Class: Scarpe::Components::AssetServer

Inherits:
Object
  • Object
show all
Includes:
Base64, Shoes::Log
Defined in:
lib/scarpe/components/asset_server.rb

Defined Under Namespace

Classes: FileServlet

Constant Summary collapse

URL_TYPES = 
[:auto, :asset, :data]

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Base64

#encode_file_to_base64, #mime_type_for_filename, #valid_url?

Constructor Details

#initialize(port: 0, app_dir:, never_start_server: false, connect_timeout: 5) ⇒ AssetServer

Port 0 will auto-assign a free port



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# File 'lib/scarpe/components/asset_server.rb', line 17

def initialize(port: 0, app_dir:, never_start_server: false, connect_timeout: 5)
  log_init("AssetServer")

  require "scarpe/components/base64"

  @server_started = false
  @server_thread = nil
  @port = port != 0 ? port : find_open_port
  @app_dir = File.expand_path app_dir
  @components_dir = File.expand_path "#{__dir__}/../../.."
  @connect_timeout = connect_timeout
  @never_start_server = never_start_server

  # For now, always use 16kb as the cutoff for preferring to serve a file with the asset server
  @auto_asset_url_size = 16 * 1024

  # Make sure the child process is dead
  at_exit do
    kill_server
  end
end

Instance Attribute Details

#dir ⇒ Object (readonly)

Returns the value of attribute dir.



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# File 'lib/scarpe/components/asset_server.rb', line 12

def dir
  @dir
end

#port ⇒ Object (readonly)

Returns the value of attribute port.



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# File 'lib/scarpe/components/asset_server.rb', line 10

def port
  @port
end

#server_started ⇒ Object (readonly)

Returns the value of attribute server_started.



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# File 'lib/scarpe/components/asset_server.rb', line 11

def server_started
  @server_started
end

Instance Method Details

#asset_url(url, url_type: :auto) ⇒ Object

Get an asset URL for the given url or filename. The asset server can return a data URL, which encodes the entire file into the URL. It can return an asset server URL, which will serve the file via a local webrick server (@see AssetServer).

If url_type is auto, asset_url will return a data URL or asset server URL depending on file size and whether it’s local to the asset server. Remote URLs will always be returned verbatim.

Parameters:

  • url (String) —

    the filename or URL

  • url_type (Symbol) (defaults to: :auto) —

    the type of URL to return - one of :auto, :asset, :data



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# File 'lib/scarpe/components/asset_server.rb', line 52

def asset_url(url, url_type: :auto)
  unless URL_TYPES.include?(url_type)
    raise ArgumentError, "The url_type arg must be one of #{URL_TYPES.inspect}!"
  end

  if valid_url?(url)
    # This is already not local, use it directly
    return url
  end

  # Invalid URLs are assumed to be file paths.
  url = File.expand_path url
  file_size = File.size(url)

  # Calculate the app-relative path to the file. If it's not outside the app
  # dir, great, use that. If it *is* outside the app dir, see if the
  # scarpe-components dir is better (e.g. for Tiranti Bootstrap CSS assets.)
  relative_app_path = relative_path_from_to(@app_dir, url)
  relative_path = relative_app_path
  if relative_app_path.start_with?("../")
    relative_comp_path = relative_path_from_to(@components_dir, url)
    relative_path = relative_comp_path unless relative_comp_path.start_with?("../")
  end

  # If url_type is :auto, we will use a data URL for small files and files that
  # would be outside the asset server's directory. Data URLs are less efficient
  # for large files, but we'll try to always serve *something* if we can.
  if url_type == :data ||
    (url_type == :auto && file_size < @auto_asset_url_size) ||
    (url_type == :auto && relative_path.start_with?("../"))

    # The MIME media type for this file
    file_type = mime_type_for_filename(url)

    # Up to 16kb per file, inline it directly to avoid an extra HTTP request
    return "data:#{file_type};base64,#{encode_file_to_base64(url)}"
  end

  # Start the server if we're returning an asset-server URL
  unless @server_started || @never_start_server
    start_server_thread
  end

  if relative_path.start_with?("../")
    raise Scarpe::OperationNotAllowedError, "Large asset is outside of application directory and asset URL was requested: #{url.inspect}"
  end
  if relative_path == relative_app_path
    "http://127.0.0.1:#{@port}/app/#{relative_path}"
  else
    "http://127.0.0.1:#{@port}/comp/#{relative_path}"
  end
end

#find_open_port ⇒ Object 



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# File 'lib/scarpe/components/asset_server.rb', line 105

def find_open_port
  require "socket"
  s = TCPServer.new('127.0.0.1', port)
  port = s.addr[1]
  s.close
  port
end

#kill_server ⇒ Object 



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# File 'lib/scarpe/components/asset_server.rb', line 167

def kill_server
  return unless @server_started && @server_thread

  @server.shutdown
  @server_thread.join if @server_thread.alive?
  @server_started = false
  @server_thread = nil
end

#port_is_responding?(port, timeout: 0.1) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/scarpe/components/asset_server.rb', line 113

def port_is_responding?(port, timeout: 0.1)
  Socket.tcp("127.0.0.1", port, connect_timeout: timeout) { true } rescue false
end

#relative_path_from_to(from, to) ⇒ Object 



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# File 'lib/scarpe/components/asset_server.rb', line 128

def relative_path_from_to(from, to)
  require 'pathname'
  Pathname.new(to).relative_path_from(Pathname.new from).to_s
end

#retry_port(port, timeout: 2.0) ⇒ Object 



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# File 'lib/scarpe/components/asset_server.rb', line 117

def retry_port(port, timeout: 2.0)
  t = Time.now
  loop do
    resp = port_is_responding?(port)

    return true if resp
    return false if Time.now - t > timeout
    sleep 0.1
  end
end

#start_server_thread ⇒ Object 



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# File 'lib/scarpe/components/asset_server.rb', line 133

def start_server_thread
  return if @server_started

  @server_thread = Thread.new do
    start_webrick
  end
  @server_started = true

  # Give the asset server a couple of seconds to respond
  retry_port(@port, timeout: @connect_timeout)
  unless port_is_responding?(@port, timeout: 0.1)
    @log.warn "Asset server port doesn't seem to be responding after #{@connect_timeout} seconds!"
  end
end

#start_webrick ⇒ Object 



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# File 'lib/scarpe/components/asset_server.rb', line 148

def start_webrick
  require "tempfile"
  log = WEBrick::Log.new Tempfile.new("scarpe_asset_server_log")
  access_log = [
    [Tempfile.new("scarpe_asset_server_access_log"), WEBrick::AccessLog::COMBINED_LOG_FORMAT]
  ]

  @server = WEBrick::HTTPServer.new(Port: @port, DocumentRoot: @app_dir, Logger: log, AccessLog: access_log)
  @server.mount('/app', FileServlet, { Type: :app, Prefix: "/app", DocumentRoot: @app_dir })
  @server.mount('/comp', FileServlet, { Type: :scarpe_components, Prefix: "/comp", DocumentRoot: @components_dir })

  @server.start

  # Set up a signal trap to gracefully shut down the server on interrupt (e.g., Ctrl+C)
  trap('INT') do
    @server.shutdown
  end
end