RFR 4358774: Add null InputStream and OutputStream

[Roger Riggs]

Hmm...

Seems like a lot of fine tuning for a function that has a low profile and no
performance data...

$.02, Roger

On 12/6/2017 10:03 PM, Vitaly Davidovich wrote:
> On Wed, Dec 6, 2017 at 4:01 PM, Jason Mehrens <jason_mehrens at hotmail.com>
> wrote:
>
>> Brian,
>>
>> My understand is JDK-6533165 is moving the bytes that are rarely invoked
>> to a cold method.
>>
>> Therefore:
>> ====
>> if (closed) {
>>     throw new IOException("Stream closed");
>> }
>> ==becomes===
>> if (closed) {
>>     throw sc();
>> }
>>
>> private static IOException sc() {
>>      return new IOException("Stream closed");
>> }
>> ================================
>>
>> Since there is no string concatenation in the IOE message there are only a
>> few bytes that can be shaved off.  I didn't benchmark it either case but I
>> would assume it would matter for the nullOutputStream since the write
>> methods could be invoked multiple times.
>>
>  From a performance angle, I'd be more concerned with the calls to
> Objects.xyz() methods there.  Unless something has changed in the JIT
> recently, those are susceptible to profile pollution and can cause missed
> optimizations.  I'd inline those methods manually to give these methods
> their own profiles.
>
>> Jason
>> ________________________________________
>> From: Brian Burkhalter <brian.burkhalter at oracle.com>
>> Sent: Wednesday, December 6, 2017 2:05 PM
>> To: Jason Mehrens
>> Cc: core-libs-dev
>> Subject: Re: RFR 4358774: Add null InputStream and OutputStream
>>
>> Jason,
>>
>> On Dec 6, 2017, at 11:54 AM, Jason Mehrens <jason_mehrens at hotmail.com<
>> mailto:jason_mehrens at hotmail.com>> wrote:
>>
>> For nullInputStream would it make any sense to use the
>> ByteArrayInputStream with a (private static) empty byte array?  Maybe
>> 'return new ByteArrayInputStream("".getBytes());'?  One side effect is
>> that mark support returns true.
>>
>> As we are trying to retain the behavior of closed streams throwing
>> IOExceptions I don’t think that BAIS would work here.
>>
>> Does it make sense to follow the advice inhttps://bugs.openjdk.java.
>> net/browse/JDK-6533165 with regards to streams being closed?
>>
>> I don’t know exactly what you intend here. In the linked issue there is
>> information to impart, namely the index and the size. Here there is only
>> the indication that the stream is closed. It’s not clear to me what could
>> be done here.
>>
>> Thanks,
>>
>> Brian
>>