Class: Runnable

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

Overview

Convert a executable command in a Ruby-like class you are able to start, define params and send signals (like kill, or stop)

Examples:

Usage:

class LS < Runnable
  command_style :extended
end

ls = LS.new
ls.alh
ls.run

Constant Summary collapse

HERTZ =

Constant to calculate cpu usage.

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@@processes =

List of runnable instances running on the system order by pid.

Hash.new

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(option_hash = {}) ⇒ Runnable

Create a new instance of a runnable command.

Parameters:

  • option_hash (Hash) (defaults to: {}) —

    Options.

Options Hash (option_hash):

  • :delete_log (Object) — default: true —

    Delete the log after execution.

  • :command_options (Object) — default: "" —

    Command options.

  • :log_path (Object) — default: "/var/log/runnable" —

    Path for the log files.



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# File 'lib/runnable.rb', line 71

def initialize( option_hash = {} )
  # keys :delete_log
  #      :command_options
  #      :log_path
  
  # If we have the command class in a namespace, we need to remove
  # the namespace name
  @command = self.class.to_s.split( "::" ).last.downcase
  
  # Set the default command option
  # Empty by default
  option_hash[:command_options] ||= ""
  @options = option_hash[:command_options]
  
  # Set the log path
  # Default path is "/var/log/runnable"
  option_hash[:log_path] ||= "/var/log/runnable/"
  @log_path = option_hash[:log_path]

  # Set the delete_log option
  # true by default
  if option_hash[:delete_log] == nil
    @delete_log = true
  else 
    @delete_log = option_hash[:delete_log]
  end

  # Store input options
  @input = Array.new

  # Store output options
  @output = Array.new

  # @todo: checks that command is in the PATH
  # ...
  
  # we dont set the pid, because we dont know until run
  @pid = nil
  @excep_array = []
  

  # Metaprogramming part  
  # Create a new instance of the parser class
  @command_line_interface = Object.const_get( command_style.to_s.capitalize.to_sym ).new
  # End Metaprogramming part
 
  #End of initialize instance variables
 
  create_log_directory
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(method, *params, &block) ⇒ nil

Convert undefined methods (ruby-like syntax) into parameters to be parsed at the execution time. This only convert methods with zero or one parameters. A hash can be passed and each key will define a new method and method name will be ignored.

Examples:

Valid calls:

find.depth                                         #=> find -depth
find.iname( '"*.rb"')                              #=> find -iname "*.rb"
find.foo( { :iname => '"*.rb"', :type => '"f"' } ) #=> find -iname "*.rb" - type "f"

Invalid calls:

sleep.5 #=> Incorrect. "5" is not a valid call to a ruby method so method_missing will not be invoked and will
raise a tINTEGER exception

Parameters:

  • method (Symbol) —

    Method called that is missing

  • params (Array) —

    Params in the call

  • block (Block) —

    Block code in method

Returns:

  • (nil) 


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# File 'lib/runnable.rb', line 309

def method_missing( method, *params, &block )
  if params.length > 1
    super( method, params, block )
  else
    if params[0].class == Hash
      # If only one param is passed and its a Hash
      # we need to expand the hash and call each key as a method with value as params
      # @see parse_hash for more information
		parse_hash( params[0] )
    else
      @command_line_interface.add_param( method.to_s,
                                        params != nil ? params.join(",") : nil )
    end
  end
end

Instance Attribute Details

#group ⇒ Object (readonly)

Process group.



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# File 'lib/runnable.rb', line 40

def group
  @group
end

#owner ⇒ Object (readonly)

Process owner.



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# File 'lib/runnable.rb', line 38

def owner
  @owner
end

#pid ⇒ Object (readonly)

Process id.



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# File 'lib/runnable.rb', line 36

def pid
  @pid
end

#pwd ⇒ Object (readonly)

Directory where process was called from.



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# File 'lib/runnable.rb', line 42

def pwd
  @pwd
end

Class Method Details

.command_style(style) ⇒ nil

Define the parameter style to be used.

