mercurial for kittens

Mercurial for KittensShuhei Takahashi<takahashi.shuhei@gmail.com>

Mercurial

Features

Simple design Decentralized system High performance Extensible framework

Outline

History model Basic operations

History model

Checking out Mercurial repo

$ hg clone http://example.com/hg exampleupdating to branch default3 files updated, 0 files merged, 0 files removed,0 files unresolved$ ls -lA example/drwxr-xr-x 3 nya nya 4096 2011-05-22 20:59 .hg-rw-r--r-- 1 nya nya 14 2011-05-22 20:59 READMEdrwxr-xr-x 2 nya nya 4096 2011-05-22 20:59 src

Standard Mercurial repo

example/ .hg/ README src/ a.cc a.h

Working copy

Repository

Standard Mercurial repo

example/ .hg/ hgrc dirstate store/ ...

repo-local configworking copy statehistory

History.hg/

First commit

Implementing X Bugfix

Merge X

Implemented X

diff -r 000000... -r 39fca2... README--- /dev/null Thu Jan 01 00:00:00 1970 +0000+++ b/README Sun May 22 20:59:40 2011 +0900@@ -0,0 +1,1 @@+Hello, world!

Improve X

Commit

nodeid: 9e66e5ae2b...rev: 42branch: featureXauthor: "Shuhei Takahashi <nya@example.com>"timestamp: 2011-06-02 11:59:28 +0900

implement feature X.

(patch...)

p1: 48334cb9e1... p2: 0000000000...

nodeid.hg/

4fcf85...

a87493... 048293...

384fca...

bcd055...8a9310...

SHA-1 hash Made from whole

commit information

parents (p1,p2).hg/

p1

p2

p1

p1

p1 p1

1 or 2 parents null = 000000...

rev.hg/

0

1 3

2

45

topological order no consistency

between repos just for

convenience!

branch.hg/

default

featureX default

featureX

defaultfeatureX

default is "default" all commits have

their branch name(c.f. git)

Notes for Git users

Different concept of branchesAll commits have their branch name

No reachability checkhg log shows all commits

Commits cannot be amended or erased (usually)

Commit

nodeid: 9e66e5ae2b...rev: 42branch: defaultauthor: "Shuhei Takahashi <nya@example.com>"timestamp: 2011-06-02 11:59:28 +0900

implement feature X.

(patch...)

p1: 48334cb9e1... p2: 0000000000...

Referring commits

rev nodeid branch name

... commit in the branch with the largest rev "tip"

... commit in any branch with the largest rev "null" ... root commit tag

Referring commits

3 tip default featureX

.hg/

default

featureX

0

1 3

2

45

Basic operations

Check out a revision

$ hg update 3

.hg/

0

1 3

2

45

Working Copy

Making commit.hg/

Working Copy

$ hg add hoge.txt... edit working copy ...

Making commit .hg/Working Copy

$ hg commit

Making branch.hg/

default

featureX default

featureX

featureX

Working Copy

default

default

$ hg update default

Making branch.hg/

default

featureX default

featureX

featureX

Working Copy

default

release

$ hg branch release

Making branch.hg/

default

featureX default

featureX

featureX

Working Copy

default $ hg commit

release

Pulllocal remote

hg pull

Pushlocal remote

hg push

Pull / Push

Just makes union of two history graphs Merge operation is never performed

(c.f. Git) Can specify subgraph by a list of heads

Merge - "healthy" branch

One head per branches

default

featureX

Merge - "unhealthy" branch

"default" branch has two heads - multiple heads

Branch tip varies by rev order!

Push that will end up with multiple heads is rejected

default

?

?

Merge

default0

12

3

Checked out rev. 1 Pulled rev. 2, 3,

resulting multiple heads (1, 3)

Merge

default0

12

3

hg merge 3 Working copy now has

two parents (1, 3) Not yet committed!

hg merge is forbidden if WC has pending changes

p1

p2

Merge

default0

12

3

hg commit

p1

p2

4

More fun stuff

hgweb.cgi Extensions

Mercurial queue (MQ)Rebase...

Hooks Mercurial as a Python module

References

Mercurial: The Definitive GuideChapter 4. Behind the scenes

google:///hgbook or available from O'reilly