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本文主要研究一下artemis的FederationManager
FederationManager
activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/federation/FederationManager.java
public class FederationManager implements ActiveMQComponent {
private final ActiveMQServer server;
private Map federations = new HashMap<>();
private State state;
enum State {
STOPPED,
STOPPING,
/**
* Deployed means {@link FederationManager#deploy()} was called but
* {@link FederationManager#start()} was not called.
*
* We need the distinction if {@link FederationManager#stop()} is called before 'start'. As
* otherwise we would leak locators.
*/
DEPLOYED, STARTED,
}
public FederationManager(final ActiveMQServer server) {
this.server = server;
}
@Override
public synchronized void start() throws ActiveMQException {
if (state == State.STARTED) return;
deploy();
for (Federation federation : federations.values()) {
federation.start();
}
state = State.STARTED;
}
@Override
public synchronized void stop() {
if (state == State.STOPPED) return;
state = State.STOPPING;
for (Federation federation : federations.values()) {
federation.stop();
}
federations.clear();
state = State.STOPPED;
}
@Override
public boolean isStarted() {
return state == State.STARTED;
}
public synchronized void deploy() throws ActiveMQException {
for (FederationConfiguration federationConfiguration : server.getConfiguration().getFederationConfigurations()) {
deploy(federationConfiguration);
}
if (state != State.STARTED) {
state = State.DEPLOYED;
}
}
public synchronized boolean undeploy(String name) {
Federation federation = federations.remove(name);
if (federation != null) {
federation.stop();
}
return true;
}
public synchronized boolean deploy(FederationConfiguration federationConfiguration) throws ActiveMQException {
Federation federation = federations.get(federationConfiguration.getName());
if (federation == null) {
federation = newFederation(federationConfiguration);
} else if (!Objects.equals(federation.getConfig().getCredentials(), federationConfiguration.getCredentials())) {
undeploy(federationConfiguration.getName());
federation = newFederation(federationConfiguration);
}
federation.deploy();
return true;
}
private synchronized Federation newFederation(FederationConfiguration federationConfiguration) throws ActiveMQException {
Federation federation = new Federation(server, federationConfiguration);
federations.put(federationConfiguration.getName(), federation);
if (state == State.STARTED) {
federation.start();
}
return federation;
}
public Federation get(String name) {
return federations.get(name);
}
public void register(FederatedAbstract federatedAbstract) {
server.registerBrokerPlugin(federatedAbstract);
}
public void unregister(FederatedAbstract federatedAbstract) {
server.unRegisterBrokerPlugin(federatedAbstract);
}
}
- FederationManager实现了ActiveMQComponent接口，它提供了start()、stop()、deploy、undeploy等方法；其中start方法会先执行deploy方法，然后遍历federations.values()执行federation.start()；stop方法则是遍历federations.values()执行federation.stop()，然后清空federations；deploy方法在federation为null时执行newFederation，然后执行federation.deploy()，若不为null且credentials与配置不一致则执行undeploy，重新newFederation；undeploy方法则是将federation从federations中移除然后执行federation.stop()
Federation
activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/federation/Federation.java
public class Federation {
private final ActiveMQServer server;
private final SimpleString name;
private final Map upstreams = new HashMap<>();
private final Map downstreams = new HashMap<>();
private final FederationConfiguration config;
private FederationManager.State state;
//......
public synchronized void deploy() throws ActiveMQException {
for (FederationUpstreamConfiguration upstreamConfiguration : config.getUpstreamConfigurations()) {
deploy(upstreamConfiguration, config.getFederationPolicyMap());
}
for (FederationDownstreamConfiguration downstreamConfiguration : config.getDownstreamConfigurations()) {
deploy(downstreamConfiguration, config.getFederationPolicyMap());
}
if (state != FederationManager.State.STARTED) {
state = FederationManager.State.DEPLOYED;
}
}
public synchronized boolean deploy(FederationUpstreamConfiguration upstreamConfiguration, Map federationPolicyMap) throws ActiveMQException {
String name = upstreamConfiguration.getName();
FederationUpstream upstream = upstreams.get(name);
//If connection has changed we will need to do a full undeploy and redeploy.
if (upstream == null) {
undeploy(name);
upstream = deploy(name, upstreamConfiguration);
} else if (!upstream.getConnection().getConfig().equals(upstreamConfiguration.getConnectionConfiguration())) {
undeploy(name);
upstream = deploy(name, upstreamConfiguration);
}
upstream.deploy(upstreamConfiguration.getPolicyRefs(), federationPolicyMap);
return true;
}
public synchronized boolean deploy(FederationDownstreamConfiguration downstreamConfiguration, Map federationPolicyMap) throws ActiveMQException {
String name = downstreamConfiguration.getName();
FederationDownstream downstream = downstreams.get(name);
//If connection has changed we will need to do a full undeploy and redeploy.
if (downstream == null) {
undeploy(name);
downstream = deploy(name, downstreamConfiguration);
} else if (!downstream.getConnection().getConfig().equals(downstreamConfiguration.getConnectionConfiguration())) {
undeploy(name);
downstream = deploy(name, downstreamConfiguration);
}
downstream.deploy(config);
return true;
}
private synchronized FederationUpstream deploy(String name, FederationUpstreamConfiguration upstreamConfiguration) {
FederationUpstream upstream = new FederationUpstream(server, this, name, upstreamConfiguration);
upstreams.put(name, upstream);
if (state == FederationManager.State.STARTED) {
upstream.start();
}
return upstream;
}
private synchronized FederationDownstream deploy(String name, FederationDownstreamConfiguration downstreamConfiguration) {
//If we have a matching upstream connection already configured then use it for the initiating downstream connection
FederationConnection connection = null;
if (downstreamConfiguration.getConnectionConfiguration().isShareConnection()) {
for (FederationUpstream upstream : upstreams.values()) {
if (upstream.getConfig().getConnectionConfiguration()
.equals(downstreamConfiguration.getConnectionConfiguration())) {
connection = upstream.getConnection();
connection.setSharedConnection(true);
break;
}
}
}
FederationDownstream downstream = new FederationDownstream(server, this, name, downstreamConfiguration, connection);
downstreams.put(name, downstream);
if (state == FederationManager.State.STARTED) {
downstream.start();
}
return downstream;
}
//......
} - Federation的deploy方法先遍历config.getUpstreamConfigurations()，进行upstream的deploy，再遍历config.getDownstreamConfigurations()，进行downstream的deploy
小结
FederationManager实现了ActiveMQComponent接口，它提供了start()、stop()、deploy、undeploy等方法；其中start方法会先执行deploy方法，然后遍历federations.values()执行federation.start()；stop方法则是遍历federations.values()执行federation.stop()，然后清空federations；deploy方法在federation为null时执行newFederation，然后执行federation.deploy()，若不为null且credentials与配置不一致则执行undeploy，重新newFederation；undeploy方法则是将federation从federations中移除然后执行federation.stop()