Mercurial

robert macleanwww.sadev.co.za ∞ @rmaclean ∞

robert@sadev.co.za

Mercurial

• April 2005• Created for Linux Kernel • DVCS– Distributed Version Control System

• It’s just source control, so what you know is still relevant

Client/Server Source Control

SVN

All code, all history, all

settings

Just working set

Merge has only working set knowledge

Connection to server needed

Cannot share between people

without the server

Server is unaware of renaming

.svn pollution

Good & established tool

(build, WI) integration

LOCKS?! ARRGGHH!

Central management

DVCS

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Everyone has full repo

Merge has full

knowledge

Can work disconnecte

d

Aware of renaming

Easy to share between people

Single .hg directory

No locking

Tool integration is still growing

So it is perfect?

• Some management (users) issues– Can be solved on the transport

• Maturity needed– No reason not to check-in ALL the time– Backups?– Can’t delete branches

• Performance issues– Can’t pull a working set

• Workflows need to change

Workflow chaos

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hg • Where is the trunk?

• Run testing, deployment builds

• What happens if you go dark?• What about security?

• How do I add or remove users?

• Where is the backup that we will use when the building burns down?

hg

The Blessed Repo Workflow

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Build server runs against blessed

repo

WI against this

Backup this

Central Management

Here

Familiar model

The Hybrid Blessed Repo Workflow

SVN

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Mercu

rial to

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N

Brid

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Network of Trust Workflow

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King

Lie

ute

nan

tsU

nw

ash

ed

Masses

Graphics Networks Disk Penguins

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Corporate Network of Trust Workflow

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Seniors

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Juniors

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Intermediates

Deployment Team Workflow

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Deploy

Development

Pre-Prod

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Can run own workflows

Can have own build and ship quality

gates

Can have own branching strategy

Proven Practises Alignment?Branching

Plan your branchingOwn the mergeLook after branches

RepoDon’t break the buildSeparate your repoDon’t forget to shelveUse labels

TechTry concurrent accessDon’t be afraid of branching conceptsAuto merge for checkout only

ManagementDon’t use the audit trail for blameUseful & meaningful check in messages

YouBe light and quick with checkoutsKeep up to dateDon’t check in unneeded binariesWorking folders should be disposableUse undo/revert sparingly

Commands (51)

Add, AddRemove, Remove [rm]Annotate [Blame]ArchiveBackoutBisectBookmarksBranch & BranchesBundle & UnbundleCatCloneCommit [ci]Copy [cp] & Rename [move, mv]Diff

Export & Import [patch]ForgetGrepHeadsHelpIdentify [id]Incoming [in] & Outgoing [out]InitLocateLog [history]ManifestMerge & ResolveParentsPath

Pull & PushRecoverRevertRollbackRootServeShowConfig [debugconfig]Status [st]Summary [sum]Tag & TagsTipUpdate [up, checkout, co]VerifyVersion

Command Cheat Sheet

Other DVCS Options

• Git– Linus Torvalds– Linux Kernal– Requires packing

maintenance– Unfriendly version numbers– FAST– Linux & Mac– Different patching ideology – No working set issue– Can delete branches

• Bazaar– Canonicial– Ubuntu– Slow– Closer to SVN

• Monotone, Darcs, Plastic, SVK, Codeville, GNU arch, Bitkeeper

Questions?