Bazaar VCS. Concepts and Workflows

Transcription

1 Bazaar VCS Concepts and Workflows

2 Paint rollers and brushes If you want to paint, you have a choice of tools, including paint rollers and brushes. If you re painting a portrait, you would use a small brush. If you re painting a house, you would use a roller. While you can t paint a portrait with a roller, you can paint a house with a small brush. If you re really patient.

3 Version control is the same Centralized Good for structured, central collaboration No support for distributed work Distributed Good for distributed work Tedious to use for structured, central collaboration Flexible (centralized + distributed) + Build on distributed tools, so same support for distributed work Also provide tools for efficient centralized use

4 Version control systems Centralized With single file system: CVS With remote access: Subversion Distributed Mercurial git Flexible (centralized + distributed) Bazaar

5 Centralized: CVS and Subversion All branches must be stored in a repository. All working copies must be checkouts. Repository Branch A Branch B Li le offline capability. Checkout B Checkout A

6 Distributed: Mercurial and git All working copies must be branches. No central repository. (But you can pretend a branch is one.) Full offline capability. Branch A Branch B Branch C Branch D

7 Flexible: Bazaar + Working copies can be checkouts. Branches can be stored in a repository. Repository (optional) Branch A Branch B Full offline capability. Checkout A Branch C Working copies can be branches. Branch D

8 What does it mean to be flexible? Your choice of a distributed, centralized, or hybrid workflow The ability to actually use these workflows efficiently The ability to switch between or combine workflows easily Having so many workflow choices, it s confusing what works well and where to start (a good problem to have)

9 Bazaar versus Subversion Even with a centralized workflow, Bazaar has important differences from Subversion. Subversion Bazaar Directory-centric (operations generally run on the current directory and below) Branch- and checkout-centric (operations generally run on the whole checkout or branch) One repository One or more repositories Checkouts are lightweight (no local copy of revision history) Checkouts are heavyweight* (checkouts are effectively branches configured to use checkout-style operations) *By default. Bazaar can also create lightweight checkouts.

10 Se ing up Bazaar Working Copy *Everything is stored in the.bzr directory.

11 Se ing up Bazaar This could be a website without version control. Working Copy *Everything is stored in the.bzr directory.

12 Se ing up Bazaar This could be a website without version control. Working Copy + bzr init Create the repository.* *Everything is stored in the.bzr directory.

13 Se ing up Bazaar This could be a website without version control. Working Copy Add files to the repository. + bzr init + bzr add Create the repository.* *Everything is stored in the.bzr directory.

14 Se ing up Bazaar This could be a website without version control. Working Copy Add files to the repository. + bzr init + bzr add Create the repository.* + bzr commit *Everything is stored in the.bzr directory. Store the files into the repository.

15 Se ing up Bazaar Branch A

16 Se ing up Bazaar Repository Branch A

17 Se ing up Bazaar Repository We can treat this as our central repository. Branch A

18 Se ing up Bazaar Repository We can treat this as our central repository. Branch A bzr checkout Checkout A

19 Se ing up Bazaar Repository We can treat this as our central repository. Branch A bzr branch bzr checkout Branch B Checkout A

20 Se ing up Bazaar Repository We can treat this as our central repository. Branch A bzr branch bzr checkout Branch B Checkout A bzr checkout Checkout B

21 Understanding Bazaar Workflows

22 Branches versus checkouts Branches in Bazaar are effectively branches configured to use checkout-style operations. Potential source of conflicts Checkout Branch Save changes locally Send changes Receive changes Convert to the other bzr commit --local bzr commit bzr update bzr unbind bzr commit bzr send (then the output) or bzr push [to branch] bzr merge [from branch] or bzr pull [from branch] bzr bind [to branch]

