# File lib/god/task.rb, line 35 def initialize @autostart ||= true # initial state is unmonitored self.state = :unmonitored # the list of behaviors self.behaviors = [] # the list of conditions for each action self.metrics = {nil => [], :unmonitored => [], :stop => []} # the condition -> metric lookup self.directory = {} # driver self.driver = Driver.new(self) end
Perform the given action.
a - The Symbol action. c - The Condition.
Returns this Task.
# File lib/god/task.rb, line 284 def action(a, c = nil) if !self.driver.in_driver_context? # Called from outside Driver. Send an async message to Driver. self.driver.message(:action, [a, c]) else # Called from within Driver. if self.respond_to?(a) command = self.send(a) case command when String msg = "#{self.name} #{a}: #{command}" applog(self, :info, msg) system(command) when Proc msg = "#{self.name} #{a}: lambda" applog(self, :info, msg) command.call else raise NotImplementedError end end end end
Events
# File lib/god/task.rb, line 317 def attach(condition) case condition when PollCondition self.driver.schedule(condition, 0) when EventCondition, TriggerCondition condition.register end end
Returns true if autostart is enabled, false if not.
# File lib/god/task.rb, line 28 def autostart? @autostart end
Convert the given input into canonical hash form which looks like:
{ true => :state } or { true => :state, false => :otherstate }
to - The Symbol or Hash destination.
Returns the canonical Hash.
# File lib/god/task.rb, line 103 def canonical_hash_form(to) to.instance_of?(Symbol) ? {true => to} : to end
Format the destination specification for use in debug logging.
metric - The Metric. condition - The Condition.
Returns the formatted String.
# File lib/god/task.rb, line 500 def dest_desc(metric, condition) if condition.transition {true => condition.transition}.inspect else if metric.destination metric.destination.inspect else 'none' end end end
# File lib/god/task.rb, line 326 def detach(condition) case condition when PollCondition condition.reset when EventCondition, TriggerCondition condition.deregister end end
Asynchronously evaluate and handle the given event condition. Handles logging notifications, and moving to the new state if necessary.
condition - The Condition to handle.
Returns nothing.
# File lib/god/task.rb, line 421 def handle_event(condition) # Lookup metric. metric = self.directory[condition] # Log. messages = self.log_line(self, metric, condition, true) # Notify. if condition.notify self.notify(condition, messages.last) end # Get the destination. dest = if condition.transition # Condition override. condition.transition else # Regular. metric.destination && metric.destination[true] end if dest self.move(dest) end end
Evaluate and handle the given poll condition. Handles logging notifications, and moving to the new state if necessary.
condition - The Condition to handle.
Returns nothing.
# File lib/god/task.rb, line 361 def handle_poll(condition) # Lookup metric. metric = self.directory[condition] # Run the test. begin result = condition.test rescue Object => e cname = condition.class.to_s.split('::').last message = format("Unhandled exception in %s condition - (%s): %s\n%s", cname, e.class, e.message, e.backtrace.join("\n")) applog(self, :error, message) result = false end # Log. messages = self.log_line(self, metric, condition, result) # Notify. if result && condition.notify self.notify(condition, messages.last) end # After-condition. condition.after # Get the destination. dest = if result && condition.transition # Condition override. condition.transition else # Regular. metric.destination && metric.destination[result] end # Transition or reschedule. if dest # Transition. begin self.move(dest) rescue EventRegistrationFailedError msg = self.name + ' Event registration failed, moving back to previous state' applog(self, :info, msg) dest = self.state retry end else # Reschedule. self.driver.schedule(condition) end end
Public: Define a lifecycle handler. Conditions that belong to a lifecycle are active as long as the process is being monitored.
Returns nothing.
# File lib/god/task.rb, line 153 def lifecycle # Create a new metric to hold the task and conditions. m = Metric.new(self) # Let the config file define some conditions on the metric. yield(m) # Populate the condition -> metric directory. m.conditions.each do |c| self.directory[c] = m end # Record the metric. self.metrics[nil] << m end
Log info about the condition and return the list of messages logged.
watch - The Watch. metric - The Metric. condition - The Condition. result - The Boolean result of the condition test evaluation.
Returns the Array of String messages.
# File lib/god/task.rb, line 466 def log_line(watch, metric, condition, result) status = if self.trigger?(metric, result) "[trigger]" else "[ok]" end messages = [] # Log info if available. if condition.info Array(condition.info).each do |condition_info| messages << "#{watch.name} #{status} #{condition_info} (#{condition.base_name})" applog(watch, :info, messages.last) end else messages << "#{watch.name} #{status} (#{condition.base_name})" applog(watch, :info, messages.last) end # Log. debug_message = watch.name + ' ' + condition.base_name + " [#{result}] " + self.dest_desc(metric, condition) applog(watch, :debug, debug_message) messages end
Actions
# File lib/god/task.rb, line 263 def method_missing(sym, *args) unless (sym.to_s =~ /=$/) super end base = sym.to_s.chop.intern unless self.valid_states.include?(base) super end self.class.send(:attr_accessor, base) self.send(sym, *args) end
Enable monitoring.
