Java tutorial
/* * Copyright 2014 Click Travel Ltd * * Licensed 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 com.clicktravel.infrastructure.persistence.aws.dynamodb; import java.beans.PropertyDescriptor; import java.util.*; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.amazonaws.AmazonServiceException; import com.amazonaws.services.dynamodbv2.AmazonDynamoDB; import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDbPropertyMarshaller; import com.amazonaws.services.dynamodbv2.model.*; import com.clicktravel.cheddar.infrastructure.persistence.database.AbstractDatabaseTemplate; import com.clicktravel.cheddar.infrastructure.persistence.database.GeneratedKeyHolder; import com.clicktravel.cheddar.infrastructure.persistence.database.Item; import com.clicktravel.cheddar.infrastructure.persistence.database.SequenceKeyGenerator; import com.clicktravel.cheddar.infrastructure.persistence.database.configuration.DatabaseSchemaHolder; import com.clicktravel.cheddar.infrastructure.persistence.database.configuration.ItemConfiguration; import com.clicktravel.cheddar.infrastructure.persistence.database.configuration.SequenceConfiguration; import com.clicktravel.cheddar.infrastructure.persistence.database.configuration.UniqueConstraint; import com.clicktravel.cheddar.infrastructure.persistence.database.exception.ItemConstraintViolationException; import com.clicktravel.cheddar.infrastructure.persistence.exception.PersistenceResourceFailureException; public abstract class AbstractDynamoDbTemplate extends AbstractDatabaseTemplate { private final Logger logger = LoggerFactory.getLogger(this.getClass()); protected boolean initialized; protected AmazonDynamoDB amazonDynamoDbClient; protected final DatabaseSchemaHolder databaseSchemaHolder; protected final HashMap<Class<? extends Item>, ItemConfiguration> itemConfigurationMap; protected final Set<String> sequenceConfigurations; private static final String SEQUENCE_TABLE_NAME = "sequences"; private static final String SEQUENCE_NAME_ATTRIBUTE = "name"; private static final String SEQUENCE_CURRENT_VALUE_ATTRIBUTE = "currentValue"; protected static final String VERSION_ATTRIBUTE = "version"; public AbstractDynamoDbTemplate(final DatabaseSchemaHolder databaseSchemaHolder) { this.databaseSchemaHolder = databaseSchemaHolder; itemConfigurationMap = new HashMap<>(); for (final ItemConfiguration itemConfiguration : databaseSchemaHolder.itemConfigurations()) { itemConfigurationMap.put(itemConfiguration.itemClass(), itemConfiguration); } sequenceConfigurations = new HashSet<>(); for (final SequenceConfiguration sequenceConfiguration : databaseSchemaHolder.sequenceConfigurations()) { sequenceConfigurations.add(sequenceConfiguration.sequenceName()); } } public void initialize(final AmazonDynamoDB amazonDynamoDbClient) { this.amazonDynamoDbClient = amazonDynamoDbClient; initialized = true; } public DatabaseSchemaHolder databaseSchemaHolder() { return databaseSchemaHolder; } @Override public GeneratedKeyHolder generateKeys(final SequenceKeyGenerator sequenceKeyGenerator) { final String sequenceName = sequenceKeyGenerator.sequenceName(); if (!sequenceConfigurations.contains(sequenceName)) { throw new IllegalStateException("Unsupported sequence: " + sequenceName); } final Map<String, AttributeValue> key = new HashMap<>(); key.put(SEQUENCE_NAME_ATTRIBUTE, new AttributeValue(sequenceName)); final AttributeValueUpdate attributeValueUpdate = new AttributeValueUpdate().withAction("ADD") .withValue(new AttributeValue().withN(String.valueOf(sequenceKeyGenerator.keyCount()))); final Map<String, AttributeValueUpdate> attributeUpdates = new HashMap<>(); attributeUpdates.put(SEQUENCE_CURRENT_VALUE_ATTRIBUTE, attributeValueUpdate); final String tableName = databaseSchemaHolder.schemaName() + "-" + SEQUENCE_TABLE_NAME; final UpdateItemRequest updateItemRequest = new UpdateItemRequest().withTableName(tableName).withKey(key) .withAttributeUpdates(attributeUpdates).withReturnValues("UPDATED_NEW"); final UpdateItemResult updateItemResult; try { updateItemResult = amazonDynamoDbClient.updateItem(updateItemRequest); } catch (final AmazonServiceException e) { throw new PersistenceResourceFailureException( "Failure while attempting DynamoDb Update (generate keys)", e); } final Map<String, AttributeValue> attributes = updateItemResult.getAttributes(); final AttributeValue currentAttributeValue = attributes.get(SEQUENCE_CURRENT_VALUE_ATTRIBUTE); final Long currentValue = Long.valueOf(currentAttributeValue.getN()); final Collection<Long> keys = new ArrayList<>(); for (long i = currentValue - sequenceKeyGenerator.keyCount(); i < currentValue; i++) { keys.add(i + 1); } return new GeneratedKeyHolder(keys); } protected final ItemConfiguration getItemConfiguration(final Class<? extends Item> itemClass) { if (!initialized) { throw new IllegalStateException("PersistenceTemplate not initialized."); } final ItemConfiguration itemConfiguration = itemConfigurationMap.get(itemClass); if (itemConfiguration == null) { throw new IllegalStateException("No ItemConfiguration for " + itemClass); } return