indexing
	description: "Execute an action every interval until stopped."
	author: "Patrick Ruckstuhl <patrick@tario.org>"
	date: "$Date$"
	revision: "$Revision$"
 
class
	TIMER
 
inherit
	THREAD
		export
			{NONE} all
		end
 
create
	make
 
feature {NONE} -- Initialization
 
	make (a_action: like action; a_interval: like interval) is
			-- Create a timer that executes a_action every a_interval milliseconds.
		require
			a_action_set: a_action /= Void
			a_interval_valid: a_interval > 0
		do
			action := a_action
			interval := a_interval
 
			create timer_mutex.make
			create timer_condition.make
		ensure
			action_set: action = a_action
			interval_set: interval = a_interval
		end
 
feature -- Status
 
	is_stop: BOOLEAN
			-- Is the timer stopped?
 
feature -- Access
 
	action: PROCEDURE [ANY, TUPLE[]]
			-- Action to execute every interval.
 
	interval: INTEGER
			-- Milliseconds to wait until action is called again.
 
feature -- Commands
 
	start is
			-- Start the timer.
		do
			is_stop := False
			launch
		end
 
	stop is
			-- Stop the timer.
		do
			is_stop := True
			timer_mutex.lock
			timer_condition.signal
			timer_mutex.unlock
			exit
		end
 
feature {NONE} -- Implementation
 
	timer_mutex: MUTEX
			-- Mutex for timer.
 
	timer_condition: CONDITION_VARIABLE
			-- Condition variable to wait on during the interval.
 
	execute is
			-- Main loop, executes action every interval until stopped.
		local
			l_tmp: BOOLEAN
		do
			timer_mutex.lock
			from
			until
				is_stop
			loop
				action.call ([])
				l_tmp := timer_condition.wait_with_timeout (timer_mutex, interval)
			end
			timer_mutex.unlock
		end
 
invariant
	action_set: action /= Void
	interval_valid: interval > 0
	timer_mutex_not_void: timer_mutex /= Void
	timer_condition_not_void: timer_condition /= Void
 
end

indexing
	description: "Sample"
	author: "Patrick Ruckstuhl <patrick@tario.org>"
	date: "$Date$"
	revision: "$Revision$"
 
class
	SAMPLE
 
create
	make
 
feature {NONE} -- Initialization
 
	make is
			-- Create.
		local
			l_timer: TIMER
		do
				-- create a new timer, that print's hello worlds every 10 seconds
			create l_timer.make (agent print("Hello World%N"), 10*1000)
			l_timer.start
		end
 
end