Add 'last run' timestamps for recurring events, and take these into

account when firing events on daemon rescheduling (via HUP.)

FossilOrigin-Name: 1620e80e8bddd27741569dea0ff4bd84ba29429861ed49d17f5777c238ae4876

README.rdoc

@@ -50,7 +50,7 @@ Symphony connection information:
 
 == Adding Actions
 
-There are two primary components to Metronome -- getting actions into
+There are two primary components to Metronome -- getting schedules into
 its database, and performing some task with those actions when the time
 is appropriate.
 
@@ -76,6 +76,15 @@ starts up or receives a HUP signal, it will re-read and schedule out
 upcoming work.
 
 
+== Performing Work
+
+Calling 'run' on the Metronome class is a blocking call, waking up upon
+a scheduled event.  The run method expects a ruby block, and it receives
+the payload and the database ID of the scheduled event.  Metronome is
+unopinioned, what you do within this block is entirely up to you.  See
+the Synopsis section above for some examples.
+
+
 == Options
 
 Metronome uses

Rakefile

@@ -140,4 +140,5 @@ lib/symphony/metronome/mixins.rb
 lib/symphony/metronome/intervalexpression.rb
 lib/symphony/metronome/scheduledevent.rb
 data/symphony-metronome/migrations/20140419_initial.rb
+data/symphony-metronome/migrations/20141028_lastrun.rb
 README.rdoc

data/symphony-metronome/migrations/20141028_lastrun.rb

@@ -0,0 +1,23 @@
+# vim: set nosta noet ts=4 sw=4:
+
+### Add a 'lastrun' time stamp for recurring events.
+###
+class Lastrun < Sequel::Migration
+
+	def initialize( db )
+		@db = db
+	end
+
+	def up
+		if @db.adapter_scheme == :postgres
+			add_column :metronome, :lastrun, timestamptz
+		else
+			add_column :metronome, :lastrun, DateTime
+		end
+	end
+
+	def down
+		drop_column :metronome, :lastrun
+	end
+end
+

lib/symphony/metronome.rb

@@ -9,7 +9,7 @@ module Symphony::Metronome
 	       Configurability
 
 	# Library version constant
-	VERSION = '0.1.0'
+	VERSION = '0.2.0'
 
 	# Version-control revision constant
 	REVISION = %q$Revision$
@@ -74,6 +74,5 @@ module Symphony::Metronome
 		return Symphony::Metronome::Scheduler.run( &block )
 	end
 
-
 end # Symphony::Metronome
 

lib/symphony/metronome/scheduledevent.rb

@@ -24,8 +24,8 @@ class Symphony::Metronome::ScheduledEvent
 	# Configure defaults.
 	#
 	CONFIG_DEFAULTS = {
-		db: 'sqlite:///tmp/metronome.db',
+		:db    => 'sqlite:///tmp/metronome.db',
-		splay: 0
+		:splay => 0
 	}
 
 	class << self
@@ -52,6 +52,7 @@ class Symphony::Metronome::ScheduledEvent
 		#
 		migrations_dir = Symphony::Metronome::DATADIR + 'migrations'
 		unless Sequel::Migrator.is_current?( self.db, migrations_dir.to_s )
+			Loggability[ Symphony ].info "Installing database schema..."
 			Sequel::Migrator.apply( self.db, migrations_dir.to_s )
 		end
 	end
@@ -97,6 +98,8 @@ class Symphony::Metronome::ScheduledEvent
 		@event    = Symphony::Metronome::IntervalExpression.parse( row[:expression], row[:created] )
 		@options  = row.delete( :options )
 		@id       = row.delete( :id )
+		@ds       = self.class.db[ :metronome ].filter( :id => self.id )
+
 		self.reset_runtime
 
 		unless self.class.splay.zero?
@@ -105,6 +108,9 @@ class Symphony::Metronome::ScheduledEvent
 		end
 	end
 
+	# The sequel dataset representing this event.
+	attr_reader :ds
+
 	# The parsed interval expression.
 	attr_reader :event
 
@@ -133,7 +139,21 @@ class Symphony::Metronome::ScheduledEvent
 		# Otherwise, the event should already be running (start time has already
 		# elapsed), so schedule it forward on it's next interval iteration.
 		#
-		@runtime = now + self.event.interval
+		# If it's a recurring event that has run before, consider the elapsed time
+		# as part of the next calculation.
+		#
+		row = self.ds.first
+		if self.event.recurring && row
+			last = row[ :lastrun ]
+			if last && now > last
+				@runtime = now + self.event.interval - ( now - last )
+			else
+				@runtime = now + self.event.interval
+			end
+
+		else
+			@runtime = now + self.event.interval
+		end
 	end
 
 
@@ -141,13 +161,32 @@ class Symphony::Metronome::ScheduledEvent
 	### deserialized options, the action ID to the supplied block if
 	### this event is okay to execute.
 	###
+	### If the event is recurring, perform additional checks against the
+	### last run time.
+	###
 	### Automatically remove the event if it has expired.
 	###
 	def fire
 		rv = self.event.fire?
 
+		# Just based on the expression parser, is this event ready to fire?
+		#
 		if rv
 			opts = Yajl.load( self.options )
+
+			# Don't fire recurring events unless their interval has elapsed.
+			# This prevents events from triggering when the daemon receives
+			# a HUP.
+			#
+			if self.event.recurring
+				now  = Time.now
+				last = self.ds.first[ :lastrun ]
+				return false if last && now - last < self.event.interval
+
+				# Mark the time this recurring event was fired.
+				self.ds.update( :lastrun => Time.now )
+			end
+
 			yield opts, self.id
 		end
 
@@ -160,7 +199,7 @@ class Symphony::Metronome::ScheduledEvent
 	###
 	def delete
 		self.log.debug "Removing action %p" % [ self.id ]
-		self.class.db[ :metronome ].filter( :id => self.id ).delete
+		self.ds.delete
 	end
 
 

lib/symphony/metronome/scheduler.rb

@@ -18,7 +18,7 @@ class Symphony::Metronome::Scheduler
 	SIGNALS = [ :HUP, :INT, :TERM ]
 
 	CONFIG_DEFAULTS = {
-		:listen => true
+		:listen => false
 	}
 
 	class << self