Added Kernel#daemonize to turn the current process into a daemon that can be killed with a TERM signal [DHH] Refactored stuff lingering in kernel.rb to the appropriate places

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3714 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/CHANGELOG

@@ -1,5 +1,7 @@
 *SVN*
 
+* Added Kernel#daemonize to turn the current process into a daemon that can be killed with a TERM signal [DHH]
+
 * Add 'around' methods to Logger,  to make it easy to log before and after messages for a given block as requested in #3809. [Michael Koziarski]  Example:
 
   logger.around_info("Start rendering component (#{options.inspect}): ", 

activesupport/lib/active_support/core_ext/kernel.rb

@@ -1,88 +1,4 @@
-class Object
-  # A Ruby-ized realization of the K combinator, courtesy of Mikael Brockman.
-  #
-  #   def foo
-  #     returning values = [] do
-  #       values << 'bar'
-  #       values << 'baz'
-  #     end
-  #   end
-  #
-  #   foo # => ['bar', 'baz']
-  #
-  def returning(value)
-    yield
-    value
-  end
-  
-  # Sets $VERBOSE to nil for the duration of the block and back to its original value afterwards.
-  #
-  #   silence_warnings do
-  #     value = noisy_call # no warning voiced
-  #   end
-  #
-  #   noisy_call # warning voiced
-  def silence_warnings
-    old_verbose, $VERBOSE = $VERBOSE, nil
-    yield
-  ensure
-    $VERBOSE = old_verbose
-  end
-
-  # Sets $VERBOSE to true for the duration of the block and back to its original value afterwards.
-  def enable_warnings
-    old_verbose, $VERBOSE = $VERBOSE, true
-    yield
-  ensure
-    $VERBOSE = old_verbose
-  end
-
-  # Silences stderr for the duration of the block.
-  #
-  #   silence_stderr do
-  #     $stderr.puts 'This will never be seen'
-  #   end
-  #
-  #   $stderr.puts 'But this will'
-  def silence_stderr
-    old_stderr = STDERR.dup
-    STDERR.reopen(RUBY_PLATFORM =~ /mswin/ ? 'NUL:' : '/dev/null')
-    STDERR.sync = true
-    yield
-  ensure
-    STDERR.reopen(old_stderr)
-  end
-
-  # Makes backticks behave (somewhat more) similarly on all platforms.
-  # On win32 `nonexistent_command` raises Errno::ENOENT; on Unix, the
-  # spawned shell prints a message to stderr and sets $?.  We emulate
-  # Unix on the former but not the latter.
-  def `(command) #:nodoc:
-    super
-  rescue Errno::ENOENT => e
-    STDERR.puts "#$0: #{e}"
-  end
-
-  # Require a library with fallback to RubyGems.  Warnings during library
-  # loading are silenced to increase signal/noise for application warnings.
-  def require_library_or_gem(library_name)
-    silence_warnings do
-      begin
-        require library_name
-      rescue LoadError => cannot_require
-        # 1. Requiring the module is unsuccessful, maybe it's a gem and nobody required rubygems yet. Try.
-        begin
-          require 'rubygems'
-        rescue LoadError => rubygems_not_installed
-          raise cannot_require
-        end
-        # 2. Rubygems is installed and loaded. Try to load the library again
-        begin
-          require library_name
-        rescue LoadError => gem_not_installed
-          raise cannot_require
-        end
-      end
-    end
-  end
-end
+require File.dirname(__FILE__) + '/kernel/daemonizing'
+require File.dirname(__FILE__) + '/kernel/reporting'
+require File.dirname(__FILE__) + '/kernel/agnostics'
+require File.dirname(__FILE__) + '/kernel/requires'

activesupport/lib/active_support/core_ext/kernel/agnostics.rb

@@ -0,0 +1,11 @@
+module Kernel
+  # Makes backticks behave (somewhat more) similarly on all platforms.
+  # On win32 `nonexistent_command` raises Errno::ENOENT; on Unix, the
+  # spawned shell prints a message to stderr and sets $?.  We emulate
+  # Unix on the former but not the latter.
+  def `(command) #:nodoc:
+    super
+  rescue Errno::ENOENT => e
+    STDERR.puts "#$0: #{e}"
+  end
+end

