Hello hackers, While developing an extension and trying to write some generic code around DSM areas, I noticed a limitation: although GetNamedDSMSegment accepts a callback function, there is no way to pass additional arguments to that callback.
For example, the documentation for creating LWLocks after startup [1] suggests creating locks in this callback. That works fine as long as the callback only needs to create a hardcoded lock. But if the lock name is a parameter to the function calling GetNamedDSMSegment, and not fixed, I do not see a clean way to pass it through to the callback (short of relying on global variables, for example). As a proper solution for this, and possibly for other similar issues, I propose adding a generic callback argument to GetNamedDSMSegment that can be forwarded to the callback function. What do you think about this? [1] https://www.postgresql.org/docs/current/xfunc-c.html#XFUNC-ADDIN-LWLOCKS-AFTER-STARTUP
0001-Add-a-callback-data-parameter-to-GetNamedDSMSegment.patch
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