/*
* Copyright 2013-2014 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.
* You may obtain a copy of the License at:
*
* http://aws.amazon.com/apache2.0
*
* 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.amazonaws.services.dynamodbv2.util;
import com.amazonaws.AmazonClientException;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.model.DescribeTableRequest;
import com.amazonaws.services.dynamodbv2.model.ResourceNotFoundException;
import com.amazonaws.services.dynamodbv2.model.TableDescription;
import com.amazonaws.services.dynamodbv2.model.TableStatus;
/**
* Utility methods for working with AWS DynamoDB tables.
*
* <pre class="brush: java">
* if (Tables.doesTableExist(dynamoDB, myTableName) == false) {
* // ... create your table ...
* Tables.waitForTableToBecomeActive(dynamoDB, myTableName);
* }
* </pre>
*/
public class Tables {
private static final int DEFAULT_WAIT_TIMEOUT = 10 * 60 * 1000;
private static final int DEFAULT_WAIT_INTERVAL = 20 * 1000;
/**
* Checks if a specified table exists and is in <code>ACTIVE</code> state.
*
* @param dynamo The AWS DynamoDB client to use to make requests.
* @param tableName The name of the table being searched for.
* @return True if a table already exists with the specified name, otherwise
* false.
*/
public static boolean doesTableExist(AmazonDynamoDB dynamo, String tableName) {
try {
TableDescription table = dynamo.describeTable(new DescribeTableRequest(tableName))
.getTable();
return TableStatus.ACTIVE.toString().equals(table.getTableStatus());
} catch (ResourceNotFoundException rnfe) {
// This means the table doesn't exist in the account yet
return false;
}
}
/**
* Waits up to 10 minutes for a specified AWS DynamoDB table to move into
* the <code>ACTIVE</code> state. If the table doesn't transition to the
* <code>ACTIVE</code> state, then an AmazonClientException is thrown.
*
* @param dynamo The AWS DynamoDB client to use to make requests.
* @param tableName The name of the table whose status is being checked.
* @throws AmazonClientException If the specified table does not transition
* into the <code>ACTIVE</code> state before this method times
* out and stops polling.
*/
public static void waitForTableToBecomeActive(AmazonDynamoDB dynamo, String tableName) {
waitForTableToBecomeActive(dynamo, tableName, DEFAULT_WAIT_TIMEOUT, DEFAULT_WAIT_INTERVAL);
}
/**
* Waits up to a specified amount of time for a specified AWS DynamoDB table
* to move into the <code>ACTIVE</code> state. If the table doesn't
* transition to the <code>ACTIVE</code> state, then an
* AmazonClientException is thrown.
*
* @param dynamo The AWS DynamoDB client to use to make requests.
* @param tableName The name of the table whose status is being checked.
* @param timeout The maximum number of milliseconds to wait.
* @param interval The poll interval in milliseconds.
* @throws AmazonClientException If the specified table does not transition
* into the <code>ACTIVE</code> state before this method times
* out and stops polling.
*/
public static void waitForTableToBecomeActive(AmazonDynamoDB dynamo, String tableName,
int timeout, int interval) {
if (timeout < 0)
throw new AmazonClientException("Timeout must be >= 0");
if (interval <= 0 || interval >= timeout)
throw new AmazonClientException("Interval must be > 0 and < timeout");
long startTime = System.currentTimeMillis();
long endTime = startTime + timeout;
while (System.currentTimeMillis() < endTime) {
try {
TableDescription table = dynamo.describeTable(new DescribeTableRequest(tableName))
.getTable();
if (table != null && table.getTableStatus().equals(TableStatus.ACTIVE.toString()))
return;
} catch (ResourceNotFoundException rnfe) {
// ResourceNotFound means the table doesn't exist yet,
// so ignore this error and just keep polling.
}
try {
Thread.sleep(interval);
} catch (InterruptedException e) {
Thread.interrupted();
throw new AmazonClientException(
"Interrupted while waiting for table to become active", e);
}
}
throw new AmazonClientException("Table " + tableName + " never became active");
}
}