activesupport/lib/active_support/core_ext/kernel/daemonizing.rb

@@ -0,0 +1,15 @@
+module Kernel
+  # Turns the current script into a daemon process that detaches from the console.
+  # It can be shut down with a TERM signal.
+  def daemonize
+    exit if fork                   # Parent exits, child continues.
+    Process.setsid                 # Become session leader.
+    exit if fork                   # Zap session leader. See [1].
+    Dir.chdir "/"                  # Release old working directory.
+    File.umask 0000                # Ensure sensible umask. Adjust as needed.
+    STDIN.reopen "/dev/null"       # Free file descriptors and
+    STDOUT.reopen "/dev/null", "a" # point them somewhere sensible.
+    STDERR.reopen STDOUT           # STDOUT/ERR should better go to a logfile.
+    trap("TERM") { exit }
+  end
+end

activesupport/lib/active_support/core_ext/kernel/reporting.rb

@@ -0,0 +1,46 @@
+module Kernel
+  # Sets $VERBOSE to nil for the duration of the block and back to its original value afterwards.
+  #
+  #   silence_warnings do
+  #     value = noisy_call # no warning voiced
+  #   end
+  #
+  #   noisy_call # warning voiced
+  def silence_warnings
+    old_verbose, $VERBOSE = $VERBOSE, nil
+    yield
+  ensure
+    $VERBOSE = old_verbose
+  end
+
+  # Sets $VERBOSE to true for the duration of the block and back to its original value afterwards.
+  def enable_warnings
+    old_verbose, $VERBOSE = $VERBOSE, true
+    yield
+  ensure
+    $VERBOSE = old_verbose
+  end
+
+  # Silences stderr for the duration of the block.
+  #
+  #   silence_stderr do
+  #     $stderr.puts 'This will never be seen'
+  #   end
+  #
+  #   $stderr.puts 'But this will'
+  def silence_stderr
+    old_stderr = STDERR.dup
+    STDERR.reopen(RUBY_PLATFORM =~ /mswin/ ? 'NUL:' : '/dev/null')
+    STDERR.sync = true
+    yield
+  ensure
+    STDERR.reopen(old_stderr)
+  end
+
+  def suppress(*exception_classes)
+    begin yield
+    rescue Exception => e
+      raise unless exception_classes.any? { |cls| e.kind_of?(cls) }
+    end
+  end
+end

activesupport/lib/active_support/core_ext/kernel/requires.rb

@@ -0,0 +1,24 @@
+module Kernel
+  # Require a library with fallback to RubyGems.  Warnings during library
+  # loading are silenced to increase signal/noise for application warnings.
+  def require_library_or_gem(library_name)
+    silence_warnings do
+      begin
+        require library_name
+      rescue LoadError => cannot_require
+        # 1. Requiring the module is unsuccessful, maybe it's a gem and nobody required rubygems yet. Try.
+        begin
+          require 'rubygems'
+        rescue LoadError => rubygems_not_installed
+          raise cannot_require
+        end
+        # 2. Rubygems is installed and loaded. Try to load the library again
+        begin
+          require library_name
+        rescue LoadError => gem_not_installed
+          raise cannot_require
+        end
+      end
+    end
+  end
+end

activesupport/lib/active_support/core_ext/object/misc.rb

@@ -1,4 +1,20 @@
 class Object #:nodoc:
+  # A Ruby-ized realization of the K combinator, courtesy of Mikael Brockman.
+  #
+  #   def foo
+  #     returning values = [] do
+  #       values << 'bar'
+  #       values << 'baz'
+  #     end
+  #   end
+  #
+  #   foo # => ['bar', 'baz']
+  #
+  def returning(value)
+    yield
+    value
+  end
+
   def with_options(options)
     yield ActiveSupport::OptionMerger.new(self, options)
   end
@@ -6,11 +22,4 @@ class Object #:nodoc:
   def to_json
     ActiveSupport::JSON.encode(self)
   end
-
-  def suppress(*exception_classes)
-    begin yield
-    rescue Exception => e
-      raise unless exception_classes.any? { |cls| e.kind_of?(cls) }
-    end
-  end
 end