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 if [ "$short_refname" == "stable" ] ; then
  85         # Stable enforcement
  86
  87         # read backwards:
  88         # - all commits from old..new
  89         # - unless they were already pointed to by a branch
  90         # = all new commits on stable
  91         count=$(git rev-parse --not --branches | git rev-list --stdin $oldrev..$newrev | wc -l)
  92         if [ "$count" -ne "1" ] ; then
  93                 echo "----------------------------------------------------"
  94                 echo
  95                 echo "Moving stable must entail a single commit"
  96                 echo
  97                 echo "----------------------------------------------------"
  98                 exit 1
  99         fi
 100
 101         number_of_parents=$(git rev-list --no-walk --parents $newrev | sed 's/ /\n/g' | grep -v $newrev | wc -l)
 102         if [ "$number_of_parents" -ne "2" ] ; then
 103                 echo "----------------------------------------------------"
 104                 echo
 105                 echo "Moving stable must entail a merge commit"
 106                 echo
 107                 echo "----------------------------------------------------"
 108                 exit 1
 109         fi
 110
 111         first_parent=$(git rev-list --no-walk --parents $newrev | sed 's/ /\n/g' | grep -v $newrev | head --lines=1)
 112         if [ "$first_parent" != "$oldrev" ] ; then
 113                 echo "----------------------------------------------------"
 114                 echo
 115                 echo "Moving stable must have the previous stable as the first parent"
 116                 echo
 117                 echo "----------------------------------------------------"
 118                 exit 1
 119         fi
 120
 121         second_parent=$(git rev-list --no-walk --parents $newrev | sed 's/ /\n/g' | grep -v $newrev | tail --lines=1)
 122         changed_lines=$(git diff $second_parent..$newrev | wc -l)
 123         if [ "$changed_lines" -ne "0" ] ; then
 124                 echo "----------------------------------------------------"
 125                 echo
 126                 echo "Moving stable must not result in any changes from $second_parent"
 127                 echo
 128                 echo "----------------------------------------------------"
 129                 exit 1
 130         fi
 131 else
 132         # Check if candidate/topic is already in stable
 133         git branch --contains "$oldrev" | grep stable >/dev/null
 134         if [ $? -eq 0 ] ; then
 135                 echo "----------------------------------------------------"
 136                 echo
 137                 echo "$short_refname has been merged into stable"
 138                 echo
 139                 echo "----------------------------------------------------"
 140                 exit 1
 141         fi
 142
 143         # For now candidates can mix amongst each other so early exit
 144         case "$refname" in
 145                 refs/heads/candidate*)
 146                         exit 0
 147                         ;;
 148                 *)
 149                         ;;
 150         esac
 151
 152         # Check if topic is already in candidates
 153         candidate=$(git branch --contains "$oldrev" | grep -oP candidate.* --max-count=1)
 154         if [ $? -eq 0 ] ; then
 155                 echo "----------------------------------------------------"
 156                 echo
 157                 echo "$short_refname has been merged into $candidate"
 158                 echo
 159                 echo "----------------------------------------------------"
 160                 exit 1
 161         fi
 162 fi
 163