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From "Mikhail Fursov" <mike.fur...@gmail.com>
Subject Re: [drlvm] the big soup of VM properties (HARMONY-1626)
Date Wed, 11 Oct 2006 05:41:23 GMT
+1 to Eugueni and Alexey and -1 to use String type in the intercomponent
interface. + AFAIK the String type is VM internal type only.

On 10/11/06, Alexey Varlamov <alexey.v.varlamov@gmail.com> wrote:
>
> 2006/10/11, Evgueni Brevnov <evgueni.brevnov@gmail.com>:
> > Gregory,
> >
> > My 2cents:
> >
> > 1cent) I think we should not integrate property module so tight (by
> > using StringPool) with VM internals. Let it be independent enough.
> > 2cent) I also don't think we should pollute StringPool any further.
> > Instead I would like to see if we can get it smaller.... say by
> > splitting into two pools whatever...
>
> Agreed. Besides properties are used in VM almost solely during init,
> no performance gain here. So -1 to using Strings for properties.
>
>
> >
> > Evgueni
> >
> > On 10/11/06, Gregory Shimansky <gshimansky@gmail.com> wrote:
> > > On Tuesday 10 October 2006 11:36 Geir Magnusson Jr. wrote:
> > > > Inline
> > > >
> > > > Dmitry Yershov wrote:
> > > >
> > > > [snip]
> > > >
> > > > >                        VM properties proposal
> > > > >                        ======================
> > > > >
> > > > >     The general purpose of VM Properties subcomponent is to
> provide
> > > > > centralized access to a common properties table. A property is
> meant
> > > > > as a pair of <key> and <value>. The properties stored
in VM
> Properties
> > > > > table represent configuration settings for a separate component
> (such
> > > > > as VMCore, GC, JIT etc) or for the whole system. Another use case
> for
> > > > > the properties is communication between different components.
> > > > >
> > > > >                             Requirements
> > > > >                             ============
> > > > >
> > > > >     1) The <key> and <value> are represented as string
(i.e.
> char*).
> > > >
> > > > and I propose that on each operation, a copy is made, so that the
> caller
> > > >    frees the  string that they got or gave.
> > >
> > > Hmm... I thought of another type. VM has a String class which
> represents an
> > > internal strings implementation. String pointers all refer to the same
> > > interned const char * memory location so comparing them is faster, you
> just
> > > compare pointers.
> > >
> > > Would it be better to have key and value be String * instead of const
> char *?
> > > It would save memory allocation, copying and comparing and lookup in
> > > properties hash table could be done using a pointer.
> > >
> > > I don't think it is a very performance critical place, properties
> aren't
> > > accessed very often, but at least it may reduce memory footprint and
> will
> > > cause less memory leaks when someone forgets to free a returned copy.
> > >
> > > On the other hand, String storage is global to the whole VM, so there
> are tons
> > > of strings kept inside of it. Lookup inside of a small hash table like
> > > properties may be much faster than lookup through all the strings that
> VM
> > > keeps... Hmm now I am not sure I want to suggest this way, just want
> it to be
> > > considered.
> > >
> > > --
> > > Gregory Shimansky, Intel Middleware Products Division
> > >
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> > >
> >
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> >
>
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>


-- 
Mikhail Fursov

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