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 # A -- B             <-- origin/topic
   9 #  \    \
  10 #   c -- d           <-- topic
  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 # A -- B             <-- origin/topic
  16 #  \    \
  17 #   c -- d -- e      <-- topic
  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 # A -- B             <-- origin/foo
  25 #  \    \
  26 #   C    \           <-- origin/topic
  27 #    \    \
  28 #     d -- e         <-- topic
  29 #
  30 # Then they had a pre-shared branch that cannot be rebased and so they
  31 # were correct in doing a merge to tie "old" and "oldrev" together.
  32 #
  33 # Also, we obviously have to be okay with:
  34 #
  35 # A -- B            <-- origin/topic
  36 #       \
  37 #        c -- d     <-- topic
  38
  39 refname="$1"
  40 oldrev="$2"
  41 newrev="$3"
  42
  43 if expr "$oldrev" : '0*$' >/dev/null ; then
  44         exit 0
  45 fi
  46
  47 # Read backwards: all commits from old..new, unless they are already referenced by a branch
  48 git rev-parse --not --branches | git rev-list --stdin $oldrev..$newrev | while read commit ; do
  49         number_of_parents=$(git rev-list -n 1 --parents $commit | sed 's/ /\n/g' | grep -v $commit | wc -l)
  50         if [[ $number_of_parents > 1 ]] ; then
  51                 # Hack to not interfer with the update-stable "--no-ff" method
  52                 if [[ "$refname" == "refs/heads/stable" && "$commit" == "$newrev" ]] ; then
  53                         exit 0
  54                 fi
  55
  56                 # Find the original branch point (B)
  57                 parents=$(git rev-list -n 1 --parents $commit | sed 's/ /\n/g' | grep -v $commit)
  58
  59                 # For each baserev
  60                 git merge-base --all $parents | while read baserev ; do
  61                         # For each parent
  62                         git rev-list -n 1 --parents $commit | sed 's/ /\n/g' | grep -v $commit | while read parent ; do
  63                                 all_commits=$(git rev-list --first-parent $baserev..$parent | wc -l)
  64                                 new_commits=$(git rev-parse --not --branches | git rev-list --stdin $baserev..$parent | wc -l)
  65                                 if [ $all_commits -eq $new_commits ] ; then
  66                                         # echo "parent=$parent"
  67                                         # echo "all_commits=$all_commits"
  68                                         # echo "new_commits=$new_commits"
  69                                         echo "----------------------------------------------------"
  70                                         echo
  71                                         echo "It looks like you should rebase instead of merging $commit"
  72                                         echo
  73                                         echo "----------------------------------------------------"
  74                                         exit 1
  75                                 fi
  76                         done
  77                         if [ $? -ne 0 ] ; then
  78                                 exit 1
  79                         fi
  80                 done
  81                 if [ $? -ne 0 ] ; then
  82                         exit 1
  83                 fi
  84         fi
  85 done
  86