Java tutorial
/** * 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.metamodel.dynamodb; import java.io.Closeable; import java.util.ArrayList; import java.util.Collections; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.stream.Collectors; import org.apache.metamodel.MetaModelException; import org.apache.metamodel.QueryPostprocessDataContext; import org.apache.metamodel.UpdateScript; import org.apache.metamodel.UpdateSummary; import org.apache.metamodel.UpdateableDataContext; import org.apache.metamodel.data.DataSet; import org.apache.metamodel.data.DefaultRow; import org.apache.metamodel.data.Row; import org.apache.metamodel.data.SimpleDataSetHeader; import org.apache.metamodel.query.FilterItem; import org.apache.metamodel.query.SelectItem; import org.apache.metamodel.schema.Column; import org.apache.metamodel.schema.ColumnType; import org.apache.metamodel.schema.MutableColumn; import org.apache.metamodel.schema.MutableSchema; import org.apache.metamodel.schema.MutableTable; import org.apache.metamodel.schema.Schema; import org.apache.metamodel.schema.Table; import org.apache.metamodel.util.SimpleTableDef; import com.amazonaws.services.dynamodbv2.AmazonDynamoDB; import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder; import com.amazonaws.services.dynamodbv2.model.AttributeDefinition; import com.amazonaws.services.dynamodbv2.model.AttributeValue; import com.amazonaws.services.dynamodbv2.model.DescribeTableResult; import com.amazonaws.services.dynamodbv2.model.GetItemRequest; import com.amazonaws.services.dynamodbv2.model.GetItemResult; import com.amazonaws.services.dynamodbv2.model.GlobalSecondaryIndexDescription; import com.amazonaws.services.dynamodbv2.model.KeySchemaElement; import com.amazonaws.services.dynamodbv2.model.ListTablesResult; import com.amazonaws.services.dynamodbv2.model.LocalSecondaryIndexDescription; import com.amazonaws.services.dynamodbv2.model.ScanRequest; import com.amazonaws.services.dynamodbv2.model.ScanResult; import com.amazonaws.services.dynamodbv2.model.TableDescription; /** * DataContext implementation for Amazon DynamoDB. */ public class DynamoDbDataContext extends QueryPostprocessDataContext implements UpdateableDataContext, Closeable { /** * System property key used for getting the read throughput capacity when * creating new tables. Defaults to 5. */ public static final String SYSTEM_PROPERTY_THROUGHPUT_READ_CAPACITY = "metamodel.dynamodb.throughput.capacity.read"; /** * System property key used for getting the write throughput capacity when * creating new tables. Defaults to 5. */ public static final String SYSTEM_PROPERTY_THROUGHPUT_WRITE_CAPACITY = "metamodel.dynamodb.throughput.capacity.write"; /** * The artificial schema name used by this DataContext. */ public static final String SCHEMA_NAME = "public"; private final AmazonDynamoDB _dynamoDb; private final boolean _shutdownOnClose; private final SimpleTableDef[] _tableDefs; public DynamoDbDataContext() { this(AmazonDynamoDBClientBuilder.defaultClient(), null, true); } public DynamoDbDataContext(SimpleTableDef[] tableDefs) { this(AmazonDynamoDBClientBuilder.defaultClient(), tableDefs, true); } public DynamoDbDataContext(AmazonDynamoDB client) { this(client, null, false); } public DynamoDbDataContext(AmazonDynamoDB client, SimpleTableDef[] tableDefs) { this(client, tableDefs, false); } private DynamoDbDataContext(AmazonDynamoDB client, SimpleTableDef[] tableDefs, boolean shutdownOnClose) { super(false); _dynamoDb = client; _tableDefs = (tableDefs == null ? new SimpleTableDef[0] : tableDefs); _shutdownOnClose = shutdownOnClose; } public AmazonDynamoDB getDynamoDb() { return _dynamoDb; } @Override public void close() { if (_shutdownOnClose) { _dynamoDb.shutdown(); } } @Override protected Schema getMainSchema() throws MetaModelException { final Map<String, SimpleTableDef> tableDefs = new HashMap<>(); for (final SimpleTableDef tableDef : _tableDefs) { tableDefs.put(tableDef.getName(), tableDef); } final MutableSchema schema = new MutableSchema(getMainSchemaName()); final ListTablesResult tables = _dynamoDb.listTables(); final List<String> tableNames = tables.getTableNames(); for (final String tableName : tableNames) { final MutableTable table = new MutableTable(tableName, schema); schema.addTable(table); final DescribeTableResult descripeTableResult = _dynamoDb.describeTable(tableName); final TableDescription tableDescription = descripeTableResult.getTable(); // add primary keys addColumnFromKeySchema("Primary index", tableDescription.getKeySchema(), table, true); // add attributes from global and local indices final List<GlobalSecondaryIndexDescription> globalSecondaryIndexes = tableDescription .getGlobalSecondaryIndexes(); if (globalSecondaryIndexes != null) { for (final GlobalSecondaryIndexDescription globalSecondaryIndex : globalSecondaryIndexes) { addColumnFromKeySchema(globalSecondaryIndex.getIndexName(), globalSecondaryIndex.getKeySchema(), table, false); } } final List<LocalSecondaryIndexDescription> localSecondaryIndexes = tableDescription .getLocalSecondaryIndexes(); if (localSecondaryIndexes != null) { for (final LocalSecondaryIndexDescription localSecondaryIndex : localSecondaryIndexes) { addColumnFromKeySchema(localSecondaryIndex.getIndexName(), localSecondaryIndex.getKeySchema(), table, false); } } // add