# Copyright 2011 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 'aws/model'
module AWS
class SQS
# Represents a message received from an Amazon SQS Queue.
class ReceivedMessage
include Model
# @return [Queue] The queue from which this message was
# received.
attr_reader :queue
# @return [String] The ID of the message.
attr_reader :id
# @return [String] A string associated with this specific
# instance of receiving the message.
attr_reader :handle
# @return [String] The message's contents.
attr_reader :body
# @return [String] An MD5 digest of the message body.
attr_reader :md5
# @private
attr_reader :attributes
# @private
ATTRIBUTE_ALIASES = {
:sent_at => :sent_timestamp,
:receive_count => :approximate_receive_count,
:first_received_at => :approximate_first_receive_timestamp
}
# @private
def initialize(queue, id, handle, opts = {})
@queue = queue
@id = id
@handle = handle
@body = opts[:body]
@md5 = opts[:md5]
@attributes = opts[:attributes] || {}
super
end
# When SNS publishes messages to SQS queues the message body is
# formatted as a json message and then base 64 encoded.
# An easy way to work with SNS messages is to call this method:
#
# sns_msg = message.as_sns_message
#
# sns_msg.topic
# #=> <AWS::SNS::Topic ...>
#
# sns_msg.to_h.inspect
# #=> { :body => '...', :topic_arn => ... }
#
# @return [ReceivedSNSMessage]
def as_sns_message
ReceivedSNSMessage.new(body, :config => config)
end
# Deletes the message from the queue. Even if the message is
# locked by another reader due to the visibility timeout
# setting, it is still deleted from the queue. If you leave a
# message in the queue for more than 4 days, SQS automatically
# deletes it.
#
# If you use {Queue#poll} or {Queue#receive_message} in block
# form, the messages you receive will be deleted automatically
# unless an exception occurs while you are processing them.
# You can still use this method if you want to delete a
# message early and then continue processing it.
#
# @note It is possible you will receive a message even after
# you have deleted it. This might happen on rare occasions
# if one of the servers storing a copy of the message is
# unavailable when you request to delete the message. The
# copy remains on the server and might be returned to you
# again on a subsequent receive request. You should create
# your system to be idempotent so that receiving a
# particular message more than once is not a problem.
#
# @return [nil]
def delete
client.delete_message(
:queue_url => queue.url,
:receipt_handle => handle
)
nil
end
# Changes the visibility timeout of a specified message in a
# queue to a new value. The maximum allowed timeout value you
# can set the value to is 12 hours. This means you can't
# extend the timeout of a message in an existing queue to more
# than a total visibility timeout of 12 hours. (For more
# information visibility timeout, see {Visibility
# Timeout}[http://docs.amazonwebservices.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/IntroductionArticle.html#AboutVT]
# in the Amazon SQS Developer Guide.)
#
# For example, let's say the timeout for the queue is 30
# seconds, and you receive a message. Once you're 20 seconds
# into the timeout for that message (i.e., you have 10 seconds
# left), you extend it by 60 seconds by calling this method
# with +timeout+ set to 60 seconds. You have then changed the
# remaining visibility timeout from 10 seconds to 60 seconds.
#
# @note If you attempt to set the timeout to an amount more
# than the maximum time left, Amazon SQS returns an
# error. It will not automatically recalculate and increase
# the timeout to the maximum time remaining.
#
# @note Unlike with a queue, when you change the visibility
# timeout for a specific message, that timeout value is
# applied immediately but is not saved in memory for that
# message. If you don't delete a message after it is
# received, the visibility timeout for the message the next
# time it is received reverts to the original timeout value,
# not the value you set with this method.
#
# @return Returns the timeout argument as passed.
#
def visibility_timeout=(timeout)
client.change_message_visibility(
:queue_url => queue.url,
:receipt_handle => handle,
:visibility_timeout => timeout
)
timeout
end
# @return [String] The AWS account number (or the IP address,
# if anonymous access is allowed) of the sender.
def sender_id
attributes["SenderId"]
end
# @return [Time] The time when the message was sent.
def sent_timestamp
@sent_at ||=
(timestamp = attributes["SentTimestamp"] and
Time.at(timestamp.to_i / 1000.0)) || nil
rescue RangeError => e
p [timestamp, timestamp.to_i]
end
alias_method :sent_at, :sent_timestamp
# @return [Integer] The number of times a message has been
# received but not deleted.
def approximate_receive_count
(count = attributes["ApproximateReceiveCount"] and
count.to_i) or nil
end
alias_method :receive_count, :approximate_receive_count
# @return [Time] The time when the message was first received.
def approximate_first_receive_timestamp
@received_at ||=
(timestamp = attributes["ApproximateFirstReceiveTimestamp"] and
Time.at(timestamp.to_i / 1000.0)) || nil
end
alias_method :first_received_at, :approximate_first_receive_timestamp
end
end
end