vdlald / file-system

Documentation with diagrams here - etc/fs_arch.drawio.png

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Task

Implement a file system (FS) based on a single file (all data must be stored within a single file):

Requirements

There should be support for at least:

• creating

• reading

• deleting

• updating files

• There should be a documented API for working with the file system -- etc/fs_arch.drawio

• The code must be close to production quality, including tests.

• For implementation, please use Java

• Preferably, please do not use any third-party libraries for the implementation of file storage itself.

Questions

• Q-1. Will it be enough to provide just a Java interface with Javadoc or do I need to provide an OpenAPI contract? It would be great to see a console app, but Java interface with Javadoc will be sufficient

• Q-2. Do I need to optimize the space used when deleting a file? It’s up to you if you want to optimize the used space

• Q-3. Should the file system be created with a specific size or unlimited? File system should not have a hard size limit but let’s assume that users won’t stress it beyond some reasonable limits

• Q-4. The result should be a mini library? Or assume it's part of the application, and I can use spring and so on? It would be great to see a console app, but Java interface with Javadoc will be sufficient

• Q-5. Should the file system be hierarchical? Up to me

• Q-6. Fast write or fast read? As for the fast write/fast read - let’s assume that we want balance between reads and writes

Tasks

• T-0. Base project template

• T-1. Creating FS file

• T-4. Store metadata in FS

• T-5. Reading blocks

• T-6. Write data in block

• T-9. Refactor file system creation

• T-12. Writing data - Serializing File descriptors

• T-10. Writing data - Write file descriptor in descriptors block

• T-13. Refactor entire project

• T-14. Find the best block for filling a data

• T-11. Writing data - Write file data in available place

• T-15. Writing data - Write big file

• T-16. Save a block size of the FS in metadata

• T-3. Reading files in FS

• T-17. Delete file in FS

• T-18. Update file in FS

• T-19. Refactor entire project

• P-6. update does not remove index blocks when compressing a file

• P-1. Two files with same name problem

• P-4. Allocated space offset validation

• T-21. Write more tests

• T-22. Write more documentation

• T-25. Extract ChainedFileDescriptorsBlock from MyFileSystemOperations

• T-26. Refactor MyFileSystemOperations

• T-23. Wrap it in console app

• T-28. Wrap all IOException

• FR-4. List files in fs

• P-7. block occupancy is not taken into account during expansion

• T-29. Extract interfaces

• T-27. Exception handling in ArgumentsApi

• T-30. Refactor exceptions

• P-9. Do not read the last block completely with null bytes

• FR-7. Checksum file

• P-10. Incorrectly handled exception in ArgumentsParser

• T-31. Write documentation of the memory organization

• FR-6. Move the file

• T-32. Write more tests for ArgumentsApi

• T-33. Update arguments_help.md

• T-34. Wrap the application in an executable file

• P-11. Limit filename size

• T-35. Refactor requests package

• T-36. Check the resources to be closed

• T-24. Check speed of RW-operations

• P-2. FS initial max size is only 2GB

• P-5. readBlocks can not allocate more than Integer.MAX bytes

• P-8. Primitive collections are not used

• T-20. Work with different block sizes

• FR-1. Compress data

• FR-2. Encrypt data

• FR-3. Defragmentation

• FR-5. Implement FileSystemProvider

Researching

1. https://www.geeksforgeeks.org/file-systems-in-operating-system/
2. https://github.com/seclerp/FileFS/blob/master/docs/Architecture-overview.md
3. https://www.geeksforgeeks.org/difference-between-internal-and-external-fragmentation/