Class: ActiveSupport::FileUpdateChecker
Relationships & Source Files | |
Inherits: | Object |
Defined in: | activesupport/lib/active_support/file_update_checker.rb |
Overview
File Update Checker
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
ActiveSupport::Reloader.to_prepare do
i18n_reloader.execute_if_updated
end
Class Method Summary
-
.new(files, dirs = {}, &block) ⇒ FileUpdateChecker
constructor
It accepts two parameters on initialization.
Instance Attribute Summary
-
#updated? ⇒ Boolean
readonly
Check if any of the entries were updated.
Instance Method Summary
-
#execute
Executes the given block and updates the latest watched files and timestamp.
-
#execute_if_updated
Execute the block given if updated.
- #compile_ext(array) private
- #compile_glob(hash) private
- #escape(key) private
-
#max_mtime(paths)
private
This method returns the maximum mtime of the files in
paths
, ornil
if the array is empty. - #updated_at(paths) private
- #watched private
Constructor Details
.new(files, dirs = {}, &block) ⇒ FileUpdateChecker
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 'activesupport/lib/active_support/file_update_checker.rb', line 44
def initialize(files, dirs = {}, &block) unless block raise ArgumentError, "A block is required to initialize a FileUpdateChecker" end @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
Instance Attribute Details
#updated? ⇒ Boolean
(readonly)
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 'activesupport/lib/active_support/file_update_checker.rb', line 63
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
Instance Method Details
#compile_ext(array) (private)
[ GitHub ]# File 'activesupport/lib/active_support/file_update_checker.rb', line 158
def compile_ext(array) array = Array(array) return if array.empty? ".{#{array.join(",")}}" end
#compile_glob(hash) (private)
[ GitHub ]# File 'activesupport/lib/active_support/file_update_checker.rb', line 144
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
#escape(key) (private)
[ GitHub ]# File 'activesupport/lib/active_support/file_update_checker.rb', line 154
def escape(key) key.gsub(",", '\,') end
#execute
Executes the given block and updates the latest watched files and timestamp.
# File 'activesupport/lib/active_support/file_update_checker.rb', line 82
def execute @last_watched = watched @last_update_at = updated_at(@last_watched) @block.call ensure @watched = nil @updated_at = nil end
#execute_if_updated
Execute the block given if updated.
#max_mtime(paths) (private)
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 'activesupport/lib/active_support/file_update_checker.rb', line 122
def max_mtime(paths) time_now = Time.now max_mtime = nil # Time comparisons are performed with #compare_without_coercion because # AS redefines these operators in a way that is much slower and does not # bring any benefit in this particular code. # # Read t1.compare_without_coercion(t2) < 0 as t1 < t2. paths.each do |path| mtime = File.mtime(path) next if time_now.compare_without_coercion(mtime) < 0 if max_mtime.nil? || max_mtime.compare_without_coercion(mtime) < 0 max_mtime = mtime end end max_mtime end
#updated_at(paths) (private)
[ GitHub ]#watched (private)
[ GitHub ]# File 'activesupport/lib/active_support/file_update_checker.rb', line 103
def watched @watched || begin all = @files.select { |f| File.exist?(f) } all.concat(Dir[@glob]) if @glob all.tap(&:uniq!) end end