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MasterFS API - Architecture Review Opinion

Issue: 40958

Submitter: Radek Matous

Inception Date: 2004/04/14

Reviewers: Jaroslav Tulach, Miloslav Metelka, Tomas Pavek

Content

Summary
Decision
Opinion
Minority Opinion
Appendixes

Summary

MasterFileSystem is a module providing an umbrella implementation over all filesystems used in the IDE. MasterFS plays a role of the arbiter that controls instantiation and life cycle of FileObjects (provided by the delegated filesystems). The need of the MasterFS has arisen with the new project environment in NB 4.0 where specialized filesystems may overlap easily (like the VCS filesystem over the local filesystem). See also the complete requirements document.

Decision

Accepted with change requests.

Opinion

We have found the MasterFS module well reasoned and prepared. Suggested just several changes that were more or less already planned by the team.

Agreed that the API will be classified as friend for promo D. The API user will be the vcscore module only.

Agreed that java.io.File should be used rather than String with abstract path in parameters in MountSupport (issue 40344).

Agreed with the limitation that the mounting points for delegated filesystems cannot be files but only folders (due to unresolved problems with files being turned to folders). See also issue 41779.

As the API will be friend (for vcscore module), we require to repackage it -- away from the official namespace (as used so far). Recommended to put all the classes to one package. This was already planned by the impl. team. This is a TCR.

As the VCSFilesystem already uses the MasterFS, remove current hacks in projects that listen on repository for mounted VCS filesystems and mounts them to Master FS (HackedVCSProvider). This is a TCR.

We suggest the team to think about how MasterFS could help other modules (e.g. MDR) with listening on external file changes -- e.g. by providing some effective refreshing of whole file trees. Possible approaches were discussed with conclusion that real requirements and use cases are needed to be known first. The required changes would be probably of bigger scope, affecting the Filesystems API too. This is a TCA.

Though this is not strictly MasterFS issue, we've also discussed how the delegated filesystems should behave. Agreed on that they should not hide any files (like e.g. VCSFileystem currently does) because hidden files are invisible and unreachable for the IDE and that may cause consistency problems in some operations (like directory copy). Hiding should be done rather in a presentation layer based on some hints provided by the filesystem implementation. Farther investigation and cooperation with VCS team was suggested.