sexp_copy_context defined as API function but not implemented

[w0utert]

sexp_copy_context defined as API function but not implemented

[ashinn]

Sorry about that, this was refactored and improved by Chris Walsh in 2005c19.

You want to use sexp dst = sexp_gc_heap_pack(ctx, new_size_or_zero).

[w0utert]

This seems to work, thanks!

I do have 2 questions about sexp_gc_heap_pack though:

1. This will re-do the packing of the source context every time I want to make copy of it, which I guess is non-trivial in terms of what it needs to do? It's relatively fast for my current contexts (~1ms) but not nearly as fast as creating child contexts & environments (which is basically free, but does not allow multithreaded use). Would it be possible to make a much faster variation of this function that just copies and doesn't do any packing?

2. I'm confused about the new_size_or_zero argument, the API comment says that passing 0 means the packed context will have exactly enough heap space to hold what was defined in the source context and nothing more. I would expect this means allocating anything in the packed context would fail with some kind of out-of-memory error, but this does not seem to be the case (I can run code that needs allocation inside it?)

[ashinn]

1. Yes, it would be possible, but 1. I'm not sure how much faster it would be, and 2. it's tricky code that I don't have time to maintain.
2. Chibi dynamically expands the heap as needed (it's actually a chain of heap blocks).