Examples with WriteType com.datastax.driver.core.WriteType used on opensource projects

Example 1 with WriteType

use of com.datastax.driver.core.WriteType in project java-driver by datastax.

the class DowngradingRetry method write.

/**
 * Inserts data, retrying if necessary with a downgraded CL.
 *
 * @param cl         the consistency level to apply.
 * @param retryCount the current retry count.
 * @throws DriverException if the current consistency level cannot be downgraded.
 */
private void write(ConsistencyLevel cl, int retryCount) {
    System.out.printf("Writing at %s (retry count: %d)%n", cl, retryCount);
    BatchStatement batch = new BatchStatement(UNLOGGED);
    batch.add(new SimpleStatement("INSERT INTO downgrading.sensor_data " + "(sensor_id, date, timestamp, value) " + "VALUES (" + "756716f7-2e54-4715-9f00-91dcbea6cf50," + "'2018-02-26'," + "'2018-02-26T13:53:46.345+01:00'," + "2.34)"));
    batch.add(new SimpleStatement("INSERT INTO downgrading.sensor_data " + "(sensor_id, date, timestamp, value) " + "VALUES (" + "756716f7-2e54-4715-9f00-91dcbea6cf50," + "'2018-02-26'," + "'2018-02-26T13:54:27.488+01:00'," + "2.47)"));
    batch.add(new SimpleStatement("INSERT INTO downgrading.sensor_data " + "(sensor_id, date, timestamp, value) " + "VALUES (" + "756716f7-2e54-4715-9f00-91dcbea6cf50," + "'2018-02-26'," + "'2018-02-26T13:56:33.739+01:00'," + "2.52)"));
    batch.setConsistencyLevel(cl);
    try {
        session.execute(batch);
        System.out.println("Write succeeded at " + cl);
    } catch (DriverException e) {
        if (retryCount == maxRetries) {
            throw e;
        }
        e = unwrapNoHostAvailableException(e);
        System.out.println("Write failed: " + e);
        if (e instanceof UnavailableException) {
            // With an UnavailableException, we know that the write wasn't even attempted.
            // Downgrade to the number of replicas reported alive and retry.
            int aliveReplicas = ((UnavailableException) e).getAliveReplicas();
            ConsistencyLevel downgraded = downgrade(cl, aliveReplicas, e);
            write(downgraded, retryCount + 1);
        } else if (e instanceof WriteTimeoutException) {
            WriteType writeType = ((WriteTimeoutException) e).getWriteType();
            int acknowledgements = ((WriteTimeoutException) e).getReceivedAcknowledgements();
            switch(writeType) {
                case SIMPLE:
                case BATCH:
                    // a retry would ever succeed.
                    if (acknowledgements == 0) {
                        throw e;
                    }
                    break;
                case UNLOGGED_BATCH:
                    // For unlogged batches, the write might have been persisted only partially,
                    // so we can't simply ignore the exception: instead, we need to retry with
                    // consistency level equal to the number of acknowledged writes.
                    ConsistencyLevel downgraded = downgrade(cl, acknowledgements, e);
                    write(downgraded, retryCount + 1);
                    break;
                case BATCH_LOG:
                    // Rare edge case: the peers that were chosen by the coordinator
                    // to receive the distributed batch log failed to respond.
                    // Simply retry with same consistency level.
                    write(cl, retryCount + 1);
                    break;
                default:
                    // Other write types are uncommon and should not be retried.
                    throw e;
            }
        } else {
            // Unexpected error: just retry with same consistency level
            // and hope to talk to a healthier coordinator.
            write(cl, retryCount + 1);
        }
    }
}