Hi Marc,
> It implements a persistent version of Phil Bagwell's HAMTs, which has
> been popularized by Clojure. HAMTs can be used when a persistent
> (functional/pure) version of a data structure akin to hash tables is
> needed. For example, the dynamic environment of a (possibly
> multi-threaded) Lisp or Scheme can be modeled with persistent HAMTs.
It is exciting to see such a datastructure with various application domains [1]
in Gnulib!
I haven't read through it line by line; nevertheless a couple of comments:
- +/* The public interface is documented in the file hamt.c.
This is not good. As a user of the module, I would want to read *only*
hamt.h and know how to use the public interface. In other words, hamt.h
should have the functions' comments.
- "Each
updating operation returns a new hamt, which shares structure with
the original one."
So, after calling hamt_insert or hamt_delete, which function should I call
to delete the original Hamt without affecting the new one? (In order to
avoid accumulating pieces of old Hamts in memory.)
- "The GL_HAMT_THREAD_SAFE flag is set if the implementation of hamts
is thread-safe as long as two threads do not simultaneously access
the same hamt."
I don't understand this sentence. Isn't the guarantee that
"is thread-safe as long as two threads do not simultaneously access
the same hamt" trivial? And what you want to achieve through the use
of _Atomic is that it is thread-safe *also* when two threads access
the same hamt?
Bruno
[1] http://infoscience.epfl.ch/record/64398/files/idealhashtrees.pdf
