RFR(S) 8231257 (CDS) Avoid calling FileMapInfo::write_region twice

[Calvin Cheung]

Hi Ioi,

Thanks for doing this cleanup.

http://cr.openjdk.java.net/~iklam/jdk14/8231257-call-write-region-once.v01/src/hotspot/share/memory/filemap.cpp.sdiff.html

1102     header_bytes += strlen(Arguments::GetSharedArchivePath() + 1);

Should the '+ 1' be outside of strlen?

              header_bytes += strlen(Arguments::GetSharedArchivePath()) + 1;

http://cr.openjdk.java.net/~iklam/jdk14/8231257-call-write-region-once.v01/src/hotspot/share/memory/filemap.hpp.sdiff.html

410   void  seek_to_position(size_t pos);

Could the above be under the private block since it is only used within 
FileMapInfo?

thanks,

Calvin

On 9/19/19 9:39 AM, Ioi Lam wrote:
> https://bugs.openjdk.java.net/browse/JDK-8231257
> http://cr.openjdk.java.net/~iklam/jdk14/8231257-call-write-region-once.v01/ 
>
>
> Please review this clean up in CDS:
>
> We call FileMapInfo::write_region twice in a loop --
>
> + first time just to store the CRC and offset into in the file header
> + second time is to actually write the region
>
> This is awkward. The whole reason is for writing the file header 
> before writing the regions.
>
> But that's not necessary. We should first write the regions, then seek 
> back to position 0, and write the header.
>
> Thanks
> - Ioi
>
>
>
> <https://bugs.openjdk.java.net/browse/JDK-8231257>