------------------------------------"
 137                 echo
 138                 echo "Moving stable must not result in any changes from $second_parent"
 139                 echo
 140                 echo "----------------------------------------------------"
 141                 exit 1
 142         fi
 143 else
 144         # Check if candidate/topic is already in stable
 145         git branch --contains "$oldrev" | grep stable >/dev/null
 146         if [ $? -eq 0 ] ; then
 147                 echo "----------------------------------------------------"
 148                 echo
 149                 echo "$short_refname has been merged into stable"
 150                 echo
 151                 echo "----------------------------------------------------"
 152                 exit 1
 153         fi
 154
 155         # For now candidates can mix amongst each other so early exit
 156         case "$refname" in
 157                 refs/heads/candidate*)
 158                         exit 0
 159                         ;;
 160                 *)
 161                         ;;
 162         esac
 163
 164         # Check if topic is already in candidates
 165         candidate=$(git branch --contains "$oldrev" | grep -oP "candidate.*" --max-count=1)
 166         if [ $? -eq 0 ] ; then
 167                 echo "----------------------------------------------------"
 168                 echo
 169                 echo "$short_refname has been merged into $candidate"
 170                 echo
 171                 echo "----------------------------------------------------"
 172                 exit 1
 173         fi
 174 fi
 175