canvas-lms/lib/progress_runner.rb

115 lines
4.0 KiB
Ruby

#
# Copyright (C) 2013 - present Instructure, Inc.
#
# This file is part of Canvas.
#
# Canvas is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, version 3 of the License.
#
# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along
# with this program. If not, see <http://www.gnu.org/licenses/>.
#
class ProgressRunner
attr_reader :progress, :completed_count, :failed_count, :errors
# Initialize the ProgressRunner
# @param progress [Progress] The Progress record to update during {#do_batch_update}
def initialize(progress)
@progress = progress
@completed_count = @failed_count = 0
@errors = {}
@completed_message = method(:default_completed_message)
@error_message = method(:default_error_message)
end
# Process a list of elements, periodically updating the Progress record and finalizing it when
# processing is complete. If processing raises exceptions, the exception messages are recorded
# as error messages and recorded in the Progress object.
#
# @param elements [Array] The collection of elements to process
# @param process_element A block that performs the actually processing on each element.
# Passed an individual element as a parameter.
def do_batch_update(elements, &process_element)
raise 'block required' unless block_given?
@progress.start!
update_every = [elements.size / 20, 4].max
elements.each_slice(update_every) do |batch|
update_batch(batch, &process_element)
@progress.calculate_completion!(@completed_count + @failed_count, elements.size)
end
finish_update
rescue => e
@progress.message = e.message
@progress.fail!
@progress.save
end
# Provide a custom "X items processed" message. The provided block overrides the default.
# @param block The block to call to format the completed message.
# @see #default_completed_message
def completed_message(&block)
raise 'block required' unless block_given?
@completed_message = block
self
end
# Provide a custom error message formatter. The provided block overrides the default
# @param block The block to call to format an error message. See #default_error_message
def error_message(&block)
raise 'block required' unless block_given?
@error_message = block
self
end
# The default completed message.
# @param [Integer] completed_count The number of items that were processed successfully.
def default_completed_message(completed_count)
I18n.t('lib.progress_runner.completed_message', {
:one => "1 item processed",
:other => "%{count} items processed"
},
:count => completed_count)
end
# The default error message formatter.
# @param message [String] The error message that was encountered for the specified elements.
# @param elements [Array] A list of elements this error message applies to.
def default_error_message(message, elements)
I18n.t('lib.progress_runner.error_message', "%{error}: %{ids}", :error => message, :ids => elements.join(', '))
end
private
def update_batch(batch, &process_element)
batch.each do |element|
update_element(element, &process_element)
end
end
def update_element(element, &process_element)
process_element.call(element)
@completed_count += 1
rescue => e
(@errors[e.message] ||= []) << element
@failed_count += 1
end
def finish_update
@progress.completion = 100.0
@progress.message = @completed_message.call(@completed_count)
@errors.each do |message, elements|
@progress.message += "\n" + @error_message.call(message, elements)
end
@completed_count > 0 ? @progress.complete! : @progress.fail!
@progress.save
end
end