聊聊artemis的HAManager

序

本文主要研究一下artemis的HAManager

HAManager

activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/cluster/ha/HAManager.java

public interface HAManager extends ActiveMQComponent {

   /**
    * return the current backup servers
    *
    * @return the backups
    */
   Map<String, ActiveMQServer> getBackupServers();
}

• HAManager继承了ActiveMQComponent接口，它定义了getBackupServers方法

StandaloneHAManager

activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/cluster/ha/StandaloneHAManager.java

public class StandaloneHAManager implements HAManager {

   Map<String, ActiveMQServer> servers = new HashMap<>();

   boolean isStarted = false;

   @Override
   public Map<String, ActiveMQServer> getBackupServers() {
      return servers;
   }

   @Override
   public void start() throws Exception {
      if (isStarted)
         return;
      isStarted = true;
   }

   @Override
   public void stop() throws Exception {
      if (!isStarted)
         return;
      isStarted = false;
   }

   @Override
   public boolean isStarted() {
      return isStarted;
   }
}

• StandaloneHAManager实现了HAManager接口，其getBackupServers方法返回空map

ColocatedHAManager

activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/cluster/ha/ColocatedHAManager.java

public class ColocatedHAManager implements HAManager {

   private final ColocatedPolicy haPolicy;

   private final ActiveMQServer server;

   private final Map<String, ActiveMQServer> backupServers = new HashMap<>();

   private boolean started;

   public ColocatedHAManager(ColocatedPolicy haPolicy, ActiveMQServer activeMQServer) {
      this.haPolicy = haPolicy;
      server = activeMQServer;
   }

   /**
    * starts the HA manager.
    */
   @Override
   public void start() {
      if (started)
         return;

      server.getActivation().haStarted();

      started = true;
   }

   /**
    * stop any backups
    */
   @Override
   public void stop() {
      for (ActiveMQServer activeMQServer : backupServers.values()) {
         try {
            activeMQServer.stop();
         } catch (Exception e) {
            ActiveMQServerLogger.LOGGER.errorStoppingServer(e);
         }
      }
      backupServers.clear();
      started = false;
   }

   @Override
   public boolean isStarted() {
      return started;
   }

   public synchronized boolean activateBackup(int backupSize,
                                              String journalDirectory,
                                              String bindingsDirectory,
                                              String largeMessagesDirectory,
                                              String pagingDirectory,
                                              SimpleString nodeID) throws Exception {
      if (backupServers.size() >= haPolicy.getMaxBackups() || backupSize != backupServers.size()) {
         return false;
      }
      if (haPolicy.getBackupPolicy().isSharedStore()) {
         return activateSharedStoreBackup(journalDirectory, bindingsDirectory, largeMessagesDirectory, pagingDirectory);
      } else {
         return activateReplicatedBackup(nodeID);
      }
   }

   /**
    * return the current backup servers
    *
    * @return the backups
    */
   @Override
   public Map<String, ActiveMQServer> getBackupServers() {
      return backupServers;
   }

   /**
    * send a request to a live server to start a backup for us
    *
    * @param connectorPair the connector for the node to request a backup from
    * @param backupSize    the current size of the requested nodes backups
    * @param replicated
    * @return true if the request wa successful.
    * @throws Exception
    */
   public boolean requestBackup(Pair<TransportConfiguration, TransportConfiguration> connectorPair,
                                int backupSize,
                                boolean replicated) throws Exception {
      ClusterController clusterController = server.getClusterManager().getClusterController();
      try
         (
            ClusterControl clusterControl = clusterController.connectToNode(connectorPair.getA());
         ) {
         clusterControl.authorize();
         if (replicated) {
            return clusterControl.requestReplicatedBackup(backupSize, server.getNodeID());
         } else {
            return clusterControl.requestSharedStoreBackup(backupSize, server.getConfiguration().getJournalLocation().getAbsolutePath(), server.getConfiguration().getBindingsLocation().getAbsolutePath(), server.getConfiguration().getLargeMessagesLocation().getAbsolutePath(), server.getConfiguration().getPagingLocation().getAbsolutePath());

         }
      }
   }

   private synchronized boolean activateSharedStoreBackup(String journalDirectory,
                                                          String bindingsDirectory,
                                                          String largeMessagesDirectory,
                                                          String pagingDirectory) throws Exception {
      Configuration configuration = server.getConfiguration().copy();
      ActiveMQServer backup = server.createBackupServer(configuration);
      try {
         int portOffset = haPolicy.getBackupPortOffset() * (backupServers.size() + 1);
         String name = "colocated_backup_" + backupServers.size() + 1;
         //make sure we don't restart as we are colocated
         haPolicy.getBackupPolicy().setRestartBackup(false);
         //set the backup policy
         backup.setHAPolicy(haPolicy.getBackupPolicy());
         updateSharedStoreConfiguration(configuration, name, portOffset, haPolicy.getExcludedConnectors(), journalDirectory, bindingsDirectory, largeMessagesDirectory, pagingDirectory, haPolicy.getBackupPolicy().getScaleDownPolicy() == null);

         backupServers.put(configuration.getName(), backup);
         backup.start();
      } catch (Exception e) {
         backup.stop();
         ActiveMQServerLogger.LOGGER.activateSharedStoreSlaveFailed(e);
         return false;
      }
      ActiveMQServerLogger.LOGGER.activatingSharedStoreSlave();
      return true;
   }

