Java tutorial
/* * Copyright 2013 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * Licensed under the Amazon Software License (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/asl/ * * 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.amazon.services.awsrum.utils; import java.util.ArrayList; import java.util.Arrays; import java.util.List; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import com.amazonaws.services.autoscaling.model.ResourceInUseException; import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient; import com.amazonaws.services.dynamodbv2.model.AttributeDefinition; import com.amazonaws.services.dynamodbv2.model.CreateTableRequest; import com.amazonaws.services.dynamodbv2.model.DeleteTableRequest; import com.amazonaws.services.dynamodbv2.model.DescribeTableRequest; import com.amazonaws.services.dynamodbv2.model.DescribeTableResult; import com.amazonaws.services.dynamodbv2.model.KeySchemaElement; import com.amazonaws.services.dynamodbv2.model.KeyType; import com.amazonaws.services.dynamodbv2.model.ProvisionedThroughput; import com.amazonaws.services.dynamodbv2.model.ResourceNotFoundException; import com.amazonaws.services.dynamodbv2.model.ScalarAttributeType; import com.amazonaws.services.dynamodbv2.model.TableDescription; import com.amazonaws.services.dynamodbv2.model.TableStatus; /** * Utilities used to create and delete DynamoDB resources. */ public class DynamoDBUtils { private static Log LOG = LogFactory.getLog(DynamoDBUtils.class); /** * Creates the DynamoDB table if it does not already exist and have the correct schema. Then it * waits for the table to become active. * * @param client * The {@link AmazonDynamoDBClient} with DynamoDB read and write privileges * @param tableName * The DynamoDB table to create * @param key * The DynamoDB table hashkey * @param readCapacityUnits * Number of read capacity units for the DynamoDB table * @param writeCapacityUnits * Number of write capacity units for the DynamoDB table * @throws IllegalStateException * Table already exists and schema does not match * @throws IllegalStateException * Table is already getting created */ public static void createTable(AmazonDynamoDBClient client, String tableName, String key, long readCapacityUnits, long writeCapacityUnits) { if (tableExists(client, tableName)) { if (tableHasCorrectSchema(client, tableName, key)) { waitForActive(client, tableName); return; } else { throw new IllegalStateException("Table already exists and schema does not match"); } } CreateTableRequest createTableRequest = new CreateTableRequest(); createTableRequest.setTableName(tableName); createTableRequest.setKeySchema(Arrays.asList(new KeySchemaElement(key, KeyType.HASH))); createTableRequest .setProvisionedThroughput(new ProvisionedThroughput(readCapacityUnits, writeCapacityUnits)); createTableRequest .setAttributeDefinitions(Arrays.asList(new AttributeDefinition(key, ScalarAttributeType.S))); try { client.createTable(createTableRequest); } catch (ResourceInUseException e) { throw new IllegalStateException("The table may already be getting created.", e); } LOG.info("Table " + tableName + " created"); waitForActive(client, tableName); } public static void createTable(AmazonDynamoDBClient client, String tableName, String key, String rangeKey, long readCapacityUnits, long writeCapacityUnits) { if (tableExists(client, tableName)) { if (tableHasCorrectSchema(client, tableName, key, rangeKey)) { waitForActive(client, tableName); return; } else { LOG.error("Table already exists and schema does not match"); } } CreateTableRequest createTableRequest = new CreateTableRequest(); createTableRequest.setTableName(tableName); createTableRequest.setKeySchema(Arrays.asList(new KeySchemaElement(key, KeyType.HASH), new KeySchemaElement(rangeKey, KeyType.RANGE))); createTableRequest .setProvisionedThroughput(new ProvisionedThroughput(readCapacityUnits, writeCapacityUnits)); createTableRequest .setAttributeDefinitions(Arrays.asList(new AttributeDefinition(key, ScalarAttributeType.S), new AttributeDefinition(rangeKey, ScalarAttributeType.N))); try { client.createTable(createTableRequest); } catch (ResourceInUseException e) { throw new IllegalStateException("The table may already be getting created.", e); } LOG.info("Table " + tableName + " created"); waitForActive(client, tableName); } /** * Helper method to wait until DynamoDB table becomes active. * * @param client * The {@link AmazonDynamoDBClient} with DynamoDB read privileges * @param tableName * The DynamoDB table to check the state of * @throws IllegalStateException * Table is in the deleting state * @throws IllegalStateException * Table did not become active before timeout */ private static void waitForActive(AmazonDynamoDBClient client, String tableName) { switch (getTableStatus(client, tableName)) { case DELETING: throw new IllegalStateException("Table " + tableName + " is in the DELETING state"); case ACTIVE: LOG.info("Table " + tableName + " is ACTIVE"); return; default: long startTime = System.currentTimeMillis(); long endTime = startTime + (10 * 60 * 1000); while (System.currentTimeMillis() < endTime) { try { Thread.sleep(10 * 1000); } catch (InterruptedException e) { } try { if (getTableStatus(client, tableName) == TableStatus.ACTIVE) { LOG.info("Table " + tableName + " is ACTIVE"); return; } } catch (ResourceNotFoundException e) { throw new IllegalStateException("Table " + tableName + " never went active"); } } } } /** * Helper