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# Copyright 2011-2013 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. A copy of
# the License is located at
#
# http://aws.amazon.com/apache2.0/
#
# 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.
require 'zlib'
module AWS
class DynamoDB
# Builds a client for Amazon DynamoDB.
#
# ddb = AWS::DynamoDB::Client.new
#
# ## API Versions
#
# Amazon DynamoDB has multiple API versions. It is important to know
# which API you are using. Each API version accepts different parameters
# and returns data in a different format.
#
# By default, the oldest API version is used. This ensures customers
# who started using DynamoDB early would not get broken by API updates.
# You can construct a client of a specific version by passing the
# `:api_version` option to the {#initialize constructor}.
#
# # defaults to the 2011-12-05 API version
# ddb = AWS::DynamoDB::Client.new
#
# # specify the API version
# ddb = AWS::DynamoDB::Client.new(:api_version => '2011-12-05')
# ddb = AWS::DynamoDB::Client.new(:api_version => '2012-08-10')
#
# You can specify a global default API version using AWS.config:
#
# AWS.config(:dynamo_db => { :api_version => '2012-08-10' })
#
# AWS::DynamoDB::Client.new
# #=> AWS::DynamoDB::Client::V20120810
#
# @see V20111205
# @see V20120810
#
class Client < Core::JSONClient
autoload :V20111205, 'aws/dynamo_db/client/v20111205'
autoload :V20120810, 'aws/dynamo_db/client/v20120810'
API_VERSION = '2011-12-05'
signature_version :Version4, 'dynamodb'
# @private
REGION_US_E1 = 'dynamodb.us-east-1.amazonaws.com'
# @private
CACHEABLE_REQUESTS = Set[:list_tables, :describe_table]
protected
def extract_error_details response
if response.http_response.status == 413
['RequestEntityTooLarge', 'Request entity too large']
elsif crc32_is_valid?(response) == false
['CRC32CheckFailed', 'CRC32 integrity check failed']
else
super
end
end
def retryable_error? response
case response.error
when Errors::ProvisionedThroughputExceededException
config.dynamo_db_retry_throughput_errors?
when Errors::CRC32CheckFailed
true
else
super
end
end
def sleep_durations response
retry_count =
if expired_credentials?(response)
config.max_retries == 0 ? 0 : 1
else
config.max_retries { 10 }
end
# given a retry_count of 10, the sleep durations will look like:
# 0, 50, 100, 200, 400, 800, 1600, 3200, 6400, 12800 (milliseconds)
(0...retry_count).map do |n|
if n == 0
0
else
50 * (2 ** (n - 1)) / 1000.0
end
end
end
private
# @return [Boolean] whether the CRC32 response header matches the body.
# @return [nil] if no CRC32 header is present or we are not verifying CRC32
def crc32_is_valid? response
return nil unless config.dynamo_db_crc32
if crcs = response.http_response.headers['x-amz-crc32']
crcs[0].to_i == calculate_crc32(response)
else
nil
end
end
def calculate_crc32 response
Zlib.crc32(response.http_response.body)
end
end
end
end
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