Mercurial for Kittens

Mercurial for Kittens
Shuhei 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 example
updating to branch default
3 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 README
drwxr-xr-x 2 nya nya 4096 2011-05-22 20:59 src

Standard Mercurial repo
example/
.hg/
README
src/
a.cc
a.h
Repository
Working copy

Standard Mercurial repo
example/
.hg/
hgrc
dirstate
store/
...
repo-local config
working copy state
history

History
.hg/
Merge X
Improve 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!
Implemented X
Implementing X
Bugfix
First commit

Commit
nodeid: 9e66e5ae2b...
rev: 42
branch: featureX
author: "Shuhei Takahashi <nya@example.com>"
timestamp: 2011-06-02 11:59:28 +0900
implement feature X.
(patch...)
p1: 48334cb9e1... p2: 0000000000...

nodeid
.hg/
bcd055...
8a9310...
SHA-1 hash
Made from whole commit information
384fca...
a87493...
048293...
4fcf85...

parents (p1,p2)
.hg/
p2
p1
p1
1 or 2 parents
null = 000000...
p1
p1
p1

rev
.hg/
4
5
topological order
no consistency between repos
just for convenience!
2
1
3
0

branch
.hg/
default
featureX
default is "default"
all commitshave their branch name(c.f. git)
featureX
featureX
default
default

Notes for Git users
Different concept of branches
All commits have their branch name
No reachability check
hg log shows all commits
Commits cannot be amended or erased (usually)

Commit
nodeid: 9e66e5ae2b...
rev: 42
branch: default
author: "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
.hg/
4
5
3
tip
default
featureX
2
featureX
1
3
default
0

Basic operations

Check out a revision
.hg/
4
5
Working Copy
2
1
3
$ hg update 3
0

Making commit
Working Copy
.hg/
$ hg add hoge.txt
... edit working copy ...

Making commit
Working Copy
.hg/
$ hg commit

Making branch
Working Copy
.hg/
default
featureX
default
$ hg update default
featureX
featureX
default
default

Making branch
Working Copy
.hg/
release
featureX
default
$ hg branch release
featureX
featureX
default
default

Making branch
Working Copy
.hg/
release
$ hg commit
featureX
default
featureX
featureX
default
default

Pull
hg pull
local
remote

Push
hg push
local
remote

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
featureX
default

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
Checked out rev. 1
Pulled rev. 2, 3, resulting multiple heads (1, 3)
3
1
2
default
0

Merge
hg merge 3
Working copy now has two parents (1, 3)
Not yet committed!
hg merge is forbidden if WC has pending changes
p2
p1
3
1
2
default
0

Merge
hg commit
4
p2
p1
3
1
2
default
0

More fun stuff
hgweb.cgi
Extensions
Mercurial queue (MQ)
Rebase
...
Hooks
Mercurial as a Python module

References
Mercurial: The Definitive Guide
Chapter 4. Behind the scenes
google:///hgbook or available from O'reilly

Mercurial for Kittens

by nya3jp on Jun 02, 2011

Accessibility

Categories

Tags

Upload Details

Usage Rights

1 Embed 1

Statistics

Mercurial for Kittens — Presentation Transcript