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From Regis <xu.re...@gmail.com>
Subject Re: interesting commentary via android bug report
Date Wed, 13 Jan 2010 06:19:45 GMT
On 2010-01-13 13:49, Jesse Wilson wrote:
> On Tue, Jan 12, 2010 at 7:47 PM, Charles Lee<littlee1032@gmail.com>  wrote:
>
>> What's the reason of bad idea? limited memory?
>>
>
> A cache that cannot be cleared is a disservice to users. It's an error in
> our implementation (and the RI!) to assume that an application requesting
> the canonical path two times wants to receive the same result. If the
> application wants the same value, why doesn't the *application* cache the
> result?!

canonical path is heavily used when checking file permission. So if a 
SecurityManager is installed, canonical path will be calculated by every file 
operation at least once, that the killer of performance, application cache can't 
help that.

>
> If we want to make Harmony faster, there are better ways to do so. The
> simpler optimization is to streamline the code that looks up the canonical
> path *the first time*. Reducing the number of times we cross a JNI boundary
> is one of many opportunities here.

Yes, as I know resolving symbol links part on Linux can be done in one JNI call. 
But it's not conflict with the cache.

>
>
> What's the reason of bad implement? Anyone knows?
>>
>
> The canonical path cache code we shipped with Android 2.0 occasionally
> caused applications to crash with a NoSuchElementException.
>

It is fixed by HARMONY-6414.

-- 
Best Regards,
Regis.

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