Hello David!
On 08.08.2013 6:18, David Holmes wrote:
Hi Ivan,
On 8/08/2013 3:53 AM, Ivan Gerasimov wrote:
Hello David!
Thanks for review.
Yes - this is NOT A BUG this is the spec for this class:
"Optionally, a PrintStream can be created so as to flush
automatically; this means that the flush method is automatically
invoked after a byte array is written, one of the println methods is
invoked, or a newline character or byte ('\n') is written. "
Sorry, I don't see how the proposed change would contradict the spec .
The code first writes a char[] buffer to an OutputStream, and then
invokes flush() if the written array contained at least one '\n' char.
In addition to that, the documentation for OutputStream#flush() says:
"Flushes this output stream and forces any buffered output bytes to be
written out." Thus, there should be no point to have several subsequent
calls to flush() with no data writes between them.
Sorry I misread the original code - it actually violates the spec as
well in my opinion. As I read it there should be a flush as soon as
the \n is written, not simply a flush at some later point in time if a
\n happened to have been written. As written those additional flushes
will be no-ops as you rightly point out. So your change is a more
efficient version of the existing "incorrect" implementation.
It's not hard to rewrite the code, so it would flush after each '\n'
occurrence.
But would it be a good change?
It would likely introduce a performance degradation and change the
current behavior of write() function.
The fix as it was proposed (reduce number of flushes to at most one)
doesn't make any difference in most cases.
As Alan said, in most implementations of OutputStream, flush() is no-op.
It can slightly improve performance with PipedOutputStream as it
synchronizes on the sink in its flush implementation.
Sincerely yours,
Ivan
That said the layering of the streams in this class is quite confusing
to me and it seems odd that if both textOut and charOut are
unconditionally flushed in this method, then why is 'out' only flushed
based on autoflush and the presence of the \n ??
But I withdraw my objections as what you propose does not change the
behaviour.
Thanks,
David
I don't insist on pushing this change, but I think it's harmless and may
be useful.
Sincerely yours,
Ivan
This bug report should be closed as "not an issue".
David
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-Alan
