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From "Alexei Fedotov" <alexei.fedo...@gmail.com>
Subject Re: [classlib][archive] java.util.jar specialists/authors wanted to clarify manifest chunks
Date Fri, 15 Feb 2008 12:52:31 GMT
Hello folks,

Alexey Zakharov kindly shared a hint with me that shorter letters have
a better chance of being read. That is why I prepared a shorter letter
asking again about manifest encodings in a form of patch, see
HARMONY-5517.

I really appreciate if people who touched the code before me (Nathan,
Tim, or Evgeniya) would take a look.
Thank you in advance.

[1] http://issues.apache.org/jira/browse/HARMONY-5517


On Thu, Feb 14, 2008 at 2:15 PM, Alexei Fedotov
<alexei.fedotov@gmail.com> wrote:
> Hello, Nathan,
>  Thanks for your interest. I'm trying to resolve a performance problem
>  described at HARMONY-4569. Gregory mentions that methods write() from
>  nextChunk() are called too many times, see lines 187, 201 of
>  working_classlib/modules/archive/src/main/java/java/util/jar/InitManifest.java
>  This slows down Harmony VM in debug and interpreter modes and may
>  affect overall Eclipse startup since many jars are read in the
>  process. I'm trying to collect more data.
>
>  As far as I was able to advance reviewing the complex code it seemed
>  that either code or my understanding may be improved.
>   * "chunks" hash table is used only for jar verification. Do we need
>  to initialize it for any manifest when this cost us much invocations?
>  Instead of using write() methods for creating chunks one may think of
>  remembering chunk positions in the stream, which should be read into
>  byte array using big buffers instead of individual writes.
>   * It seems that manifests longer than 1024 characters may result in
>  "string too long" exception - the buffer they are read in just gets as
>  much characters from stream as possible, and reports error if the
>  stream is not read fully.
>   * I don't know a reason why manifests are read in different
>  encodings. The spec [1] mentions UTF-8 only. Nice to know.
>   * Close functionality of readLines and nextChunk containing long
>  conditional sequences may be rewritten in more transparent and
>  documented way. Generally idea behind "rewriting" of chunks is above
>  of my understanding: I have not noticed in the specification that line
>  breaks or anything else should be "rewritten" using eight-if algorithm
>  instead of taken as is. BTW, I have noticed that Tim was behind
>  readability improvements of the code. I wonder what was there before
>  and will check it after lunch.
>   * The whole class InitManifest seems to be redundant and may be
>  replaced with a set of static methods. It seems that specific
>  functionality for two calls to InitManifest should be kept in the
>  place where InitManifest is called rather than passed to InitManifest
>  as a parameter for internal check.
>
>  I appreciate your comments and help.
>
>  [1] http://java.sun.com/j2se/1.5.0/docs/guide/jar/jar.html
>
>
>
>  On Feb 14, 2008 6:00 AM, Nathan Beyer <ndbeyer@apache.org> wrote:
>  > Can you point out the painful bits (line numbers, etc)?
>  >
>  >
>  > On Feb 13, 2008 11:01 AM, Alexei Fedotov <alexei.fedotov@gmail.com> wrote:
>  > > Hello folks,
>  > >
>  > > Do we have original
>  > > working_classlib/modules/archive/src/main/java/java/util/jar/ module
>  > > contributors on board? Could anyone clarify the reasons behind heavy
>  > > solution to copy manifest chunks into a separate hash table descried
>  > > at HARMONY-4569? Aren't entity hash table the only object which should
>  > > be populated?
>  > >
>  > > --
>  > > With best regards,
>  > > Alexei
>  > >
>  > > [1] http://issues.apache.org/jira/browse/HARMONY-4569
>  > >
>  >
>
>
>
>  --
>  With best regards,
>  Alexei
>



-- 
With best regards,
Alexei

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