top-level attribute definitions final List<AttributeDefinition> attributeDefinitions = tableDescription.getAttributeDefinitions(); for (final AttributeDefinition attributeDefinition : attributeDefinitions) { final String attributeName = attributeDefinition.getAttributeName(); MutableColumn column = (MutableColumn) table.getColumnByName(attributeName); if (column == null) { column = new MutableColumn(attributeName, table); table.addColumn(column); } final String attributeType = attributeDefinition.getAttributeType(); column.setType(DynamoDbUtils.toColumnType(attributeName, attributeType)); column.setIndexed(true); column.setNativeType(attributeType); } // add additional metadata from SimpleTableDefs if available final SimpleTableDef tableDef = tableDefs.get(tableName); if (tableDef != null) { final String[] columnNames = tableDef.getColumnNames(); final ColumnType[] columnTypes = tableDef.getColumnTypes(); for (int i = 0; i < columnNames.length; i++) { final String columnName = columnNames[i]; final ColumnType columnType = columnTypes[i]; MutableColumn column = (MutableColumn) table.getColumnByName(columnName); if (column == null) { column = new MutableColumn(columnName, table); table.addColumn(column); } if (column.getType() == null && columnType != null) { column.setType(columnType); } } } // add additional attributes based on global and local indices if (globalSecondaryIndexes != null) { for (final GlobalSecondaryIndexDescription globalSecondaryIndex : globalSecondaryIndexes) { final List<String> nonKeyAttributes = globalSecondaryIndex.getProjection() .getNonKeyAttributes(); for (final String attributeName : nonKeyAttributes) { addColumnFromNonKeyAttribute(globalSecondaryIndex.getIndexName(), table, attributeName); } } } if (localSecondaryIndexes != null) { for (final LocalSecondaryIndexDescription localSecondaryIndex : localSecondaryIndexes) { final List<String> nonKeyAttributes = localSecondaryIndex.getProjection().getNonKeyAttributes(); for (final String attributeName : nonKeyAttributes) { addColumnFromNonKeyAttribute(localSecondaryIndex.getIndexName(), table, attributeName); } } } } return schema; } private void addColumnFromNonKeyAttribute(String indexName, MutableTable table, String attributeName) { MutableColumn column = (MutableColumn) table.getColumnByName(attributeName); if (column == null) { column = new MutableColumn(attributeName, table); table.addColumn(column); } appendRemarks(column, indexName + " non-key attribute"); } private void addColumnFromKeySchema(String indexName, List<KeySchemaElement> keySchema, MutableTable table, boolean primaryKey) { for (final KeySchemaElement keySchemaElement : keySchema) { final String attributeName = keySchemaElement.getAttributeName(); if (table.getColumnByName(attributeName) == null) { final String keyType = keySchemaElement.getKeyType(); final MutableColumn column = new MutableColumn(attributeName, table).setPrimaryKey(primaryKey); appendRemarks(column, indexName + " member ('" + keyType + "' type)"); table.addColumn(column); } } } private static void appendRemarks(MutableColumn column, String remarks) { final String existingRemarks = column.getRemarks(); if (existingRemarks == null) { column.setRemarks(remarks); } else { column.setRemarks(existingRemarks + ", " + remarks); } } @Override protected String getMainSchemaName() throws MetaModelException { return SCHEMA_NAME; } @Override protected Number executeCountQuery(Table table, List<FilterItem> whereItems, boolean functionApproximationAllowed) { if (!whereItems.isEmpty()) { return null; } return _dynamoDb.describeTable(table.getName()).getTable().getItemCount(); } @Override protected DataSet materializeMainSchemaTable(Table table, List<Column> columns, int maxRows) { final List<String> attributeNames = columns.stream().map(col -> col.getName()).collect(Collectors.toList()); final ScanRequest scanRequest = new ScanRequest(table.getName()); scanRequest.setAttributesToGet(attributeNames); if (maxRows > 0) { scanRequest.setLimit(maxRows); } final ScanResult result = _dynamoDb.scan(scanRequest); return new DynamoDbDataSet(columns, result); } @Override protected Row executePrimaryKeyLookupQuery(Table table, List<SelectItem> selectItems, Column primaryKeyColumn, Object keyValue) { final List<String> attributeNames = new ArrayList<>(); for (SelectItem selectItem : selectItems) { attributeNames.add(selectItem.getColumn().getName()); } final GetItemRequest getItemRequest = new GetItemRequest(table.getName(), Collections.singletonMap(primaryKeyColumn.getName(), DynamoDbUtils.toAttributeValue(keyValue))) .withAttributesToGet(attributeNames); final GetItemResult item = _dynamoDb.getItem(getItemRequest); final Object[] values = new Object[selectItems.size()]; for (int i = 0; i < values.length; i++) { final AttributeValue attributeValue = item.getItem().get(attributeNames.get(i)); values[i] = DynamoDbUtils.toValue(attributeValue); } return new DefaultRow(new SimpleDataSetHeader(selectItems), values); } @Override public UpdateSummary executeUpdate(UpdateScript update) { final DynamoDbUpdateCallback callback = new DynamoDbUpdateCallback(this); try { update.run(callback); } finally { if (callback.isInterrupted()) { Thread.currentThread().interrupt(); } } return callback.getUpdateSummary(); } }