My name is Daniel Flores and I’m a student from Spain. I study in Barcelona School of Informatics, which is a faculty of Polytechnic University of Catalonia, and it’s my last year before I graduate.
I sent a mail with this proposal to Matthew 4 days ago, but I didn't get a reply yet, so I decided to send this to the mailing list, as it is suggested on Dragonfly's GSoC page. Before submitting any official application, I would like to ask for your opinion and criticism regarding my proposal and whether I have the required skill and adequate planning to successfully finish this project.
I’m interested in implementing the block compression feature in HAMMER2, which is described on Dragonfly’s GSoC page . The feature consists in that any written block should be compressed, if possible, to 50% of its size or less (in powers of 2 – 32 KB, 16 KB and so on, the initial size of block being 64 KB). It should be possible to set that compression mode on any directory, so that new contents written in it and its subdirectories would be compressed.
I believe that I can succeed because I have programming experience in C/C++, since we use those languages for most practices in our university. I also completed courses centered on algorithms and their implementation in C or C++. I also have an interest in operating systems, their concepts and their development. I completed a course on Operating Systems development where I and a partner implemented a simple linux-based kernel called “ZeOS” (using C and, at times, x86 assembler). It’s a very simple kernel that has a task scheduler, system calls, exceptions, interruptions, memory management and a file system. We were able to successfully run it on bochs emulator and it passed all tests needed to successfully finish the course.
If you wish, you may take a look at it .
Sadly, it’s documented in Spanish, but I just want to provide it as an example of code that I can produce.
In spite of it being a kernel implementation, I think that my skills and knowledge aren’t yet the best suitable for kernel development projects, so instead I prefer to do something moderately difficult, yet related to operating systems, like HAMMER2 block compression feature.
My initial outline for project planning is the following:
1. (Starting May 27 or before – June 17) During community bonding period I would get myself familiarized with the community, Dragonfly BSD system/code and “hammer2” branch code. I would also refresh my knowledge on compression algorithms and would complete a design for the future implementation, like choosing the appropriate algorithm and having defined everything needed to be done. I have read Matthew's design document for HAMMER2  and, as I understand, the algorithm #2 is not yet determined, so I believe this should be decided before the actual coding period will start. Also, more detailed planning for coding period would be done, with clear milestones and deliverables.
The deliverables for this phase would be in the form of documents that would describe the design, the chosen algorithm(s) and the calendar with milestones.
2. (June 17 – July 29) I would start by coding a prototype application that would implement the defined design, consisting of algorithms #0, #1 and #2. I would need it to insure that the algorithm is implemented correctly and to do all necessary debugging and refining before integrating it in HAMMER2. I would create a series of tests to prove that the algorithm works well. If time allows, I would also try to study its behavior statistically and to improve it, if possible.
The deliverables would be code of the prototype as well as any supporting applications (to generate tests, for example) and tests themselves.
3. (July 29 – September 16) After confirming that the prototype works well, I would start actually integrating it into HAMMER2 filesystem. At this point, the task would be gradually adding prototype’s code without any conceptual modification into HAMMER2 and testing if it works correctly in real-life. A series of testing applications with appropriate system calls would be created and the results checked for correctness. Also, the appropriate hammer2 utility command to set the compression feature to directories would be created and tested.
The deliverables would be the code of implemented feature and application tests for it.
4. (September 16 – End of GSoC 2013) Hopefully, all known bugs would be corrected at this point, so I would take the time to do final refinements to documentation, to write a detailed description of what was implemented for future developers and to finish everything needed to start submitting my code to Google.
Generally, my philosophy is to start “as soon as possible”, so if some phase is done before the deadline, I would immediately go to the next phase. If project goes smoothly and there is some time left, I would be happy to do small refinements or bugs fixes on general system or HAMMER2.
During the coding period (June 17 – September 16) I don’t have any commitments (like courses or trips) at all, so I should be able to easily dedicate 40 hours per week or more to this project. Prior to June 17 I have my studies and some exams, but generally it should not prevent me from getting familiarized with code and getting the design/algorithm decisions done, because my workload is not very big.
I don’t have any past experience with Open Source or generally big projects, but I believe that I can accomplish this task since it is generally related to C programming and algorithms, and I believe that I have sufficient knowledge of those fields from my university courses.
Currently I am getting myself familiarized with Dragonfly 3.2 (for i386) running it on Oracle VM Virtual Box 4.2.12, but I’m able to install it on physical machine, if necessary. I’m also trying to learn as much as possible about BSD in general and particularly Dragonfly.
If you think that my set of skills is more appropriate to some other project related to HAMMER2 or Dragonfly, I would be grateful if you pointed at them. I also would consider working on HAMMER2 block encryption feature, since it is similar in requirements to my current proposal, if there is already a strong candidate to implement the block compression feature.