3 perlrepository - Using the Perl source repository
7 All of Perl's source code is kept centrally in a Git repository. The
8 repository contains many Perl revisions from Perl 1 onwards and all
9 the revisions from Perforce, the version control system we were using
10 previously. This repository is accessible in different ways.
12 The full repository takes up about 80MB of disk space. A check out of
13 the blead branch (that is, the master branch, which contains bleadperl,
14 the development version of perl 5) takes up about 160MB of disk space
15 (including the repository). A build of bleadperl takes up about 200MB
16 (including the repository and the check out).
18 =head1 GETTING ACCESS TO THE REPOSITORY
20 =head2 READ ACCESS VIA THE WEB
22 You may access this over the web. This allows you to browse the tree,
23 see recent commits, search for particular commits and more. You may
26 http://perl5.git.perl.org/perl.git
28 =head2 READ ACCESS VIA GIT
30 You will need a copy of Git for your computer. You can fetch a copy of
31 the repository using the Git protocol (which uses port 9418):
33 git clone git://perl5.git.perl.org/perl.git perl-git
35 This clones the repository and makes a local copy in the 'perl-git'
38 If your local network does not allow you to use port 9418, then you can
39 fetch a copy of the repository over HTTP (this is slower):
41 git clone http://perl5.git.perl.org/perl.git perl-http
43 This clones the repository and makes a local copy in the 'perl-http'
46 =head2 WRITE ACCESS TO THE REPOSITORY
48 If you are a committer, then you can fetch a copy of the repository that
49 you can push back on with:
51 git clone ssh://perl5.git.perl.org/gitroot/perl.git perl-ssh
53 This clones the repository and makes a local copy in the 'perl-ssh'
56 If you clone using git, which is faster than ssh, then you will need to
57 modify your config in order to enable pushing. Edit F<.git/config> where
58 you will see something like:
61 url = git://perl5.git.perl.org/perl.git
63 change that to something like this:
66 url = ssh://perl5.git.perl.org/gitroot/perl.git
68 NOTE: there are symlinks set up so that the /gitroot is actually optional.
70 You can also set up your user name and e-mail address. For example
72 % git config user.name "Leon Brocard"
73 % git config user.email acme@astray.com
75 It is also possible to keep C<origin> as a git remote, and add a new remote for ssh access:
77 % git remote add camel user@camel:/gitroot/perl.git
79 This allows you to update your local repository by pulling from C<origin>, which is faster and doesn't require you to authentify, and to push your changes back with the C<camel> remote:
84 The C<fetch> command just updates the C<camel> refs, as the objects themselves should have been fetched when pulling from C<origin>.
86 =head1 OVERVIEW OF THE REPOSITORY
88 Once you have changed into the repository directory, you can inspect it.
91 After a clone the repository will contain a single local branch, which
92 will be the current branch as well, as indicated by the asterix.
97 Using the -a switch to branch will also show the remote tracking branches in the
106 The branches that begin with "origin" correspond to the "git remote" that
107 you cloned from (which is named "origin"). Each branch on the remote will
108 be exactly tracked by theses branches. You should NEVER do work on these
109 remote tracking branches. You only ever do work in a local branch. Local
110 branches can be configured to automerge (on pull) from a designated remote
111 tracking branch. This is the case with the default branch C<blead> which
112 will be configured to merge from the remote tracking branch
115 You can see recent commits:
119 And pull new changes from the repository, and update your local repository
120 (must be clean first)
124 Assuming we are on the branch C<blead> immediately after a pull, this command
125 would be more or less equivalent to:
128 % git merge origin/blead
130 In fact if you want to update your local repository without touching your working
135 And if you want to update your remote-tracking branches for all defined remotes
136 simultaneously you can do
140 Neither of these last two commands will update your working directory, however
141 both will update the remote-tracking branches in your repository.
