Andrew's git - gitweb.git/blob - templates/hooks--pre-rebase

   1#!/bin/sh
   2#
   3# Copyright (c) 2006 Junio C Hamano
   4#
   5
   6publish=next
   7basebranch="$1"
   8if test "$#" = 2
   9then
  10        topic="refs/heads/$2"
  11else
  12        topic=`git symbolic-ref HEAD`
  13fi
  14
  15case "$basebranch,$topic" in
  16master,refs/heads/??/*)
  17        ;;
  18*)
  19        exit 0 ;# we do not interrupt others.
  20        ;;
  21esac
  22
  23# Now we are dealing with a topic branch being rebased
  24# on top of master.  Is it OK to rebase it?
  25
  26# Is topic fully merged to master?
  27not_in_master=`git-rev-list --pretty=oneline ^master "$topic"`
  28if test -z "$not_in_master"
  29then
  30        echo >&2 "$topic is fully merged to master; better remove it."
  31        exit 1 ;# we could allow it, but there is no point.
  32fi
  33
  34# Is topic ever merged to next?  If so you should not be rebasing it.
  35only_next_1=`git-rev-list ^master "^$topic" ${publish} | sort`
  36only_next_2=`git-rev-list ^master           ${publish} | sort`
  37if test "$only_next_1" = "$only_next_2"
  38then
  39        not_in_topic=`git-rev-list "^$topic" master`
  40        if test -z "$not_in_topic"
  41        then
  42                echo >&2 "$topic is already up-to-date with master"
  43                exit 1 ;# we could allow it, but there is no point.
  44        else
  45                exit 0
  46        fi
  47else
  48        not_in_next=`git-rev-list --pretty=oneline ^${publish} "$topic"`
  49        perl -e '
  50                my $topic = $ARGV[0];
  51                my $msg = "* $topic has commits already merged to public branch:\n";
  52                my (%not_in_next) = map {
  53                        /^([0-9a-f]+) /;
  54                        ($1 => 1);
  55                } split(/\n/, $ARGV[1]);
  56                for my $elem (map {
  57                                /^([0-9a-f]+) (.*)$/;
  58                                [$1 => $2];
  59                        } split(/\n/, $ARGV[2])) {
  60                        if (!exists $not_in_next{$elem->[0]}) {
  61                                if ($msg) {
  62                                        print STDERR $msg;
  63                                        undef $msg;
  64                                }
  65                                print STDERR " $elem->[1]\n";
  66                        }
  67                }
  68        ' "$topic" "$not_in_next" "$not_in_master"
  69        exit 1
  70fi
  71
  72exit 0
  73
  74################################################################
  75
  76This sample hook safeguards topic branches that have been
  77published from being rewound.
  78
  79The workflow assumed here is:
  80
  81 * Once a topic branch forks from "master", "master" is never
  82   merged into it again (either directly or indirectly).
  83
  84 * Once a topic branch is fully cooked and merged into "master",
  85   it is deleted.  If you need to build on top of it to correct
  86   earlier mistakes, a new topic branch is created by forking at
  87   the tip of the "master".  This is not strictly necessary, but
  88   it makes it easier to keep your history simple.
  89
  90 * Whenever you need to test or publish your changes to topic
  91   branches, merge them into "next" branch.
  92
  93The script, being an example, hardcodes the publish branch name
  94to be "next", but it is trivial to make it configurable via
  95$GIT_DIR/config mechanism.
  96
  97With this workflow, you would want to know:
  98
  99(1) ... if a topic branch has ever been merged to "next".  Young
 100    topic branches can have stupid mistakes you would rather
 101    clean up before publishing, and things that have not been
 102    merged into other branches can be easily rebased without
 103    affecting other people.  But once it is published, you would
 104    not want to rewind it.
 105
 106(2) ... if a topic branch has been fully merged to "master".
 107    Then you can delete it.  More importantly, you should not
 108    build on top of it -- other people may already want to
 109    change things related to the topic as patches against your
 110    "master", so if you need further changes, it is better to
 111    fork the topic (perhaps with the same name) afresh from the
 112    tip of "master".
 113
 114Let's look at this example:
 115
 116                   o---o---o---o---o---o---o---o---o---o "next"
 117                  /       /           /           /
 118                 /   a---a---b A     /           /
 119                /   /               /           /
 120               /   /   c---c---c---c B         /
 121              /   /   /             \         /
 122             /   /   /   b---b C     \       /
 123            /   /   /   /             \     /
 124    ---o---o---o---o---o---o---o---o---o---o---o "master"
 125
 126
 127A, B and C are topic branches.
 128
 129 * A has one fix since it was merged up to "next".
 130
 131 * B has finished.  It has been fully merged up to "master" and "next",
 132   and is ready to be deleted.
 133
 134 * C has not merged to "next" at all.
 135
 136We would want to allow C to be rebased, refuse A, and encourage
 137B to be deleted.
 138
 139To compute (1):
 140
 141        git-rev-list ^master ^topic next
 142        git-rev-list ^master        next
 143
 144        if these match, topic has not merged in next at all.
 145
 146To compute (2):
 147
 148        git-rev-list master..topic
 149
 150        if this is empty, it is fully merged to "master".