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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 'timeout'
module AWS
class SimpleWorkflow
# Provides an interface to count, and receive decision tasks
# ({DecisionTask} objects) from the service.
#
# ## Counting
#
# To get a count of decision tasks needing attention, call {#count}
# with a task list name:
#
# domain.decision_tasks.count('my-task-list').to_i #=> 7
#
# ## Getting a single decision task
#
# To process a single task use {#poll_for_single_task}:
#
# domain.decision_tasks.poll_for_single_task('my-task-list') do |task|
# # this block is yielded to only if a task is found
# # within 60 seconds.
# end
#
# At the end of the block, the decision task is auto-completed.
# If you prefer you can omit the block and `nil` or a {DecisionTask}
# will be returned.
#
# if task = domain.decision_tasks.poll_for_single_task('my-task-list')
# # you need to call complete! or the decision task will time out
# task.complete!
# end
#
# ## Polling for Tasks in a Loop
#
# You can poll indefinitely for tasks in a loop with {#poll}:
#
# domain.decision_tasks.poll('my-task-list') do |task|
# # yields once for every decision task found
# end
#
# Just like the block form above, the decision task is auto completed at
# the end of the block. Please note, if you call `break` or `return`
# from inside the block, you *MUST* call {DecisionTask#complete!} or
# the task will timeout.
#
# ## Events and Decisions
#
# Each decision task provides an enumerable collection of both
# new events ({DecisionTask#new_events}) and all events
# ({DecisionTask#events}).
#
# Based on the events in the workflow execution history, you should
# call methods on the decision task. See {DecisionTask} for
# a complete list of decision methods.
#
class DecisionTaskCollection
include Core::Model
include OptionFormatters
# @api private
def initialize domain, options = {}
@domain = domain
super
end
# @return [Domain]
attr_reader :domain
# Returns the number of decision tasks in the specified `task_list`.
#
# count = decision_tasks.count('task-list-name')
# count.truncated? #=> false
# count.to_i #=> 7
#
# @note This operation is eventually consistent. The results are best
# effort and may not exactly reflect recent updates and changes.
#
# @param [String] task_list Name of the task list to count
# decision tasks for.
#
# @return [Count] Returns a {Count} object that specifies the number
# of decision tasks for the given task list. This count will
# also indicate if the count was truncated.
#
def count task_list
options = {}
options[:domain] = domain.name
options[:task_list] = { :name => task_list }
response = client.count_pending_decision_tasks(options)
Count.new(response.data['count'], response.data['truncated'])
end
# Polls the service for a single decision task. The service may
# hold the request for up to 60 seconds before responding.
#
# # try to get a single task, may return nil when no tasks available
# task = domain.decision_tasks.poll_for_single_task('task-list')
# if task
# # make decisions ...
# task.complete!
# end
#
# You can optionally pass a block and that will only be yielded
# to when a decision task is available within the 60 seconds.
#
# domain.decision_tasks.poll_for_single_task('task-list') do |task|
# # make decisions
# # task.complete! is called for you at the end of the block
# end
#
# With the block form you do not need to call #complete! on the
# decision task. It will be called when the block exists.
#
# @note If you are not using the block form you must call
# {DecisionTask#complete!} yourself or your decision task will
# timeout.
#
# @param [String] task_list Specifies the task list to poll for
# decision tasks.
#
# @param [Hash] options
#
# @option options [String] :identity The identity of the decider
# requesting a decision task. This will be recorded in the
# DecisionTaskStarted event in the workflow history.
# If `:identity` is not passed then the hostname and
# process id will be sent (e.g. "hostname:pid").
#
# @option options [Boolean] :reverse_event_order (false) When true,
# the history events on the decision task will enumerate in
# reverse chronological order (newest events first). By default
# the events are enumerated in chronological order (oldest first).
#
# @option options [Integer] :event_batch_size (1000) When enumerating
# events on the decision task, multiple requests may be required
# to fetch all of the events. You can specify the maximum number
# of events to request each time (must not be greater than 1000).
#
# @yieldparam [DecisionTask] decision_task
#
# @return [DecisionTask,nil] Returns a decision task or `nil`. If
# a block was passed then `nil` is always returned. If a block
# is not passed, then `nil` or a {DecisionTask} will be returned.
#
def poll_for_single_task task_list, options = {}, &block
client_opts = {}
client_opts[:domain] = domain.name
client_opts[:identity] = identity_opt(options)
client_opts[:task_list] = { :name => task_list }
client_opts[:maximum_page_size] = options[:event_batch_size] || 1000
client_opts[:reverse_order] = options.key?(:reverse_event_order) ?
options[:reverse_event_order] : false
response = client.poll_for_decision_task(client_opts)
if response.data['taskToken']
decision_task = DecisionTask.new(domain, client_opts, response.data)
if block_given?
yield(decision_task)
decision_task.complete! unless decision_task.responded?
nil
else
decision_task
end
else
nil
end
end
# Polls indefinitely for decision tasks. Each decision task found is
# yielded to the block. At the end of the block the decision task
# is auto-completed ({DecisionTask#complete!} is called).
#
# # yields once for each decision task found, indefinitely
# domain.decision_tasks.poll do |decision_task|
# # make decisions here
# end
#
# @note If you to terminate the block (by calling `break` or `return`)
# then it is your responsibility to call #complete! on the decision
# task.
#
# @param (see #poll_for_single_task)
#
# @option (see #poll_for_single_task)
#
# @yieldparam [DecisionTask] decision_task
#
# @return [nil]
#
def poll task_list, options = {}, &block
loop do
begin
poll_for_single_task(task_list, options) do |decision_task|
yield(decision_task)
end
rescue Timeout::Error
retry
end
end
nil
end
end
end
end
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