Checkout of Instiki Trunk 1/21/2007.

vendor/rails/railties/lib/fcgi_handler.rb

@@ -0,0 +1,207 @@
+require 'fcgi'
+require 'logger'
+require 'dispatcher'
+require 'rbconfig'
+
+class RailsFCGIHandler
+  SIGNALS = {
+    'HUP'     => :reload,
+    'TERM'    => :exit_now,
+    'USR1'    => :exit,
+    'USR2'    => :restart,
+    'SIGTRAP' => :breakpoint
+  }
+
+  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
+
+    # Start error timestamp at 11 seconds ago.
+    @last_error_on = Time.now - 11
+
+    dispatcher_log :info, "starting"
+  end
+
+  def process!(provider = FCGI)
+    # Make a note of $" so we can safely reload this instance.
+    mark!
+
+    run_gc! if gc_request_period
+
+    provider.each_cgi do |cgi| 
+      process_request(cgi)
+
+      case when_ready
+        when :reload
+          reload!
+        when :restart
+          close_connection(cgi)
+          restart!
+        when :exit
+          close_connection(cgi)
+          break
+        when :breakpoint
+          close_connection(cgi)
+          breakpoint!
+      end
+
+      gc_countdown
+    end
+
+    GC.enable
+    dispatcher_log :info, "terminated gracefully"
+
+  rescue SystemExit => exit_error
+    dispatcher_log :info, "terminated by explicit exit"
+
+  rescue Object => fcgi_error
+    # retry on errors that would otherwise have terminated the FCGI process,
+    # but only if they occur more than 10 seconds apart.
+    if !(SignalException === fcgi_error) && Time.now - @last_error_on > 10
+      @last_error_on = Time.now
+      dispatcher_error(fcgi_error, "almost killed by this error")
+      retry
+    else
+      dispatcher_error(fcgi_error, "killed by this error")
+    end
+  end
+  
+  
+  private
+    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 Object => log_error
+      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
+      SIGNALS.each do |signal, handler_name|
+        install_signal_handler(signal, method("#{handler_name}_handler").to_proc)
+      end
+    end
+
+    def install_signal_handler(signal, handler)
+      trap(signal, handler)
+    rescue ArgumentError
+      dispatcher_log :warn, "Ignoring unsupported signal #{signal}."
+    end
+
+    def exit_now_handler(signal)
+      dispatcher_log :info, "asked to terminate immediately"
+      exit
+    end
+
+    def exit_handler(signal)
+      dispatcher_log :info, "asked to terminate ASAP"
+      @when_ready = :exit
+    end
+
+    def reload_handler(signal)
+      dispatcher_log :info, "asked to reload ASAP"
+      @when_ready = :reload
+    end
+
+    def restart_handler(signal)
+      dispatcher_log :info, "asked to restart ASAP"
+      @when_ready = :restart
+    end
+
+    def breakpoint_handler(signal)
+      dispatcher_log :info, "asked to breakpoint ASAP"
+      @when_ready = :breakpoint
+    end
+
+    def process_request(cgi)
+      Dispatcher.dispatch(cgi)
+    rescue Object => e
+      raise if SignalException === e
+      dispatcher_error(e)
+    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"
+
+      exec(command_line)
+    end
+
+    def reload!
+      run_gc! if gc_request_period
+      restore!
+      @when_ready = nil
+      dispatcher_log :info, "reloaded"
+    end
+
+    def mark!
+      @features = $".clone
+    end
+
+    def restore!
+      $".replace @features
+      Dispatcher.reset_application!
+      ActionController::Routing::Routes.reload
+    end
+    
+    def breakpoint!
+      require 'breakpoint'
+      port = defined?(BREAKPOINT_SERVER_PORT) ? BREAKPOINT_SERVER_PORT : 42531
+      Breakpoint.activate_drb("druby://localhost:#{port}", nil, !defined?(FastCGI))
+      dispatcher_log :info, "breakpointing"
+      breakpoint
+      @when_ready = nil
+    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 -= 1
+        run_gc! if @gc_request_countdown <= 0
+      end
+    end
+    
+    def close_connection(cgi)
+      cgi.instance_variable_get("@request").finish
+    end
+end