[asterisk-bugs] [JIRA] (ASTERISK-25067) Sorcery Caching: Implement a new caching module

[Joshua Colp (JIRA)]

     [ https://issues.asterisk.org/jira/browse/ASTERISK-25067?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Joshua Colp reassigned ASTERISK-25067:
--------------------------------------

    Assignee: Joshua Colp

> Sorcery Caching: Implement a new caching module
> -----------------------------------------------
>
>                 Key: ASTERISK-25067
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-25067
>             Project: Asterisk
>          Issue Type: Improvement
>      Security Level: None
>          Components: Core/Sorcery
>            Reporter: Matt Jordan
>            Assignee: Joshua Colp
>
> h2. Overview
> See [Sorcery Caching|https://wiki.asterisk.org/wiki/display/~jcolp/Sorcery+Caching] for more background and information.
> This issue is to create a specific sorcery wizard for in-memory caching, {{res_sorcery_memory_cache}}. It should be specified in the same way as existing caching wizards, except that it will provide a smarter set of policies for how items in the cache are managed.
> Example configuration:
> {code}
> [res_pjsip]
> endpoint/cache=memory_cache
> endpoint=realtime,ps_endpoints
> {code}
> h2. Implementation
> # Create a new module, {{res_sorcery_memory_cache}}. Implement the standard suite of callbacks for a {{ast_sorcery_wizard}} struct. The initial implementation of this can start from {{res_sorcery_memory}}.
> # Add configuration options documented on the wiki page. Note that this step is purely to add the hooks necessary to parse the configuration passed in from the {{.open}} callback.
> # Implement expiration of objects. If an object is expired, it should be removed from the cache, and the cache should return NULL. The next wizard down that returns a valid object should re-add it to the cache exactly as if it were a new item being added to the cache.
> # Add a maximum limit to the size of the cache. Since the underlying container will be an ao2 container, this will require some finesse:
> ** Look at the container count when adding a new item. If it is under the count, add away.
> ** If not, perform a lookup on the container based on the oldest known item. This should almost certainly *not* be done using an ao2_callback, as that would require iterating over all the objects, which would be absolute garbage for performance. Instead, an alternate container that organizes the entries by age should be used.
> ** Get the oldest as mentioned above, remove it from both containers, then add the new one.
> # Add staleness. If an item is stale, return it, but queue up a check to see if the next wizard down has it. If that fails, remove the item from the cache (auto-expire it).
> *NOTE*: There are other options, but the ones listed above are a bit higher priority than the others on the page. If the others are necessary, they will be implemented as well.
> h2. Testing
> h3. Initial Caching
> Write tests that cover the following:
> # Write basic tests for the wizard. Confirm items can be created, retrieved, updated, and deleted using the standard callbacks.
> # Create a cache with an expiration time.
> ** Verify that a non-expired item is retrieved without hitting a backing layer.
> ** Verify that an expired item is removed from the cache and hits a backing layer.
> *** Verify that a backing layer not having the item results in an overall NULL value being returned.
> *** Verify that a backing layer having the item results in it being returned, and re-populated in the cache with the correct new expiration time.
> # Add a maximum size to the cache (10)
> ** Add 15 objects, verify that only 10 were created.
> ** Add 10 objects. Verify the 5 oldest. Add 5 more. Verify that 10 are in the cache, and the 5 oldest were removed.
> # Create a cache with staleness.
> ** Verify that stale objects are returned when retrieved.
> *** Verify that a stale object that is still in the backing storage is updated, and that its expiration time is updated.
> *** Verify that a stale object that is not in the backing storage is removed from the cache.



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