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C oncurrent V ersions S ystem

C oncurrent V ersions S ystem. Overview of CVS architecture. Repository structure. Basic development tasks in WinCvs. Branching and merging. Other CVS interfaces CVS internals. CVS Features. Concurrent access by multiple developers Multiple development lines in a single repository

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C oncurrent V ersions S ystem

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  1. Concurrent Versions System • Overview of CVS architecture. • Repository structure. • Basic development tasks in WinCvs. • Branching and merging. • Other CVS interfaces • CVS internals

  2. CVS Features • Concurrent access by multiple developers • Multiple development lines in a single repository • Grouping sources into modules • Symbolic source tagging • Diffs between versions • Configurable logging support • Binary files support • Repository event triggers

  3. Client-server architecture • separate server (UNIX or NT) • no shared filesystems • a server process per connection ewacvs

  4. The CVS Repository ewacvs:/data1/cvsroot CVSROOT shr project1 project2 project3 devkits ar cgi doc install reports util web unix nt cgipr esapps forms • Resides on a server • No working files inside the repository

  5. CVS Usage ModelCheckout, Commit, Update • Checkout Makes private copy in working directory Can check out anywhere Check out multiple copies, multiple versions • Commit Commit changes to the repository when finished Working copies must be up to date with repository • Update Brings working copy up to date with repository

  6. Working Copy V1.7 Working Copy V1.1 Working Copy V1.2 Working Copy V1.7 Working Copy V1.2.2.1 Concurrent checkout Checkout does not lock the files in repository Master Repository foo.c checkout latest checkout branch rel_1_fix checkout V1.1 checkout V1.2 checkout latest Karen Patrick Brigid Michael Chris checkin checkin checkin X X V1.8 or 1.9 V1.2.2.2 checkin prohibited V1.8 or 1.9

  7. CVS and the Development Cycle 1. Check out source files in working directory. 2. Edit source files. 3. Unit test your code. 4. Update working files to merge in changes from other developers (if necessary). 5. Test again if the sources were merged on step 4. 6. Commit changes. 7. Repeat from step 2 until you have a new release. 8. Tag the release. 9. Submit the module name and release tag for integration build.

  8. Ideal development with CVS Developer A update development checkout checkin repository Developer B

  9. checkin conflict resolution checkin update X conflict Real development with CVS Developer A repository Developer B

  10. WinCVS on your desktop • Configuration • Main screen • Checking out the sources • Viewing source history • Diff • Commit • Update • Tag

  11. WinCVS: Configuration Your UNIX login

  12. revision number branch name file type state icon file view modules status view WinCvs: Main screen

  13. Checking out the sources

  14. Source history & diff

  15. commit update tag Commit, Update & Tag

  16. When to commit • Commit to mark a working state that you might want to return to later. • Commit related files in a single operation. Use a common log message for all the files. • Commit to backup your sources. • Commit from an office desktop to be able to access the files from home much faster than through filesystem sharing.

  17. patch cvs tag -b rel_1_fix rel_1_fix 1.2.2.1 1.2.2.2 1.1 1.2 1.3 1.4 release_1 release_2 cvs up -r rel_1_fix cvs tag release_1 cvs tag release_2 Working on branches

  18. Branch if you need ... • to create sustaining (patch) releases • to have multiple development lines from a single repository • to do experimental development to merge later or forget about it • to keep temporary state of development without affecting builds

  19. Common CVS commands cvs [cvs-options] command [cmd-options] [files] cvs checkout Check out source for editing. cvs add Add new file/directory to repository. cvs remove Remove an entry from the repository. cvs status Show status of checked out files. cvs log Show revision history for files. cvs diff Compare working files to version in repository or versions inside the repository. cvs update Bring working files into sync with repository. cvs commit check files into the repository cvs tag Label the sources.

  20. Directory listing Diff between 2 versions of the file Other CVS clients CVSweb

  21. Directory listing Diff between 2 versions of the file Other CVS clients jCVS

  22. CVS online • Official CVS site: http://www.cyclic.com • CVS Bubbles: http://www.loria.fr/~molli/cvs-index.html • CVS for Web development: http://durak.org:81/cvswebsites • WinCvs: http://www.wincvs.org • jCVS: http://www.jcvs.org/ • Netscape’s Mozilla under CVS: http://cvs-mirror.mozilla.org/webtools/tindertest/showbuilds.cgi?tree=SeaMonkey • FreeBSD CVS repository: http://www.freebsd.org/support.html#cvs

  23. CVS Internals • Server is started via inetd (UNIX) with a process per connection • Client-server protocol has embedded compression • Update sends file’s diff across the line, not the whole file (when possible) • UNIX authentication, optional CVS specific passwords/groups, Kerberos and SSH support • CVS does not have to run as root • SCCI and OLE support are in development • Event triggers are implemented via external programs (Perl, sh, C, anything else)

  24. Reserved Checkouts and CVS Exclusive file locking prevents parallel development and is not recommended for plain text files • advisory locks: implemented via cvs edit and cvs watch. Get notification when someone edits or checks in the file. • all-o-nothing advisory locks: cvs edit does not succeed if files are already edited by someone else. Implemented using a patch to cvs edit • exclusive locks (RCS style): implemented via cvs admin. You cannot commit unless you’ve locked the file. One lock per file per branch.

  25. email alert CVS server edit/watch edit Advisory locks Developer A Developer B Editors: Developer A Editors: Developer A Developer B

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