Class: Iyyov::Daemon

Inherits:
Object
  • Object
show all
Includes:
RJack
Defined in:
lib/iyyov/daemon.rb

Overview

A daemon instance to start and monitor

Constant Summary collapse

STATES =

States tracked

[ :begin, :up, :failed, :stopped ]
LVARS =

Instance variables which may be set as Procs

[ :@instance, :@exe_path, :@args, :@base_dir, :@run_dir, :@pid_file,
:@gem_name, :@version, :@init_name ]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(context = Iyyov.context) {|_self| ... } ⇒ Daemon

New daemon given specified or default global Iyyov.context. Yields self to block for configuration.

Yields:

  • (_self)

Yield Parameters:

  • _self (Iyyov::Daemon) —

    the object that the method was called on



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# File 'lib/iyyov/daemon.rb', line 116

def initialize( context = Iyyov.context )

  @context      = context
  @name         = nil

  @instance     = nil
  @exe_path     = method :gem_exe_path
  @args         = []
  @base_dir     = method :default_base_dir
  @run_dir      = method :default_run_dir
  @make_run_dir = @context.make_run_dir
  @stop_on_exit = @context.stop_on_exit
  @stop_delay   = @context.stop_delay

  @pid_file     = method :default_pid_file
  @gem_name     = method :name
  @version      = '>= 0'
  @init_name    = method :name

  @state        = :begin
  @gem_spec     = nil
  @rotators     = {}

  yield self if block_given?

  raise "name not specified" unless name

  @log = SLF4J[ [ SLF4J[ self.class ].name,
                  name, instance ].compact.join( '.' ) ]
end

Instance Attribute Details

#args=(value) ⇒ Object (writeonly)

Any additional args to use on start

Proc,Array (default: [])



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# File 'lib/iyyov/daemon.rb', line 49

def args=(value)
  @args = value
end

#base_dir=(value) ⇒ Object (writeonly)

Base directory under which run directories are found

Proc,~to_s (default: Context.base_dir)



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# File 'lib/iyyov/daemon.rb', line 54

def base_dir=(value)
  @base_dir = value
end

#exe_path=(value) ⇒ Object (writeonly)

Full path to executable to start.

Proc,~to_s (default: compute from gem_name, init_name, and version)



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# File 'lib/iyyov/daemon.rb', line 44

def exe_path=(value)
  @exe_path = value
end

#gem_name=(value) ⇒ Object (writeonly)

The gem name used, in conjunction with version for gem-based default exe_path

Proc,~to_s (default: name)



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# File 'lib/iyyov/daemon.rb', line 87

def gem_name=(value)
  @gem_name = value
end

#init_name=(value) ⇒ Object (writeonly)

The init script name used for gem-based default exe_path.

Proc,~to_s (default: name)



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# File 'lib/iyyov/daemon.rb', line 97

def init_name=(value)
  @init_name = value
end

#instance=(value) ⇒ Object (writeonly)

Optional specific instance identifier, distinguishing this daemon from others of the same name. For example, a port number could be used.

Proc,~to_s (default: nil)



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# File 'lib/iyyov/daemon.rb', line 39

def instance=(value)
  @instance = value
end

#log ⇒ Object (readonly)

SLF4J logger



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# File 'lib/iyyov/daemon.rb', line 105

def log
  @log
end

#make_run_dir ⇒ Object

Whether to make run_dir, if not already present

Boolean (default: Context.make_run_dir )



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# File 'lib/iyyov/daemon.rb', line 64

def make_run_dir
  @make_run_dir
end

#name ⇒ Object

Name of this daemon. Must be unique in combination with any specified instance.

String (required)



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# File 'lib/iyyov/daemon.rb', line 32

def name
  @name
end

#pid_file=(value) ⇒ Object (writeonly)

PID file written by the daemon process after start, containing the running daemon Process ID

Proc,~to_s (default: run_dir, init_name + ‘.pid’)



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# File 'lib/iyyov/daemon.rb', line 81

def pid_file=(value)
  @pid_file = value
end

#run_dir=(value) ⇒ Object (writeonly)

Directory to execute under

Proc,~to_s (default: base_dir / full_name)



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# File 'lib/iyyov/daemon.rb', line 59

def run_dir=(value)
  @run_dir = value
end

#state ⇒ Object (readonly)

Last found state of this daemon.

