Re: [PATCH v2] alloc.h|c: migrate alloc_states to mem-pool

[胡哲宁 <adlternative@gmail.com>]

To René Scharfe:
Thanks for checking in.

René Scharfe <l.s.r@web.de> 于2021年2月2日周二 上午1:55写道：
>
> Am 01.02.21 um 11:39 schrieb 阿德烈 via GitGitGadget:
> > From: ZheNing Hu <adlternative@gmail.com>
> >
> > "alloc_state" may have similar effects with "mem_pool".
> > Using the new memory pool API may be more beneficial
> > to our memory management in the future.
>
> Replacing the custom object allocator with mem-pool would allow reducing
> the code size.  What other effects might it have?  Do you expect changes
> in memory use and/or performance with the current code and your patch?
>
> > functions "alloc_*_node" now change to "mem_pool_alloc_*_node".
>
> Why rename these functions?  Do callers need to care about the
> underlying allocator?  The function signatures stay the same.  In any
> case, this renaming would be easier to review if it was moved to a
> separate patch.
>
Truly,I will change it.
> > At the same time ,I add the member `alloc_count` of
> > struct mem_pool ,so that we can effective track
> > node alloc count,and adapt to the original interface `alloc_report`.
>
> This function has no callers.  Why not remove it (in a separate patch)?
>
Before I may have some confuse about choosing `alloc_state`or`mem_pool`,
so It has not been deleted yet.I remember that now.
> > diff --git a/alloc.c b/alloc.c
> > index 957a0af3626..951ef3e4ed7 100644
> > --- a/alloc.c
> > +++ b/alloc.c
> > @@ -71,30 +71,30 @@ static inline void *alloc_node(struct alloc_state *s, size_t node_size)
> >       return ret;
> >  }
>
> This keeps the now unused function alloc_node(), which breaks the build
> with -Werror.
>
> allocate_alloc_state() and clear_alloc_state() become unused as well,
> but the compiler doesn't complain because those functions are
> exported.  Nevertheless this patch should remove them, no?
>
> > diff --git a/object.h b/object.h
> > index 59daadce214..43031d8dc04 100644
> > --- a/object.h
> > +++ b/object.h
> > @@ -10,11 +10,11 @@ struct parsed_object_pool {
> >       int nr_objs, obj_hash_size;
> >
> >       /* TODO: migrate alloc_states to mem-pool? */
>
> This comment becomes stale with this patch and should be removed at
> the same time.
>
OK.
> > -     struct alloc_state *blob_state;
> > -     struct alloc_state *tree_state;
> > -     struct alloc_state *commit_state;
> > -     struct alloc_state *tag_state;
> > -     struct alloc_state *object_state;
> > +     struct mem_pool *blob_pool;
> > +     struct mem_pool *tree_pool;
> > +     struct mem_pool *commit_pool;
> > +     struct mem_pool *tag_pool;
> > +     struct mem_pool *object_pool;
>
> Why have pointers here instead of the structs themselves?  It's not like
> a struct parsed_object_pool is of much use without them, right?
>
> The same question applies to the original code as well, of course.
Here I may have some questions: why use `struct mem_pool` instead of
using `struct mem_pool *`?
I hope you can answer my doubts, thank you!
>
> René