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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2018 AT&T Intellectual Property. All rights reserved.
* Modifications Copyright (C) 2024 Nordix Foundation.
* ================================================================================
* Licensed 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 specific language governing permissions and
* limitations under the License.
* ============LICENSE_END=========================================================
*/
package org.onap.policy.drools.pooling.state;
import java.util.TreeSet;
import org.onap.policy.drools.pooling.PoolingManager;
import org.onap.policy.drools.pooling.message.BucketAssignments;
import org.onap.policy.drools.pooling.message.Identification;
import org.onap.policy.drools.pooling.message.Leader;
import org.onap.policy.drools.pooling.message.Offline;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* The Query state. In this state, the host waits for the other hosts to identify
* themselves. Eventually, a leader should come forth. If not, it will transition to the
* active or inactive state, depending on whether it has an assignment in the
* current bucket assignments. The other possibility is that it may <i>become</i> the
* leader, in which case it will also transition to the active state.
*/
public class QueryState extends ProcessingState {
private static final Logger logger = LoggerFactory.getLogger(QueryState.class);
/**
* Hosts that have sent an "Identification" message. Always includes this host.
*/
private final TreeSet<String> alive = new TreeSet<>();
/**
* {@code True} if we saw our own Identification method, {@code false} otherwise.
*/
private boolean sawSelfIdent = false;
/**
* Constructor.
*
* @param mgr manager
*/
public QueryState(PoolingManager mgr) {
// this host is the leader, until a better candidate identifies itself
super(mgr, mgr.getHost());
alive.add(getHost());
}
@Override
public void start() {
super.start();
// start identification timer
awaitIdentification();
}
/**
* Starts a timer to wait for all Identification messages to arrive.
*/
private void awaitIdentification() {
/*
* Once we've waited long enough for all Identification messages to arrive, become
* the leader, assuming we should.
*/
schedule(getProperties().getIdentificationMs(), () -> {
if (!sawSelfIdent) {
// didn't see our identification
logger.error("missed our own Ident message on topic {}", getTopic());
return missedHeartbeat();
} else if (isLeader()) {
// "this" host is the new leader
logger.info("this host is the new leader for topic {}", getTopic());
return becomeLeader(alive);
} else {
// not the leader - return to previous state
logger.info("no new leader on topic {}", getTopic());
return goActive(getAssignments());
}
});
}
@Override
public State goQuery() {
return null;
}
@Override
public State process(Identification msg) {
if (getHost().equals(msg.getSource())) {
logger.info("saw our own Ident message on topic {}", getTopic());
sawSelfIdent = true;
} else {
logger.info("received Ident message from {} on topic {}", msg.getSource(), getTopic());
recordInfo(msg.getSource(), msg.getAssignments());
}
return null;
}
/**
* If the message leader is better than the leader we have, then go active with it.
* Otherwise, simply treat it like an {@link Identification} message.
*/
@Override
public State process(Leader msg) {
if (!isValid(msg)) {
return null;
}
String source = msg.getSource();
BucketAssignments asgn = msg.getAssignments();
// go active, if this has a leader that's the same or better than the one we have
if (source.compareTo(getLeader()) <= 0) {
logger.warn("leader with {} on topic {}", source, getTopic());
return goActive(asgn);
}
/*
* The message does not have an acceptable leader, but we'll still record its
* info.
*/
logger.info("record leader info from {} on topic {}", source, getTopic());
recordInfo(source, asgn);
return null;
}
@Override
public State process(Offline msg) {
String host = msg.getSource();
if (host != null && !host.equals(getHost())) {
logger.warn("host {} offline on topic {}", host, getTopic());
alive.remove(host);
setLeader(alive.first());
} else {
logger.info("ignored offline message from {} on topic {}", msg.getSource(), getTopic());
}
return null;
}
/**
* Records info from a message, adding the source host name to {@link #alive}, and
* updating the bucket assignments.
*
* @param source the message's source host
* @param assignments assignments, or {@code null}
*/
private void recordInfo(String source, BucketAssignments assignments) {
// add this message's source host to "alive"
if (source != null) {
alive.add(source);
setLeader(alive.first());
}
if (assignments == null || assignments.getLeader() == null) {
return;
}
// record assignments, if we don't have any yet
BucketAssignments current = getAssignments();
if (current == null) {
logger.info("received initial assignments on topic {}", getTopic());
setAssignments(assignments);
return;
}
/*
* Record assignments, if the new assignments have a better (i.e., lesser) leader.
*/
String curldr = current.getLeader();
if (curldr == null || assignments.getLeader().compareTo(curldr) < 0) {
logger.info("use new assignments from {} on topic {}", source, getTopic());
setAssignments(assignments);
}
}
}
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