Symbol (in STATES)



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# File 'lib/iyyov/daemon.rb', line 102

def state
  @state
end

#stop_delay ⇒ Object

Duration in seconds between SIGTERM and final SIGKILL when stopping.

Numeric (default: Context.stop_delay)



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# File 'lib/iyyov/daemon.rb', line 75

def stop_delay
  @stop_delay
end

#stop_on_exit ⇒ Object

Whether to stop this daemon when Iyyov exits

Boolean (default: Context.stop_on_exit)



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# File 'lib/iyyov/daemon.rb', line 69

def stop_on_exit
  @stop_on_exit
end

#version=(value) ⇒ Object (writeonly)

The gem version requirements, i.e ‘~> 1.1.3’

Proc,~to_s,Array (default: ‘>= 0’)



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# File 'lib/iyyov/daemon.rb', line 92

def version=(value)
  @version = value
end

Instance Method Details

#alive?(p = pid) ⇒ Boolean

True if process is up

Returns:

  • (Boolean) 


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# File 'lib/iyyov/daemon.rb', line 307

def alive?( p = pid )
  ( Process.getpgid( p ) != -1 ) if p
rescue Errno::ESRCH
  false
end

#default_base_dir ⇒ Object 



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# File 'lib/iyyov/daemon.rb', line 204

def default_base_dir
  @context.base_dir
end

#default_log ⇒ Object 



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# File 'lib/iyyov/daemon.rb', line 216

def default_log
  in_dir( init_name + '.log' )
end

#default_pid_file ⇒ Object 



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# File 'lib/iyyov/daemon.rb', line 212

def default_pid_file
  in_dir( init_name + '.pid' )
end

#default_run_dir ⇒ Object 



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# File 'lib/iyyov/daemon.rb', line 208

def default_run_dir
  File.join( base_dir, full_name )
end

#do_exit ⇒ Object 



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# File 'lib/iyyov/daemon.rb', line 200

def do_exit
  stop if stop_on_exit
end

#do_first(scheduler) ⇒ Object

Post initialization validation, attempt immediate start if needed, and add appropriate tasks to scheduler.



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# File 'lib/iyyov/daemon.rb', line 163

def do_first( scheduler )
  unless File.directory?( run_dir )
    if make_run_dir
      @log.info { "Creating run_dir [#{run_dir}]." }
      FileUtils.mkdir_p( run_dir, :mode => 0755 )
    else
      raise( DaemonFailed, "run_dir [#{run_dir}] not found" )
    end
  end

  res = start_check
  unless res == :stop
    tasks.each { |t| scheduler.add( t ) }
  end
  res
rescue DaemonFailed, SystemCallError => e
  #FIXME: Ruby 1.4.0 throws SystemCallError when mkdir fails from
  #permissions
  @log.error( "Do first", e )
  @state = :failed
  :stop
end

#exec_key ⇒ Object

Return array suitable for comparing this daemon with prior running instance.



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# File 'lib/iyyov/daemon.rb', line 279

def exec_key
  epath = begin
            exe_path
          rescue Gem::LoadError, Gem::GemNotFoundException => e
            @log.warn( e.to_s )
            # Use a bogus, unique path instead
            "/tmp/gem-not-found/#{ Time.now.usec }/#{ rand( 2**31 ) }"
          end

  keys = [ run_dir, epath ].map { |p| File.expand_path( p ) }
  keys += args.map { |a| a.to_s.strip }
  keys.compact
end

#find_gem_spec ⇒ Object 



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# File 'lib/iyyov/daemon.rb', line 229

def find_gem_spec
  @gem_spec ||=
    if Gem::Specification.respond_to?( :find_by_name )
      Gem::Specification.find_by_name( gem_name, version )
    else
      Gem.source_index.find_name( gem_name, version ).last
    end
  unless @gem_spec
    raise( Gem::GemNotFoundException, "Missing gem #{gem_name} (#{version})" )
  end
  @gem_spec
end

#full_name ⇒ Object

Given name + ( ‘-’ + instance ) if provided.



