org.apache.cassandra.service.ResponseResolver Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* 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 "AS IS" BASIS,
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* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cassandra.service;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.cassandra.db.*;
import org.apache.cassandra.db.partitions.*;
import org.apache.cassandra.net.MessageIn;
import org.apache.cassandra.utils.concurrent.Accumulator;
public abstract class ResponseResolver
{
protected static final Logger logger = LoggerFactory.getLogger(ResponseResolver.class);
protected final Keyspace keyspace;
protected final ReadCommand command;
protected final ConsistencyLevel consistency;
// Accumulator gives us non-blocking thread-safety with optimal algorithmic constraints
protected final Accumulator> responses;
public ResponseResolver(Keyspace keyspace, ReadCommand command, ConsistencyLevel consistency, int maxResponseCount)
{
this.keyspace = keyspace;
this.command = command;
this.consistency = consistency;
this.responses = new Accumulator<>(maxResponseCount);
}
public abstract PartitionIterator getData();
public abstract PartitionIterator resolve() throws DigestMismatchException;
/**
* Compares received responses, potentially triggering a digest mismatch (for a digest resolver) and read-repairs
* (for a data resolver).
*
* This is functionally equivalent to calling {@link #resolve()} and consuming the result, but can be slightly more
* efficient in some case due to the fact that we don't care about the result itself. This is used when doing
* asynchronous read-repairs.
*
* @throws DigestMismatchException if it's a digest resolver and the responses don't match.
*/
public abstract void compareResponses() throws DigestMismatchException;
public abstract boolean isDataPresent();
public void preprocess(MessageIn message)
{
responses.add(message);
}
public Iterable> getMessages()
{
return responses;
}
}