RFR: 8284638: store skip buffers in InputStream Object [v3]

[liach]

On Wed, 13 Apr 2022 14:56:12 GMT, XenoAmess <duke at openjdk.java.net> wrote:

>> @jmehrens what about this then?
>> I think it safe now(actually this mechanism is learned from Reader)
>
> XenoAmess has updated the pull request incrementally with one additional commit since the last revision:
> 
>   moving nr declaration from the beginning of the method to where it's actually used

Yeah forgot about that part. Thus I guess using soft reference would be a better way to deal with this extra memory use issue. So something like

private SoftReference<byte[]> skipBuffer;

private byte[] skipBuffer(long remaining) {
    int size = (int) Math.min(MAX_SKIP_BUFFER_SIZE, remaining);
    SoftReference<byte[]> ref = this.skipBuffer;
    byte[] buffer;
    if (ref == null || (buffer = ref.get()) == null || buffer.length < size) {
        buffer = new byte[size];
        this.skipBuffer = new SoftReference(buffer);
    }
    return buffer;
}


This should be thread-safe, and we can just call `byte[] skipBuffer = skipBuffer(remaining);`

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PR: https://git.openjdk.java.net/jdk/pull/5872