Mercurial training

MERCURIAL TRAINING
www.phuongdo.vn
https://www.facebook.com/kezaburo
6/4/2012 HCM city

Agenda
• Install the Mercurial on a SUSE machine
• Behind the Mercurial
• Basic commands in the Mercurial
• Mq extension tool for patching
• Common Issues
• The Mercurial vs other SCM
www.phuongdo.vn Eng. TrungHuynh™

INSTALL on SuSE
• Find the version of SUSE
– cat /etc/SuSE-release
• Find the path of repo of the Mercurial for that SuSE version
– http://mercurial.selenic.com/wiki/Download
– http://download.opensuse.org/repositories/devel:/tools:/scm/
openSUSE_11.4/devel:tools:scm.repo
• Use the zypper tool to add the repo’s path
zypper ar http://download.opensuse.org/repositories/devel:/tools:/scm/openSUSE_11.4/devel:tools:scm.repo
• Use the zypper/yast tool to install the Mercurial
zypper install mercurial
Check the installation: hg debuginstall
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Eng. TrungHuynh™

Basic Concepts
• Topology
– Mercurial is completely decentralized system, and thus has no concept of central
repository
– In Mercurial, the user can define the topology by themselves for sharing the changes
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Eng. TrungHuynh™

Basic Concepts
• Repository and working directory
– Mercurial repositories contain a working coupled with a store
– For example: /home/repository/ directory is as below figure
• In working directory, the state of files will be refer to a specific revision of repository
• In .hg/store/data/ folder, it contains in formation about changes of each file
Main.c Main.h
.hg
Rev 0 Rev 1 Rev 2 Rev 3parent parent parent
Working directory
repository

Basic Concepts
• Revision is local version index for the project
• Changeset is unique version index for global
• In above figure, we have a repository with two heads
and two branches
• Head is the revision has no child revision. And the
biggest revsion head is the tip
0 1 2 3 4
5
6(tip)
Working
dirhead
head
Branch Achangeset: 1:d7fd576b6c9b
| user: trunghuynh
| date: Fri Jun 08 17:28:32
2012 +0700
| files: hello1.cc
revision

Common Commands
hg help <command>
• Hg init -> initialize a repository, of course it is a directory
• Hg add -> inform the Mercurial that you want it keep track your files
• Hg clone -> clone the project from a Mercurial repository
– Especial, we can clone with the specific branch: hg clone <main-repo> <new-repo> -r <head of specific
branc>
• Hg pull -> get the changes from our peers into our repository
– Notice that pull command just update our backlog information of our repository
• Hg update -> will update the changes after pulling, in fact it is merging the current
working revision with the change from pulling
• Hg commit -> like saving edited word file. It will create a changeset
• Hg push -> pushing our changes for others pulling
– The backlog information of main repo will automatically update when the child repos push their
changes
• Hg branch ->check the current branch or set branch
– Notice that branch name is permanently recorded as part of the changeset’s metadata
– Branch name is used as the tip revision when we want checkout a branch
• Hg log ->show the information about the repository
• Hg tip ->show information of the “tip” revision. The “tip” revision is the head with largest
revision www.phuongdo.vn
Eng. TrungHuynh™

Common Commands
• Hg merge -> merge the working directory with other
revision
• Hg diff -> show what is changed since the last committing
• Hg revert -> revert the specific file into the unmodified
state
• Hg incoming ->see what will be updated when we do a pull
action
• Hg rollback  uncommit…
• Hg annotate <filename>
• Hg strip <revision number> ->delete a specific revision
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Eng. TrungHuynh™

