Use SIGHUP to dynamically reload an fcgi process without restarting it. Refactored dispatch.fcgi so that the RailsFCGIHandler is in the lib dir.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@1565 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

5 files changed, 182 insertions, 134 deletions

diff --git a/railties/CHANGELOG b/railties/CHANGELOG
index 867ed839ff..437f78bba8 100644
--- a/railties/CHANGELOG
+++ b/railties/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Allow dynamic application reloading for dispatch.fcgi processes by sending a SIGHUP. If the process is currently handling a request, the request will be allowed to complete first. This allows production fcgi's to be reloaded without having to restart them.
+
 * RailsFCGIHandler (dispatch.fcgi) no longer tries to explicitly flush $stdout (CgiProcess#out always calls flush)
 
 * Fixed rakefile actions against PostgreSQL when the password is all numeric #1462 [michael@schubert.cx]
@@ -22,7 +24,7 @@
 
 * Added graceful exit from pressing CTRL-C during the run of the rails command #1150 [Caleb Tennis]
 
-* Allow graceful exits for dispatch.fcgi processes by sending a SIGUSR1 or SIGHUP. If the process is currently handling a request, the request will be allowed to complete and then will terminate itself. If a request is not being handled, the process is terminated immediately (via #exit). This basically works like restart graceful on Apache. [Jamis Buck]
+* Allow graceful exits for dispatch.fcgi processes by sending a SIGUSR1. If the process is currently handling a request, the request will be allowed to complete and then will terminate itself. If a request is not being handled, the process is terminated immediately (via #exit). This basically works like restart graceful on Apache. [Jamis Buck]
 
 * Made dispatch.fcgi more robust by catching fluke errors and retrying unless its a permanent condition. [Jamis Buck]
 
diff --git a/railties/dispatches/dispatch.fcgi b/railties/dispatches/dispatch.fcgi
index 684f04db86..5164669f2e 100755
--- a/railties/dispatches/dispatch.fcgi
+++ b/railties/dispatches/dispatch.fcgi
@@ -1,98 +1,6 @@
 #!/usr/local/bin/ruby
 
-# to allow unit testing
-if !defined?(RAILS_ROOT)
-  require File.dirname(__FILE__) + "/../config/environment"
-end
+require File.dirname(__FILE__) + "/../config/environment"
+require 'fcgi_handler'
 
-require 'dispatcher'
-require 'fcgi'
-require 'logger'
-
-class RailsFCGIHandler
-  attr_reader :please_exit_at_your_earliest_convenience
-  attr_reader :i_am_currently_processing_a_request
-
-  def initialize(log_file_path = "#{RAILS_ROOT}/log/fastcgi.crash.log")
-    @please_exit_at_your_earliest_convenience = false
-    @i_am_currently_processing_a_request = false
-
-    trap_handler = method(:trap_handler).to_proc
-    trap("HUP",  trap_handler)
-    trap("USR1", trap_handler)
-
-    # initialize to 11 seconds from now to minimize special cases
-    @last_error_on = Time.now - 11
-
-    @log_file_path = log_file_path
-    dispatcher_log(:info, "fcgi #{$$} starting")
-  end
-
-  def process!
-    FCGI.each_cgi do |cgi| 
-      process_request(cgi)
-      break if please_exit_at_your_earliest_convenience
-    end
-
-    dispatcher_log(:info, "fcgi #{$$} terminated gracefully")
-
-  rescue SystemExit => exit_error
-    dispatcher_log(:info, "fcgi #{$$} terminated by explicit exit")
-
-  rescue Object => fcgi_error
-    # retry on errors that would otherwise have terminated the FCGI process,
-    # but only if they occur more than 10 seconds apart.
-    if !(SignalException === fcgi_error) && Time.now - @last_error_on > 10
-      @last_error_on = Time.now
-      dispatcher_error(fcgi_error,
-        "FCGI process #{$$} almost killed by this error\n")
-      retry
-    else
-      dispatcher_error(fcgi_error, "FCGI process #{$$} killed by this error\n")
-    end
-  end
-
-  private
-    def logger
-      @logger ||= Logger.new(@log_file_path)
-    end
-
-    def dispatcher_log(level, msg)
-      logger.send(level, msg)
-    rescue Object => log_error
-      STDERR << "Couldn't write to #{@log_file_path.inspect}: #{msg}\n"
-      STDERR << "  #{log_error.class}: #{log_error.message}\n"
-    end
-
-    def dispatcher_error(e,msg="")
-      error_message =
-        "[#{Time.now}] Dispatcher failed to catch: #{e} (#{e.class})\n" +
-        "  #{e.backtrace.join("\n  ")}\n#{msg}"
-      dispatcher_log(:error, error_message)
-    end
-
-    def trap_handler(signal)
-      if i_am_currently_processing_a_request
-        dispatcher_log(:info, "asking #{$$} to terminate ASAP")
-        @please_exit_at_your_earliest_convenience = true
-      else
-        dispatcher_log(:info, "telling #{$$} to terminate NOW")
-        exit
-      end
-    end
-
-    def process_request(cgi)
-      @i_am_currently_processing_a_request = true
-      Dispatcher.dispatch(cgi)
-    rescue Object => e
-      raise if SignalException === e
-      dispatcher_error(e)
-    ensure
-      @i_am_currently_processing_a_request = false
-    end
-end
-
-if __FILE__ == $0
-  handler = RailsFCGIHandler.new
-  handler.process!
-end
+RailsFCGIHandler.process!
diff --git a/railties/lib/dispatcher.rb b/railties/lib/dispatcher.rb
index 1455168ba9..aaea8dd277 100644
--- a/railties/lib/dispatcher.rb
+++ b/railties/lib/dispatcher.rb
@@ -33,9 +33,16 @@ class Dispatcher
       rescue Object => exception
         ActionController::Base.process_with_exception(request, response, exception).out(output)
       ensure
-        reset_application
+        reset_after_dispatch
       end
     end
+
+    def reset_application!
+      Controllers.clear!
+      Dependencies.clear
+      Dependencies.remove_subclasses_for(ActiveRecord::Base, ActiveRecord::Observer, ActionController::Base)
+      Dependencies.remove_subclasses_for(ActionMailer::Base) if defined?(ActionMailer::Base)
+    end
     