itemConfiguration; } protected final Collection<PropertyDescriptor> constraintPropertyDescriptors( final ItemConfiguration itemConfiguration) { final Collection<PropertyDescriptor> contraintPropertyDescriptors = new HashSet<>(); for (final UniqueConstraint uniqueConstraint : itemConfiguration.uniqueConstraints()) { contraintPropertyDescriptors.add(uniqueConstraint.propertyDescriptor()); } return contraintPropertyDescriptors; } protected final <T extends Item> Collection<PropertyDescriptor> createUniqueConstraintIndexes(final T item, final ItemConfiguration itemConfiguration) { return createUniqueConstraintIndexes(item, itemConfiguration, constraintPropertyDescriptors(itemConfiguration)); } protected final <T extends Item> Collection<PropertyDescriptor> createUniqueConstraintIndexes(final T item, final ItemConfiguration itemConfiguration, final Collection<PropertyDescriptor> constraintPropertyDescriptors) { final Set<PropertyDescriptor> createdConstraintPropertyDescriptors = new HashSet<>(); ItemConstraintViolationException itemConstraintViolationException = null; for (final UniqueConstraint uniqueConstraint : itemConfiguration.uniqueConstraints()) { final String uniqueConstraintPropertyName = uniqueConstraint.propertyName(); final PropertyDescriptor uniqueConstraintPropertyDescriptor = uniqueConstraint.propertyDescriptor(); if (constraintPropertyDescriptors.contains(uniqueConstraintPropertyDescriptor)) { final AttributeValue uniqueConstraintAttributeValue = DynamoDbPropertyMarshaller.getValue(item, uniqueConstraintPropertyDescriptor); if (uniqueConstraintAttributeValue == null) { continue; } if (uniqueConstraintAttributeValue.getS() != null) { uniqueConstraintAttributeValue.setS(uniqueConstraintAttributeValue.getS().toUpperCase()); } final Map<String, AttributeValue> attributeMap = new HashMap<>(); attributeMap.put("property", new AttributeValue(uniqueConstraintPropertyName)); attributeMap.put("value", uniqueConstraintAttributeValue); final Map<String, ExpectedAttributeValue> expectedResults = new HashMap<>(); expectedResults.put("value", new ExpectedAttributeValue(false)); final String indexTableName = databaseSchemaHolder.schemaName() + "-indexes." + itemConfiguration.tableName(); final PutItemRequest itemRequest = new PutItemRequest().withTableName(indexTableName) .withItem(attributeMap).withExpected(expectedResults); try { amazonDynamoDbClient.putItem(itemRequest); createdConstraintPropertyDescriptors.add(uniqueConstraintPropertyDescriptor); } catch (final ConditionalCheckFailedException e) { itemConstraintViolationException = new ItemConstraintViolationException( uniqueConstraintPropertyName, "Unique constraint violation on property '" + uniqueConstraintPropertyName + "' ('" + uniqueConstraintAttributeValue + "') of item " + item.getClass()); break; } catch (final AmazonServiceException e) { throw new PersistenceResourceFailureException( "Failure while attempting DynamoDb put (creating unique constraint index entry)", e); } } } if (itemConstraintViolationException != null) { try { deleteUniqueConstraintIndexes(item, itemConfiguration, createdConstraintPropertyDescriptors); } catch (final Exception e) { logger.error(e.getMessage(), e); } throw itemConstraintViolationException; } return createdConstraintPropertyDescriptors; } protected final <T extends Item> void deleteUniqueConstraintIndexes(final T item, final ItemConfiguration itemConfiguration) { deleteUniqueConstraintIndexes(item, itemConfiguration, constraintPropertyDescriptors(itemConfiguration)); } protected final <T extends Item> void deleteUniqueConstraintIndexes(final T item, final ItemConfiguration itemConfiguration, final Collection<PropertyDescriptor> constraintPropertyDescriptors) { if (constraintPropertyDescriptors.isEmpty()) { return; } for (final UniqueConstraint uniqueConstraint : itemConfiguration.uniqueConstraints()) { final String uniqueConstraintPropertyName = uniqueConstraint.propertyName(); final PropertyDescriptor uniqueConstraintPropertyDescriptor = uniqueConstraint.propertyDescriptor(); if (constraintPropertyDescriptors.contains(uniqueConstraintPropertyDescriptor)) { final AttributeValue uniqueConstraintAttributeValue = DynamoDbPropertyMarshaller.getValue(item, uniqueConstraintPropertyDescriptor); if (uniqueConstraintAttributeValue != null) { if (uniqueConstraintAttributeValue.getS() != null) { uniqueConstraintAttributeValue.setS(uniqueConstraintAttributeValue.getS().toUpperCase()); } final Map<String, AttributeValue> key = new HashMap<>(); key.put("property", new AttributeValue(uniqueConstraintPropertyName)); key.put("value", uniqueConstraintAttributeValue); final String indexTableName = databaseSchemaHolder.schemaName() + "-indexes." + itemConfiguration.tableName(); final DeleteItemRequest itemRequest = new DeleteItemRequest().withTableName(indexTableName) .withKey(key); try { amazonDynamoDbClient.deleteItem(itemRequest); } catch (final AmazonServiceException e) { throw new PersistenceResourceFailureException( "Failed while attempting to perform DynamoDb Delete (for unique constraints)", e); } } } } } }