Endpoints that don't do database access shouldn't have UnitOfWork annotation

Feature Request

The @UnitOfWork annotation should only be present on endpoints whose implementations access the database.

When present, the annotation starts a database transaction, which requires a database connection. When contention for database pool connections gets tight (there are 32 available connections), this can slow down the endpoints, cause them to fail (if unable to get a connection soon enough), and/or also the same effect on other endpoints that do require a connection.

Off-hand, noticed 3 endpoints in MetadataResource that have but do not need the annotation. There may be more – implementor should check.

• getSourceControlList
• getDockerRegistries
• getDescriptorLanguages

┆Issue is synchronized with this Jira Story ┆Fix Versions: Dockstore 1.7 ┆Issue Number: DOCK-628 ┆Sprint: Seabright Sprint 7 Gondola ┆Issue Type: Story

[david4096]

The UnitOfWork annotation can be used “non-transactionally” by setting transactional to false for things that won’t need to be rolled back.

Similarly, when an item is read only or if you want to set a different cache mode, it can be done using parameters to the annotation. I believe there is an advantage to keeping the annotation so that Hibernate can handle caching even for resources that don’t require a write transaction.

For example, metadata/sourceControlList does not “need” a hibernate session in that it doesn’t touch the DB. However, other endpoints that don’t perform write transactions should probably get the read-only tag to answer @denis-yuen .

https://www.dropwizard.io/0.7.1/dropwizard-hibernate/apidocs/io/dropwizard/hibernate/UnitOfWork.html

[denis-yuen]

On the other hand, this isn’t really user-visible.