Class: Foreman::Engine

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

Direct Known Subclasses

CLI

Defined Under Namespace

Classes: CLI

Constant Summary collapse

HANDLED_SIGNALS =

The signals that the engine cares about.

[ :TERM, :INT, :HUP, :USR1, :USR2 ]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Engine

Create an Engine for running processes

Parameters:

  • options (Hash) (defaults to: {})

Options Hash (options):

  • :formation (String) — default: all=1 —

    The process formation to use

  • :port (Fixnum) — default: 5000 —

    The base port to assign to processes

  • :root (String) — default: Dir.pwd —

    The root directory from which to run processes



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# File 'lib/foreman/engine.rb', line 27

def initialize(options={})
  @options = options.dup

  @options[:formation] ||= "all=1"
  @options[:timeout] ||= 5

  @env       = {}
  @mutex     = Mutex.new
  @names     = {}
  @processes = []
  @running   = {}
  @readers   = {}
  @shutdown  = false

  # Self-pipe for deferred signal-handling (ala djb: http://cr.yp.to/docs/selfpipe.html)
  reader, writer       = create_pipe
  reader.close_on_exec = true if reader.respond_to?(:close_on_exec)
  writer.close_on_exec = true if writer.respond_to?(:close_on_exec)
  @selfpipe            = { :reader => reader, :writer => writer }

  # Set up a global signal queue
  # http://blog.rubybestpractices.com/posts/ewong/016-Implementing-Signal-Handlers.html
  Thread.main[:signal_queue] = []
end

Instance Attribute Details

#env ⇒ Object (readonly)

Returns the value of attribute env.



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# File 'lib/foreman/engine.rb', line 15

def env
  @env
end

#options ⇒ Object (readonly)

Returns the value of attribute options.



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# File 'lib/foreman/engine.rb', line 16

def options
  @options
end

#processes ⇒ Object (readonly)

Returns the value of attribute processes.



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# File 'lib/foreman/engine.rb', line 17

def processes
  @processes
end

Instance Method Details

#base_port ⇒ Object

Get the base port for this foreman instance



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# File 'lib/foreman/engine.rb', line 283

def base_port
  (options[:port] || env["PORT"] || ENV["PORT"] || 5000).to_i
end

#clear ⇒ Object

Clear the processes registered to this Engine



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# File 'lib/foreman/engine.rb', line 158

def clear
  @names     = {}
  @processes = []
end

#each_process ⇒ Object

Yield each Process in order



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# File 'lib/foreman/engine.rb', line 250

def each_process
  process_names.each do |name|
    yield name, process(name)
  end
end

#environment ⇒ Object

deprecated



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# File 'lib/foreman/engine.rb', line 288

def environment
  env
end

#formation ⇒ Object

Get the process formation



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# File 'lib/foreman/engine.rb', line 226

def formation
  @formation ||= parse_formation(options[:formation])
end

#handle_hangup ⇒ Object

Handle a HUP signal



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# File 'lib/foreman/engine.rb', line 130

def handle_hangup
  system "SIGHUP received, starting shutdown"
  @shutdown = true
end

#handle_interrupt ⇒ Object

Handle an INT signal



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# File 'lib/foreman/engine.rb', line 123

def handle_interrupt
  system "SIGINT received, starting shutdown"
  @shutdown = true
end

#handle_signal(sig) ⇒ Object

Invoke the real handler for signal sig. This shouldn’t be called directly by signal handlers, as it might invoke code which isn’t re-entrant.

Parameters:

  • sig (Symbol) —

    the name of the signal to be handled



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# File 'lib/foreman/engine.rb', line 99

def handle_signal(sig)
  case sig
  when :TERM
    handle_term_signal
  when :INT
    handle_interrupt
  when :HUP
    handle_hangup
  when *HANDLED_SIGNALS
    handle_signal_forward(sig)
  else
    system "unhandled signal #{sig}"
  end
end

#handle_signal_forward(signal) ⇒ Object 



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# File 'lib/foreman/engine.rb', line 135

def handle_signal_forward(signal)
  system "#{signal} received, forwarding it to children"
  kill_children signal
end

#handle_term_signal ⇒ Object

Handle a TERM signal



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# File 'lib/foreman/engine.rb', line 116

def handle_term_signal
  system "SIGTERM received, starting shutdown"
  @shutdown = true
end

#kill_children(signal = "SIGTERM") ⇒ Object

Send a signal to all processes started by this Engine

Parameters:

  • signal (String) (defaults to: "SIGTERM") —

    The signal to send to each process



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# File 'lib/foreman/engine.rb', line 189

def kill_children(signal="SIGTERM")
  if Foreman.windows?
    @running.each do |pid, (process, index)|
      system "sending #{signal} to #{name_for(pid)} at pid #{pid}"
      begin
        Process.kill(signal, pid)
      rescue Errno::ESRCH, Errno::EPERM
      end
    end
  else
    begin
      pids = @running.keys.compact
      Process.kill signal, *pids unless pids.empty?
    rescue Errno::ESRCH, Errno::EPERM
    end
  end
end

#killall(signal = "SIGTERM") ⇒ Object

Send a signal to the whole process group.

