org.apache.brooklyn.api.mgmt.ha.HighAvailabilityManager Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
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* 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
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* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.brooklyn.api.mgmt.ha;
import java.util.Map;
import com.google.common.annotations.Beta;
import com.google.common.annotations.VisibleForTesting;
/**
* Monitors other management nodes (via the {@link ManagementPlaneSyncRecordPersister}) to detect
* if the current master has failed or stopped. If so, then deterministically chooses a new master.
* If that master is self, then promotes.
* Users are not expected to implement this class, or to call methods on it directly.
*
* Expected lifecycle of methods calls on this is:
*
* - {@link #setPersister(ManagementPlaneSyncRecordPersister)}
*
- Exactly one of {@link #disabled()} or {@link #start(HighAvailabilityMode)}
*
- {@link #stop()}
*
*
* @since 0.7.0
*/
@Beta
public interface HighAvailabilityManager {
ManagementNodeState getNodeState();
/** The time in milliseconds when the state was last changed. -1 if no state transition has occurred yet.*/
long getLastStateChange();
/**
* @param persister
* @return self
*/
HighAvailabilityManager setPersister(ManagementPlaneSyncRecordPersister persister);
/**
* Indicates that HA is disabled: this node will act as the only management node in this management plane,
* and will not persist HA meta-information (meaning other nodes cannot join).
*
* Subsequently can expect {@link #getNodeState()} to be {@link ManagementNodeState#MASTER}
* and {@link #loadManagementPlaneSyncRecord(boolean)} to show just this one node --
* as if it were running HA with just one node --
* but {@link #isRunning()} will return false.
*
* Currently this method is intended to be called early in the lifecycle,
* instead of {@link #start(HighAvailabilityMode)}. It may be an error if
* this is called after this HA Manager is started.
*/
@Beta
void disabled();
/** Whether HA mode is operational */
boolean isRunning();
/**
* Starts the monitoring of other nodes (and thus potential promotion of this node from standby to master).
*
* When this method returns, the status of this node will be set,
* either {@link ManagementNodeState#MASTER} if appropriate
* or {@link ManagementNodeState#STANDBY} / {@link ManagementNodeState#HOT_STANDBY} / {@link ManagementNodeState#HOT_BACKUP}.
*
* @param startMode mode to start with
* @throws IllegalStateException if current state of the management-plane doesn't match that desired by {@code startMode}
*/
void start(HighAvailabilityMode startMode);
/**
* Stops this node, then publishes own status (via {@link ManagementPlaneSyncRecordPersister} of {@link ManagementNodeState#TERMINATED}.
*/
void stop();
/** changes the mode that this HA server is running in
*
* note it will be an error to {@link #changeMode(HighAvailabilityMode)} to {@link ManagementNodeState#MASTER}
* when there is already a master; to promote a node explicitly set its priority higher than
* the others and invoke {@link #changeMode(HighAvailabilityMode)} to a standby mode on the existing master */
void changeMode(HighAvailabilityMode mode);
/** sets the priority, and publishes it synchronously so it is canonical */
void setPriority(long priority);
long getPriority();
/** deletes non-master node records; active nodes (including this) will republish,
* so this provides a simple way to clean out the cache of dead brooklyn nodes */
@Beta
void publishClearNonMaster();
/**
* Returns a snapshot of the management-plane's current / most-recently-known status,
* as last read from {@link #loadManagementPlaneSyncRecord(boolean)}, or null if none read.
*/
ManagementPlaneSyncRecord getLastManagementPlaneSyncRecord();
/**
* @param useLocalKnowledgeForThisNode - if true, the record for this mgmt node will be replaced with the
* actual current status known in this JVM (may be more recent than what is persisted);
* for most purposes there is little difference but in some cases the local node being updated
* may be explicitly wanted or not wanted
*/
ManagementPlaneSyncRecord loadManagementPlaneSyncRecord(boolean useLocalKnowledgeForThisNode);
@VisibleForTesting
ManagementPlaneSyncRecordPersister getPersister();
/** Returns a collection of metrics */
Map getMetrics();
}