[ZOOKEEPER-1972] Fix invalid volatile long/int increment (++)

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.5.0
• Fix Version/s: 3.5.0
• Hadoop Flags: Reviewed
• Release Note: Awesome! thanks Hongchao! Committed to trunk
• Assignee: Hongchao Deng
• Reporter: Hongchao Deng
• Created: 18/Jul/14 23:44
• Updated: 20/Jul/14 11:24
• Resolved: 20/Jul/14 02:51

Description

The findbugs complains about incrementing a volatile variable in AuthFastLeaderElection and FastLeaderElection:

volatile long logicalclock; /* Election instance */
...
logicalclock++;

Actually this is a bug. It should use AtomicLong here instead of volatile.

Leader.java and QuorumPeer.java and LearnerHandler.java:

volatile int tick;

I don't think it needs volatile here. The tick is incremented only in Leader.java:

  synchronized (this) {
          ...
                    if (!tickSkip) {
                        self.tick++;
                    }
  }

and it's protected by the synchronized statement. I just remove volatile keyword.