Java tutorial
/* * Copyright 2013-2019 Amazon Technologies, Inc. * * 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 org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import com.amazonaws.SdkClientException; import com.amazonaws.services.dynamodbv2.AmazonDynamoDB; 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.ResourceInUseException; 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 DynamoDB tables. * * <pre class="brush: java"> * // ... create DynamoDB table ... * try { * waitUntilActive(dynamoDB, myTableName()); * } catch (AmazonClientException e) { * // table didn't become active * } * // ... start making calls to table ... * </pre> */ public class TableUtils { /** * Thrown by {@link TableUtils} when a table never reaches a desired state */ public static class TableNeverTransitionedToStateException extends SdkClientException { private static final long serialVersionUID = 8920567021104846647L; public TableNeverTransitionedToStateException(String tableName, TableStatus desiredStatus) { super("Table " + tableName + " never transitioned to desired state of " + desiredStatus.toString()); } } private static final int DEFAULT_WAIT_TIMEOUT = 10 * 60 * 1000; private static final int DEFAULT_WAIT_INTERVAL = 20 * 1000; /** * The logging utility. */ private static final Log LOG = LogFactory.getLog(TableUtils.class); /** * Waits up to 10 minutes for a specified DynamoDB table to resolve, * indicating that it exists. If the table doesn't return a result after * this time, a SdkClientException is thrown. * * @param dynamo * The DynamoDB client to use to make requests. * @param tableName * The name of the table being resolved. * * @throws SdkClientException * If the specified table does not resolve before this method * times out and stops polling. * @throws InterruptedException * If the thread is interrupted while waiting for the table to * resolve. */ public static void waitUntilExists(final AmazonDynamoDB dynamo, final String tableName) throws InterruptedException { waitUntilExists(dynamo, tableName, DEFAULT_WAIT_TIMEOUT, DEFAULT_WAIT_INTERVAL); } /** * Waits up to a specified amount of time for a specified DynamoDB table to * resolve, indicating that it exists. If the table doesn't return a result * after this time, a SdkClientException is thrown. * * @param dynamo * The DynamoDB client to use to make requests. * @param tableName * The name of the table being resolved. * @param timeout * The maximum number of milliseconds to wait. * @param interval * The poll interval in milliseconds. * * @throws SdkClientException * If the specified table does not resolve before this method * times out and stops polling. * @throws InterruptedException * If the thread is interrupted while waiting for the table to * resolve. */ public static void waitUntilExists(final AmazonDynamoDB dynamo, final String tableName, final int timeout, final int interval) throws InterruptedException { TableDescription table = waitForTableDescription(dynamo, tableName, null, timeout, interval); if (table == null) { throw new SdkClientException("Table " + tableName + " never returned a result"); } } /** * Waits up to 10 minutes for a specified DynamoDB table to move into the * <code>ACTIVE</code> state. If the table does not exist or does not * transition to the <code>ACTIVE</code> state after this time, then * SdkClientException is thrown. * * @param dynamo * The DynamoDB client to use to make requests. * @param tableName * The name of the table whose status is being checked. * * @throws TableNeverTransitionedToStateException * If the specified table does not exist or does not transition * into the <code>ACTIVE</code> state before this method times * out and stops polling. * @throws InterruptedException * If the thread is interrupted while waiting for the table to * transition into the <code>ACTIVE</code> state. */ public static void waitUntilActive(final AmazonDynamoDB dynamo, final String tableName) throws InterruptedException, TableNeverTransitionedToStateException { waitUntilActive(dynamo, tableName, DEFAULT_WAIT_TIMEOUT, DEFAULT_WAIT_INTERVAL); } /** * Waits up to a specified amount of time for a specified DynamoDB table to * move into the <code>ACTIVE</code> state. If the table does not exist or * does not transition to the <code>ACTIVE</code> state after this time, * then a SdkClientException is thrown. * * @param dynamo * The 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 TableNeverTransitionedToStateException * If the specified table does not exist or does not transition * into the <code>ACTIVE</code> state before this method times * out and stops polling. * @throws InterruptedException * If the thread is interrupted while waiting for the table to * transition into the <code>ACTIVE</code> state. */ public static void waitUntilActive(final AmazonDynamoDB dynamo, final String tableName, final int timeout, final int interval) throws InterruptedException, TableNeverTransitionedToStateException { TableDescription table = waitForTableDescription(dynamo, tableName, TableStatus.ACTIVE, timeout, interval); if (table == null || !table.getTableStatus().equals(TableStatus.ACTIVE.toString())) { throw new TableNeverTransitionedToStateException(tableName, TableStatus.ACTIVE); } } /** * Wait for the table to reach the desired status and returns the table * description * * @param dynamo * Dynamo client to use * @param tableName * Table name to poll status of * @param desiredStatus * Desired {@link TableStatus} to wait for. If null this method * simply waits until DescribeTable returns something non-null * (i.e. any status) * @param timeout * Timeout in milliseconds to continue to poll for desired status * @param interval * Time to wait in milliseconds between poll attempts * @return Null if DescribeTables never returns a result, otherwise the * result of the last poll attempt (which may or may not have the * desired state) * @throws InterruptedException * @throws {@link * IllegalArgumentException} If timeout or interval is invalid */ private static TableDescription waitForTableDescription(final AmazonDynamoDB dynamo, final String tableName, TableStatus desiredStatus, final int timeout, final int interval) throws InterruptedException, IllegalArgumentException { if (timeout < 0) { throw new IllegalArgumentException("Timeout must be >= 0"); } if (interval <= 0 || interval >= timeout) { throw new IllegalArgumentException("Interval must be > 0 and < timeout"); } long startTime = System.currentTimeMillis(); long endTime = startTime + timeout; TableDescription table = null; while (System.currentTimeMillis() < endTime) { try { table = dynamo.describeTable(new DescribeTableRequest(tableName)).getTable(); if (desiredStatus == null || table.getTableStatus().equals(desiredStatus.toString())) { return table; } } catch (ResourceNotFoundException rnfe) { // ResourceNotFound means the table doesn't exist yet, // so ignore this error and just keep polling. } Thread.sleep(interval); } return table; } /** * Creates the table and ignores any errors if it already exists. * @param dynamo The Dynamo client to use. * @param createTableRequest The create table request. * @return True if created, false otherwise. */ public static final boolean createTableIfNotExists(final AmazonDynamoDB dynamo, final CreateTableRequest createTableRequest) { try { dynamo.createTable(createTableRequest); return true; } catch (final ResourceInUseException e) { if (LOG.isTraceEnabled()) { LOG.trace("Table " + createTableRequest.getTableName() + " already exists", e); } } return false; } /** * Deletes the table and ignores any errors if it doesn't exist. * @param dynamo The Dynamo client to use. * @param deleteTableRequest The delete table request. * @return True if deleted, false otherwise. */ public static final boolean deleteTableIfExists(final AmazonDynamoDB dynamo, final DeleteTableRequest deleteTableRequest) { try { dynamo.deleteTable(deleteTableRequest); return true; } catch (final ResourceNotFoundException e) { if (LOG.isTraceEnabled()) { LOG.trace("Table " + deleteTableRequest.getTableName() + " does not exist", e); } } return false; } }