Examples with LeadershipToken com.palantir.leader.LeaderElectionService.LeadershipToken used on opensource projects

Example 1 with LeadershipToken

use of com.palantir.leader.LeaderElectionService.LeadershipToken in project atlasdb by palantir.

the class AwaitingLeadershipProxy method handleInvocation.

@Override
protected Object handleInvocation(Object proxy, Method method, Object[] args) throws Throwable {
    final LeadershipToken leadershipToken = leadershipTokenRef.get();
    if (leadershipToken == null) {
        throw notCurrentLeaderException("method invoked on a non-leader");
    }
    if (method.getName().equals("close") && args.length == 0) {
        isClosed = true;
        executor.shutdownNow();
        clearDelegate();
        return null;
    }
    Object delegate = delegateRef.get();
    StillLeadingStatus leading = null;
    for (int i = 0; i < MAX_NO_QUORUM_RETRIES; i++) {
        // TODO(nziebart): check if leadershipTokenRef has been nulled out between iterations?
        leading = leaderElectionService.isStillLeading(leadershipToken);
        if (leading != StillLeadingStatus.NO_QUORUM) {
            break;
        }
    }
    // and should assume we're not the leader
    if (leading == StillLeadingStatus.NOT_LEADING || leading == StillLeadingStatus.NO_QUORUM) {
        markAsNotLeading(leadershipToken, null);
    }
    if (isClosed) {
        throw new IllegalStateException("already closed proxy for " + interfaceClass.getName());
    }
    Preconditions.checkNotNull(delegate, "%s backing is null", interfaceClass.getName());
    try {
        return method.invoke(delegate, args);
    } catch (InvocationTargetException e) {
        if (e.getTargetException() instanceof ServiceNotAvailableException || e.getTargetException() instanceof NotCurrentLeaderException) {
            markAsNotLeading(leadershipToken, e.getCause());
        }
        // Prevent blocked lock requests from receiving a non-retryable 500 on interrupts in case of a leader election.
        if (e.getTargetException() instanceof InterruptedException && !isStillCurrentToken(leadershipToken)) {
            throw notCurrentLeaderException("received an interrupt due to leader election.", e.getTargetException());
        }
        throw e.getTargetException();
    }
}

Example 2 with LeadershipToken

use of com.palantir.leader.LeaderElectionService.LeadershipToken in project atlasdb by palantir.

the class AwaitingLeadershipProxy method gainLeadershipBlocking.

private void gainLeadershipBlocking() {
    try {
        LeadershipToken leadershipToken = leaderElectionService.blockOnBecomingLeader();
        onGainedLeadership(leadershipToken);
    } catch (InterruptedException e) {
        log.warn("attempt to gain leadership interrupted", e);
    } catch (Throwable e) {
        log.error("problem blocking on leadership", e);
    }
}

Example 3 with LeadershipToken

use of com.palantir.leader.LeaderElectionService.LeadershipToken in project atlasdb by palantir.

the class PaxosConsensusFastTest method loseQuorum.

@Test
public void loseQuorum() {
    LeadershipToken t = state.gainLeadership(0);
    for (int i = 1; i < NUM_POTENTIAL_LEADERS - QUORUM_SIZE + 2; i++) {
        state.goDown(i);
    }
    assertFalse("leader cannot maintain leadership withou quorum", state.leader(0).isStillLeading(t) == StillLeadingStatus.LEADING);
    state.comeUp(1);
    state.gainLeadership(0);
    assertTrue("leader can confirm leadership with quorum", state.leader(0).isStillLeading(t) != StillLeadingStatus.NOT_LEADING);
}

Example 4 with LeadershipToken

use of com.palantir.leader.LeaderElectionService.LeadershipToken in project atlasdb by palantir.

the class PaxosConsensusFastTest method loseQuorumDiffToken.

@Test
public void loseQuorumDiffToken() throws InterruptedException {
    for (int i = QUORUM_SIZE; i < NUM_POTENTIAL_LEADERS; i++) {
        state.goDown(i);
    }
    LeadershipToken t = state.gainLeadership(0);
    state.goDown(QUORUM_SIZE - 1);
    ExecutorService exec = PTExecutors.newSingleThreadExecutor();
    Future<Void> f = exec.submit(() -> {
        int i = QUORUM_SIZE - 1;
        while (!Thread.currentThread().isInterrupted()) {
            int next = i + 1;
            if (next == NUM_POTENTIAL_LEADERS) {
                next = QUORUM_SIZE - 1;
            }
            state.goDown(next);
            state.comeUp(i);
            i = next;
        }
        return null;
    });
    // Don't check leadership immediately after gaining it, since quorum might get lost.
    LeadershipToken token2 = state.gainLeadershipWithoutCheckingAfter(0);
    assertTrue("leader can confirm leadership with quorum", t.sameAs(token2));
    f.cancel(true);
    exec.shutdown();
    exec.awaitTermination(10, TimeUnit.SECONDS);
    for (int i = 0; i < NUM_POTENTIAL_LEADERS; i++) {
        state.comeUp(i);
    }
}