     private
       def prepare_application
@@ -44,14 +51,8 @@ class Dispatcher
         Controllers.const_load!(:ApplicationController, "application") unless Controllers.const_defined?(:ApplicationController)
       end
     
-      def reset_application
-        if Dependencies.load?
-          Controllers.clear!
-          Dependencies.clear
-          Dependencies.remove_subclasses_for(ActiveRecord::Base, ActiveRecord::Observer, ActionController::Base)
-          Dependencies.remove_subclasses_for(ActionMailer::Base) if defined?(ActionMailer::Base)
-        end
-
+      def reset_after_dispatch
+        reset_application! if Dependencies.load?
         Breakpoint.deactivate_drb if defined?(BREAKPOINT_SERVER_PORT)
       end
   end
diff --git a/railties/lib/fcgi_handler.rb b/railties/lib/fcgi_handler.rb
new file mode 100644
index 0000000000..f615ff6d34
--- /dev/null
+++ b/railties/lib/fcgi_handler.rb
@@ -0,0 +1,112 @@
+require 'fcgi'
+require 'logger'
+require 'dispatcher'
+
+class RailsFCGIHandler
+  attr_reader :when_ready
+  attr_reader :processing
+
+  def self.process!
+    new.process!
+  end
+
+  def initialize(log_file_path = "#{RAILS_ROOT}/log/fastcgi.crash.log")
+    @when_ready = nil
+    @processing = false
+
+    trap("HUP",  method(:restart_handler).to_proc)
+    trap("USR1", method(:trap_handler).to_proc)
+
+    # initialize to 11 seconds ago to minimize special cases
+    @last_error_on = Time.now - 11
+
+    @log_file_path = log_file_path
+    dispatcher_log(:info, "starting")
+  end
+
+  def process!
+    mark!
+
+    FCGI.each_cgi do |cgi| 
+      if when_ready == :restart
+        restore!
+        @when_ready = nil
+        dispatcher_log(:info, "restarted")
+      end
+
+      process_request(cgi)
+      break if when_ready == :exit
+    end
+
+    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 trap_handler(signal)
+      if processing
+        dispatcher_log :info, "asked to terminate ASAP"
+        @when_ready = :exit
+      else
+        dispatcher_log :info, "told to terminate NOW"
+        exit
+      end
+    end
+
+    def restart_handler(signal)
+      @when_ready = :restart
+      dispatcher_log :info, "asked to restart ASAP"
+    end
+
+    def process_request(cgi)
+      @processing = true
+      Dispatcher.dispatch(cgi)
+    rescue Object => e
+      raise if SignalException === e
+      dispatcher_error(e)
+    ensure
+      @processing = false
+    end
+
+    def mark!
+      @features = $".clone
+    end
+
+    def restore!
+      $".replace @features
+      Dispatcher.reset_application!
+      ActionController::Routing::Routes.reload
+    end
+end
diff --git a/railties/test/fcgi_dispatcher_test.rb b/railties/test/fcgi_dispatcher_test.rb
index 466eefe225..d9f147b13d 100644
--- a/railties/test/fcgi_dispatcher_test.rb
+++ b/railties/test/fcgi_dispatcher_test.rb
@@ -1,15 +1,15 @@
+$:.unshift File.dirname(__FILE__) + "/../lib"
 $:.unshift File.dirname(__FILE__) + "/mocks"
 
 require 'test/unit'
 require 'stringio'
+require 'fcgi_handler'
 
