End of Google Summer of Code 2011

Officially coding period in Google Summer of Code was closed last Monday (August 22nd) , so this is good time to sum up last three months of my work on EGit project.

During that time I’ve manage to contribute 32 commits (29 of them are already merged into master, rest is pending for review). I have also two not finished changes in my local git repository. First is about supporting non-workspace files in Workspace presentation model in sync-view, second is refactoring of current Git Change Set implementation.

Here is detailed list of things that was done during GSoC and are available in current nightly build:

  • improved synchronize wizard
  • Workspace presentation model will refresh after repository change
  • pushing from sync view to multiple repositories is now possible
  • Git Change Set presentation model will be refreshed after workspace change
  • context menu in synchronize view was cleaned up and git actions are shown for multiple selections
  • synchronization on folder level is now possible and it will narrow results just for selected folder (when synchronization is launched for project then results will show changes in whole repository)
  • local changes can be drag and dropped between and nodes in Git Change Set presentation model

Performance improvements for Workspace presentation model are still awaiting for review in Gerrit. Some part of performance and memory usage improvements for Git Change Set are also pending in Gerri, I’m currently working on rest of required refactoring in Git Change Set presentation model.

I want to thank my mentor Matthias Sohn for his commitment in GSoC, for reviewing my patches and his feedback. It was a great pleasure working  with him! 😉

Progress on non-workspace files in Workspace presentation model

For last three weeks I was working on including non-workspace files in Workspace presentation model in Synchronize View. This idea can sounds weird since the Workspace presentation model was designed to show only changed files that are in Eclipse workspace … but there are some use cases in which such behavior seams to be reasonable (eg. EGit and JGit projects doesn’t import repository root into workspace only projects are imported and files like master pom.xml, README, LICENCE and so on are left outside workspace).

If you don’t import all data into Eclipse workspace you won’t see any incoming nor outgoing changes. Even more, after merge/rebase actions changes in non-workspace files will magically appear in those resources and can even brake something (eg. massed up in master pom.xml file).

So, what is current status ? First of all I want to point that I’m describing here current situation in my working copy, described here changes currently are not available in public. After hours of debugging, code analysis and rewriting my code I’ve manage to show some indication in synchornize view that there are some non-workspace chagnes. The next step will be to show what particular file was changed and then enable all operations like overwrite, mark as merged, etc.

Here is a screenshot showing current status:

Non-workspace files in Workspace presenation model
As you can see there is home folder in sync results. It even have expand indicator (but after expanding it there is nothing inside). I suppose that on windows this folder will correspond to drive letter, but I’m not sure here.  Now I only need to tell Team Framework that there are some files inside home node …

This seams to be quite easy task, since parent folder is already included in view … but this isn’t that easy. First of all Workspace model is based on IResource‘s with are manageable by Eclipse platform. Of course I can create such resource using IWorkspaceRoot.getFolder() and IWorkspaceRoot.getFile(). Unfortunately non-workspace resources created by those two methods will return theirs first segment (on unix system it will be usually /home) as theirs project. Of course such project doesn’t exist in workspace therefore this node is empty.

Honestly speaking I currently don’t have any good ides how to move things forward … as usually I’ll dive into debugging and code analysis …

Any hints and ideas from the community are kindly welcome!

Huge performance boost for EGit sync-view

For last few days I was working on EGit Synchronize View performance, especially on Workspace presentation model (the Git Change Set is next on my list ;)). My starting point was 1m 40s to compare two linux kernel versions, v2.6.36 versus v2.6.38-rc2. Such result seams to be very good, but you need to know that it was achived on SSD hard drive and comparing to regular HDD it would be much worst (maybe more then 3 or 4 minutes).

What can be improved ? Fist of all, current implementation whenever it is asked for members of particular folder it opens repository* and read data directly from it. Of course there is a cashing mechanism, but it is only on single resource level. Therefore when you are launching synchronization on repository that have about 300 folders, current implementation will create and configure 300 connections* to repository to read data and then will cache it.

So, my idea was to create only one connection*, read all data at once and put them into global cache. This cache will be used whenever any list of members for given folder will be required. This approach gives about 2.5x performance boost to synchronization (from 1m 40s down to 40s). This result looks much better and maybe on HDD this action will take less then 2 minutes … but this isn’t over 😉

Reading members of folder is one thing, but getting information about particular file (it is changed, added or removed and does this change is incoming, outgoing or conflicting) is another. Currently we are reusing default implementation of SyncInfo class from Team Framework. This is really good implementation … when you cannot obtain such information from version control system. In Git  we have SHA-1 for each file and folder version and we didn’t have to compare file contents to check they are similar or not, comparing SHA-1 is sufficient. This should save lots of CPU time, disk IO’s and developer time waiting for synchronization to finish ;).

Now when I already have cache that contains list of all changed resources it was natural thing to add information about change type to it. Then whenever Team Framework need to know change type it can be easily obtained from this cache … no IO’s are needed, no comparison just read from in-memory-cache and return proper value.

I’m sure that you are wondering how fast synchronization can be now … I can only that it is REALLY fast … as you can remember my stating point was 1m 40s, now same comparison will finish in less than 7s!! This means that now synchronization will be 14 times faster then before! What this means for a regular user? Well, it meas that you will get results of ‘Synchronize Workspace‘ action almost instantly.

