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  1. Core Server
  2. SERVER-69434

Make the DSS acquisition a RAII

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Details

    • Fully Compatible
    • Sharding EMEA 2022-09-19
    • 130

    Description

      Currently the DSS (database sharding state) service is protected by a ResourceMutex, which is owned by the DSS itself. This means it is not possible to lock it before a reference to that service is obtained or from outside. This prevents implementing dropping and the lock-free concurrency control scenarios where we require several services to be kept in sync.

      This ticket is to pull the locking of the DSS outside of the DSS object itself, so that it can be held locked for longer than the lifetime of the DSS. Furthermore, it will serve as an input to the "optimistic services snapshots" work later on, which needs to obtain a snapshot of everything about a collection in an atomic manner without holding locks.

      This lock must be acquired always at a level-0 or 1, meaning it must be the last lock acquired or the second to last, with the last being the CSS lock.

      It is either:

      • Only the DSS lock by itself
      • Only DSS lock + CSS lock
      • The db/collection locking hierarchy + DSS lock + CSS lock

      Attachments

        Issue Links

          causes

          Bug - A problem which impairs or prevents the functions of the product. SERVER-70154 DatabaseShardingState inappropriately constructs a RESOURCE_MUTEX ResourceId, leading to uncaught exception

          • Major - P3 - Major loss of function.
          • Closed
          depends on

          Improvement - An improvement or enhancement to an existing feature or task. SERVER-69444 Make the joining of concurrent critical section and refresh look the same between DSS and CSS

          • Major - P3 - Major loss of function.
          • Closed
          is depended on by

          Task - A task that needs to be done. SERVER-69435 Make the CSS acquisition a RAII

          • Major - P3 - Major loss of function.
          • Closed

          Task - A task that needs to be done. SERVER-69445 Implement the CollectionSnapshot(s) infrastructure to back CollectionPtr

          • Major - P3 - Major loss of function.
          • Closed
          is related to

          Task - A task that needs to be done. SERVER-70198 Use one single RESOURCE_MUTEX to protect concurrent operations on DatabaseShardingState for all databases

          • Major - P3 - Major loss of function.
          • Closed

          Activity

            People

              kaloian.manassiev@mongodb.com Kaloian Manassiev
              kaloian.manassiev@mongodb.com Kaloian Manassiev
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              Dates

                Created:
                Updated:
                Resolved: