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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
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package org.apache.brooklyn.entity.brooklynnode.effector;
import java.util.NoSuchElementException;
import java.util.concurrent.Callable;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.brooklyn.api.effector.Effector;
import org.apache.brooklyn.api.entity.Entity;
import org.apache.brooklyn.api.entity.Group;
import org.apache.brooklyn.api.mgmt.ha.HighAvailabilityMode;
import org.apache.brooklyn.api.mgmt.ha.ManagementNodeState;
import org.apache.brooklyn.core.effector.EffectorBody;
import org.apache.brooklyn.core.effector.Effectors;
import org.apache.brooklyn.core.entity.EntityPredicates;
import org.apache.brooklyn.entity.brooklynnode.BrooklynCluster;
import org.apache.brooklyn.entity.brooklynnode.BrooklynNode;
import org.apache.brooklyn.entity.brooklynnode.BrooklynCluster.SelectMasterEffector;
import org.apache.brooklyn.entity.brooklynnode.BrooklynNode.SetHighAvailabilityModeEffector;
import org.apache.brooklyn.entity.brooklynnode.BrooklynNode.SetHighAvailabilityPriorityEffector;
import org.apache.brooklyn.util.collections.MutableMap;
import org.apache.brooklyn.util.core.config.ConfigBag;
import org.apache.brooklyn.util.core.task.DynamicTasks;
import org.apache.brooklyn.util.repeat.Repeater;
import org.apache.brooklyn.util.time.Duration;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.base.Preconditions;
import com.google.common.base.Objects;
import com.google.common.collect.Iterables;
public class SelectMasterEffectorBody extends EffectorBody<Void> implements SelectMasterEffector {
public static final Effector<Void> SELECT_MASTER = Effectors.effector(SelectMasterEffector.SELECT_MASTER).impl(new SelectMasterEffectorBody()).build();
private static final Logger LOG = LoggerFactory.getLogger(SelectMasterEffectorBody.class);
private static final int HA_STANDBY_PRIORITY = 0;
private static final int HA_MASTER_PRIORITY = 1;
private AtomicBoolean selectMasterInProgress = new AtomicBoolean();
@Override
public Void call(ConfigBag parameters) {
if (!selectMasterInProgress.compareAndSet(false, true)) {
throw new IllegalStateException("A master change is already in progress.");
}
try {
selectMaster(parameters);
} finally {
selectMasterInProgress.set(false);
}
return null;
}
private void selectMaster(ConfigBag parameters) {
String newMasterId = parameters.get(NEW_MASTER_ID);
Preconditions.checkNotNull(newMasterId, NEW_MASTER_ID.getName() + " parameter is required");
final Entity oldMaster = entity().getAttribute(BrooklynCluster.MASTER_NODE);
if (oldMaster != null && oldMaster.getId().equals(newMasterId)) {
LOG.info(newMasterId + " is already the current master, no change needed.");
return;
}
final Entity newMaster = getMember(newMasterId);
//1. Increase the priority of the node we wish to become master
toggleNodePriority(newMaster, HA_MASTER_PRIORITY);
//2. Demote the existing master so a new election takes place
try {
// this allows the finally block to run even on failure
DynamicTasks.swallowChildrenFailures();
if (oldMaster != null) {
demoteOldMaster(oldMaster, HighAvailabilityMode.HOT_STANDBY);
}
waitMasterHandover(oldMaster, newMaster);
} finally {
//3. Revert the priority of the node once it has become master
toggleNodePriority(newMaster, HA_STANDBY_PRIORITY);
}
checkMasterSelected(newMaster);
}
private void waitMasterHandover(final Entity oldMaster, final Entity newMaster) {
boolean masterChanged = Repeater.create()
.backoff(Repeater.DEFAULT_REAL_QUICK_PERIOD, 1.5, Duration.FIVE_SECONDS)
.limitTimeTo(Duration.ONE_MINUTE)
.until(new Callable<Boolean>() {
@Override
public Boolean call() throws Exception {
Entity master = getMasterNode();
return !Objects.equal(master, oldMaster) && master != null;
}
})
.run();
if (!masterChanged) {
LOG.warn("Timeout waiting for node to become master: " + newMaster + ".");
}
}
private void demoteOldMaster(Entity oldMaster, HighAvailabilityMode mode) {
ManagementNodeState oldState = DynamicTasks.queue(
Effectors.invocation(
oldMaster,
BrooklynNode.SET_HIGH_AVAILABILITY_MODE,
MutableMap.of(SetHighAvailabilityModeEffector.MODE, mode))
).asTask().getUnchecked();
if (oldState != ManagementNodeState.MASTER) {
LOG.warn("The previous HA state on node " + oldMaster.getId() + " was " + oldState +
", while the expected value is " + ManagementNodeState.MASTER + ".");
}
}
private void toggleNodePriority(Entity node, int newPriority) {
Integer oldPriority = DynamicTasks.queue(
Effectors.invocation(
node,
BrooklynNode.SET_HIGH_AVAILABILITY_PRIORITY,
MutableMap.of(SetHighAvailabilityPriorityEffector.PRIORITY, newPriority))
).asTask().getUnchecked();
Integer expectedPriority = (newPriority == HA_MASTER_PRIORITY ? HA_STANDBY_PRIORITY : HA_MASTER_PRIORITY);
if (oldPriority != expectedPriority) {
LOG.warn("The previous HA priority on node " + node.getId() + " was " + oldPriority +
", while the expected value is " + expectedPriority + " (while setting priority " +
newPriority + ").");
}
}
private void checkMasterSelected(Entity newMaster) {
Entity actualMaster = getMasterNode();
if (actualMaster != newMaster) {
throw new IllegalStateException("Expected node " + newMaster + " to be master, but found that " +
"master is " + actualMaster + " instead.");
}
}
private Entity getMember(String memberId) {
Group cluster = (Group)entity();
try {
return Iterables.find(cluster.getMembers(), EntityPredicates.idEqualTo(memberId));
} catch (NoSuchElementException e) {
throw new IllegalStateException(memberId + " is not an ID of brooklyn node in this cluster");
}
}
private Entity getMasterNode() {
return entity().getAttribute(BrooklynCluster.MASTER_NODE);
}
}