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# Copyright (c) 2009 Michael Fellinger m.fellinger@gmail.com
# Rack::Reloader is subject to the terms of an MIT-style license.
# See COPYING or http://www.opensource.org/licenses/mit-license.php.
require 'pathname'
module Rack
# High performant source reloader
#
# This class acts as Rack middleware.
#
# What makes it especially suited for use in a production environment is that
# any file will only be checked once and there will only be made one system
# call stat(2).
#
# Please note that this will not reload files in the background, it does so
# only when actively called.
#
# It is performing a check/reload cycle at the start of every request, but
# also respects a cool down time, during which nothing will be done.
class Reloader
def initialize(app, cooldown = 10, backend = Stat)
@app = app
@cooldown = cooldown
@last = (Time.now - cooldown)
@cache = {}
@mtimes = {}
extend backend
end
def call(env)
if @cooldown and Time.now > @last + @cooldown
if Thread.list.size > 1
Thread.exclusive{ reload! }
else
reload!
end
@last = Time.now
end
@app.call(env)
end
def reload!(stderr = $stderr)
rotation do |file, mtime|
previous_mtime = @mtimes[file] ||= mtime
safe_load(file, mtime, stderr) if mtime > previous_mtime
end
end
# A safe Kernel::load, issuing the hooks depending on the results
def safe_load(file, mtime, stderr = $stderr)
load(file)
stderr.puts "#{self.class}: reloaded `#{file}'"
file
rescue LoadError, SyntaxError => ex
stderr.puts ex
ensure
@mtimes[file] = mtime
end
module Stat
def rotation
files = [$0, *$LOADED_FEATURES].uniq
paths = ['./', *$LOAD_PATH].uniq
files.map{|file|
next if file =~ /\.(so|bundle)$/ # cannot reload compiled files
found, stat = figure_path(file, paths)
next unless found && stat && mtime = stat.mtime
@cache[file] = found
yield(found, mtime)
}.compact
end
# Takes a relative or absolute +file+ name, a couple possible +paths+ that
# the +file+ might reside in. Returns the full path and File::Stat for the
# path.
def figure_path(file, paths)
found = @cache[file]
found = file if !found and Pathname.new(file).absolute?
found, stat = safe_stat(found)
return found, stat if found
paths.find do |possible_path|
path = ::File.join(possible_path, file)
found, stat = safe_stat(path)
return ::File.expand_path(found), stat if found
end
return false, false
end
def safe_stat(file)
return unless file
stat = ::File.stat(file)
return file, stat if stat.file?
rescue Errno::ENOENT, Errno::ENOTDIR
@cache.delete(file) and false
end
end
end
end
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