server/update-prefer-rebase

   1 #!/bin/sh
   2 #
   3 # Watches for merges that had only local merges (e.g. should have been rebases).
   4 #
   5 # If they are introducing non-merge commits /and/ merge commits, it could
   6 # look like one of two ways. This way:
   7 #
   8 # * --- B --- * --- oldrev
   9 #        \             \
  10 #        new --- new --- newrev
  11 #
  12 # They basically had an un-shared local dev branch (probably by making a
  13 # merge) and instead should have done a rebase. Also, if they did:
  14 #
  15 # * --- B --- * --- oldrev
  16 #        \             \
  17 #        new --- new --- new -- newrev
  18 #
  19 # We should try and catch them--where the merge happened previously to
  20 # them doing more work in the newrev commit.
  21 #
  22 # But if it looks like:
  23 #
  24 # * --- B --- * --- oldrev
  25 #        \              \
  26 #        old --- new --- newrev
  27 #
  28 # Then they had a pre-shared branch that cannot be rebased and so they
  29 # were correct in doing a merge to tie "old" and "oldrev" together.
  30 #
  31 # Also, we obviously have to be okay with:
  32 #
  33 # * --- * --- * --- oldrev --- new --- new --- newrev
  34
  35 refname="$1"
  36 oldrev="$2"
  37 newrev="$3"
  38
  39 if expr "$oldrev" : '0*$' >/dev/null ; then
  40         exit 0
  41 fi
  42
  43 # Read backwards: all commits from old..new, unless they are already referenced by a branch
  44 git rev-parse --not --branches | git rev-list --stdin $oldrev..$newrev | while read commit ; do
  45         number_of_parents=$(git rev-list -n 1 --parents $commit | sed 's/ /\n/g' | grep -v $commit | wc -l)
  46         if [[ $number_of_parents > 1 ]] ; then
  47                 # Hack to not interfer with the update-stable "--no-ff" method
  48                 if [[ "$refname" == "refs/heads/stable" && "$commit" == "$newrev" ]] ; then
  49                         exit 0
  50                 fi
  51
  52                 # Find the original branch point (B)
  53                 parents=$(git rev-list -n 1 --parents $commit | sed 's/ /\n/g' | grep -v $commit)
  54
  55                 # For each baserev
  56                 git merge-base --all $parents | while read baserev ; do
  57                         # For each parent
  58                         git rev-list -n 1 --parents $commit | sed 's/ /\n/g' | grep -v $commit | while read parent ; do
  59                                 parent_is_old=$(git branch --contains $parent | wc -l)
  60                                 all_commits=$(git rev-list --first-parent $baserev..$parent | wc -l)
  61                                 new_commits=$(git rev-parse --not --branches | git rev-list --stdin $baserev..$parent | wc -l)
  62                                 if [ $parent_is_old -gt 0 -a $all_commits -eq $new_commits ] ; then
  63                                         # echo "parent=$parent"
  64                                         # echo "all_commits=$all_commits"
  65                                         # echo "new_commits=$new_commits"
  66                                         echo "----------------------------------------------------"
  67                                         echo
  68                                         echo "It looks like you should rebase instead of merging $commit"
  69                                         echo
  70                                         echo "----------------------------------------------------"
  71                                         exit 1
  72                                 fi
  73                         done
  74                         if [ $? -ne 0 ] ; then
  75                                 exit 1
  76                         fi
  77                 done
  78                 if [ $? -ne 0 ] ; then
  79                         exit 1
  80                 fi
  81         fi
  82 done
  83