[LU-20207] llapi_project_get() should cache /etc/projid contents for repeated lookups

• Type: Bug
• Resolution: Unresolved
• Priority: Medium
• Labels: easy
• Severity: 3
• Assignee: WC Triage
• Reporter: Vadakkumuri Valappil Abooback

Description

llapi_project_get()  iterates through the /etc/projid file every time a project id is resolved to a project name to project id or vice versa.

llapi_projid_get() should read the /etc/projid file once build an in-memory cache for the name<->projid mappings, so that repeated llapi_project_getnam() and llapi_project_getprjid() calls can avoid re-scanning the list multiple times. It would also make sense to cache the last PROJID-to-PROJNAME mapping in ll_project_handle to avoid any lookup in the common case of repeated lookup of the same NAME/ID.

If implementation time is a concern, a linear array search would be an acceptable starting point, and still far better than opening and re-reading the file multiple times. Ideally, this would implement a hash table to efficiently look up PROJID and PROJNAME entries, as a large system may have tens of thousands or potentially even millions of projids (eg. if a new project is being automatically created for each Kubernetes container/user or similar).

Issue Links

• is related to: LU-18638 print project name with 'lfs project'
• is related to: LU-15723 Add 'llapi_projid_fget()' and 'llapi_projid_fset()' to llapi