Re: [Haskell-cafe] pure Haskell database

30 Sep 2008


      Graham Fawcett ha scritto:
...
On Thu, Sep 25, 2008 at 5:09 PM, Manlio Perillo
 wrote:
...
Graham Fawcett ha scritto:
...
If you're on Intel/Itanium, I believe there's a CMPXCHG instruction
that will do atomic compare-and-set on a memory address, and I'm not
sure you could get much faster than that. :-)
I have an early draft of this type of database (written in D).
Operations on integers use CMPXCHG, and for other operations a simple spin
lock (implemented following the implementation in Nginx) is used.
And I thought I was being original. :-)
...
The problem is that it is a simple shared array!
I'm guessing you've also ruled out sparse arrays? If not, what
complexity is acceptable on your lookup function?
Never though about sparse array, what is the advantage?
For the complexity, the same of a good hash map.
...
[...]
By the way, for the moment I think I will use Data.Map, serializing it 
to a file, since only one process will update it, and the other 
processes needs not to read an up-to-date snapshot.
The only thing that needs to be taken care of, is to write the file 
atomically, but this is easy.


Thanks   Manlio Perillo