C bindings and finalize

Help & Support
1

Hi there.

Next code involving C bindings for Hunspell library.

@[Link("hunspell")]
lib LibHunspell
  type Hunhandle = Void*

  fun create = Hunspell_create(affpath : LibC::Char*, dpath : LibC::Char*) : Hunhandle
  fun destroy = Hunspell_destroy(p_hunspell : Hunhandle)
  fun spell = Hunspell_spell(p_hunspell : Hunhandle, x1 : LibC::Char*) : LibC::Int
end

class Hunspell
  @handle : LibHunspell::Hunhandle

  def initialize(affpath : String, dpath : String)
    @closed = false
    @handle = LibHunspell.create(affpath, dpath) # => Pointer(Void)
  end

  def spellcheck(word : String) : Bool
    LibHunspell.spell(@handle, word) != 0
  end

  def finalize
    puts "__finalize__"
    close
  end

  def close
    LibHunspell.destroy(@handle) unless @closed
    @closed = true
  end
end

loop do
  hunspell = Hunspell.new("/usr/share/hunspell/en_US.aff", "/usr/share/hunspell/en_US.dic")
  hunspell.spellcheck("d0g")
  # hunspell.close
end

You can notice finalize method is never called.
Of course, I can call the close method manually so this is not an issue at all for me.
I’m just curious does Crystal have a natural way to do this automatically?
Thanks for any advice.

2

Hi!

I just ran it, the finalize method is called. Can you print something else in the loop to make sure the program is actually running?

3

Hm, interesting.

puts hunspell.spellcheck("d0g")

Yes, is actually running in a loop.

Maybe it’s Hunspell issue.
What OS and Hunspell version are you using?

4

@asterite

I forget that the GC running after some time (around 20sec in this case).

What is more interesting. On macOS everything is ok.

crystal -v
Crystal 0.36.0 (2021-01-26)

LLVM: 9.0.1
Default target: x86_64-apple-macosx

But on Ubuntu 20.04 finalize method is never called. This is really weird.

crystal -v                     
Crystal 0.36.1 [c3a3c1823] (2021-02-02)

LLVM: 10.0.0
Default target: x86_64-unknown-linux-gnu
5

What if you forget about hunspell and just create a plain object with finalize on a loop? I’m also on Mac.

6

No issue.