diff options
Diffstat (limited to 'activesupport/lib/active_support/evented_file_update_checker.rb')
-rw-r--r-- | activesupport/lib/active_support/evented_file_update_checker.rb | 166 |
1 files changed, 105 insertions, 61 deletions
diff --git a/activesupport/lib/active_support/evented_file_update_checker.rb b/activesupport/lib/active_support/evented_file_update_checker.rb index 315be85fb3..f54f88eb0a 100644 --- a/activesupport/lib/active_support/evented_file_update_checker.rb +++ b/activesupport/lib/active_support/evented_file_update_checker.rb @@ -1,8 +1,35 @@ -require 'set' -require 'pathname' -require 'concurrent/atomic/atomic_boolean' +require "set" +require "pathname" +require "concurrent/atomic/atomic_boolean" module ActiveSupport + # Allows you to "listen" to changes in a file system. + # The evented file updater does not hit disk when checking for updates + # instead it uses platform specific file system events to trigger a change + # in state. + # + # The file checker takes an array of files to watch or a hash specifying directories + # and file extensions to watch. It also takes a block that is called when + # EventedFileUpdateChecker#execute is run or when EventedFileUpdateChecker#execute_if_updated + # is run and there have been changes to the file system. + # + # Note: Forking will cause the first call to `updated?` to return `true`. + # + # Example: + # + # checker = EventedFileUpdateChecker.new(["/tmp/foo"], -> { puts "changed" }) + # checker.updated? + # # => false + # checker.execute_if_updated + # # => nil + # + # FileUtils.touch("/tmp/foo") + # + # checker.updated? + # # => true + # checker.execute_if_updated + # # => "changed" + # class EventedFileUpdateChecker #:nodoc: all def initialize(files, dirs = {}, &block) @ph = PathHelper.new @@ -13,20 +40,35 @@ module ActiveSupport @dirs[@ph.xpath(dir)] = Array(exts).map { |ext| @ph.normalize_extension(ext) } end - @block = block - @updated = Concurrent::AtomicBoolean.new(false) - @lcsp = @ph.longest_common_subpath(@dirs.keys) + @block = block + @updated = Concurrent::AtomicBoolean.new(false) + @lcsp = @ph.longest_common_subpath(@dirs.keys) + @pid = Process.pid + @boot_mutex = Mutex.new - if (dtw = directories_to_watch).any? + if (@dtw = directories_to_watch).any? # Loading listen triggers warnings. These are originated by a legit # usage of attr_* macros for private attributes, but adds a lot of noise # to our test suite. Thus, we lazy load it and disable warnings locally. - silence_warnings { require 'listen' } - Listen.to(*dtw, &method(:changed)).start + silence_warnings do + begin + require "listen" + rescue LoadError => e + raise LoadError, "Could not load the 'listen' gem. Add `gem 'listen'` to the development group of your Gemfile", e.backtrace + end + end end + boot! end def updated? + @boot_mutex.synchronize do + if @pid != Process.pid + boot! + @pid = Process.pid + @updated.make_true + end + end @updated.true? end @@ -37,12 +79,16 @@ module ActiveSupport def execute_if_updated if updated? + yield if block_given? execute true end end private + def boot! + Listen.to(*@dtw, &method(:changed)).start + end def changed(modified, added, removed) unless updated? @@ -78,73 +124,71 @@ module ActiveSupport @ph.filter_out_descendants(dtw) end - class PathHelper - using Module.new { - refine Pathname do - def ascendant_of?(other) - self != other && other.ascend do |ascendant| - break true if self == ascendant - end - end + class PathHelper + def xpath(path) + Pathname.new(path).expand_path end - } - - def xpath(path) - Pathname.new(path).expand_path - end - def normalize_extension(ext) - ext.to_s.sub(/\A\./, '') - end + def normalize_extension(ext) + ext.to_s.sub(/\A\./, "") + end - # Given a collection of Pathname objects returns the longest subpath - # common to all of them, or +nil+ if there is none. - def longest_common_subpath(paths) - return if paths.empty? - - lcsp = Pathname.new(paths[0]) - - paths[1..-1].each do |path| - until lcsp.ascendant_of?(path) - if lcsp.root? - # If we get here a root directory is not an ascendant of path. - # This may happen if there are paths in different drives on - # Windows. - return - else - lcsp = lcsp.parent + # Given a collection of Pathname objects returns the longest subpath + # common to all of them, or +nil+ if there is none. + def longest_common_subpath(paths) + return if paths.empty? + + lcsp = Pathname.new(paths[0]) + + paths[1..-1].each do |path| + until ascendant_of?(lcsp, path) + if lcsp.root? + # If we get here a root directory is not an ascendant of path. + # This may happen if there are paths in different drives on + # Windows. + return + else + lcsp = lcsp.parent + end end end - end - lcsp - end + lcsp + end - # Returns the deepest existing ascendant, which could be the argument itself. - def existing_parent(dir) - dir.ascend do |ascendant| - break ascendant if ascendant.directory? + # Returns the deepest existing ascendant, which could be the argument itself. + def existing_parent(dir) + dir.ascend do |ascendant| + break ascendant if ascendant.directory? + end end - end - # Filters out directories which are descendants of others in the collection (stable). - def filter_out_descendants(dirs) - return dirs if dirs.length < 2 + # Filters out directories which are descendants of others in the collection (stable). + def filter_out_descendants(dirs) + return dirs if dirs.length < 2 - dirs_sorted_by_nparts = dirs.sort_by { |dir| dir.each_filename.to_a.length } - descendants = [] + dirs_sorted_by_nparts = dirs.sort_by { |dir| dir.each_filename.to_a.length } + descendants = [] - until dirs_sorted_by_nparts.empty? - dir = dirs_sorted_by_nparts.shift + until dirs_sorted_by_nparts.empty? + dir = dirs_sorted_by_nparts.shift - dirs_sorted_by_nparts.reject! do |possible_descendant| - dir.ascendant_of?(possible_descendant) && descendants << possible_descendant + dirs_sorted_by_nparts.reject! do |possible_descendant| + ascendant_of?(dir, possible_descendant) && descendants << possible_descendant + end end + + # Array#- preserves order. + dirs - descendants end - # Array#- preserves order. - dirs - descendants + private + + def ascendant_of?(base, other) + base != other && other.ascend do |ascendant| + break true if base == ascendant + end + end end - end end end |