Java Code Examples for com.netflix.astyanax.model.ConsistencyLevel#CL_QUORUM

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Example 1
Source File: ConsistencyTopologyAdapter.java    From emodb with Apache License 2.0 6 votes vote down vote up 
/**
 * Reduce the desired consistency level to be compatible with the deployed ring topology.
 */
public ConsistencyLevel clamp(ConsistencyLevel consistencyLevel) {
    // Cassandra only allows the use of LOCAL_QUORUM and EACH_QUORUM if the keyspace
    // placement strategy is NetworkTopologyStrategy
    if ((consistencyLevel == ConsistencyLevel.CL_LOCAL_QUORUM || consistencyLevel == ConsistencyLevel.CL_EACH_QUORUM) && !_networkTopology) {
        consistencyLevel = ConsistencyLevel.CL_QUORUM;
    }
    if (consistencyLevel == ConsistencyLevel.CL_LOCAL_ONE && !_networkTopology) {
        consistencyLevel = ConsistencyLevel.CL_ONE;
    }

    // we may want to write to at two or three servers to ensure the write survives the
    // permanent failure of any single server.  but if the ring has fewer servers to
    // begin with (ie. it's a test ring) we must reduce the consistency level.
    if (consistencyLevel == ConsistencyLevel.CL_THREE && _replicationFactor < 3) {
        consistencyLevel = ConsistencyLevel.CL_TWO;
    }
    if (consistencyLevel == ConsistencyLevel.CL_TWO && _replicationFactor < 2) {
        consistencyLevel = ConsistencyLevel.CL_ONE;
    }

    return consistencyLevel;
}