Parameters:

  • signal (String) (defaults to: "SIGTERM") —

    The signal to send



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# File 'lib/foreman/engine.rb', line 211

def killall(signal="SIGTERM")
  if Foreman.windows?
    kill_children(signal)
  else
    begin
      Process.kill "-#{signal}", Process.pid
    rescue Errno::ESRCH, Errno::EPERM
    end
  end
end

#load_env(filename) ⇒ Object

Load a .env file into the env for this Engine

Parameters:

  • filename (String) —

    A .env file to load into the environment



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# File 'lib/foreman/engine.rb', line 179

def load_env(filename)
  Foreman::Env.new(filename).entries do |name, value|
    @env[name] = value
  end
end

#load_procfile(filename) ⇒ Object

Register processes by reading a Procfile

Parameters:

  • filename (String) —

    A Procfile from which to read processes to register



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# File 'lib/foreman/engine.rb', line 167

def load_procfile(filename)
  options[:root] ||= File.dirname(filename)
  Foreman::Procfile.new(filename).entries do |name, command|
    register name, command, :cwd => options[:root]
  end
  self
end

#notice_signal ⇒ Object

Wake the main thread up via the selfpipe when there’s a signal



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# File 'lib/foreman/engine.rb', line 85

def notice_signal
  @selfpipe[:writer].write_nonblock( '.' )
rescue Errno::EAGAIN
  # Ignore writes that would block
rescue Errno::EINTR
  # Retry if another signal arrived while writing
  retry
end

#port_for(process, instance, base = nil) ⇒ Object

Get the port for a given process and offset

Parameters:

  • process (Foreman::Process) —

    A Process associated with this engine

  • instance (Fixnum) —

    The instance of the process



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# File 'lib/foreman/engine.rb', line 271

def port_for(process, instance, base=nil)
  if base
    base + (@processes.index(process.process) * 100) + (instance - 1)
  else
    base_port + (@processes.index(process) * 100) + (instance - 1)
  end
end

#process(name) ⇒ Object

Get the Process for a specifid name

Parameters:

  • name (String) —

    The process name



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# File 'lib/foreman/engine.rb', line 244

def process(name)
  @names.invert[name]
end

#process_names ⇒ Object

List the available process names



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# File 'lib/foreman/engine.rb', line 234

def process_names
  @processes.map { |p| @names[p] }
end

#register(name, command, options = {}) ⇒ Object

Register a process to be run by this Engine

Parameters:

  • name (String) —

    A name for this process

  • command (String) —

    The command to run

  • options (Hash) (defaults to: {})

Options Hash (options):

  • :env (Hash) —

    A custom environment for this process



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# File 'lib/foreman/engine.rb', line 148

def register(name, command, options={})
  options[:env] ||= env
  options[:cwd] ||= File.dirname(command.split(" ").first)
  process = Foreman::Process.new(command, options)
  @names[process] = name
  @processes << process
end

#register_signal_handlers ⇒ Object

Set up deferred signal handlers



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# File 'lib/foreman/engine.rb', line 67

def register_signal_handlers
  HANDLED_SIGNALS.each do |sig|
    if ::Signal.list.include? sig.to_s
      trap(sig) { Thread.main[:signal_queue] << sig ; notice_signal }
    end
  end
end

#restore_default_signal_handlers ⇒ Object

Unregister deferred signal handlers



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# File 'lib/foreman/engine.rb', line 77

def restore_default_signal_handlers
  HANDLED_SIGNALS.each do |sig|
    trap(sig, :DEFAULT) if ::Signal.list.include? sig.to_s
  end
end

#root ⇒ Object

Get the root directory for this Engine



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# File 'lib/foreman/engine.rb', line 260

def root
  File.expand_path(options[:root] || Dir.pwd)
end

#start ⇒ Object

Start the processes registered to this Engine



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# File 'lib/foreman/engine.rb', line 54

def start
  register_signal_handlers
  startup
  spawn_processes
  watch_for_output
  sleep 0.1
  wait_for_shutdown_or_child_termination
  shutdown
  exit(@exitstatus) if @exitstatus
end