| /* |
| * 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, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.cassandra.service; |
| |
| import java.nio.ByteBuffer; |
| import java.util.concurrent.TimeUnit; |
| |
| import org.apache.cassandra.db.*; |
| import org.apache.cassandra.db.partitions.PartitionIterator; |
| import org.apache.cassandra.db.partitions.UnfilteredPartitionIterators; |
| import org.apache.cassandra.net.MessageIn; |
| |
| public class DigestResolver extends ResponseResolver |
| { |
| private volatile ReadResponse dataResponse; |
| |
| public DigestResolver(Keyspace keyspace, ReadCommand command, ConsistencyLevel consistency, int maxResponseCount) |
| { |
| super(keyspace, command, consistency, maxResponseCount); |
| } |
| |
| @Override |
| public void preprocess(MessageIn<ReadResponse> message) |
| { |
| super.preprocess(message); |
| if (dataResponse == null && !message.payload.isDigestResponse()) |
| dataResponse = message.payload; |
| } |
| |
| /** |
| * Special case of resolve() so that CL.ONE reads never throw DigestMismatchException in the foreground |
| */ |
| public PartitionIterator getData() |
| { |
| assert isDataPresent(); |
| return UnfilteredPartitionIterators.filter(dataResponse.makeIterator(command), command.nowInSec()); |
| } |
| |
| /* |
| * This method handles two different scenarios: |
| * |
| * a) we're handling the initial read of data from the closest replica + digests |
| * from the rest. In this case we check the digests against each other, |
| * throw an exception if there is a mismatch, otherwise return the data row. |
| * |
| * b) we're checking additional digests that arrived after the minimum to handle |
| * the requested ConsistencyLevel, i.e. asynchronous read repair check |
| */ |
| public PartitionIterator resolve() throws DigestMismatchException |
| { |
| int responseCount = responses.size(); |
| |
| assert responseCount > 0 : "Attempted response match comparison while no responses have been received."; |
| |
| if (responseCount == 1) |
| return getData(); |
| |
| if (logger.isTraceEnabled()) |
| logger.trace("resolving {} responses", responseCount); |
| |
| compareResponses(); |
| |
| return UnfilteredPartitionIterators.filter(dataResponse.makeIterator(command), command.nowInSec()); |
| } |
| |
| public void compareResponses() throws DigestMismatchException |
| { |
| long start = System.nanoTime(); |
| |
| // validate digests against each other; throw immediately on mismatch. |
| ByteBuffer digest = null; |
| for (MessageIn<ReadResponse> message : responses) |
| { |
| ReadResponse response = message.payload; |
| |
| ByteBuffer newDigest = response.digest(command); |
| if (digest == null) |
| digest = newDigest; |
| else if (!digest.equals(newDigest)) |
| // rely on the fact that only single partition queries use digests |
| throw new DigestMismatchException(((SinglePartitionReadCommand)command).partitionKey(), digest, newDigest); |
| } |
| |
| if (logger.isTraceEnabled()) |
| logger.trace("resolve: {} ms.", TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - start)); |
| } |
| |
| public boolean isDataPresent() |
| { |
| return dataResponse != null; |
| } |
| } |