Re: [Windows] Any way to distinguish ^C Induced EOF from ^Z EOF?

From:
Jan Burse <janburse@fastmail.fm>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 13 Mar 2012 18:17:33 +0100
Message-ID:
<jjnvfe$jb2$1@news.albasani.net>
Sorry its a solution by "Maxim Khitrov". So how does
the solution look like in Java?

I did some measurement with System.nanoTime(), which
is only available since JDK 1.5. It showed the
following:

    There is in the average a delay of ~1 (ms)
    between that readLine() returns EOF and
    that the SIGINT handler is invoked.

So I opted for a Gabriel Genellina solution with a
threshold of EOF_SLEEP = 10 (ms). The code reads
as follows:

     for(;;) {
        String line = br.readLine();
        INThappened = false;
        if (line != null) {
           return line;
        } else {
           long when = System.currentTimeMillis() + EOF_SLEEP;
           long sleep = EOF_SLEEP;
           while (sleep > 0) {
               Thread.sleep(sleep);
               sleep = when - System.currentTimeMillis();
           }
           if (!INThappened) {
               return null;
           }
        }
     }

I don't particularly like the solution, since
it might give false negatives. For example if
there is a really an EOF and in the same time
a SIGINT, the EOF might be suppressed.

The SIGINT handler is supposed to do as it
first statement:

    INThappened = true;

I did the time measurement with Windows 7 / JDK
1.7 / Sony VAIO VPC-SA3J1E/XI. Maybe another
hardware / software might yield a different
estimate of the average delay. Also the delay
might depend on the system load.

So eventually EOF_SLEEP would need adjustment.
But it is below the 50ms that Maxim Khitrov
suggested:

http://www.gossamer-threads.com/lists/python/python/781893

But eventually should use ReentrantLock and
Condition with awaitNano() from java.concurrent,
since the Thread.sleep might anyway not deliver
the fine grained 10ms.

Bye

Jan Burse schrieb:

Arne Vajh??j schrieb:

Joshua would have had implemented one of the proposed
solutions by know and moved on to next problem.


I was faster, I implemented already Gabriel Genellina
solution (see Link in my very first post) a couple
of days ago.

But maybe Joshua could share his solution, so that
we could compare notes.

Bye

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