Add MongoDB GridFS Adapter

[GromNaN]

GridFS is a file system that uses MongoDB as storage. I would like to propose this adapter which uses the MongoDB PHP Library.

Docs PR: https://github.com/thephpleague/flysystem/pull/1795

The legacy GridFS Flysystem adapter had some significant number of installations, even if it used the legacy Mongo extension. It shows there's some interest.

Important notes:

• Directories does not exist in GridFS. I use the same technic as for S3 when explicitly creating a directory: an empty file with a trailing / is created. The creation of a file with a name ending in a / is therefore prohibited.
• Permissions are not supported by GridFS. When explicitly set, I store the visibility in the metadata.flysystem_visibility attribute of the file.
• GridFS' contentType attribute is deprecated. The attribute metadata.contentType is used instead.
• GridFS supports versioning by default. Writing to an existing file creates a new revision. Deleting removes all the revisions. Moving renames all the revisions.
• For GitHub Action, the mongodb extension is installed and a mongodb server is started using Docker Compose.
• I added some tests in the shared FilesystemAdapterTestCase in order to improve coverage on mimeType and visibility.

[frankdejonge]

Hi all, I'm out this week but will get on this ASAP to get this out. Thanks for the effort and the interest to contribute. Would there be anybody interested from your end to do continued maintenance in this adapter? And if so, who? Then I know who to rope in with issues.

[GromNaN]

Hello Frank, we are a team of currently 3 devs, led by @alcaeus. We use an open Jira to organise our work and Flysystem is one of the packages we want to maintain.

[frankdejonge]

Looks like the test case GridFSAdapterTest::move_all_revisions is failing.

[GromNaN]

Looks like the test case GridFSAdapterTest::move_all_revisions is failing.

Where do you see that? It seems to work in GitHub Actions: https://github.com/thephpleague/flysystem/actions/runs/9161336038/job/25242807530?pr=1794

[frankdejonge]

@GromNaN this is an example; https://github.com/thephpleague/flysystem/actions/runs/9180056390/job/25244027378?pr=1794 might be because of eventual consistency in MongoDB? Is that a thing? Previous run had more errors on the same test case.

[GromNaN]

Ok, I suspect that it's because 2 files are created in the same millisecond and revisions are sorted using this date.

[frankdejonge]

@GromNaN still one failing, is there another way to deal with this or to configure it? https://github.com/GromNaN/flysystem/actions/runs/9181466558/job/25248713035

[GromNaN]

It seems that my previous guess was correct but the fix incorrectly implemented. I added usleep(1000) (1ms) between each insertion of a revision to have a different uploadDate.