source: python-simple-websocket-server/simple-websocket-server/.git/hooks/pre-rebase.sample @ 1309

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1#!/bin/sh
2#
3# Copyright (c) 2006, 2008 Junio C Hamano
4#
5# The "pre-rebase" hook is run just before "git rebase" starts doing
6# its job, and can prevent the command from running by exiting with
7# non-zero status.
8#
9# The hook is called with the following parameters:
10#
11# $1 -- the upstream the series was forked from.
12# $2 -- the branch being rebased (or empty when rebasing the current branch).
13#
14# This sample shows how to prevent topic branches that are already
15# merged to 'next' branch from getting rebased, because allowing it
16# would result in rebasing already published history.
17
18publish=next
19basebranch="$1"
20if test "$#" = 2
21then
22        topic="refs/heads/$2"
23else
24        topic=`git symbolic-ref HEAD` ||
25        exit 0 ;# we do not interrupt rebasing detached HEAD
26fi
27
28case "$topic" in
29refs/heads/??/*)
30        ;;
31*)
32        exit 0 ;# we do not interrupt others.
33        ;;
34esac
35
36# Now we are dealing with a topic branch being rebased
37# on top of master.  Is it OK to rebase it?
38
39# Does the topic really exist?
40git show-ref -q "$topic" || {
41        echo >&2 "No such branch $topic"
42        exit 1
43}
44
45# Is topic fully merged to master?
46not_in_master=`git rev-list --pretty=oneline ^master "$topic"`
47if test -z "$not_in_master"
48then
49        echo >&2 "$topic is fully merged to master; better remove it."
50        exit 1 ;# we could allow it, but there is no point.
51fi
52
53# Is topic ever merged to next?  If so you should not be rebasing it.
54only_next_1=`git rev-list ^master "^$topic" ${publish} | sort`
55only_next_2=`git rev-list ^master           ${publish} | sort`
56if test "$only_next_1" = "$only_next_2"
57then
58        not_in_topic=`git rev-list "^$topic" master`
59        if test -z "$not_in_topic"
60        then
61                echo >&2 "$topic is already up-to-date with master"
62                exit 1 ;# we could allow it, but there is no point.
63        else
64                exit 0
65        fi
66else
67        not_in_next=`git rev-list --pretty=oneline ^${publish} "$topic"`
68        /usr/bin/perl -e '
69                my $topic = $ARGV[0];
70                my $msg = "* $topic has commits already merged to public branch:\n";
71                my (%not_in_next) = map {
72                        /^([0-9a-f]+) /;
73                        ($1 => 1);
74                } split(/\n/, $ARGV[1]);
75                for my $elem (map {
76                                /^([0-9a-f]+) (.*)$/;
77                                [$1 => $2];
78                        } split(/\n/, $ARGV[2])) {
79                        if (!exists $not_in_next{$elem->[0]}) {
80                                if ($msg) {
81                                        print STDERR $msg;
82                                        undef $msg;
83                                }
84                                print STDERR " $elem->[1]\n";
85                        }
86                }
87        ' "$topic" "$not_in_next" "$not_in_master"
88        exit 1
89fi
90
91<<\DOC_END
92
93This sample hook safeguards topic branches that have been
94published from being rewound.
95
96The workflow assumed here is:
97
98 * Once a topic branch forks from "master", "master" is never
99   merged into it again (either directly or indirectly).
100
101 * Once a topic branch is fully cooked and merged into "master",
102   it is deleted.  If you need to build on top of it to correct
103   earlier mistakes, a new topic branch is created by forking at
104   the tip of the "master".  This is not strictly necessary, but
105   it makes it easier to keep your history simple.
106
107 * Whenever you need to test or publish your changes to topic
108   branches, merge them into "next" branch.
109
110The script, being an example, hardcodes the publish branch name
111to be "next", but it is trivial to make it configurable via
112$GIT_DIR/config mechanism.
113
114With this workflow, you would want to know:
115
116(1) ... if a topic branch has ever been merged to "next".  Young
117    topic branches can have stupid mistakes you would rather
118    clean up before publishing, and things that have not been
119    merged into other branches can be easily rebased without
120    affecting other people.  But once it is published, you would
121    not want to rewind it.
122
123(2) ... if a topic branch has been fully merged to "master".
124    Then you can delete it.  More importantly, you should not
125    build on top of it -- other people may already want to
126    change things related to the topic as patches against your
127    "master", so if you need further changes, it is better to
128    fork the topic (perhaps with the same name) afresh from the
129    tip of "master".
130
131Let's look at this example:
132
133                   o---o---o---o---o---o---o---o---o---o "next"
134                  /       /           /           /
135                 /   a---a---b A     /           /
136                /   /               /           /
137               /   /   c---c---c---c B         /
138              /   /   /             \         /
139             /   /   /   b---b C     \       /
140            /   /   /   /             \     /
141    ---o---o---o---o---o---o---o---o---o---o---o "master"
142
143
144A, B and C are topic branches.
145
146 * A has one fix since it was merged up to "next".
147
148 * B has finished.  It has been fully merged up to "master" and "next",
149   and is ready to be deleted.
150
151 * C has not merged to "next" at all.
152
153We would want to allow C to be rebased, refuse A, and encourage
154B to be deleted.
155
156To compute (1):
157
158        git rev-list ^master ^topic next
159        git rev-list ^master        next
160
161        if these match, topic has not merged in next at all.
162
163To compute (2):
164
165        git rev-list master..topic
166
167        if this is empty, it is fully merged to "master".
168
169DOC_END
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