Re: [patch 2/9] Conditional Calls - Hash Table

Matt Mackall
2007-06-01T17:08:31Z

On Fri, Jun 01, 2007 at 12:46:23PM -0400, Mathieu Desnoyers wrote:
> * Matt Mackall (mpm@selenic.com) wrote:
> > On Thu, May 31, 2007 at 03:42:50PM +0200, Andi Kleen wrote:
> > > Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> writes:
> > >
> > > > Reimplementation of the cond calls which uses a hash table to hold the active
> > > > cond_calls. It permits to first arm a cond_call and then load supplementary
> > > > modules that contain this cond_call.
> > >
> > > Hash table is probably overkill. This is a very very slow path operation.
> > > Can you simplify the code? Just a linked list of all the condcall segments
> > > should be enough and then walk it.
> >
> > I think it could be greatly simplified by using symbols instead of
> > strings.
> >
> > That is, doing cond_call(foo, func()) rather than cond_call("foo",
> > func()). Here foo is a structure or type holding the relevant info to
> > deal with the cond_call infrastructure. For unoptimized architectures,
> > it can simply be a bool, which will be faster.
> >
> > This has the added advantage that the compiler will automatically pick
> > up any misspellings of these things. And it saves the space we'd use
> > on the hash table too.
> >
>
> The idea is interesting, but does not fit the problem: AFAIK, it will
> not be possible to do multiple declarations of the same symbol, which is
> needed whenever we want to declare a cond_call() more than once or to
> embed it in an inline function.

It's not clear to me why either of those things are necessary. An
example please?

--
Mathematics is the supreme nostalgia of our time.