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Feature #13133

closed

TracePoint: Add event type for constant access

Added by burke (Burke Libbey) over 5 years ago. Updated over 5 years ago.

Status:
Rejected
Priority:
Normal
Target version:
-
[ruby-core:79102]

Description

Hi there,

I've attached a patch to add a new :constant_access TracePoint event.

One feature and/or bug, depending on your perspective: since this event fires from setinlinecache, the event is only triggered:

  • after nested constant resolution: for A::B, only one event is triggered (because getinlinecache/getconstant/getconstant/setinlinecache);
  • on cache miss: it cannot be used for things like counting iterations, which limits possible uses, but reduces overhead (because getinlinecache jumps over setinlinecache on a hit).

The use-case I have in mind here is to enable building runtime package/component boundary enforcement systems. For this case, both of the above properties are ideal.

Enforcing package boundaries is a problem we've been discussing a lot lately at Shopify.

If you want a more concrete usage example for this patch, I have some proof-of-concept code posted that makes use of it to construct a fairly minimal package system. Packages::CONSTANT_ACCESS_TRACEPOINT is the particularly relevant bit.


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