FileUpdateChecker specifies the API used by Rails to watch files and control reloading. The API depends on four methods:
initialize
which expects two parameters and one block as
described below.
updated?
which returns a boolean if there were updates in the
filesystem or not.
execute
which executes the given block on initialization and
updates the latest watched files and timestamp.
execute_if_updated
which just executes the block if it was
updated.
After initialization, a call to execute_if_updated
must
execute the block only if there was really a change in the filesystem.
This class is used by Rails to reload the I18n framework whenever they are changed upon a new request.
i18n_reloader = ActiveSupport::FileUpdateChecker.new(paths) do I18n.reload! end ActionDispatch::Reloader.to_prepare do i18n_reloader.execute_if_updated end
It accepts two parameters on initialization. The first is an array of files and the second is an optional hash of directories. The hash must have directories as keys and the value is an array of extensions to be watched under that directory.
This method must also receive a block that will be called once a path changes. The array of files and list of directories cannot be changed after FileUpdateChecker has been initialized.
# File lib/active_support/file_update_checker.rb, line 38 def initialize(files, dirs={}, &block) @files = files.freeze @glob = compile_glob(dirs) @block = block @watched = nil @updated_at = nil @last_watched = watched @last_update_at = updated_at(@last_watched) end
Executes the given block and updates the latest watched files and timestamp.
# File lib/active_support/file_update_checker.rb, line 72 def execute @last_watched = watched @last_update_at = updated_at(@last_watched) @block.call ensure @watched = nil @updated_at = nil end
Execute the block given if updated.
# File lib/active_support/file_update_checker.rb, line 82 def execute_if_updated if updated? execute true else false end end
Check if any of the entries were updated. If so, the watched and/or #updated_at values
are cached until the block is executed via execute
or
execute_if_updated
.
# File lib/active_support/file_update_checker.rb, line 53 def updated? current_watched = watched if @last_watched.size != current_watched.size @watched = current_watched true else current_updated_at = updated_at(current_watched) if @last_update_at < current_updated_at @watched = current_watched @updated_at = current_updated_at true else false end end end
# File lib/active_support/file_update_checker.rb, line 131 def compile_ext(array) array = Array(array) return if array.empty? ".{#{array.join(",")}}" end
# File lib/active_support/file_update_checker.rb, line 117 def compile_glob(hash) hash.freeze # Freeze so changes aren't accidentally pushed return if hash.empty? globs = hash.map do |key, value| "#{escape(key)}/**/*#{compile_ext(value)}" end "{#{globs.join(",")}}" end
# File lib/active_support/file_update_checker.rb, line 127 def escape(key) key.gsub(',','\,') end
This method returns the maximum mtime of the files in paths
,
or nil
if the array is empty.
Files with a mtime in the future are ignored. Such abnormal situation can happen for example if the user changes the clock by hand. It is healthy to consider this edge case because with mtimes in the future reloading is not triggered.
# File lib/active_support/file_update_checker.rb, line 112 def max_mtime(paths) time_now = Time.now paths.map {|path| File.mtime(path)}.reject {|mtime| time_now < mtime}.max end
# File lib/active_support/file_update_checker.rb, line 101 def updated_at(paths) @updated_at || max_mtime(paths) || Time.at(0) end
# File lib/active_support/file_update_checker.rb, line 93 def watched @watched || begin all = @files.select { |f| File.exist?(f) } all.concat(Dir[@glob]) if @glob all end end