153 lines
5.1 KiB
Ruby
153 lines
5.1 KiB
Ruby
# frozen_string_literal: true
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require 'faye/websocket/client'
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require 'json_schemer'
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class Runner::Connection
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# These are events for which callbacks can be registered.
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EVENTS = %i[start output exit stdout stderr].freeze
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WEBSOCKET_MESSAGE_TYPES = %i[start stdout stderr error timeout exit].freeze
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BACKEND_OUTPUT_SCHEMA = JSONSchemer.schema(JSON.parse(File.read('lib/runner/backend-output.schema.json')))
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attr_writer :status
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attr_reader :error
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def initialize(url, strategy, event_loop, locale = I18n.locale)
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@socket = Faye::WebSocket::Client.new(url, [], ping: 5)
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@strategy = strategy
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@status = :established
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@event_loop = event_loop
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@locale = locale
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# For every event type of Faye WebSockets, the corresponding
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# RunnerConnection method starting with `on_` is called.
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%i[open message error close].each do |event_type|
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@socket.on(event_type) do |event|
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# The initial locale when establishing the connection is used for all callbacks
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I18n.with_locale(@locale) { __send__(:"on_#{event_type}", event) }
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end
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end
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# This registers empty default callbacks.
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EVENTS.each {|event_type| instance_variable_set(:"@#{event_type}_callback", ->(e) {}) }
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@start_callback = -> {}
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# Fail if no exit status was returned.
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@exit_code = 1
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end
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# Register a callback based on the WebSocket connection state
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def on(event, &block)
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return unless EVENTS.include? event
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instance_variable_set(:"@#{event}_callback", block)
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end
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# Send arbitrary data in the WebSocket connection
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def send(raw_data)
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encoded_message = encode(raw_data)
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Rails.logger.debug { "#{Time.zone.now.getutc}: Sending to #{@socket.url}: #{encoded_message.inspect}" }
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@socket.send(encoded_message)
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end
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# Close the WebSocket connection
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def close(status)
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return unless active?
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@status = status
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@socket.close
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end
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# Check if the WebSocket connection is currently established
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def active?
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@status == :established
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end
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private
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def decode(_raw_event)
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raise NotImplementedError
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end
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def encode(_data)
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raise NotImplementedError
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end
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# === WebSocket Callbacks
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# These callbacks are executed based on events indicated by Faye WebSockets and are
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# independent of the JSON specification that is used within the WebSocket once established.
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def on_message(raw_event)
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Rails.logger.debug { "#{Time.zone.now.getutc}: Receiving from #{@socket.url}: #{raw_event.data.inspect}" }
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# The WebSocket connection might group multiple lines. For further processing, we require all lines
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# to be processed separately. Therefore, we split the lines by each newline character not part of an enclosed
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# substring either in single or double quotes (e.g., within a JSON)
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# Inspired by https://stackoverflow.com/questions/13040585/split-string-by-spaces-properly-accounting-for-quotes-and-backslashes-ruby
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raw_event.data.scan(/(?:"(?:\\.|[^"])*"|'(?:\\.|[^'])*'|[^"\n])+/).each do |event_data|
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event = decode(event_data)
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next unless BACKEND_OUTPUT_SCHEMA.valid?(event)
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event = event.deep_symbolize_keys
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message_type = event[:type].to_sym
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if WEBSOCKET_MESSAGE_TYPES.include?(message_type)
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__send__("handle_#{message_type}", event)
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else
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@error = Runner::Error::UnexpectedResponse.new("Unknown WebSocket message type: #{message_type}")
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close(:error)
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end
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end
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end
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def on_open(_event)
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@start_callback.call
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end
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def on_error(_event); end
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def on_close(_event)
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Rails.logger.debug { "#{Time.zone.now.getutc}: Closing connection to #{@socket.url} with status: #{@status}" }
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case @status
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when :timeout
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@error = Runner::Error::ExecutionTimeout.new('Execution exceeded its time limit')
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when :terminated_by_codeocean, :terminated_by_management
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@exit_callback.call @exit_code
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when :terminated_by_client, :error
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else # :established
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# If the runner is killed by the DockerContainerPool after the maximum allowed time per user and
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# while the owning user is running an execution, the command execution stops and log output is incomplete.
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@error = Runner::Error::Unknown.new('Execution terminated with an unknown reason')
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end
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@event_loop.stop
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end
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# === Message Handlers
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# Each message type indicated by the +type+ attribute in the JSON
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# sent be the runner management has a dedicated method.
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# Context:: All registered handlers are executed in the scope of
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# the bindings they had where they were registered.
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# Information not stored in the binding, such as the
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# locale or call stack are not available during execution!
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def handle_exit(event)
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@status = :terminated_by_management
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@exit_code = event[:data]
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end
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def handle_stdout(event)
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@stdout_callback.call event[:data]
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@output_callback.call event[:data]
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end
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def handle_stderr(event)
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@stderr_callback.call event[:data]
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@output_callback.call event[:data]
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end
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def handle_error(_event); end
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def handle_start(_event); end
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def handle_timeout(_event)
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@status = :timeout
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end
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end
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