method to get the status of a DynamoDB table * * @param client * The {@link AmazonDynamoDBClient} with DynamoDB read privileges * @param tableName * The DynamoDB table to get the status of * @return */ private static TableStatus getTableStatus(AmazonDynamoDBClient client, String tableName) { DescribeTableRequest describeTableRequest = new DescribeTableRequest(); describeTableRequest.setTableName(tableName); DescribeTableResult describeTableResult = client.describeTable(describeTableRequest); String status = describeTableResult.getTable().getTableStatus(); return TableStatus.fromValue(status); } /** * Verifies if the table has the expected schema. * @param client * The {@link AmazonDynamoDBClient} with DynamoDB read privileges * @param tableName * The DynamoDB table to check * @param key * The expected hashkey for the DynamoDB table * @return true if the DynamoDB table exists and the expected hashkey matches the table schema, * otherwise return false */ private static boolean tableHasCorrectSchema(AmazonDynamoDBClient client, String tableName, String key) { DescribeTableRequest describeTableRequest = new DescribeTableRequest(); describeTableRequest.setTableName(tableName); DescribeTableResult describeTableResult = client.describeTable(describeTableRequest); TableDescription tableDescription = describeTableResult.getTable(); if (tableDescription.getAttributeDefinitions().size() != 1) { LOG.error("The number of attribute definitions does not match the existing table."); return false; } AttributeDefinition attributeDefinition = tableDescription.getAttributeDefinitions().get(0); if (!attributeDefinition.getAttributeName().equals(key) || !attributeDefinition.getAttributeType().equals(ScalarAttributeType.S.toString())) { LOG.error("Attribute name or type does not match existing table."); return false; } List<KeySchemaElement> KSEs = tableDescription.getKeySchema(); if (KSEs.size() != 1) { LOG.error("The number of key schema elements does not match the existing table."); return false; } KeySchemaElement kse = KSEs.get(0); if (!kse.getAttributeName().equals(key) || !kse.getKeyType().equals(KeyType.HASH.toString())) { LOG.error("The hash key does not match the existing table."); return false; } return true; } private static boolean tableHasCorrectSchema(AmazonDynamoDBClient client, String tableName, String key, String rangeKey) { DescribeTableRequest describeTableRequest = new DescribeTableRequest(); describeTableRequest.setTableName(tableName); DescribeTableResult describeTableResult = client.describeTable(describeTableRequest); TableDescription tableDescription = describeTableResult.getTable(); if (tableDescription.getAttributeDefinitions().size() != 2) { LOG.error("The number of attribute definitions does not match the existing table."); return false; } AttributeDefinition attributeDefinition = tableDescription.getAttributeDefinitions().get(0); if (!attributeDefinition.getAttributeName().equals(key) || !attributeDefinition.getAttributeType().equals(ScalarAttributeType.S.toString())) { if (!attributeDefinition.getAttributeName().equals(rangeKey) || !attributeDefinition.getAttributeType().equals(ScalarAttributeType.N.toString())) { LOG.error("Attribute name or type does not match existing table."); return false; } } if (!attributeDefinition.getAttributeName().equals(rangeKey) || !attributeDefinition.getAttributeType().equals(ScalarAttributeType.N.toString())) { if (!attributeDefinition.getAttributeName().equals(key) || !attributeDefinition.getAttributeType().equals(ScalarAttributeType.S.toString())) { LOG.error("Attribute name or type does not match existing table."); return false; } } List<KeySchemaElement> KSEs = tableDescription.getKeySchema(); if (KSEs.size() != 2) { LOG.error("The number of key schema elements does not match the existing table."); return false; } KeySchemaElement kse = KSEs.get(0); if (!kse.getAttributeName().equals(key) || !kse.getKeyType().equals(KeyType.HASH.toString())) { LOG.error("The hash key does not match the existing table."); return false; } KeySchemaElement seconndKse = KSEs.get(1); if (!seconndKse.getAttributeName().equals(rangeKey) || !seconndKse.getKeyType().equals(KeyType.RANGE.toString())) { LOG.error("The hash range key does not match the existing table."); return false; } return true; } /** * Helper method to determine if a DynamoDB table exists. * * @param client * The {@link AmazonDynamoDBClient} with DynamoDB read privileges * @param tableName * The DynamoDB table to check for * @return true if the DynamoDB table exists, otherwise return false */ private static boolean tableExists(AmazonDynamoDBClient client, String tableName) { DescribeTableRequest describeTableRequest = new DescribeTableRequest(); describeTableRequest.setTableName(tableName); try { client.describeTable(describeTableRequest); return true; } catch (ResourceNotFoundException e) { return false; } } /** * Deletes a DynamoDB table if it exists. * * @param client * The {@link AmazonDynamoDBClient} with DynamoDB read and write privileges * @param tableName * The DynamoDB table to delete */ public static void deleteTable(AmazonDynamoDBClient client, String tableName) { if (tableExists(client, tableName)) { DeleteTableRequest deleteTableRequest = new DeleteTableRequest(); deleteTableRequest.setTableName(tableName); client.deleteTable(deleteTableRequest); LOG.info("Deleted table " + tableName); } else { LOG.warn("Table " + tableName + " does not exist"); } } }