/*
* Copyright 2013-2014 Amazon.com, Inc. or its affiliates. All Rights Reserved.
* SPDX-License-Identifier: Apache-2.0
*/
package samples.utils;
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 Amazon DynamoDB resources.
*/
public class DynamoDBUtils {
private static Log LOG = LogFactory.getLog(DynamoDBUtils.class);
/**
* Creates the Amazon 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 Amazon DynamoDB read and write privileges
* @param tableName
* The Amazon DynamoDB table to create
* @param key
* The Amazon DynamoDB table hashkey
* @param readCapacityUnits
* Number of read capacity units for the Amazon DynamoDB table
* @param writeCapacityUnits
* Number of write capacity units for the Amazon 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);
}
/**
* Helper method to wait until Amazon DynamoDB table becomes active.
*
* @param client
* The {@link AmazonDynamoDBClient} with Amazon DynamoDB read privileges
* @param tableName
* The Amazon 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 an Amazon DynamoDB table
*
* @param client
* The {@link AmazonDynamoDBClient} with Amazon DynamoDB read privileges
* @param tableName
* The Amazon 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 Amazon DynamoDB read privileges
* @param tableName
* The Amazon DynamoDB table to check
* @param key
* The expected hashkey for the Amazon DynamoDB table
* @return true if the Amazon 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;
}
/**
* Helper method to determine if an Amazon DynamoDB table exists.
*
* @param client
* The {@link AmazonDynamoDBClient} with Amazon DynamoDB read privileges
* @param tableName
* The Amazon DynamoDB table to check for
* @return true if the Amazon 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 an Amazon DynamoDB table if it exists.
*
* @param client
* The {@link AmazonDynamoDBClient} with Amazon DynamoDB read and write privileges
* @param tableName
* The Amazon 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");
}
}
}
