Piotr Kazmierczak 611452e1af stateful deployments: use TaskGroupVolumeClaim table to associate volume requests with volume IDs (#24993) ...

We introduce an alternative solution to the one presented in #24960 which is
based on the state store and not previous-next allocation tracking in the
reconciler. This new solution reduces cognitive complexity of the scheduler
code at the cost of slightly more boilerplate code, but also opens up new
possibilities in the future, e.g., allowing users to explicitly "un-stick"
volumes with workloads still running.

The diagram below illustrates the new logic:

     SetVolumes()                                               upsertAllocsImpl()          
     sets ns, job                             +-----------------checks if alloc requests    
     tg in the scheduler                      v                 sticky vols and consults    
            |                  +-----------------------+        state. If there is no claim,
            |                  | TaskGroupVolumeClaim: |        it creates one.             
            |                  | - namespace           |                                    
            |                  | - jobID               |                                    
            |                  | - tg name             |                                    
            |                  | - vol ID              |                                    
            v                  | uniquely identify vol |                                    
     hasVolumes()              +----+------------------+                                    
     consults the state             |           ^                                           
     and returns true               |           |               DeleteJobTxn()              
     if there's a match <-----------+           +---------------removes the claim from      
     or if there is no                                          the state                   
     previous claim                                                                         
|                             | |                                                      |    
+-----------------------------+ +------------------------------------------------------+    
                                                                                            
           scheduler                                  state store

2025-02-07 17:41:01 +01:00

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