Class: ActiveSupport::FileUpdateChecker
- Defined in:
- lib/active_support/file_update_checker.rb
Overview
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 counter to the latest 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.
Examples
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
Instance Method Summary collapse
-
#execute ⇒ Object
Executes the given block and updates the counter to latest timestamp.
-
#execute_if_updated ⇒ Object
Execute the block given if updated.
-
#initialize(files, dirs = {}, &block) ⇒ FileUpdateChecker
constructor
It accepts two parameters on initialization.
-
#updated? ⇒ Boolean
Check if any of the entries were updated.
Constructor Details
#initialize(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.
Implementation details
This particular implementation checks for added and updated files, but not removed files. Directories lookup are compiled to a glob for performance. Therefore, while someone can add new files to the files
array after initialization (and parts of Rails do depend on this feature), adding new directories after initialization is not allowed.
Notice that other objects that implements FileUpdateChecker API may not even allow new files to be added after initialization. If this is the case, we recommend freezing the files
after initialization to avoid changes that won’t make effect.
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# File 'lib/active_support/file_update_checker.rb', line 55 def initialize(files, dirs={}, &block) @files = files @glob = compile_glob(dirs) @block = block @updated_at = nil @last_update_at = updated_at end |
Instance Method Details
#execute ⇒ Object
Executes the given block and updates the counter to latest timestamp.
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# File 'lib/active_support/file_update_checker.rb', line 76 def execute @last_update_at = updated_at @block.call ensure @updated_at = nil end |
#execute_if_updated ⇒ Object
Execute the block given if updated.
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# File 'lib/active_support/file_update_checker.rb', line 84 def execute_if_updated if updated? execute true else false end end |
#updated? ⇒ Boolean
Check if any of the entries were updated. If so, the updated_at value is cached until the block is executed via execute
or execute_if_updated
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# File 'lib/active_support/file_update_checker.rb', line 65 def updated? current_updated_at = updated_at if @last_update_at < current_updated_at @updated_at = updated_at true else false end end |