...

• Jira Legacy
  server System JIRA serverId ba6fb084-9827-3160-8067-8ac7470f78b2 key PLFM-5604

  - Introduction of Google Cloud external storage locations makes additive changes necessary
  • Need to add a new type - GoogleCloudFileHandle
  • We can generate previews of Google Cloud files, but the existing PreviewFileHandle implements S3FileHandleInterface, requiring some sort of change.
• /wiki/spaces/SYNPY/pages/819855621 - We can consider taking take this opportunity to clear up confusion with this API
  Attempt to make entirely additive changes to avoid making breaking API changes (especially for clients)
  • Fix up cruft and simplify design decisions

Changes

I am proposing the following changes:

• Introduction of three new interfaces
  • PreviewFileHandleInterface - Defines which objects are preview file handles.
  • GoogleCloudFileHandleInterface - Defines which objects represent file handles that exist in Google Cloud
  • CloudProviderFileHandleInterface - Defines which objects represent file handles stored by a cloud provider (e.g. S3, Google Cloud, potentially others in the future)
• Introduction of two new classes:
  • GoogleCloudFileHandle - A file handle that represents a file in Google Cloud (analogous to S3FileHandle)
  • GoogleCloudPreviewFileHandle - A file handle that represents a preview of a GoogleCloudFileHandle (analogous to PreviewFileHandle)

Current Hierarchy

Image Removed

Proposed Hierarchy

Image Removed

Alternative Considerations

We could simply add a GoogleCloudFileHandleInterface that extends the FileHandle interface, but clients should rarely (if ever) be concerned whether a FileHandle is in S3 vs. Google Cloud (this can be contrasted with external file handles). This is a reason to introduce an interface that both S3FileHandle and GoogleCloudFileHandle implement.

PreviewFileHandle implements S3FileHandleInterface, which means we must do at least one of:

• Add a new GoogleCloudPreviewFileHandle class or
• Add a field to PreviewFileHandle that indicates if the file is in S3 or Google Cloud and break the hierarchy (remove implements S3FileHandleInterface)Would this be a breaking change for clients?Rename S3FileHandleInterface to CloudProviderFileHandleInterface
  
  • Still defines bucket and key
  • Add fields previewId and isPreview
• Add class GoogleCloudFileHandle (implements CloudProviderFileHandleInterface)
• Remove PreviewFileHandle
  • PreviewFileHandles are just S3FileHandles or GoogleCloudFileHandles where isPreview is true
• Remove HasPreviewId
  • The information necessary for locating and identifying previews moves to the CloudProviderFileHandleInterface class
  • While ExternalFileHandle and ProxyFileHandle can have previews under the old tree, there are 0 previews of external files in production (as of 2019-07-22)

Current Hierarchy

Image Added

Proposed Hierarchy

Image Added

Additional Considerations

We can rename ExternalFileHandleInterface if we want to. One suggestion is OtherFileHandleInterface, since it seems to be a catch all for everything that doesn't fall under the other category.

Other naming suggestions are welcome.