[jboss-jira] [JBoss JIRA] (JGRP-1877) System.nanoTime() may be negative

[Bela Ban (JIRA)]

Bela Ban created JGRP-1877:
------------------------------

             Summary: System.nanoTime() may be negative
                 Key: JGRP-1877
                 URL: https://issues.jboss.org/browse/JGRP-1877
             Project: JGroups
          Issue Type: Bug
      Security Level: Public (Everyone can see)
            Reporter: Bela Ban
            Assignee: Bela Ban
             Fix For: 3.5.1, 3.6


According to the javadoc, {{System.nanoTime()}} should only be used to measure _elapsed time_, but not compute a _target time in the future_, as {{nanoTime()}} might return a negative value. 

Code like the one below might fail:

{code:title=Responses.waitFor()|borderStyle=solid}
public boolean waitFor(long timeout) {
        long wait_time;
        final long target_time=System.nanoTime() + TimeUnit.NANOSECONDS.convert(timeout, TimeUnit.MILLISECONDS); // ns

        lock.lock();
        try {
            while(!done && (wait_time=target_time - System.nanoTime()) > 0) {
                try {
                    cond.await(wait_time,TimeUnit.NANOSECONDS);
                }
                catch(InterruptedException e) {
                }
            }
            return done;
        }
        finally {
            lock.unlock();
        }
    }
{code}

Investigate all occurrences where we use {{nanoTime()}} to compute a time in the future, and see what impact a negative value could have. Possibly replace with {{System.currentTimeMillis()}} or the _time service_.



--
This message was sent by Atlassian JIRA
(v6.3.1#6329)