Class: FileWatcher

Inherits:
Object
  • Object
show all
Defined in:
lib/filewatcher.rb

Overview

Simple file watcher. Detect changes in files and directories.

Issues: Currently doesn’t monitor changes in directorynames

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(unexpanded_filenames, print_filelist = false, dontwait = false, show_spinner = false) ⇒ FileWatcher

Returns a new instance of FileWatcher.



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# File 'lib/filewatcher.rb', line 18

def initialize(unexpanded_filenames, print_filelist=false, dontwait=false, =false)
  @unexpanded_filenames = unexpanded_filenames
  @filenames = nil
  @stored_update = nil
  @keep_watching = false
  @pausing = false
  @last_snapshot = mtime_snapshot
  @end_snapshot = nil
  @dontwait = dontwait
   = 
  puts 'Watching:' if print_filelist
  @filenames.each do |filename|
    raise 'File does not exist' unless File.exist?(filename)
    puts filename if print_filelist
  end
end

Instance Attribute Details

#filenames ⇒ Object

Returns the value of attribute filenames.



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# File 'lib/filewatcher.rb', line 6

def filenames
  @filenames
end

Class Method Details

.VERSION ⇒ Object 



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# File 'lib/filewatcher.rb', line 8

def self.VERSION
  return '0.5.1'
end

Instance Method Details

#expand_directories(patterns) ⇒ Object 



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# File 'lib/filewatcher.rb', line 141

def expand_directories(patterns)
  if(!patterns.kind_of?Array)
    patterns = [patterns]
  end
  patterns.map { |it| Dir[fulldepth(it)] }.flatten.uniq
end

#filesystem_updated?(snapshot_to_use = nil) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/filewatcher.rb', line 112

def filesystem_updated?(snapshot_to_use = nil)
  snapshot = snapshot_to_use ? snapshot_to_use : mtime_snapshot
  forward_changes = snapshot.to_a - @last_snapshot.to_a

  forward_changes.each do |file,mtime|
    @updated_file = file
    unless @last_snapshot.fetch(@updated_file,false)
      @last_snapshot[file] = mtime
      @event = :new
      return true
    else
      @last_snapshot[file] = mtime
      @event = :changed
      return true
    end
  end

  backward_changes = @last_snapshot.to_a - snapshot.to_a
  forward_names = forward_changes.map{|change| change.first}
  backward_changes.reject!{|f,m| forward_names.include?(f)}
  backward_changes.each do |file,mtime|
    @updated_file = file
    @last_snapshot.delete(file)
    @event = :delete
    return true
  end
  return false
end

#finalize(&on_update) ⇒ Object

Calls the update block repeatedly until all changes in the current snapshot are dealt with



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# File 'lib/filewatcher.rb', line 89

def finalize(&on_update)
  on_update = @stored_update if !block_given?
  snapshot = @end_snapshot ? @end_snapshot : mtime_snapshot
  while filesystem_updated?(snapshot)
    ('Finalizing')
    on_update.call(@updated_file, @event)
  end
  @end_snapshot =nil
  return nil
end

#mtime_snapshot ⇒ Object

Takes a snapshot of the current status of watched files. (Allows avoidance of potential race condition during #finalize)



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# File 'lib/filewatcher.rb', line 102

def mtime_snapshot
  snapshot = {}
  @filenames = expand_directories(@unexpanded_filenames)
  @filenames.each do |filename|
    mtime = File.exist?(filename) ? File.stat(filename).mtime : Time.new(0)
    snapshot[filename] = mtime
  end
  return snapshot
end

#pause ⇒ Object 



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# File 'lib/filewatcher.rb', line 62

def pause
  @pausing = true
  ('Initiating pause')
  Kernel.sleep @sleep # Ensure we wait long enough to enter pause loop
                      # in #watch
end

#resume ⇒ Object 



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# File 'lib/filewatcher.rb', line 69

def resume
  if !@keep_watching || !@pausing
    raise "Can't resume unless #watch and #pause were first called"
  end
  @last_snapshot = mtime_snapshot  # resume with fresh snapshot
  @pausing = false
  ('Resuming')
  Kernel.sleep @sleep # Wait long enough to exit pause loop in #watch
end

#stop ⇒ Object

Ends the watch, allowing any remaining changes to be finalized. Used mainly in multi-threaded situations.



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# File 'lib/filewatcher.rb', line 81

def stop
  @keep_watching = false
  ('Stopping')
  return nil
end

#update_spinner(label) ⇒ Object 



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# File 'lib/filewatcher.rb', line 12

def (label)
  return nil unless 
   ||= %w(\\ | / -)
  print "#{' ' * 30}\r#{label}  #{@spinner.rotate!.first}\r"
end

#watch(sleep = 0.5, &on_update) ⇒ Object 



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# File 'lib/filewatcher.rb', line 35

def watch(sleep=0.5, &on_update)
  trap("SIGINT") {return }
  @sleep = sleep
  @stored_update = on_update
  @keep_watching = true
  if(@dontwait)
    yield '',''
  end
  while @keep_watching
    @end_snapshot = mtime_snapshot if @pausing
    while @keep_watching && @pausing
      ('Pausing')
      Kernel.sleep sleep
    end
    while @keep_watching && !filesystem_updated? && !@pausing
      ('Watching')
      Kernel.sleep sleep
    end
    # test and null @updated_file to prevent yielding the last
    # file twice if @keep_watching has just been set to false
    yield @updated_file, @event if @updated_file
    @updated_file = nil
  end
  @end_snapshot = mtime_snapshot
  finalize(&on_update)
end