Class: God::Process

Inherits:
Object
  • Object
show all
Defined in:
lib/god/process.rb

Constant Summary collapse

WRITES_PID = 
[:start, :restart]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Process

Returns a new instance of Process.



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# File 'lib/god/process.rb', line 7

def initialize
  self.log = '/dev/null'
  
  @pid_file = nil
  @tracking_pid = true
  @user_log = false
  @pid = nil
end

Instance Attribute Details

#gid ⇒ Object

Returns the value of attribute gid.



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# File 'lib/god/process.rb', line 5

def gid
  @gid
end

#log ⇒ Object

Returns the value of attribute log.



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# File 'lib/god/process.rb', line 5

def log
  @log
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/god/process.rb', line 5

def name
  @name
end

#restart ⇒ Object

Returns the value of attribute restart.



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# File 'lib/god/process.rb', line 5

def restart
  @restart
end

#start ⇒ Object

Returns the value of attribute start.



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# File 'lib/god/process.rb', line 5

def start
  @start
end

#stop ⇒ Object

Returns the value of attribute stop.



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# File 'lib/god/process.rb', line 5

def stop
  @stop
end

#uid ⇒ Object

Returns the value of attribute uid.



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# File 'lib/god/process.rb', line 5

def uid
  @uid
end

Instance Method Details

#alive? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/god/process.rb', line 16

def alive?
  if self.pid
    System::Process.new(self.pid).exists?
  else
    false
  end
end

#call_action(action) ⇒ Object 



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# File 'lib/god/process.rb', line 158

def call_action(action)
  command = send(action)
  
  if action == :stop && command.nil?
    pid = self.pid
    name = self.name
    command = lambda do
      applog(self, :info, "#{self.name} stop: default lambda killer")
      
      ::Process.kill('TERM', pid) rescue nil
      applog(self, :info, "#{self.name} sent SIGTERM")
      
      # Poll to see if it's dead
      5.times do
        begin
          ::Process.kill(0, pid)
        rescue Errno::ESRCH
          # It died. Good.
          applog(self, :info, "#{self.name} process stopped")
          return
        end
        
        sleep 1
      end
      
      ::Process.kill('KILL', pid) rescue nil
      applog(self, :info, "#{self.name} still alive; sent SIGKILL")
    end
  end
        
  if command.kind_of?(String)
    pid = nil
    
    if @tracking_pid
      # double fork god-daemonized processes
      # we don't want to wait for them to finish
      r, w = IO.pipe
      begin
        opid = fork do
          STDOUT.reopen(w)
          r.close
          pid = self.spawn(command)
          puts pid.to_s # send pid back to forker
        end
        
        ::Process.waitpid(opid, 0)
        w.close
        pid = r.gets.chomp
      ensure
        # make sure the file descriptors get closed no matter what
        r.close rescue nil
        w.close rescue nil
      end
    else
      # single fork self-daemonizing processes
      # we want to wait for them to finish
      pid = self.spawn(command)
      status = ::Process.waitpid2(pid, 0)
      exit_code = status[1] >> 8
      
      if exit_code != 0
        applog(self, :warn, "#{self.name} #{action} command exited with non-zero code = #{exit_code}")
      end
      
      ensure_stop if action == :stop
    end
    
    if @tracking_pid or (@pid_file.nil? and WRITES_PID.include?(action))
      File.open(default_pid_file, 'w') do |f|
        f.write pid
      end
      
      @tracking_pid = true
      @pid_file = default_pid_file
    end
  elsif command.kind_of?(Proc)
    # lambda command
    command.call
  else
    raise NotImplementedError
  end
end

#default_pid_file ⇒ Object 



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# File 'lib/god/process.rb', line 154

def default_pid_file
  File.join(God.pid_file_directory, "#{self.name}.pid")
end

#ensure_stop ⇒ Object

Ensure that a stop command actually stops the process. Force kill if necessary.

Returns nothing



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# File 'lib/god/process.rb', line 267

def ensure_stop
  unless self.pid
    applog(self, :warn, "#{self.name} stop called but pid is uknown")
    return
  end
  
  # Poll to see if it's dead
  10.times do
    begin
      ::Process.kill(0, self.pid)
    rescue Errno::ESRCH
      # It died. Good.
      return
    end
    
    sleep 1
  end
  
  # last resort
  ::Process.kill('KILL', self.pid) rescue nil
  applog(self, :warn, "#{self.name} process still running 10 seconds after stop command returned. Force killing.")
end

#file_writable?(file) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/god/process.rb', line 24

def file_writable?(file)
  pid = fork do
    ::Process::Sys.setgid(Etc.getgrnam(self.gid).gid) if self.gid
    ::Process::Sys.setuid(Etc.getpwnam(self.uid).uid) if self.uid
    
    File.writable?(file) ? exit(0) : exit(1)
  end
  
  wpid, status = ::Process.waitpid2(pid)
  status.exitstatus == 0 ? true : false
end

#pid ⇒ Object

Fetch the PID from pid_file. If the pid_file does not exist, then use the PID from the last time it was read. If it has never been read, then return nil.