Returns nothing.
# File lib/god/task.rb, line 178 def monitor self.move(self.initial_state) end
Move to the given state.
to_state - The Symbol representing the state to move to.
Returns this Task.
# File lib/god/task.rb, line 194 def move(to_state) if !self.driver.in_driver_context? # Called from outside Driver. Send an async message to Driver. self.driver.message(:move, [to_state]) else # Called from within Driver. Record original info. orig_to_state = to_state from_state = self.state # Log. msg = "#{self.name} move '#{from_state}' to '#{to_state}'" applog(self, :info, msg) # Cleanup from current state. self.driver.clear_events self.metrics[from_state].each { |m| m.disable } if to_state == :unmonitored self.metrics[nil].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. self.metrics[to_state].each { |m| m.enable } # If no from state, enable lifecycle metric. if from_state == :unmonitored self.metrics[nil].each { |m| m.enable } end # Set state. self.state = to_state # Broadcast to interested TriggerConditions. Trigger.broadcast(self, :state_change, [from_state, orig_to_state]) # Log. msg = "#{self.name} moved '#{from_state}' to '#{to_state}'" applog(self, :info, msg) end self end
Notify all recipients of the given condition with the specified message.
condition - The Condition. message - The String message to send.
Returns nothing.
# File lib/god/task.rb, line 518 def notify(condition, message) spec = Contact.normalize(condition.notify) unmatched = [] # Resolve contacts. resolved_contacts = spec[:contacts].inject([]) do |acc, contact_name_or_group| cons = Array(God.contacts[contact_name_or_group] || God.contact_groups[contact_name_or_group]) unmatched << contact_name_or_group if cons.empty? acc += cons acc end # Warn about unmatched contacts. unless unmatched.empty? msg = "#{condition.watch.name} no matching contacts for '#{unmatched.join(", ")}'" applog(condition.watch, :warn, msg) end # Notify each contact. resolved_contacts.each do |c| host = `hostname`.chomp rescue 'none' begin c.notify(message, Time.now, spec[:priority], spec[:category], host) msg = "#{condition.watch.name} #{c.info ? c.info : "notification sent for contact: #{c.name}"} (#{c.base_name})" applog(condition.watch, :info, msg % []) rescue Exception => e applog(condition.watch, :error, "#{e.message} #{e.backtrace}") msg = "#{condition.watch.name} Failed to deliver notification for contact: #{c.name} (#{c.base_name})" applog(condition.watch, :error, msg % []) end end end
Initialize the metrics to an empty state.
Returns nothing.
# File lib/god/task.rb, line 57 def prepare self.valid_states.each do |state| self.metrics[state] ||= [] end end
Registration
# File lib/god/task.rb, line 341 def register! # override if necessary end
Public: Define a transition handler which consists of a set of conditions
start_states - The Symbol or Array of Symbols start state(s). end_states - The Symbol or Hash end states.
Yields the Metric for this transition.
Returns nothing.
# File lib/god/task.rb, line 115 def transition(start_states, end_states) # Convert end_states into canonical hash form. canonical_end_states = canonical_hash_form(end_states) Array(start_states).each do |start_state| # Validate start state. unless self.valid_states.include?(start_state) abort "Invalid state :#{start_state}. Must be one of the symbols #{self.valid_states.map{|x| ":#{x}"}.join(', ')}" end # Create a new metric to hold the task, end states, and conditions. m = Metric.new(self, canonical_end_states) if block_given? # Let the config file define some conditions on the metric. yield(m) else # Add an :always condition if no block was given. m.condition(:always) do |c| c.what = true end end # Populate the condition -> metric directory. m.conditions.each do |c| self.directory[c] = m end # Record the metric. self.metrics[start_state] ||= [] self.metrics[start_state] << m end end
Notify the Driver that an EventCondition has triggered.
condition - The Condition.
Returns nothing.
# File lib/god/task.rb, line 249 def trigger(condition) self.driver.message(:handle_event, [condition]) end
Determine whether a trigger happened.
metric - The Metric. result - The Boolean result from the condition's test.
Returns Boolean
# File lib/god/task.rb, line 454 def trigger?(metric, result) metric.destination && metric.destination[result] end
Disable monitoring.
Returns nothing.
# File lib/god/task.rb, line 185 def unmonitor self.move(:unmonitored) end
# File lib/god/task.rb, line 345 def unregister! driver.shutdown end
Verify that the minimum set of configuration requirements has been met.
Returns true if valid, false if not.
# File lib/god/task.rb, line 66 def valid? valid = true # A name must be specified. if self.name.nil? valid = false applog(self, :error, "No name String was specified.") end # Valid states must be specified. if self.valid_states.nil? valid = false applog(self, :error, "No valid_states Array or Symbols was specified.") end # An initial state must be specified. if self.initial_state.nil? valid = false applog(self, :error, "No initial_state Symbol was specified.") end valid end
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