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require 'fcgi'
require 'logger'
require 'dispatcher'
require 'rbconfig'
class RailsFCGIHandler
SIGNALS = {
'HUP' => :reload,
'INT' => :exit_now,
'TERM' => :exit_now,
'USR1' => :exit,
'USR2' => :restart
}
GLOBAL_SIGNALS = SIGNALS.keys - %w(USR1)
attr_reader :when_ready
attr_accessor :log_file_path
attr_accessor :gc_request_period
# Initialize and run the FastCGI instance, passing arguments through to new.
def self.process!(*args, &block)
new(*args, &block).process!
end
# Initialize the FastCGI instance with the path to a crash log
# detailing unhandled exceptions (default RAILS_ROOT/log/fastcgi.crash.log)
# and the number of requests to process between garbage collection runs
# (default nil for normal GC behavior.) Optionally, pass a block which
# takes this instance as an argument for further configuration.
def initialize(log_file_path = nil, gc_request_period = nil)
self.log_file_path = log_file_path || "#{RAILS_ROOT}/log/fastcgi.crash.log"
self.gc_request_period = gc_request_period
# Yield for additional configuration.
yield self if block_given?
# Safely install signal handlers.
install_signal_handlers
@app = Dispatcher.new
# Start error timestamp at 11 seconds ago.
@last_error_on = Time.now - 11
end
def process!(provider = FCGI)
mark_features!
dispatcher_log :info, 'starting'
process_each_request provider
dispatcher_log :info, 'stopping gracefully'
rescue Exception => error
case error
when SystemExit
dispatcher_log :info, 'stopping after explicit exit'
when SignalException
dispatcher_error error, 'stopping after unhandled signal'
else
# Retry if exceptions occur more than 10 seconds apart.
if Time.now - @last_error_on > 10
@last_error_on = Time.now
dispatcher_error error, 'retrying after unhandled exception'
retry
else
dispatcher_error error, 'stopping after unhandled exception within 10 seconds of the last'
end
end
end
protected
def process_each_request(provider)
request = nil
catch :exit do
provider.each do |request|
process_request(request)
case when_ready
when :reload
reload!
when :restart
close_connection(request)
restart!
when :exit
close_connection(request)
throw :exit
end
end
end
rescue SignalException => signal
raise unless signal.message == 'SIGUSR1'
close_connection(request)
end
def process_request(request)
@processing, @when_ready = true, nil
gc_countdown
with_signal_handler 'USR1' do
begin
::Rack::Handler::FastCGI.serve(request, @app)
rescue SignalException, SystemExit
raise
rescue Exception => error
dispatcher_error error, 'unhandled dispatch error'
end
end
ensure
@processing = false
end
def logger
@logger ||= Logger.new(@log_file_path)
end
def dispatcher_log(level, msg)
time_str = Time.now.strftime("%d/%b/%Y:%H:%M:%S")
logger.send(level, "[#{time_str} :: #{$$}] #{msg}")
rescue Exception => log_error # Logger errors
STDERR << "Couldn't write to #{@log_file_path.inspect}: #{msg}\n"
STDERR << " #{log_error.class}: #{log_error.message}\n"
end
def dispatcher_error(e, msg = "")
error_message =
"Dispatcher failed to catch: #{e} (#{e.class})\n" +
" #{e.backtrace.join("\n ")}\n#{msg}"
dispatcher_log(:error, error_message)
end
def install_signal_handlers
GLOBAL_SIGNALS.each { |signal| install_signal_handler(signal) }
end
def install_signal_handler(signal, handler = nil)
if SIGNALS.include?(signal) && self.class.method_defined?(name = "#{SIGNALS[signal]}_handler")
handler ||= method(name).to_proc
begin
trap(signal, handler)
rescue ArgumentError
dispatcher_log :warn, "Ignoring unsupported signal #{signal}."
end
else
dispatcher_log :warn, "Ignoring unsupported signal #{signal}."
end
end
def with_signal_handler(signal)
install_signal_handler(signal)
yield
ensure
install_signal_handler(signal, 'DEFAULT')
end
def exit_now_handler(signal)
dispatcher_log :info, "asked to stop immediately"
exit
end
def exit_handler(signal)
dispatcher_log :info, "asked to stop ASAP"
if @processing
@when_ready = :exit
else
throw :exit
end
end
def reload_handler(signal)
dispatcher_log :info, "asked to reload ASAP"
if @processing
@when_ready = :reload
else
reload!
end
end
def restart_handler(signal)
dispatcher_log :info, "asked to restart ASAP"
if @processing
@when_ready = :restart
else
restart!
end
end
def restart!
config = ::Config::CONFIG
ruby = File::join(config['bindir'], config['ruby_install_name']) + config['EXEEXT']
command_line = [ruby, $0, ARGV].flatten.join(' ')
dispatcher_log :info, "restarted"
# close resources as they won't be closed by
# the OS when using exec
logger.close rescue nil
Rails.logger.close rescue nil
exec(command_line)
end
def reload!
run_gc! if gc_request_period
restore!
@when_ready = nil
dispatcher_log :info, "reloaded"
end
# Make a note of $" so we can safely reload this instance.
def mark_features!
@features = $".clone
end
def restore!
$".replace @features
Dispatcher.reset_application!
ActionController::Routing::Routes.reload
end
def run_gc!
@gc_request_countdown = gc_request_period
GC.enable; GC.start; GC.disable
end
def gc_countdown
if gc_request_period
@gc_request_countdown ||= gc_request_period
@gc_request_countdown -= 1
run_gc! if @gc_request_countdown <= 0
end
end
def close_connection(request)
request.finish if request
end
end
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