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# File 'lib/iyyov/daemon.rb', line 148

def full_name
  [ name, instance ].compact.join('-')
end

#gem_exe_path ⇒ Object 



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# File 'lib/iyyov/daemon.rb', line 225

def gem_exe_path
  File.join( find_gem_spec.full_gem_path, 'init', init_name )
end

#in_dir(file_name) ⇒ Object

Return full path to file_name within run_dir



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# File 'lib/iyyov/daemon.rb', line 221

def in_dir( file_name )
  File.join( run_dir, file_name )
end

#log_rotate(&block) ⇒ Object

Create a new LogRotator and yields it to block for configuration. The default log path is name + “.log” in run_dir



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# File 'lib/iyyov/daemon.rb', line 155

def log_rotate( &block )
  lr = LogRotator.new( default_log, &block )
  @rotators[ lr.log ] = lr
  nil
end

#pid ⇒ Object

Return process ID from pid_file if exists or nil otherwise



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# File 'lib/iyyov/daemon.rb', line 352

def pid
  id = IO.read( pid_file ).strip.to_i
  ( id > 0 ) ? id : nil
rescue Errno::ENOENT # Pid file doesn't exist
  nil
end

#pre_check ⇒ Object

Return true if passes initial checks for start. This includes gem availability and/or if the exe_path is executable, i.e. everything that can be checked before starting.



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# File 'lib/iyyov/daemon.rb', line 267

def pre_check
  epath = File.expand_path( exe_path )
  is_exec = File.executable?( epath )
  @log.warn( "#{epath} is not executable" ) unless is_exec
  is_exec
rescue Gem::LoadError, Gem::GemNotFoundException, Errno::ENOENT => e
  @log.warn( e.to_s )
  false
end

#start ⇒ Object 



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# File 'lib/iyyov/daemon.rb', line 242

def start
  epath = File.expand_path( exe_path )
  eargs = args.map { |a| a.to_s.strip }.compact
  aversion = @gem_spec && @gem_spec.version
  @log.info { ( [ "starting", aversion || epath ] + eargs ).join(' ') }

  unless File.executable?( epath )
    raise( DaemonFailed, "Exe path: #{epath} not found/executable." )
  end

  Dir.chdir( run_dir ) do
    system( epath, *eargs ) or raise( DaemonFailed, "Start failed with #{$?}" )
  end

  @state = :up
  true
rescue Gem::LoadError, Gem::GemNotFoundException, DaemonFailed, Errno::ENOENT => e
  @log.error( "On exec", e )
  @state = :failed
  false
end

#start_check ⇒ Object 



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# File 'lib/iyyov/daemon.rb', line 293

def start_check
  p = pid
  if alive?( p )
    @log.debug { "checked: alive pid: #{p}" }
    @state = :up
  else
    unless start
      @log.info "start failed, done trying"
      :stop
    end
  end
end

#stop ⇒ Object

Stop via SIGTERM, waiting for shutdown for up to stop_delay, then SIGKILL as last resort. Return true if a process was stopped.



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# File 'lib/iyyov/daemon.rb', line 315

def stop
  p = pid
  if p
    @log.info "Sending TERM signal"
    Process.kill( "TERM", p )
    unless wait_pid( p )
      @log.info "Sending KILL signal"
      Process.kill( "KILL", p )
    end
    @status = :stopped
    true
  end
  false
rescue Errno::ESRCH
  # No such process: only raised by MRI ruby currently
  false
rescue Errno::EPERM => e
  # Not permitted: only raised by MRI ruby currently
  @log.error( "On stop", e )
  false
end

#tasks ⇒ Object 



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# File 'lib/iyyov/daemon.rb', line 186

def tasks
  t = [ Task.new( :name => full_name, :period => 5.0 ) { start_check } ]
  t += @rotators.values.map do |lr|
    Task.new( :name => "#{full_name}.rotate",
              :mode => :async,
              :period => lr.check_period ) do
      lr.check_rotate( pid ) do |rlog|
        @log.info { "Rotating log #{rlog}" }
      end
    end
  end
  t
end

#wait_pid(p = pid) ⇒ Object

Wait for process to go away



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# File 'lib/iyyov/daemon.rb', line 338

def wait_pid( p = pid )
  delta = 1.0 / 16
  delay = 0.0
  check = false
  while delay < stop_delay do
    break if ( check = ! alive?( p ) )
    sleep delta
    delay += delta
    delta += ( 1.0 / 16 ) if delta < 0.50
  end
  check
end