Unfortunately, mentioned above changes are sill awaiting for review in gerrit, you can grab them from change #3891 and build it locally. I hope this will be included in 1.1 release …

* jgit uses concept of walks (with filters) through repository, but I’ve used more commonly recognized terminology here

Drag-and-Drop staging/un-staging in Git Change Set model

The EGit 1.0 will be officially released in upcoming days, but I’ve already started to working on version 1.1. Today I would like to demonstrate you a feature that I was recently working on. To be honest the main idea of this functionality comes from my GSoC 2010 proposal, but I didn’t manage to implement it … until now ;), so what it is?

The post title should told you everything about it … but (if not) I’ve also prepared a screencast that is embedded above where you can clearly see how it works in real environment.

I know that in version 1.0 the Staging view was introduced, to be honest, I don’t think that separate view for staging is really needed. But I don’t have anything against it, it looks cool and works properly ;). Also I don’t see anything bad with having this functionality doubled in Git Change Set model and give users possibility to choose between both of them.

I’ve pushed this feature (and all dependent changes) yesterday. This is quite huge change so I think that we’ll iterate few times with it before it will be merged into master, but I hope it will be included in 1.1.

As always feel free to share any ideas and comments!

EGit Synchronize View Workflow Updates

One part of my Google Summer of Code project is to improve EGit Synchronization workflow and make it easier for new user to understood how it works.

So almost two weeks ago I’ve write a post with proposed new workflow for Synchronize Wizard. The main idea of that post was to initialize discussion with community how they want to use this wizard. According to Google Analytics this post was displayed around 120 times with isn’t that bad I think … but only one person leave a comment on it with isn’t a good result. Maybe I’m doing something wrong or I’m not making myself clear enough. Or maybe this topic isn’t so important for other people … I don’t know, maybe you can help me and give me some hints?

Apart from this, here is another part of changes that are proposed to be done in Synchronize workflow. Most of them are waiting for comments and approval in gerrit. This a good moment for comments and share thoughts about current implementation, before it will be merged into master branch. Additionally I’ve opened two bugs for discussion on Synchronize Wizard and Team menu based workflows:

I’m understood that you don’t want to play with our code base and struggle with project setup only to check one of two new features, so here is a short description of my ideas and some screenshots:

  1. Always use current selected branch (HEAD) as source of synchronization
    As you may know currently the synchronization-dialog (this is a dialog that pops up after you select Team > Synchronize… from project’s context menu) allows select source and destination branch, and after that you can launch the synchronization action.When I was implementing this feature I had in mind git diff command, where you can easily compare two given points in repository history. But this command produces a patch-like output. You cannot move changes around, the only action that you can do with it is to only review it. In case of Synchronize View we use to use it to move changes around and prepare commit. So it is more then simple git diff.

    Another huge issue with this approach is that handling Synchronize View context menu actions like ‘Commit‘, ‘Merge‘, ‘Overwrite and Update‘ gets really complicated when base branch isn’t actual working branch.

    Because of that I’ve decided that in new workflow you need to select only a destination branch! For now I think that I’ll not remove this functionality from EGit code, because maybe in feature we’ll found a use case when comparing two given branches without switching on one of them could be use full.

  2. Always fetch changes before synchronization
    I’ve spotted that new git users that comes from CVS or SVN doesn’t really get the idea of ‘fetching changes locally’. They launch synchronization and want to see incoming changes without fetching them into repository. This feature could be also useful for old git users, because it will save couple of mouse clicks ;)The implementation that I’ve proposed don’t launch fetch action all the time. It checks does current branch tracks any remote branch, if yes it fetches changes from that remote, otherwise it will not do anything.

    OK, but what when I’m off-line and I’m working on branch that tracks origin/master, I would be forced to wait until connection timeout occurs?

    Well … it depends 😉 Every time fetch fails you will be informed by dialog that you can disable automatic-fetch in Team > Git preferences. So in the worst case you will wait only once for connection timeout, then you will be informed that you can disable auto-fetch.

  3. New Synchronize Wizard
    After discussion in bug 344888 I’ve decided to abandon changes that I’ve presented two weeks ago. And implement it this way:EGit Synchronize Wizard

    As you can see there is only destination branch. Also all project names have decorations that describes repository name and current branch name. There i a single button for include local changes and that’s all, no more pages and logic’s.

    Additionally, the Destination branch list will contain also additional refs like FETCH_HEAD

  4. New context menu option ‘Synchronize Workspace’

    EGit Synchronize Workspace

    This a short cut for comparing HEAD against HEAD with included locally made changes. It is useful when you want to see what changes you made in workspace before you commit them. I think that this is a most use case for synchronize view therefore I’ve decided to add this shortcut.

  5. No more Synchronize-dialog
    This a Matthias Sohn idea to replace synchronize-dialog with dynamically build sub menu entry (same as in ‘Switch To‘ action).

    EGit Synchronize... Sum Menu

    This sub menu will contain 20 elements at most. They are alphabetically ordered and include local and remote branches, tags and additional refs like FETCH_HEAD. You don’t find here HEAD and name of current selected branch, because for synchronizing against those is ‘Synchronize Workspace‘ action. If you don’t see branch or tag that you would like to synchronize against, you need to choose ‘Custom…‘ option. After that the Synchronize Wizard will be shown where you can choose destination from complete list of branches, tags and additional refs.

  6. Push and Pull actions in Synchronize View toolbar
     

    EGit SynchronizeView Push and Pull Toolbat Actions

    This change is merged into current master, so if you want to check out that you need to install a nightly build of EGit.

    There is only one limitation for push action, it works only when you are synchronizing one repository. It would be disabled when you synchronizing more then one repo.

It is all for now. Any ideas and comments are welcome (and needed ;))!.