RFR: 8269685: Optimize HeapHprofBinWriter implementation [v7]

[Serguei Spitsyn]

On Mon, 6 Sep 2021 07:17:58 GMT, Lin Zang <lzang at openjdk.org> wrote:

>> This PR rewrite the implementation of the HeapHprofBinWriter, which could simplify the logic of current implementation.
>> please see detail description at https://bugs.openjdk.java.net/browse/JDK-8269685.
>
> Lin Zang has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains seven commits:
> 
>  - Merge branch 'master' into hprof
>  - make calculateGlobalJNIHandlesDumpRecordSize abstract
>  - code clean up and remove useless methods
>  - Merge branch 'master' into hprof
>  - fix write size issue
>  - Merge branch 'master' into hprof
>  - 8269685: Optimize HeapHprofBinWriter implementation

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/utilities/HeapHprofBinWriter.java line 422:

> 420:                 };
> 421:             }
> 422:             hprofBufferedOut = dataOut;

I do not understand why the local variable `dataOut` is needed.
The code will be simpler without it:

    OutputStream dataOut = fos;
     hprofBufferedOut = dataOut;
     if (useSegmentedHeapDump) {
         if (isCompression()) {
             dataOut = new GZIPOutputStream(fos) {
                 {
                     this.def.setLevel(gzLevel);
                 }
             };
         }
         hprofBufferedOut = dataOut;
     }

=====>

     hprofBufferedOut = fos;
     if (useSegmentedHeapDump) {
         if (isCompression()) {
             hprofBufferedOut = new GZIPOutputStream(fos) {
                 {
                     this.def.setLevel(gzLevel);
                 }
             };
         }
     }

-------------

PR: https://git.openjdk.java.net/jdk/pull/4666