   /**
    * activate a backup server replicating from a specified node.
    *
    * decline and the requesting server can cast a re vote
    *
    * @param nodeID the id of the node to replicate from
    * @return true if the server was created and started
    * @throws Exception
    */
   private synchronized boolean activateReplicatedBackup(SimpleString nodeID) throws Exception {
      final TopologyMember member;
      try {
         member = server.getClusterManager().getDefaultConnection(null).getTopology().getMember(nodeID.toString());
         if (!Objects.equals(member.getBackupGroupName(), haPolicy.getBackupPolicy().getBackupGroupName())) {
            return false;
         }
      } catch (Exception e) {
         ActiveMQServerLogger.LOGGER.activateReplicatedBackupFailed(e);
         return false;
      }
      Configuration configuration = server.getConfiguration().copy();
      ActiveMQServer backup = server.createBackupServer(configuration);
      try {
         int portOffset = haPolicy.getBackupPortOffset() * (backupServers.size() + 1);
         String name = "colocated_backup_" + backupServers.size() + 1;
         //make sure we don't restart as we are colocated
         haPolicy.getBackupPolicy().setRestartBackup(false);
         //set the backup policy
         backup.setHAPolicy(haPolicy.getBackupPolicy());
         updateReplicatedConfiguration(configuration, name, portOffset, haPolicy.getExcludedConnectors(), haPolicy.getBackupPolicy().getScaleDownPolicy() == null);
         backup.addActivationParam(ActivationParams.REPLICATION_ENDPOINT, member);
         backupServers.put(configuration.getName(), backup);
         backup.start();
      } catch (Exception e) {
         backup.stop();
         ActiveMQServerLogger.LOGGER.activateReplicatedBackupFailed(e);
         return false;
      }
      ActiveMQServerLogger.LOGGER.activatingReplica(nodeID);
      return true;
   }

   //......
}

• ColocatedHAManager实现了HAManager接口，其getBackupServers方法返回backupServers；activateSharedStoreBackup方法以及activateReplicatedBackup方法都会通过server.createBackupServer(configuration)创建backup，然后添加到backupServers；activateBackup方法则根据haPolicy.getBackupPolicy()来选择执行activateSharedStoreBackup或者是activateReplicatedBackup方法

ColocatedPolicy

activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/cluster/ha/ColocatedPolicy.java

public class ColocatedPolicy implements HAPolicy<LiveActivation> {

   /*live stuff*/
   private boolean requestBackup = ActiveMQDefaultConfiguration.isDefaultHapolicyRequestBackup();

   private int backupRequestRetries = ActiveMQDefaultConfiguration.getDefaultHapolicyBackupRequestRetries();

   private long backupRequestRetryInterval = ActiveMQDefaultConfiguration.getDefaultHapolicyBackupRequestRetryInterval();

   private int maxBackups = ActiveMQDefaultConfiguration.getDefaultHapolicyMaxBackups();

   private int backupPortOffset = ActiveMQDefaultConfiguration.getDefaultHapolicyBackupPortOffset();

   /*backup stuff*/
   private List<String> excludedConnectors = new ArrayList<>();

   private BackupPolicy backupPolicy;

   private HAPolicy<LiveActivation> livePolicy;

   //......
}

• ColocatedPolicy实现了HAPolicy接口，其定义了backupPolicy属性

BackupPolicy

activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/cluster/ha/BackupPolicy.java

public abstract class BackupPolicy implements HAPolicy<Activation> {

   protected ScaleDownPolicy scaleDownPolicy;
   protected boolean restartBackup = ActiveMQDefaultConfiguration.isDefaultRestartBackup();

   public ScaleDownPolicy getScaleDownPolicy() {
      return scaleDownPolicy;
   }

   public void setScaleDownPolicy(ScaleDownPolicy scaleDownPolicy) {
      this.scaleDownPolicy = scaleDownPolicy;
   }

   @Override
   public boolean isBackup() {
      return true;
   }

   @Override
   public String getScaleDownClustername() {
      return null;
   }

   @Override
   public String getScaleDownGroupName() {
      return getScaleDownPolicy() != null ? getScaleDownPolicy().getGroupName() : null;
   }

   public boolean isRestartBackup() {
      return restartBackup;
   }

   public void setRestartBackup(boolean restartBackup) {
      this.restartBackup = restartBackup;
   }
}

• BackupPolicy声明实现了HAPolicy接口，其isBackup方法返回true；它有两个实现类分别是SharedStoreSlavePolicy与ReplicaPolicy