Returns:

  • (nil) 


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# File 'lib/runnable.rb', line 48

def self.command_style( style )
  define_method( :command_style ) do
    style
  end
end

.processes ⇒ Hash

List of runnable instances running on the system.

Returns:

  • (Hash) —

    Using process pids as keys and instances as values.



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# File 'lib/runnable.rb', line 327

def self.processes
  @@processes
end

Instance Method Details

#command_style ⇒ Symbol

Parameter style used for the command.

Returns:

  • (Symbol) —

    Command style.



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# File 'lib/runnable.rb', line 56

def command_style
  :gnu
end

#cpu ⇒ Number

Estimated CPU usage in %.

Returns:

  • (Number) —

    The estimated cpu usage.



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# File 'lib/runnable.rb', line 245

def cpu
  # Open the proc stat file
  begin
    stat = File.open( "/proc/#{@pid}/stat" ).read.split
    
    # Get time variables
    # utime = User Time
    # stime = System Time
    # start_time = Time passed from process starting
    utime = stat[13].to_f
    stime = stat[14].to_f
    start_time = stat[21].to_f
    
    # uptime = Time passed from system starting
    uptime = File.open( "/proc/uptime" ).read.split[0].to_f
    
    # Total time that the process has been executed
    total_time = utime + stime # in jiffies

    # Seconds passed between start the process and now
    seconds = uptime - ( start_time / HERTZ ) 
    # Percentage of used CPU ( ESTIMATED )
    (total_time / seconds.to_f)
  rescue IOError
    # Fails to open file
    0
  rescue ZeroDivisionError
    # Seconds is Zero!
    0
  end

end

#exceptions ⇒ Hash

This method is abstract.
Note:

This method should be overwritten in child classes.

Returns a hash of regular expressions and exceptions associated to them. Command output is match against those regular expressions, if it does match an appropiate exception is included in the return value of execution.

Examples:

Usage:

class ls < Runnable
  def exceptions
    { /ls: (invalid option.*)/ => ArgumentError }
  end
end

Returns:

  • (Hash) —

    Using regular expressions as keys and exceptions that should be raised as values.



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# File 'lib/runnable.rb', line 345

def exceptions
  {}
end

#failed(exceptions) ⇒ nil

This method is abstract.

Method called when command executions fail. This method is a hook so it should be overwritten in child classes.

Parameters:

  • exceptions (Array) —

    Array containing exceptions raised during the command execution.

Returns:

  • (nil) 


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# File 'lib/runnable.rb', line 361

def failed( exceptions )
end

#finish ⇒ nil

This method is abstract.

Method called when command ends with no erros. This method is a hook so it should be overwritten in child classes.

Returns:

  • (nil) 


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# File 'lib/runnable.rb', line 353

def finish
end

#input(param) ⇒ nil

Set the input files.

Parameters:

  • param (String) —

    Input to be parsed as command options.

Returns:

  • (nil) 


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# File 'lib/runnable.rb', line 281

def input( param )
  @input << param
end

#join ⇒ nil

Wait for command thread to finish it execution.

Returns:

  • (nil) 


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# File 'lib/runnable.rb', line 229

def join
  @run_thread.join if @run_thread.alive?
end

#kill ⇒ nil

TODO:

Raise an exeption if process is not running.

Kill the comand.

Returns:

  • (nil) 


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# File 'lib/runnable.rb', line 219

def kill
  send_signal( :kill )

  # In order to maintain consistency of @@processes
  # we must assure that @run_thread finish correctly
  join
end

#mem ⇒ Number

Calculate the estimated memory usage in Kb.

Returns:

  • (Number) —

    Estimated mem usage in Kb.



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# File 'lib/runnable.rb', line 239

def mem
  File.open( "/proc/#{@pid}/status" ).read.split( "\n" )[11].split( " " )[1].to_i
end

#output(param) ⇒ nil

Set the output files.