23 Branching and merging Branch A

24 Branching and merging Branch A Rev 1

25 Branching and merging Branch A Rev 1 Rev 2

26 Branching and merging Branch A Rev 1 Rev 2 bzr branch Branch B Rev 1 Rev 2

27 Branching and merging Branch A Rev 1 Rev 2 bzr branch Branch B Rev 1 Rev 2 Rev 3

28 Branching and merging Branch A Rev 1 Rev 2 bzr branch Branch B Rev 1 Rev 2 Rev 3 Rev 3

29 Branching and merging Branch A Rev 1 Rev 2 bzr branch Branch B Rev 1 Rev 2 Rev 3 Rev 3 Rev 4

30 Branching and merging Branch A Rev 1 Rev 2 bzr branch Branch B Rev 1 Rev 2 Rev 3 Rev 3 Rev 4 Rev 4

31 Branching and merging Branch A Rev 1 Rev 2 Branch B Rev 1 Rev 2 Rev 3 Rev 4 Rev 3 Rev 4 Rev bzr merge

32 Branching and merging Branch A Rev 1 Rev 2 Branch B Rev 1 Rev 2 Rev 3 Rev 4 Rev 3 Rev 4 Rev bzr merge Rev 5

33 Branching and merging Merging takes changes from another branch and integrates them into the local branch. Trivial if changes have only been made to one branch. If changes have been made to both, Bazaar tracks this. Bazaar remembers the last time you merged from another branch, and it will only try to merge in changes made since. You can also cherry pick changes to selectively merge them from branch to branch. This is generally a bad idea because you ll have to personally track what s been merged.

34 How can we best use Bazaar s flexibility to develop and deploy?

35 The four-stage workflow Dev A How changes flow: bzr update bzr commit bzr merge Potential site for conflicts Changes allowed Browsable online Dev B Development Staging Production Staging Dev C Production

36 Dev X workflow General development happens on these instances. Most changes are commi ed locally: bzr commit --local New features are commi ed to Development Staging: bzr commit Updates are pulled from Development Staging: bzr update Conflicts are resolved: bzr resolve Dev A Dev B Dev C

37 Development Staging workflow This stage is coordination point for new feature testing. Development Staging is updated to reflect developer commits: bzr update Development Staging is updated to reflect changes to Production Staging: bzr merge Conflicts are resolved: bzr resolve + bzr commit Development Staging

38 Production Staging workflow Cosmetic and emergency changes happen here. Changes are commi ed:* bzr commit Updates are pulled from Development Staging: bzr merge Conflicts are resolved: bzr resolve + bzr commit Production *Commits to branches are always local. Staging

39 Production workflow No direct changes happen here, ever. Updates are pulled from Production Staging: bzr update Production

40 Further flexibility It s possible to create checkouts of Production Staging if more than one person needs to work on cosmetic or emergency changes for quick deployment to production. Developers can make checkouts to their local machines to perform offline work. Local commits and access to revision history still function.

41 The Bazaar Command Toolkit

42 Important Bazaar commands bzr status bzr diff bzr diff [file] bzr diff -r [reva]..[revb] bzr help [command] bzr missing --theirs-only :bound bzr missing --theirs-only [branch] bzr log -l [number] bzr whoami [name bzr search [text]

43 bzr status Lists notable files Modified Created Missing Unknown status (neither versioned nor ignored) Lists pending local commits Best time to run: before commi ing

44 bzr diff Lists local file changes since the last commit, line by line Best time to run: before commi ing

45 bzr diff [file] Lists changes to a single file since the last commit, line by line Best time to run: before commi ing

46 bzr diff -r [reva]..[revb] Lists line-by-line changes occurring between the specified revisions Best times to run: When you know what revisions you ll get in an update or merge, and you want to know exactly what they ll do When an item in the revision log isn t clear, and you want to know what it changed

47 bzr help [command] Lists syntax, common options, and examples for the specified command Best time to run: kind of obvious

48 bzr missing --theirs-only :bound Lists revisions you can expect to get from updating your checkout Only works on checkouts, not branches Consider using the --include-merges option to show a more verbose history Best time to run: right before updating your checkout

49 bzr missing --theirs-only [branch] Lists revisions you can expect to get from merging from [branch] Consider using the --include-merges option to show a more verbose history Best time to run: right before merging

50 bzr log -l [number] Lists information about the last [number] revisions Consider using bzr diff a erward to view detailed changes Best times to run When you want to review local commits Right a er merging or updating

51 bzr whoami [me Sets the identification information a ached to your commits You can also run it without any arguments to view the current identification you have on file Best time to run: on personal accounts (but not shared ones) before commi ing any changes

52 bzr search [text] Searches the full text of the Bazaar repository for the specified text This requires the Search plugin Best time to run: when you re looking for something that isn t in the current working copy grep -R [text]. is a be er choice for searching in the current working copy

53 Bizarre (Bazaar s quirks) Local commits cannot be combined with single-file commits. Sticky, group-writable repositories are o en unreliable because of inconsistent umasks. It s best to access repositories under single users and make use of bzr whoami.