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Merged
merged 5 commits into from
May 6, 2022
Merged

Complete listener on rejection in FollowersChecker #86259

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b0e2c84
Complete listener on rejection in FollowersChecker
DaveCTurner Apr 28, 2022
c3edfa8
No more throws
DaveCTurner Apr 28, 2022
9ef23aa
Merge branch 'master' into 2022-04-28-follower-checker-rejection
DaveCTurner May 6, 2022
f802d96
Merge branch 'master' into 2022-04-28-follower-checker-rejection
DaveCTurner May 6, 2022
10df9cf
Merge branch 'master' into 2022-04-28-follower-checker-rejection
DaveCTurner May 6, 2022
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41 changes: 14 additions & 27 deletions server/src/main/java/org/elasticsearch/cluster/coordination/FollowersChecker.java
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,9 @@
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.message.ParameterizedMessage;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionRunnable;
import org.elasticsearch.action.support.ChannelActionListener;
import org.elasticsearch.cluster.coordination.Coordinator.Mode;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.cluster.node.DiscoveryNodes;
Expand All @@ -27,7 +30,6 @@
import org.elasticsearch.transport.ConnectTransportException;
import org.elasticsearch.transport.ReceiveTimeoutTransportException;
import org.elasticsearch.transport.Transport;
import org.elasticsearch.transport.TransportChannel;
import org.elasticsearch.transport.TransportConnectionListener;
import org.elasticsearch.transport.TransportException;
import org.elasticsearch.transport.TransportRequest;
Expand Down Expand Up @@ -123,7 +125,10 @@ public FollowersChecker(
false,
false,
FollowerCheckRequest::new,
(request, transportChannel, task) -> handleFollowerCheck(request, transportChannel)
(request, transportChannel, task) -> handleFollowerCheck(
request,
new ChannelActionListener<>(transportChannel, FOLLOWER_CHECK_ACTION_NAME, request)
)
);
transportService.addConnectionListener(new TransportConnectionListener() {
@Override
Expand Down Expand Up @@ -172,7 +177,7 @@ public void updateFastResponseState(final long term, final Mode mode) {
fastResponseState = new FastResponseState(term, mode);
}

private void handleFollowerCheck(FollowerCheckRequest request, TransportChannel transportChannel) throws IOException {
private void handleFollowerCheck(FollowerCheckRequest request, ActionListener<Empty> listener) {
final StatusInfo statusInfo = nodeHealthService.getHealth();
if (statusInfo.getStatus() == UNHEALTHY) {
final String message = "handleFollowerCheck: node is unhealthy ["
Expand All @@ -186,37 +191,19 @@ private void handleFollowerCheck(FollowerCheckRequest request, TransportChannel
final FastResponseState responder = this.fastResponseState;
if (responder.mode == Mode.FOLLOWER && responder.term == request.term) {
logger.trace("responding to {} on fast path", request);
transportChannel.sendResponse(Empty.INSTANCE);
listener.onResponse(Empty.INSTANCE);
return;
}

if (request.term < responder.term) {
throw new CoordinationStateRejectedException("rejecting " + request + " since local state is " + this);
}

transportService.getThreadPool().executor(Names.CLUSTER_COORDINATION).execute(new AbstractRunnable() {
@Override
protected void doRun() throws IOException {
logger.trace("responding to {} on slow path", request);
try {
handleRequestAndUpdateState.accept(request);
} catch (Exception e) {
transportChannel.sendResponse(e);
return;
}
transportChannel.sendResponse(Empty.INSTANCE);
}

@Override
public void onFailure(Exception e) {
logger.debug(new ParameterizedMessage("exception while responding to {}", request), e);
}

@Override
public String toString() {
return "slow path response to " + request;
}
});
transportService.getThreadPool().executor(Names.CLUSTER_COORDINATION).execute(ActionRunnable.supply(listener, () -> {
logger.trace("responding to {} on slow path", request);
handleRequestAndUpdateState.accept(request);
return Empty.INSTANCE;
}));
}

/**
Expand Down
61 changes: 51 additions & 10 deletions server/src/test/java/org/elasticsearch/cluster/coordination/FollowersCheckerTests.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,9 @@
import org.elasticsearch.cluster.node.DiscoveryNodes;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.settings.Settings.Builder;
import org.elasticsearch.common.util.concurrent.AbstractRunnable;
import org.elasticsearch.common.util.concurrent.DeterministicTaskQueue;
import org.elasticsearch.common.util.concurrent.EsRejectedExecutionException;
import org.elasticsearch.monitor.NodeHealthService;
import org.elasticsearch.monitor.StatusInfo;
import org.elasticsearch.test.ESTestCase;
Expand Down Expand Up @@ -575,16 +577,21 @@ protected void onSendRequest(long requestId, String action, TransportRequest req
}
};

final TransportService transportService = mockTransport.createTransportService(
settings,
deterministicTaskQueue.getThreadPool(),
TransportService.NOOP_TRANSPORT_INTERCEPTOR,
boundTransportAddress -> follower,
null,
emptySet()
);
transportService.start();
transportService.acceptIncomingRequests();
final AtomicBoolean rejectExecution = new AtomicBoolean();

final TransportService transportService = mockTransport.createTransportService(settings, deterministicTaskQueue.getThreadPool(r -> {
if (rejectExecution.get()) {
final var exception = new EsRejectedExecutionException("simulated rejection", true);
if (r instanceof AbstractRunnable ar) {
ar.onRejection(exception);
return () -> {};
} else {
throw exception;
}
} else {
return r;
}
}), TransportService.NOOP_TRANSPORT_INTERCEPTOR, boundTransportAddress -> follower, null, emptySet());

final AtomicBoolean calledCoordinator = new AtomicBoolean();
final AtomicReference<RuntimeException> coordinatorException = new AtomicReference<>();
Expand All @@ -597,6 +604,9 @@ protected void onSendRequest(long requestId, String action, TransportRequest req
}
}, (node, reason) -> { assert false : node; }, () -> new StatusInfo(HEALTHY, "healthy-info"));

transportService.start();
transportService.acceptIncomingRequests();

{
// Does not call into the coordinator in the normal case
final long term = randomNonNegativeLong();
Expand Down Expand Up @@ -699,6 +709,37 @@ public void handleException(TransportException exp) {
assertTrue(calledCoordinator.get());
assertThat(receivedException.get(), not(nullValue()));
assertThat(receivedException.get().getRootCause().getMessage(), equalTo(exceptionMessage));
calledCoordinator.set(false);
}

{
// If it calls into the coordinator but the threadpool is shut down then the rejection is passed back to the caller
rejectExecution.set(true);
final long term = randomNonNegativeLong();
followersChecker.updateFastResponseState(term, randomFrom(Mode.LEADER, Mode.CANDIDATE));

final AtomicReference<TransportException> receivedException = new AtomicReference<>();
transportService.sendRequest(
follower,
FOLLOWER_CHECK_ACTION_NAME,
new FollowerCheckRequest(term, leader),
new TransportResponseHandler.Empty() {
@Override
public void handleResponse(TransportResponse.Empty response) {
fail("unexpected success");
}

@Override
public void handleException(TransportException exp) {
assertThat(exp, not(nullValue()));
assertTrue(receivedException.compareAndSet(null, exp));
}
}
);
deterministicTaskQueue.runAllTasks();
assertFalse(calledCoordinator.get());
assertThat(receivedException.get(), not(nullValue()));
assertThat(receivedException.get().getRootCause().getMessage(), equalTo("simulated rejection"));
}
}

Expand Down