143 To switch to another branch:
145 % git checkout origin/maint-5.8-dor
147 To switch back to blead:
151 =head2 FINDING OUT YOUR STATUS
153 The most common git command you will use will probably be
157 This command will produce as output a description of the current state of the
158 repository, including modified files and unignored untracked files, and in addition
159 it will show things like what files have been staged for the next commit,
160 and usually some useful information about how to change things. For instance the
165 # Your branch is ahead of 'origin/blead' by 1 commit.
167 # Changes to be committed:
168 # (use "git reset HEAD <file>..." to unstage)
170 # modified: pod/perlrepository.pod
172 # Changed but not updated:
173 # (use "git add <file>..." to update what will be committed)
175 # modified: pod/perlrepository.pod
178 # (use "git add <file>..." to include in what will be committed)
180 # deliberate.untracked
182 This shows that there were changes to this document staged for commit, and
183 that there were further changes in the working directory not yet staged. It
184 also shows that there was an untracked file in the working directory, and as
185 you can see shows how to change all of this. It also shows that there
186 is one commit on the working branch C<blead> which has not been pushed to the
187 C<origin> remote yet. B<NOTE>: that this output is also what you see as a
188 template if you do not provide a message to C<git commit>.
190 Assuming we commit all the mentioned changes above:
192 % git commit -a -m'explain git status and stuff about remotes'
193 Created commit daf8e63: explain git status and stuff about remotes
194 1 files changed, 83 insertions(+), 3 deletions(-)
196 We can re-run git status and see something like this:
200 # Your branch is ahead of 'origin/blead' by 2 commits.
203 # (use "git add <file>..." to include in what will be committed)
205 # deliberate.untracked
206 nothing added to commit but untracked files present (use "git add" to track)
209 When in doubt, before you do anything else, check your status and read it
210 carefully, many questions are answered directly by the git status output.
212 =head1 SUBMITTING A PATCH
214 If you have a patch in mind for Perl, you should first get a copy of
217 % git clone git://perl5.git.perl.org/perl.git perl-git
219 Then change into the directory:
223 Alternatively, if you already have a Perl repository, you should
224 ensure that you're on the I<blead> branch, and your repository
230 Now that we have everything up to date, we need to create a temporary new
231 branch for these changes and switch into it:
233 % git checkout -b orange
235 which is the short form of
238 % git checkout orange
240 Then make your changes. For example, if Leon Brocard changes his name
241 to Orange Brocard, we should change his name in the AUTHORS file:
243 % perl -pi -e 's{Leon Brocard}{Orange Brocard}' AUTHORS
245 You can see what files are changed:
249 # Changes to be committed:
250 # (use "git reset HEAD <file>..." to unstage)
255 And you can see the changes:
258 diff --git a/AUTHORS b/AUTHORS
259 index 293dd70..722c93e 100644
262 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
263 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
264 Leif Huhn <leif@hale.dkstat.com>
265 Len Johnson <lenjay@ibm.net>
266 -Leon Brocard <acme@astray.com>
267 +Orange Brocard <acme@astray.com>
268 Les Peters <lpeters@aol.net>
269 Lesley Binks <lesley.binks@gmail.com>
270 Lincoln D. Stein <lstein@cshl.org>
272 Now commit your change locally:
275 % git commit -m 'Rename Leon Brocard to Orange Brocard'
276 Created commit 6196c1d: Rename Leon Brocard to Orange Brocard
277 1 files changed, 1 insertions(+), 1 deletions(-)
279 Now you should create a patch file for all your local changes:
281 % git format-patch origin
282 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
284 You should now send an email to perl5-porters@perl.org with a
285 description of your changes, and attach this patch file as an
288 If you want to delete your temporary branch, you may do so with:
291 % git branch -d orange
292 error: The branch 'orange' is not an ancestor of your current HEAD.
293 If you are sure you want to delete it, run 'git branch -D orange'.
294 % git branch -D orange
295 Deleted branch orange.
297 =head1 ACCEPTING A PATCH
299 If you have received a patch file generated using the above section,
300 you should try out the patch.