Hg commit
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Eng. TrungHuynh™
0:qe7
1:de5
2:ye2
3:af9
@
Alice’s Repo
main.c
model.h
model.c
Working directory
socket.c
3:a3e
changed
When we commit a new
changeset will be created

hg push/pull
Main Repos
0:qe7
1:de5
0:qe7
1:de5
2:af9
Bob’s Repo
0:qe7
1:de5
2:ye2
Alice’s Repo
2:af9
2:af9
hg pull <Bob’s repo>
@
@
@
@ Mark parent revision
of working directory
A revision of repo

hg merge/update
Alice’s Repo
0:qe7
1:de5
2:ye2
3:af9
@
The “hg update” command will
change our current working
revision that we are working
on.
The “hg merge” command will
merge a specific revision to the
current working revision. In this
case, the change from af9
changeset will merge into the
revsion 2.
After successful merging, we
has to commit to create a new
changeset/revision which
contains both change from
revision 3 and 2
4:kq6

Advance Using Mercurial
• Merge conflict:
– The conflict happens when two changesets have modified the same file’s section
with different way. In this case, the Mercurial need a help from user.
Main()
{
printf(“hello Mercurial world”);
printf(“Merge is fun and easy”);
}
Main()
{
printf(“hello Mercurial world”);
printf(“Merge is difficult”);
}
Changeset 4 Changeset 7

Common Issues
• To resolve that conflicts we need to open that file
and edit to what we want. After that we use “hg
resolve <filename> to correct the confliction.
• To support merging, we can use a graphical tool
such as kdiff3 as the best tool.

Common Issues
• abort: outstanding uncommitted changes
– The cause is merging with uncommitted changes.
– There open happens when we pull while there are some
uncommitted change
– Have two solutions are:
• Always commit changes before pulling
• Extract the uncommit changes into the file and pulling. After that imports
the uncommit change file
• abort: push creates new remote heads on branch 'default'!
– When we push some things that will create new heads in remote
repo. Mercurial thinks that is an impolite action. The best way is
when pulling and merge before pushing
• “abort: crosses branches (use 'hg merge' or 'hg update -C')”
– Update the working revision in the different branch

MQ tool
• MQ is the extension tool of Mercurial that
manages your patches
– Modify the .hgrc to enable MQ
[extensions]
hgext.mq =

MQ tool
what is patch file?
diff --git a/opensaf.spec.in b/opensaf.spec.in
--- a/opensaf.spec.in
+++ b/opensaf.spec.in
@@ -14,6 +14,7 @@
%define is_ais_msg %(test "@AIS_MSG_ENABLED@" = "yes" && echo 1 || echo 0)
%define is_ais_smf %(test "@AIS_SMF_ENABLED@" = "yes" && echo 1 || echo 0)
%define is_tipc_trans %(test "@TIPC_TRANSPORT_ENABLED@" = "yes" && echo 1 || echo 0)
+%define is_ais_pm %(test "@AIS_PM_ENABLED@" = "yes" && echo 1 || echo 0)
%define _pkglibdir %{_libdir}/%{name}
%define _pkgsysconfdir %{_sysconfdir}/%{name}
@@ -541,6 +542,46 @@
%endif
+%if %is_ais_pm
Diff header
Hunk

MQ tool
• Create a patch repository
– Hg qinit
• This command will create a “patches” directory in “.hg” directory and
also create a patch queue
• In patches folder contains our patches and more two files that are a
series file and a status file
• The series file contains all of patches name that MQ knows
• The status file contains status of all patches that are applied currently
• Hg qseries command lists every patch that MQ knows
about in a repository
• Hg qapplied command lists every patch that MQ has
applied in a repository

MQ tool
• Hg qnew –m “message for patch” <patch name>
– Create a new patch with a patch name
• Hg qrefresh
– Save new change to the top applied patch
Note: hg revert will let you come back the last refresh
state.

MQ tool
• Hg qpop
– Pop out the top patch from the queue
• Hg qpush
– Push a patch into the queue
• Hg qdelete <patch.name>
– Delete a patch from a queue. The file is still preserve
in patch repository
• Hg qfinish ??

Mercurial vs Others
From www.infoQ.com

Mercurial training

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