CassandraConnectionProvider.java

package eu.europeana.cloud.cassandra;

import com.datastax.driver.core.AtomicMonotonicTimestampGenerator;
import com.datastax.driver.core.Cluster;
import com.datastax.driver.core.ConsistencyLevel;
import com.datastax.driver.core.Host;
import com.datastax.driver.core.Metadata;
import com.datastax.driver.core.ProtocolVersion;
import com.datastax.driver.core.Session;

import javax.annotation.PreDestroy;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;


/**
 * Connector to Cassandra cluster.
 */
@Component
public class CassandraConnectionProvider {

    private static final Logger LOGGER = LoggerFactory.getLogger(CassandraConnectionProvider.class);

    private final Cluster cluster;

    private final Session session;

    private final ConsistencyLevel consistencyLevel = ConsistencyLevel.QUORUM;

    private String hosts;

    private String port;

    private String keyspaceName;

    /**
     * Constructor. Use it when your Cassandra cluster does not support
     * authentication.
     *
     * @param hosts        cassandra node hosts, comma separated
     * @param port         cassandra node cql service port
     * @param keyspaceName name of keyspace
     */
    public CassandraConnectionProvider(String hosts, int port, String keyspaceName) {
        this.hosts = hosts;
        this.port = String.valueOf(port);
        this.keyspaceName = keyspaceName;

        String[] contactPoints = hosts.split(",");
        cluster = getClusterBuilder(port, contactPoints)
                .build();
        init();
        session = cluster.connect(keyspaceName);
    }


    /**
     * Constructor. Use it when your Cassandra cluster does support
     * authentication.
     *
     * @param hosts        cassandra node hosts, comma separated
     * @param port         cassandra node cql service port
     * @param keyspaceName name of keyspace
     * @param userName     user name
     * @param password     password
     */
    public CassandraConnectionProvider(String hosts, int port, String keyspaceName, String userName, String password) {
        this.hosts = hosts;
        this.port = String.valueOf(port);
        this.keyspaceName = keyspaceName;

        String[] contactPoints = hosts.split(",");
        cluster = getClusterBuilder(port, contactPoints)
                .withCredentials(userName, password).build();
        init();
        session = cluster.connect(keyspaceName);
    }

    /**
     * Common initializer.
     */
    private void init() {
        Metadata metadata = cluster.getMetadata();
        LOGGER.info("Connected to cluster: {}", metadata.getClusterName());
        for (Host h : metadata.getAllHosts()) {
            LOGGER.info("Data center: {}; Hosts: {}; Rack: {}", h.getDatacenter(), h.getAddress(), h.getRack());
        }
    }

    /**
     * Obtain common cassandra Cluster Builder.
     *
     * @param port          port of endpoints
     * @param contactPoints list of cassandra ip addresses
     * @return {@link com.datastax.driver.core.Cluster.Builder}
     */
    private Cluster.Builder getClusterBuilder(int port, String[] contactPoints) {
        return Cluster.builder().addContactPoints(contactPoints).withPort(port)
                .withProtocolVersion(ProtocolVersion.V3)
                .withTimestampGenerator(new AtomicMonotonicTimestampGenerator());
    }


    @PreDestroy
    private void closeConnections() {
        LOGGER.info("Cluster is shutting down.");
        cluster.close();
    }


    /**
     * Expose a singleton instance connection to a database on the requested
     * host and keyspace
     *
     * @return A session to a Cassandra connection
     */
    public Session getSession() {
        return session;
    }


    /**
     * Returns the default consistency level;
     *
     * @return the consistencyLevel
     */
    public ConsistencyLevel getConsistencyLevel() {
        return consistencyLevel;
    }


    /**
     * Expose the contact server IP address
     *
     * @return The host name
     */
    public String getHosts() {
        return hosts;
    }


    /**
     * Expose the contact server port
     *
     * @return The host port
     */
    public String getPort() {
        return port;
    }


    /**
     * Expose the keyspace
     *
     * @return The keyspace name
     */
    public String getKeyspaceName() {
        return keyspaceName;
    }
}