121 lines
3.6 KiB
Ruby
121 lines
3.6 KiB
Ruby
require "active_support/core_ext/array/extract_options"
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module ActiveSupport
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# \FileUpdateChecker specifies the API used by Rails to watch files
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# and control reloading. The API depends on four methods:
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#
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# * +initialize+ which expects two parameters and one block as
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# described below;
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#
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# * +updated?+ which returns a boolean if there were updates in
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# the filesystem or not;
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#
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# * +execute+ which executes the given block on initialization
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# and updates the counter to the latest timestamp;
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#
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# * +execute_if_updated+ which just executes the block if it was updated;
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#
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# After initialization, a call to +execute_if_updated+ must execute
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# the block only if there was really a change in the filesystem.
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#
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# == Examples
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#
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# This class is used by Rails to reload the I18n framework whenever
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# they are changed upon a new request.
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#
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# i18n_reloader = ActiveSupport::FileUpdateChecker.new(paths) do
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# I18n.reload!
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# end
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#
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# ActionDispatch::Reloader.to_prepare do
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# i18n_reloader.execute_if_updated
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# end
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#
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class FileUpdateChecker
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# It accepts two parameters on initialization. The first is an array
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# of files and the second is an optional hash of directories. The hash must
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# have directories as keys and the value is an array of extensions to be
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# watched under that directory.
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#
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# This method must also receive a block that will be called once a path changes.
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#
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# == Implementation details
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#
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# This particular implementation checks for added and updated files,
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# but not removed files. Directories lookup are compiled to a glob for
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# performance. Therefore, while someone can add new files to the +files+
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# array after initialization (and parts of Rails do depend on this feature),
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# adding new directories after initialization is not allowed.
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#
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# Notice that other objects that implements FileUpdateChecker API may
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# not even allow new files to be added after initialization. If this
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# is the case, we recommend freezing the +files+ after initialization to
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# avoid changes that won't make effect.
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def initialize(files, dirs={}, &block)
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@files = files
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@glob = compile_glob(dirs)
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@block = block
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@updated_at = nil
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@last_update_at = updated_at
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end
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# Check if any of the entries were updated. If so, the updated_at
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# value is cached until the block is executed via +execute+ or +execute_if_updated+
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def updated?
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current_updated_at = updated_at
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if @last_update_at < current_updated_at
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@updated_at = updated_at
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true
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else
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false
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end
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end
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# Executes the given block and updates the counter to latest timestamp.
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def execute
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@last_update_at = updated_at
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@block.call
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ensure
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@updated_at = nil
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end
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# Execute the block given if updated.
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def execute_if_updated
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if updated?
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execute
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true
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else
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false
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end
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end
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private
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def updated_at #:nodoc:
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@updated_at || begin
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all = []
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all.concat @files.select { |f| File.exists?(f) }
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all.concat Dir[@glob] if @glob
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all.map { |path| File.mtime(path) }.max || Time.at(0)
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end
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end
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def compile_glob(hash) #:nodoc:
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hash.freeze # Freeze so changes aren't accidently pushed
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return if hash.empty?
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globs = []
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hash.each do |key, value|
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globs << "#{key}/**/*#{compile_ext(value)}"
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end
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"{#{globs.join(",")}}"
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end
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def compile_ext(array) #:nodoc:
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array = Array(array)
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return if array.empty?
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".{#{array.join(",")}}"
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end
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end
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end
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