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/*
* ============LICENSE_START=======================================================
* ONAP
* ================================================================================
* Copyright (C) 2018 AT&T Intellectual Property. All rights reserved.
* ================================================================================
* 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;
// TODO add logging
/**
* 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 or not 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 {
/**
* Hosts that have sent an "Identification" message. Always includes this
* host.
*/
private TreeSet<String> alive = new TreeSet<>();
/**
*
* @param mgr
*/
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(), xxx -> {
if (isLeader()) {
// "this" host is the new leader
return becomeLeader(alive);
} else if (hasAssignment()) {
/*
* this host is not the new leader, but it does have an
* assignment - return to the active state while we wait for the
* leader
*/
return goActive();
} else {
// not the leader and no assignment yet
return goInactive();
}
});
}
/**
* Remains in this state.
*/
@Override
public State goQuery() {
return null;
}
/**
* Determines if this host has an assignment in the CURRENT assignments.
*
* @return {@code true} if this host has an assignment, {@code false}
* otherwise
*/
protected boolean hasAssignment() {
BucketAssignments asgn = getAssignments();
return (asgn != null && asgn.hasAssignment(getHost()));
}
@Override
public State process(Identification msg) {
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) {
BucketAssignments asgn = msg.getAssignments();
if (asgn == null) {
return null;
}
// ignore Leader messages from ourself
String source = msg.getSource();
if (source == null || source.equals(getHost())) {
return null;
}
// the new leader must equal the source
if (!source.equals(asgn.getLeader())) {
return null;
}
// go active, if this has a better leader than the one we have
if (source.compareTo(getLeader()) < 0) {
return super.process(msg);
}
/*
* The message does not have an acceptable leader, but we'll still
* record its info.
*/
recordInfo(msg.getSource(), msg.getAssignments());
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) {
setAssignments(assignments);
return;
}
/*
* Record assignments, if the new assignments have a better (i.e.,
* lesser) leader.
*/
String curldr = current.getLeader();
if (curldr == null || curldr.compareTo(assignments.getLeader()) > 0) {
setAssignments(assignments);
}
}
@Override
public State process(Offline msg) {
String host = msg.getSource();
if (host != null && !host.equals(getHost())) {
alive.remove(host);
setLeader(alive.first());
}
return null;
}
}
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