302 First we need to create a temporary new branch for these changes and
305 % git checkout -b experimental
307 Patches that were formatted by C<git format-patch> are applied with C<git am>:
309 % git am 0001-Rename-Leon-Brocard-to-Orange-Brocard.patch
310 Applying Rename Leon Brocard to Orange Brocard
312 If just a raw diff is provided, it is also possible use this two-step process:
314 % git apply bugfix.diff
315 % git commit -am "Some fixing" --author="That Guy <that.guy@internets.com>"
317 Now we can inspect the change:
320 commit b1b3dab48344cff6de4087efca3dbd63548ab5e2
321 Author: Leon Brocard <acme@astray.com>
322 Date: Fri Dec 19 17:02:59 2008 +0000
324 Rename Leon Brocard to Orange Brocard
328 diff --git a/AUTHORS b/AUTHORS
329 index 293dd70..722c93e 100644
332 @@ -541,7 +541,7 @@ Lars Hecking <lhecking@nmrc.ucc.ie>
333 Laszlo Molnar <laszlo.molnar@eth.ericsson.se>
334 Leif Huhn <leif@hale.dkstat.com>
335 Len Johnson <lenjay@ibm.net>
336 -Leon Brocard <acme@astray.com>
337 +Orange Brocard <acme@astray.com>
338 Les Peters <lpeters@aol.net>
339 Lesley Binks <lesley.binks@gmail.com>
340 Lincoln D. Stein <lstein@cshl.org>
342 If you are a committer to Perl and you think the patch is good, you can
343 then merge it into blead then push it out to the main repository:
346 % git merge experimental
349 If you want to delete your temporary branch, you may do so with:
352 % git branch -d experimental
353 error: The branch 'experimental' is not an ancestor of your current HEAD.
354 If you are sure you want to delete it, run 'git branch -D experimental'.
355 % git branch -D experimental
356 Deleted branch experimental.
358 =head1 CLEANING A WORKING DIRECTORY
360 The command C<git clean> can with varying arguments be used as a replacement for make-clean.
362 To reset your working directory to a pristine condition you can do:
366 However, be aware this will delete ALL untracked content. You can use
370 to remove all ignored untracked files, such as build and test byproduct, but leave any
371 manually created files alone.
375 C<git> provides a built-in way to determine, with a binary search in the history, which commit should be blamed for introducing a given bug.
377 Suppose that we have a script F<~/testcase.pl> that exits with C<0> when some behaviour is correct, and with C<1> when it's faulty. We need an helper script that automates building C<perl> and running the testcase:
382 # If you can use ccache, add -Dcc=ccache\ gcc -Dld=gcc to the Configure line
383 sh Configure -des -Dusedevel -Doptimize="-g" || exit 125
385 ./perl -Ilib ~/testcase.pl
387 This script may return C<125> to indicate that the corresponding commit should be skipped. Otherwise, it returns the status of F<~/testcase.pl>.
389 We first enter in bisect mode with:
393 For example, if the bug is present on C<HEAD> but wasn't in 5.10.0, C<git> will learn about this when you enter:
396 % git bisect good perl-5.10.0
397 Bisecting: 853 revisions left to test after this
399 This results in checking out the median commit between C<HEAD> and C<perl-5.10.0>. We can then run the bisecting process with:
401 % git bisect run ~/run
403 When the first bad commit is isolated, C<git bisect> will tell you so:
405 ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5 is first bad commit
406 commit ca4cfd28534303b82a216cfe83a1c80cbc3b9dc5
407 Author: Dave Mitchell <davem@fdisolutions.com>
408 Date: Sat Feb 9 14:56:23 2008 +0000
410 [perl #49472] Attributes + Unkown Error
415 You can peek into the bisecting process with C<git bisect log> and C<git bisect visualize>. C<git bisect reset> will get you out of bisect mode.
417 Please note that the first C<good> state must be an ancestor of the first C<bad> state. If you want to search for the commit that I<solved> some bug, you have to negate your test case (i.e. exit with C<1> if OK and C<0> if not) and still mark the lower bound as C<good> and the upper as C<bad>. The "first bad commit" has then to be understood as the "first commit where the bug is solved".
419 C<git help bisect> has much more information on how you can tweak your binary searches.