Returns Integer(pid) or nil



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# File 'lib/god/process.rb', line 130

def pid
  contents = File.read(self.pid_file).strip rescue ''
  real_pid = contents =~ /^\d+$/ ? contents.to_i : nil
  
  if real_pid
    @pid = real_pid
    real_pid
  else
    @pid
  end
end

#pid_file ⇒ Object 



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# File 'lib/god/process.rb', line 121

def pid_file
  @pid_file ||= default_pid_file
end

#pid_file=(value) ⇒ Object

DON’T USE THIS INTERNALLY. Use the instance variable. – Kev No really, trust me. Use the instance variable.



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# File 'lib/god/process.rb', line 110

def pid_file=(value)
  # if value is nil, do the right thing
  if value
    @tracking_pid = false
  else
    @tracking_pid = true
  end
  
  @pid_file = value
end

#restart! ⇒ Object 



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# File 'lib/god/process.rb', line 150

def restart!
  call_action(:restart)
end

#spawn(command) ⇒ Object

Fork/exec the given command, returns immediately

+command+ is the String containing the shell command

Returns nothing



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# File 'lib/god/process.rb', line 245

def spawn(command)
  fork do
    ::Process.setsid
    ::Process::Sys.setgid(Etc.getgrnam(self.gid).gid) if self.gid
    ::Process::Sys.setuid(Etc.getpwnam(self.uid).uid) if self.uid
    Dir.chdir "/"
    $0 = command
    STDIN.reopen "/dev/null"
    STDOUT.reopen self.log, "a"
    STDERR.reopen STDOUT
    
    # close any other file descriptors
    3.upto(256){|fd| IO::new(fd).close rescue nil}
    
    exec command unless command.empty?
  end
end

#start! ⇒ Object 



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# File 'lib/god/process.rb', line 142

def start!
  call_action(:start)
end

#stop! ⇒ Object 



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# File 'lib/god/process.rb', line 146

def stop!
  call_action(:stop)
end

#valid? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/god/process.rb', line 36

def valid?
  # determine if we're tracking pid or not
  self.pid_file
  
  valid = true
  
  # a start command must be specified
  if self.start.nil?
    valid = false
    applog(self, :error, "No start command was specified")
  end
  
  # self-daemonizing processes must specify a stop command
  if !@tracking_pid && self.stop.nil?
    valid = false
    applog(self, :error, "No stop command was specified")
  end
  
  # uid must exist if specified
  if self.uid
    begin
      Etc.getpwnam(self.uid)
    rescue ArgumentError
      valid = false
      applog(self, :error, "UID for '#{self.uid}' does not exist")
    end
  end
  
  # gid must exist if specified
  if self.gid
    begin
      Etc.getgrnam(self.gid)
    rescue ArgumentError
      valid = false
      applog(self, :error, "GID for '#{self.gid}' does not exist")
    end
  end
  
  # pid dir must exist if specified
  if !@tracking_pid && !File.exist?(File.dirname(self.pid_file))
    valid = false
    applog(self, :error, "PID file directory '#{File.dirname(self.pid_file)}' does not exist")
  end
  
  # pid dir must be writable if specified
  if !@tracking_pid && File.exist?(File.dirname(self.pid_file)) && !file_writable?(File.dirname(self.pid_file))
    valid = false
    applog(self, :error, "PID file directory '#{File.dirname(self.pid_file)}' is not writable by #{self.uid || Etc.getlogin}")
  end
  
  # log dir must exist
  if !File.exist?(File.dirname(self.log))
    valid = false
    applog(self, :error, "Log directory '#{File.dirname(self.log)}' does not exist")
  end
  
  # log file or dir must be writable
  if File.exist?(self.log)
    unless file_writable?(self.log)
      valid = false
      applog(self, :error, "Log file '#{self.log}' exists but is not writable by #{self.uid || Etc.getlogin}")
    end
  else
    unless file_writable?(File.dirname(self.log))
      valid = false
      applog(self, :error, "Log directory '#{File.dirname(self.log)}' is not writable by #{self.uid || Etc.getlogin}")
    end
  end
  
  valid
end