lambda_context.rb

# Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.

# frozen_string_literal: true

class LambdaContext
  attr_reader :aws_request_id, :invoked_function_arn, :log_group_name,
              :log_stream_name, :function_name, :memory_limit_in_mb, :function_version,
              :identity, :client_context, :deadline_ms

  def initialize(request)
    @clock_diff = Process.clock_gettime(Process::CLOCK_REALTIME, :millisecond) - Process.clock_gettime(Process::CLOCK_MONOTONIC, :millisecond)
    @deadline_ms = request['Lambda-Runtime-Deadline-Ms'].to_i
    @aws_request_id = request['Lambda-Runtime-Aws-Request-Id']
    @invoked_function_arn = request['Lambda-Runtime-Invoked-Function-Arn']
    @log_group_name = ENV['AWS_LAMBDA_LOG_GROUP_NAME']
    @log_stream_name = ENV['AWS_LAMBDA_LOG_STREAM_NAME']
    @function_name = ENV['AWS_LAMBDA_FUNCTION_NAME']
    @memory_limit_in_mb = ENV['AWS_LAMBDA_FUNCTION_MEMORY_SIZE']
    @function_version = ENV['AWS_LAMBDA_FUNCTION_VERSION']
    @identity = JSON.parse(request['Lambda-Runtime-Cognito-Identity']) unless request['Lambda-Runtime-Cognito-Identity'].to_s.empty?
    @client_context = JSON.parse(request['Lambda-Runtime-Client-Context']) unless request['Lambda-Runtime-Client-Context'].to_s.empty?
  end

  def get_remaining_time_in_millis
    now = Process.clock_gettime(Process::CLOCK_MONOTONIC, :millisecond) + @clock_diff
    remaining = @deadline_ms - now
    remaining.positive? ? remaining : 0
  end
end