-if !defined?(RailsFCGIHandler)
-  RAILS_ROOT = File.dirname(__FILE__)
-  load File.dirname(__FILE__) + "/../dispatches/dispatch.fcgi"
-end
+RAILS_ROOT = File.dirname(__FILE__) if !defined?(RAILS_ROOT)
 
 class RailsFCGIHandler
   attr_reader :exit_code
+  attr_reader :restarted
   attr_accessor :thread
 
   def trap(signal, handler, &block)
@@ -25,6 +25,10 @@ class RailsFCGIHandler
   def send_signal(which)
     @signal_handlers[which].call(which)
   end
+
+  def restore!
+    @restarted = true
+  end
 end
 
 class RailsFCGIHandlerTest < Test::Unit::TestCase
@@ -40,32 +44,53 @@ class RailsFCGIHandlerTest < Test::Unit::TestCase
   def test_uninterrupted_processing
     @handler.process!
     assert_nil @handler.exit_code
-    assert !@handler.please_exit_at_your_earliest_convenience
-    assert !@handler.i_am_currently_processing_a_request
+    assert_nil @handler.when_ready
+    assert !@handler.processing
   end
 
-  %w(HUP USR1).each do |signal|
-    define_method("test_interrupted_via_#{signal}_when_not_in_request") do
-      FCGI.time_to_sleep = 1
-      @handler.thread = Thread.new { @handler.process! }
-      sleep 0.1 # let the thread get started
-      @handler.send_signal(signal)
-      @handler.thread.join
-      assert_equal 0, @handler.exit_code
-      assert !@handler.please_exit_at_your_earliest_convenience
-      assert !@handler.i_am_currently_processing_a_request
-    end
+  def test_interrupted_via_HUP_when_not_in_request
+    FCGI.time_to_sleep = 1
+    @handler.thread = Thread.new { @handler.process! }
+    sleep 0.1 # let the thread get started
+    @handler.send_signal("HUP")
+    @handler.thread.join
+    assert_nil @handler.exit_code
+    assert_nil @handler.when_ready
+    assert !@handler.processing
+    assert @handler.restarted
+  end
 
-    define_method("test_interrupted_via_#{signal}_when_in_request") do
-      Dispatcher.time_to_sleep = 1
-      @handler.thread = Thread.new { @handler.process! }
-      sleep 0.1 # let the thread get started
-      @handler.send_signal(signal)
-      @handler.thread.join
-      assert_nil @handler.exit_code
-      assert @handler.please_exit_at_your_earliest_convenience
-      assert !@handler.i_am_currently_processing_a_request
-    end
+  def test_interrupted_via_HUP_when_in_request
+    Dispatcher.time_to_sleep = 1
+    @handler.thread = Thread.new { @handler.process! }
+    sleep 0.1 # let the thread get started
+    @handler.send_signal("HUP")
+    @handler.thread.join
+    assert_nil @handler.exit_code
+    assert_equal :restart, @handler.when_ready
+    assert !@handler.processing
+  end
+
+  def test_interrupted_via_USR1_when_not_in_request
+    FCGI.time_to_sleep = 1
+    @handler.thread = Thread.new { @handler.process! }
+    sleep 0.1 # let the thread get started
+    @handler.send_signal("USR1")
+    @handler.thread.join
+    assert_equal 0, @handler.exit_code
+    assert_nil @handler.when_ready
+    assert !@handler.processing
+  end
+
+  def test_interrupted_via_USR1_when_in_request
+    Dispatcher.time_to_sleep = 1
+    @handler.thread = Thread.new { @handler.process! }
+    sleep 0.1 # let the thread get started
+    @handler.send_signal("USR1")
+    @handler.thread.join
+    assert_nil @handler.exit_code
+    assert @handler.when_ready
+    assert !@handler.processing
   end
 
   %w(RuntimeError SignalException).each do |exception|
@@ -77,7 +102,7 @@ class RailsFCGIHandlerTest < Test::Unit::TestCase
         when "RuntimeError"
           assert_match %r{almost killed}, @log.string
         when "SignalException"
-          assert_match %r{\d killed}, @log.string
+          assert_match %r{^killed}, @log.string
       end
     end
 
@@ -89,7 +114,7 @@ class RailsFCGIHandlerTest < Test::Unit::TestCase
         when "RuntimeError"
           assert_no_match %r{killed}, @log.string
         when "SignalException"
-          assert_match %r{\d killed}, @log.string
+          assert_match %r{^killed}, @log.string
       end
     end
   end