SharedStoreSlavePolicy

activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/cluster/ha/SharedStoreSlavePolicy.java

public class SharedStoreSlavePolicy extends BackupPolicy {

   private boolean failoverOnServerShutdown = ActiveMQDefaultConfiguration.isDefaultFailoverOnServerShutdown();

   private boolean allowAutoFailBack = ActiveMQDefaultConfiguration.isDefaultAllowAutoFailback();

   private boolean isWaitForActivation = ActiveMQDefaultConfiguration.isDefaultWaitForActivation();

   //this is how we act once we have failed over
   private SharedStoreMasterPolicy sharedStoreMasterPolicy;

   public SharedStoreSlavePolicy() {
   }

   public SharedStoreSlavePolicy(boolean failoverOnServerShutdown,
                                 boolean restartBackup,
                                 boolean allowAutoFailBack,
                                 ScaleDownPolicy scaleDownPolicy) {
      this.failoverOnServerShutdown = failoverOnServerShutdown;
      this.restartBackup = restartBackup;
      this.allowAutoFailBack = allowAutoFailBack;
      this.scaleDownPolicy = scaleDownPolicy;
   }

   @Deprecated
   public long getFailbackDelay() {
      return -1;
   }

   @Deprecated
   public void setFailbackDelay(long failbackDelay) {
   }

   public boolean isFailoverOnServerShutdown() {
      return failoverOnServerShutdown;
   }

   public void setFailoverOnServerShutdown(boolean failoverOnServerShutdown) {
      this.failoverOnServerShutdown = failoverOnServerShutdown;
   }

   public SharedStoreMasterPolicy getSharedStoreMasterPolicy() {
      if (sharedStoreMasterPolicy == null) {
         sharedStoreMasterPolicy = new SharedStoreMasterPolicy(failoverOnServerShutdown, isWaitForActivation);
      }
      return sharedStoreMasterPolicy;
   }

   public void setSharedStoreMasterPolicy(SharedStoreMasterPolicy sharedStoreMasterPolicy) {
      this.sharedStoreMasterPolicy = sharedStoreMasterPolicy;
   }

   @Override
   public boolean isSharedStore() {
      return true;
   }

   @Override
   public boolean canScaleDown() {
      return scaleDownPolicy != null;
   }

   public boolean isAllowAutoFailBack() {
      return allowAutoFailBack;
   }

   public void setAllowAutoFailBack(boolean allowAutoFailBack) {
      this.allowAutoFailBack = allowAutoFailBack;
   }

   public void setIsWaitForActivation(boolean isWaitForActivation) {
      this.isWaitForActivation = isWaitForActivation;
   }

   @Override
   public Activation createActivation(ActiveMQServerImpl server,
                                      boolean wasLive,
                                      Map<String, Object> activationParams,
                                      ActiveMQServerImpl.ShutdownOnCriticalErrorListener shutdownOnCriticalIO) {
      return new SharedStoreBackupActivation(server, this);
   }

   @Override
   public String getBackupGroupName() {
      return null;
   }
}

• SharedStoreSlavePolicy继承了BackupPolicy，其isSharedStore方法返回true

ReplicaPolicy

activemq-artemis-2.11.0/artemis-server/src/main/java/org/apache/activemq/artemis/core/server/cluster/ha/ReplicaPolicy.java

public class ReplicaPolicy extends BackupPolicy {

   private String clusterName;

   private int maxSavedReplicatedJournalsSize = ActiveMQDefaultConfiguration.getDefaultMaxSavedReplicatedJournalsSize();

   private String groupName = null;

   private boolean restartBackup = ActiveMQDefaultConfiguration.isDefaultRestartBackup();

   //used if we create a replicated policy for when we become live.
   private boolean allowFailback = ActiveMQDefaultConfiguration.isDefaultAllowAutoFailback();

   private long initialReplicationSyncTimeout = ActiveMQDefaultConfiguration.getDefaultInitialReplicationSyncTimeout();

   /*
   * what quorum size to use for voting
   * */
   private int quorumSize;

   /*
   * whether or not this live broker should vote to remain live
   * */
   private boolean voteOnReplicationFailure;

   private ReplicatedPolicy replicatedPolicy;

   private final NetworkHealthCheck networkHealthCheck;

   private int voteRetries;

   private long voteRetryWait;

   private final int quorumVoteWait;

   private long retryReplicationWait;

   //......

   @Override
   public boolean isRestartBackup() {
      return restartBackup;
   }

   @Override
   public void setRestartBackup(boolean restartBackup) {
      this.restartBackup = restartBackup;
   }

   @Override
   public boolean isSharedStore() {
      return false;
   }

   //......   
}

• ReplicaPolicy继承了BackupPolicy，其isSharedStore方法返回false

小结

HAManager继承了ActiveMQComponent接口，它定义了getBackupServers方法；StandaloneHAManager实现了HAManager接口，其getBackupServers方法返回空map；ColocatedHAManager实现了HAManager接口，其getBackupServers方法返回backupServers；activateSharedStoreBackup方法以及activateReplicatedBackup方法都会通过server.createBackupServer(configuration)创建backup，然后添加到backupServers；activateBackup方法则根据haPolicy.getBackupPolicy()来选择执行activateSharedStoreBackup或者是activateReplicatedBackup方法

doc

• HAManager