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once: add Once::init_from_ref() method - #179
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During the initialization of Once, several operations need to be performed on the internal atomic status to properly get the right to initialize the internal cell. Abstract these operations away into separate methods, in preparation for a new initialization method that will reuse this functionality.
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Thanks for the PR. I think this is a good change, and the implementation passes the sniff test. I've just one comment.
Add a method to initialize a Once from a reference to a &T (which implements Copy). This method can be used to avoid expensive copies into the stack in debug builds, which might not be able to optimize away the moving of the value into the internal cell. Add as well a basic test to ensure the functionality is correct.
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Thanks! |
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Add a
Once::init_from_ref()method, which initializes theOnceonly once by copying from a&T. This is a simpler initialization method that can be used to avoid expensive copies to the stack in debug builds, since the compiler might not be able to optimize away the move of the value into the internal cell.The method has a very simple signature:
To implement this reusing the existing functionality I had to refactor some code out of
try_call_once_slowinto separate methods.