Class: God::Watch

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/god/watch.rb

Constant Summary collapse

VALID_STATES = 
[:init, :up, :start, :restart]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Watch 



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# File 'lib/god/watch.rb', line 29

def initialize
  @autostart ||= true
  @process = God::Process.new
        
  # no grace period by default
  self.grace = self.start_grace = self.stop_grace = self.restart_grace = 0
  
  # the list of behaviors
  self.behaviors = []
  
  # the list of conditions for each action
  self.metrics = {:init => [],
                  :start => [],
                  :restart => [],
                  :up => []}
                     
  # mutex
  self.mutex = Mutex.new
end

Instance Attribute Details

#autostart=(value) ⇒ Object (writeonly)

Sets the attribute autostart



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# File 'lib/god/watch.rb', line 14

def autostart=(value)
  @autostart = value
end

#behaviors ⇒ Object

api



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# File 'lib/god/watch.rb', line 23

def behaviors
  @behaviors
end

#grace ⇒ Object

config



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# File 'lib/god/watch.rb', line 10

def grace
  @grace
end

#group ⇒ Object

config



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# File 'lib/god/watch.rb', line 10

def group
  @group
end

#interval ⇒ Object

config



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# File 'lib/god/watch.rb', line 10

def interval
  @interval
end

#metrics ⇒ Object

api



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# File 'lib/god/watch.rb', line 23

def metrics
  @metrics
end

#mutex ⇒ Object

internal



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# File 'lib/god/watch.rb', line 26

def mutex
  @mutex
end

#restart_grace ⇒ Object

config



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# File 'lib/god/watch.rb', line 10

def restart_grace
  @restart_grace
end

#start_grace ⇒ Object

config



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# File 'lib/god/watch.rb', line 10

def start_grace
  @start_grace
end

#state ⇒ Object

config



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# File 'lib/god/watch.rb', line 10

def state
  @state
end

#stop_grace ⇒ Object

config



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# File 'lib/god/watch.rb', line 10

def stop_grace
  @stop_grace
end

Instance Method Details

#action(a, c = nil) ⇒ Object 



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# File 'lib/god/watch.rb', line 167

def action(a, c = nil)
  case a
  when :start
    Syslog.debug(self.start.to_s)
    puts self.start.to_s
    call_action(c, :start)
    sleep(self.start_grace + self.grace)
  when :restart
    if self.restart
      Syslog.debug(self.restart.to_s)
      puts self.restart
      call_action(c, :restart)
    else
      action(:stop, c)
      action(:start, c)
    end
    sleep(self.restart_grace + self.grace)
  when :stop
    Syslog.debug(self.stop.to_s)
    puts self.stop.to_s
    call_action(c, :stop)
    sleep(self.stop_grace + self.grace)
  end      
end

#autostart? ⇒ Boolean 



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# File 'lib/god/watch.rb', line 15

def autostart?; @autostart; end

#behavior(kind) {|b| ... } ⇒ Object

Yields:

  • (b) 


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# File 'lib/god/watch.rb', line 49

def behavior(kind)
  # create the behavior
  begin
    b = Behavior.generate(kind, self)
  rescue NoSuchBehaviorError => e
    abort e.message
  end
  
  # send to block so config can set attributes
  yield(b) if block_given?
  
  # abort if the Behavior is invalid, the Behavior will have printed
  # out its own error messages by now
  abort unless b.valid?
  
  self.behaviors << b
end

#call_action(condition, action) ⇒ Object 



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# File 'lib/god/watch.rb', line 192

def call_action(condition, action)
  # before
  before_items = self.behaviors
  before_items += [condition] if condition
  before_items.each { |b| b.send("before_#{action}") }
  
  @process.call_action(action)

  # after
  after_items = self.behaviors
  after_items += [condition] if condition
  after_items.each { |b| b.send("after_#{action}") }
end

#canonical_hash_form(to) ⇒ Object 



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# File 'lib/god/watch.rb', line 206

def canonical_hash_form(to)
  to.instance_of?(Symbol) ? {true => to} : to
end

#monitor ⇒ Object

Enable monitoring



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

def monitor
  # start monitoring at the first available of the init or up states
  if !self.metrics[:init].empty?
    self.move(:init)
  else
    self.move(:up)
  end
end

#move(to_state) ⇒ Object

Move from one state to another



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# File 'lib/god/watch.rb', line 136

def move(to_state)
  msg = "#{self.name} move '#{self.state}' to '#{to_state}'"
  Syslog.debug(msg)
  puts msg
   
  # cleanup from current state
  from_state = self.state
  if from_state
    self.metrics[from_state].each { |m| m.disable }
  end
  
  # perform action
  self.action(to_state)
  
  # enable simple mode
  if [:start, :restart].include?(to_state) && self.metrics[to_state].empty?
    to_state = :up
  end
  
  # move to new state
  if to_state
    self.metrics[to_state].each { |m| m.enable }
  end
  
  # set state
  self.state = to_state
  
  # return self
  self
end

#register! ⇒ Object 



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# File 'lib/god/watch.rb', line 210

def register!
  God.registry.add(@process)
end

#restart_if ⇒ Object 



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# File 'lib/god/watch.rb', line 108

def restart_if
  self.transition(:up, :restart) do |on|
    yield(on)
  end
end

#start_if ⇒ Object

Simple mode



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# File 'lib/god/watch.rb', line 102

def start_if
  self.transition(:up, :start) do |on|
    yield(on)
  end
end

#transition(start_states, end_states) ⇒ Object

Define a transition handler which consists of a set of conditions



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# File 'lib/god/watch.rb', line 74

def transition(start_states, end_states)
  # convert to into canonical hash form
  canonical_end_states = canonical_hash_form(end_states)
  
  # for each start state do
  Array(start_states).each do |start_state|
    # validate start state
    unless VALID_STATES.include?(start_state)
      abort "Invalid state :#{start_state}. Must be one of the symbols #{VALID_STATES.map{|x| ":#{x}"}.join(', ')}"
    end
    
    # create a new metric to hold the watch, end states, and conditions
    m = Metric.new(self, canonical_end_states)
    
    # let the config file define some conditions on the metric
    yield(m)
    
    # record the metric
    self.metrics[start_state] << m
  end
end

#unmonitor ⇒ Object

Disable monitoring



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# File 'lib/god/watch.rb', line 131

def unmonitor
  self.move(nil)
end