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/**
 * Entity managing read writes to the metastore for {@link org.apache.samza.container.placement.ContainerPlacementRequestMessage}
 * and {@link org.apache.samza.container.placement.ContainerPlacementResponseMessage}
 */
public class ContainerPlacementMetadataStore {

/**
 * Writes a {@link ContainerPlacementRequestMessage} to the underlying metastore. This method should be used by external controllers
 * to issue a request to JobCoordinator
 *
 * @param deploymentId identifier of the deployment
 * @param processorId logical id of the samza container 0,1,2
 * @param destinationHost host where the container is desired to move
 * @param requestExpiry optional per request expiry timeout for requests to cluster manager
 * @param timestamp timestamp of the request
 * @return uuid generated for the request
 */
public UUID writeContainerPlacementRequestMessage(String deploymentId, String processorId, String destinationHost,
      Duration requestExpiry, long timestamp) {...}

/**
 * Reads a {@link ContainerPlacementRequestMessage} from the underlying metastore
 * @param uuid uuid of the request
 * @return ContainerPlacementRequestMessage is its present
 */
public Optional<ContainerPlacementRequestMessage> readContainerPlacementRequestMessage(UUID uuid) {...}

/**
 * Reads a {@link ContainerPlacementResponseMessage} from the underlying metastore
 * @param uuid uuid of the request
 * @return ContainerPlacementResponseMessage is its present
 */
public Optional<ContainerPlacementResponseMessage> readContainerPlacementResponseMessage(UUID uuid) {..}

/**
 * Deletes a {@link ContainerPlacementRequestMessage} if present identified by the key {@code uuid}
 * @param uuid uuid of the request
 */
public void deleteContainerPlacementRequestMessage(UUID uuid) {..}

/**
 * Deletes a {@link ContainerPlacementResponseMessage} if present identified by the key {@code uuid}
 * @param uuid uuid of the request
 */
public void deleteContainerPlacementResponseMessage(UUID uuid) {..}

/**
 * Deletes both {@link ContainerPlacementRequestMessage} and {@link ContainerPlacementResponseMessage} identified by uuid
 * @param uuid uuid of request and response message
 */
public void deleteAllContainerPlacementMessages(UUID uuid) {...}

/**
 * Deletes all {@link ContainerPlacementMessage}
 * @param uuid uuid of the request or response message
 */
public void deleteAllContainerPlacementMessages(UUID uuid) {..}

/**
 * Writes a {@link ContainerPlacementResponseMessage} to the underlying metastore. 
 * This method should be used by Job Coordinator only to write responses to Container Placement Action
 * @param responseMessage response message
 */
void writeContainerPlacementResponseMessage(ContainerPlacementResponseMessage responseMessage) {..}

}