Module: ModelContextProtocol::Server::Progressable

Included in:
Prompt, Resource, Tool
Defined in:
lib/model_context_protocol/server/progressable.rb

Instance Method Summary collapse

Instance Method Details

#progressable(max_duration:, message: nil) { ... } ⇒ Object

Execute a block with automatic time-based progress reporting. Uses Concurrent::TimerTask to send progress notifications at regular intervals.

Examples:

progressable(max_duration: 30) do  # 30 seconds
  perform_long_operation
end

Parameters:

  • max_duration (Numeric) —

    Expected duration in seconds

  • message (String, nil) (defaults to: nil) —

    Optional custom progress message

Yields:

  • block to execute with progress tracking

Returns:

  • (Object) —

    the result of the block



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# File 'lib/model_context_protocol/server/progressable.rb', line 17

def progressable(max_duration:, message: nil, &block)
  context = Thread.current[:mcp_context]
  return yield unless context && context[:progress_token] && context[:transport]

  progress_token = context[:progress_token]
  transport = context[:transport]
  jsonrpc_request_id = context[:jsonrpc_request_id]
  request_store = context[:request_store]
  stream_id = context[:stream_id]

  start_time = Time.now
  update_interval = [1.0, max_duration * 0.05].max

  timer_task = Concurrent::TimerTask.new(execution_interval: update_interval) do
    Thread.current[:mcp_context] = {jsonrpc_request_id:}

    begin
      if request_store && jsonrpc_request_id
        break if request_store.cancelled?(jsonrpc_request_id)
      end

      elapsed_seconds = Time.now - start_time
      progress_pct = [(elapsed_seconds / max_duration) * 100, 99].min

      progress_message = if message
        "#{message} (#{elapsed_seconds.round(1)}s / ~#{max_duration}s)"
      else
        "Processing... (#{elapsed_seconds.round(1)}s / ~#{max_duration}s)"
      end

      begin
        transport.send_notification("notifications/progress", {
          progressToken: progress_token,
          progress: progress_pct.round(1),
          total: 100,
          message: progress_message
        }, session_id: stream_id)
      rescue
        break
      end

      timer_task.shutdown if elapsed_seconds >= max_duration
    ensure
      Thread.current[:mcp_context] = nil
    end
  end

  begin
    timer_task.execute

    result = yield

    original_context = Thread.current[:mcp_context]
    Thread.current[:mcp_context] = {jsonrpc_request_id:}

    begin
      transport.send_notification("notifications/progress", {
        progressToken: progress_token,
        progress: 100,
        total: 100,
        message: "Completed"
      }, session_id: stream_id)
    rescue
      nil
    ensure
      Thread.current[:mcp_context] = original_context
    end

    result
  ensure
    if timer_task&.running?
      timer_task.shutdown
      sleep(0.1) if timer_task.running?
    end
  end
end