Java tutorial
/* * Copyright 2014-2015 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * Licensed under the Apache License, Version 2.0 (the "License"). * You may not use this file except in compliance with the License. * A copy of the License is located at * * http://aws.amazon.com/apache2.0 * * or in the "license" file accompanying this file. This file 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 com.rapid7.diskstorage.dynamodb; import java.util.Map; import org.apache.commons.lang.builder.EqualsBuilder; import org.apache.commons.lang.builder.ToStringBuilder; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.google.common.base.Preconditions; import com.google.common.collect.Maps; import com.thinkaurelius.titan.diskstorage.BackendException; import com.thinkaurelius.titan.diskstorage.BaseTransactionConfig; import com.thinkaurelius.titan.diskstorage.StaticBuffer; import com.thinkaurelius.titan.diskstorage.common.AbstractStoreTransaction; import com.thinkaurelius.titan.diskstorage.keycolumnvalue.StoreTransaction; /** * Transaction is used to store expected values of each column for each key in a transaction * * @author Matthew Sowders * @author Michael Rodaitis * @author Alexander Patrikalakis * */ public final class DynamoDBStoreTransaction extends AbstractStoreTransaction { private static final Logger LOG = LoggerFactory.getLogger(DynamoDBStoreTransaction.class); public static DynamoDBStoreTransaction getTx(StoreTransaction txh) { Preconditions.checkArgument(txh != null); Preconditions.checkArgument(txh instanceof DynamoDBStoreTransaction, "Unexpected transaction type %s", txh.getClass().getName()); return (DynamoDBStoreTransaction) txh; } /** * This is only used for toString for debugging purposes. */ private String id; private final Map<StaticBuffer, Map<StaticBuffer, StaticBuffer>> expectedValues = Maps.newHashMap(); public DynamoDBStoreTransaction(BaseTransactionConfig config) { super(config); id = Constants.HEX_PREFIX + Long.toHexString(System.currentTimeMillis()); LOG.debug("begin id:{} config:{}", id, config); } @Override public void commit() throws BackendException { LOG.debug("commit id:{}", id); expectedValues.clear(); super.commit(); } public boolean contains(StaticBuffer key, StaticBuffer column) { if (expectedValues.containsKey(key)) { return expectedValues.get(key).containsKey(column); } return false; } @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof DynamoDBStoreTransaction)) { return false; } DynamoDBStoreTransaction rhs = (DynamoDBStoreTransaction) obj; return new EqualsBuilder().append(id, rhs.id).isEquals(); } @Override public int hashCode() { return id.hashCode(); } public StaticBuffer get(StaticBuffer key, StaticBuffer column) { // This method assumes the caller has called contains(..) and received a positive response return expectedValues.get(key).get(column); } public void put(StaticBuffer key, StaticBuffer column, StaticBuffer expectedValue) { Map<StaticBuffer, StaticBuffer> valueMap; if (expectedValues.containsKey(key)) { valueMap = expectedValues.get(key); } else { valueMap = Maps.newHashMap(); expectedValues.put(key, valueMap); } // Ignore any calls to put if we already have an expected value if (!valueMap.containsKey(column)) { valueMap.put(column, expectedValue); } } @Override public void rollback() throws BackendException { LOG.debug("rollback id:{}", id); expectedValues.clear(); super.rollback(); } @Override public String toString() { return new ToStringBuilder(this).append(id).append(expectedValues).toString(); } }