rb_check_symbol_cstr is not yet implemented

[larskanis]

pg-1.2.0 will probably introduce field names deliverable as symbols. In MRI there are two types of symbols: dynamic and static symbols. PG will primary use dynamic symbols per rb_check_symbol_cstr() , to allow GC'ing of field names. Static symbols on the other hand can lead to memory bloat if field names are dynamically generated.

Unfortunately Truffleruby doesn't implement rb_check_symbol_cstr so that tests fail currently.

However the tests run fine on Truffleruby with static symbols allocated by ID2SYM().

So my questions are:

1. Does Truffleruby distinguish between static and dynamic symbols like MRI does?
2. Can I use ID2SYM() to allocate symbols on Truffleruby?
3. Will you support rb_check_symbol_cstr() to make pg-1.2.0 work?

[eregon]

Thanks for the bug report!

1. No, all Symbols are the same and GC'd.
2. Yes.
3. We will, but that will need to wait for the next release (20.0), so it would be helpful if pg can use ID2SYM() on TruffleRuby.

[larskanis]

Thank you @eregon ! I switched symbol allocation to ID2SYM in ged/ruby-pg#306 on Truffleruby and it works great. So you could drop the "priority" flag from this issue.

[eregon]

@larskanis Thanks!
Using rb_str_intern always would work on both MRI and TruffleRuby, but that requires to allocate a temporary String so I guess that's why rb_check_symbol_cstr is used?

rb_check_symbol_cstr is mentioned in extension.rdoc and it seems useful for your case, so we'll implement it soon for compatibility.

[larskanis]

requires to allocate a temporary String so I guess that's why rb_check_symbol_cstr is used?

Exactly! Most of the time the symbols are already allocated, so that we allocate strings only when necessary.

[eregon]

I implemented rb_check_symbol_cstr in 2aafcec, it will be in the next release.

[larskanis]

Thank you @eregon ! Good to know it's in ruby spec now.