Parameters:

  • param (String) —

    Output to be parsed as command options.

Returns:

  • (nil) 


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# File 'lib/runnable.rb', line 288

def output( param )
  @output << param
end

#run ⇒ nil

Start the execution of the command.

Returns:

  • (nil) 


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# File 'lib/runnable.rb', line 124

def run
  # Create a new mutex
  @pid_mutex = Mutex.new

  # Create pipes to redirect Standar I/O
  out_rd, out_wr = IO.pipe
  # Redirect Error I/O
  err_rd, err_wr = IO.pipe
  
  # Set up the command line
  command = []          
  command << @command
  command << @input.join( " " )
  command << @options
  command << @command_line_interface.parse
  command << @output.join( " " )
  command = command.join( " " )

  @pid = Process.spawn( command, { :out => out_wr, :err => err_wr } )
  
  # Include instance in class variable
  @@processes[@pid] = self

  # Prepare the process info file to be read
  file_status = File.open( "/proc/#{@pid}/status" ).read.split( "\n" )
  # Owner: Read the owner of the process from /proc/@pid/status
  @owner = file_status[6].split( " " )[1]
  # Group: Read the Group owner from /proc/@pid/status
  @group = file_status[7].split( " " )[1]
 
  # Set @output_thread with new threads
  # wich execute the input/ouput loop
  create_logs(:out => [out_wr, out_rd], :err => [err_wr, err_rd])
  
  # Create a new thread to avoid blocked processes
  @run_thread = Thread.new do
    # Wait to get the pid process even if it has finished
    Process.wait( @pid, Process::WUNTRACED )

    # Wait each I/O thread
    @output_threads.each { |thread| thread.join }
    # Delete log if its necesary
    delete_log

    # Get the exit code from command
    exit_status = $?.exitstatus
    
    # In case of error add an Exception to the @excep_array
    @excep_array << SystemCallError.new( exit_status ) if exit_status != 0
    
    # Call methods according to the exit code
    if @excep_array.empty?
      finish
    else
      failed( @excep_array )
    end
    
    # This instance is finished and we remove it
    @@processes.delete( @pid )
  end
  
  # Satuts Variables
  # PWD: Current Working Directory get by /proc/@pid/cwd
  # @rescue If a fast process is runned there isn't time to get
  # the correct PWD. If the readlink fails, we retry, if the process still alive
  # until the process finish.
  begin
    @pwd = File.readlink( "/proc/#{@pid}/cwd" )
  rescue
    # If cwd is not available rerun @run_thread
    if @run_thread.alive?
      #If it is alive, we retry to get cwd
      @run_thread.run
      retry
    else
      #If process has terminated, we set pwd to current working directory of ruby
      @pwd = Dir.getwd
    end
  end
end

#running? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/runnable.rb', line 233

def running?
  Dir.exists?( "/proc/#{@pid}") 
end

#send_signal(signal) ⇒ Object

TODO:

raise ESRCH if pid is not in system or EPERM if pid is not from user.

Send the desired signal to the command.

Parameters:

  • Signal (Symbol) —

    to be send to the command.



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# File 'lib/runnable.rb', line 368

def send_signal( signal )      
  if signal == :stop
    signal = :SIGINT
  elsif signal == :kill
    signal = :SIGKILL
  end
  
  `ps -ef`.each_line do |line|
    line = line.split
    pid = line[1]
    ppid = line[2]
   
    if ppid.to_i == @pid
      Process.kill( signal, pid.to_i )
    end
  end
  
  begin
    Process.kill( signal, @pid )
  rescue Errno::ESRCH
    # As we kill child processes, main process may have exit already
  end
end

#stop ⇒ nil

TODO:

Raise an exception if process is not running.

Stop the command.

Returns:

  • (nil) 


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# File 'lib/runnable.rb', line 208

def stop
  send_signal( :stop )

  # In order to maintain consistency of @@processes
  # we must assure that @run_thread finish correctly
  @run_thread.run if @run_thread.alive?
end