function differentialevolutionslave(slaveFileDir)
%DIFFERENTIALEVOLUTIONSLAVE  Start differential evolution slave process.
%		DIFFERENTIALEVOLUTIONSLAVE(DIRNAME) starts a slave process for function
%		DIFFERENTIALEVOLUTION. The given directory DIRNAME is checked for data
%		files including which function to run and which parameters to use.
%
%		DIFFERENTIALEVOLUTIONSLAVE (without input arguments) uses the default
%		directory <TEMPDIR2>/differentialevolution, where <TEMPDIR2> is the
%		temporary directory returned by function TEMPDIR2.
%
%		Markus Buehren
%		Last modified 03.02.2008 
%
%		See also DIFFERENTIALEVOLUTION, TEMPDIR2.

% get slave file directory name
if ~exist('slaveFileDir', 'var') || isempty(slaveFileDir)
	slaveFileDir = concatpath(tempdir2, 'differentialevolution');	
end
if ~exist(slaveFileDir, 'dir')
	% create slave file directory if not existing
	mkdir(slaveFileDir);
end

firstWarnTime = 10;
startWarnTime = 10*60;
maxWarnTime   = 24*3600;
startWaitTime = 0.5;
maxWaitTime   = 5;

% set random states
rand ('state', sum(clock*100));
randn('state', sum(clock*100));

lastEvaluationEndClock = clock;
lastWarnClock          = clock;
firstRun    = true;
curWarnTime = firstWarnTime;
curWaitTime = startWaitTime;
while 1
	slaveFileList = findfiles(slaveFileDir, 'iteration_*_member_*_parameters.mat', 'nonrecursive');
	
	for fileNr = 1:length(slaveFileList)
		% check if there are invalid results
		resultFileName = strrep(slaveFileList{fileNr}, 'parameters', 'result');
		if existfile(resultFileName)
			deletewithsemaphores(resultFileName);
		end
	end

	% get last file that is not a semaphore file
	slaveFileName = '';
	for fileNr = length(slaveFileList):-1:1
		if isempty(strfind(slaveFileList{fileNr}, 'semaphore'))
			slaveFileName = slaveFileList{fileNr};
			break
		end
	end
	
	if ~isempty(slaveFileName)

		% load parameters from last file and remove file
		slaveFileName  = slaveFileList{end};
		resultFileName = strrep(slaveFileName, 'parameters', 'result');
		sem = setfilesemaphore(slaveFileName);
		loadSuccessful = true;
		if existfile(slaveFileName)
			try
				load(slaveFileName, 'objFctHandle', 'argumentCell');
				delete(slaveFileName);
			catch
				disp(sprintf('Error loading or deleting file %s.', slaveFileName));
				displayerrorstruct;
				loadSuccessful = false;
			end
		else
			loadSuccessful = false;
		end
		removefilesemaphore(sem);

		% check
		if loadSuccessful && (~exist('argumentCell', 'var') || ~exist('objFctHandle', 'var'))
			disp(textwrap2(sprintf('Warning: Either variable ''%s'' or ''%s'' not existing after loading file %s.', ...
				'objFctHandle', 'argumentCell', slaveFileName)));
			loadSuccessful = false;
		end

		% continue if loading was not successful
		if ~loadSuccessful
			continue
		end

		%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
		% evaluate objective function %
		%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
		if firstRun
			disp(sprintf('First function evaluation (%s)', datestr(clock, 'mmm dd, HH:MM')));
			firstRun = false;
		elseif etime(clock, lastEvaluationEndClock) > 60
			disp(sprintf('First function evaluation after %s (%s)', ...
				formattime(etime(clock, lastEvaluationEndClock)), datestr(clock, 'mmm dd, HH:MM')));
		end		
		testval = objFctHandle(argumentCell{:}); %#ok

		% check if result is valid and save
		sem = setfilesemaphore({slaveFileName, resultFileName});
		if ~existfile(slaveFileName)
			% if the same slave file was generated again in the meantime, the
			% current result is invalid
			save(resultFileName, 'testval');
		end
		removefilesemaphore(sem);		
		
		% save time
		lastEvaluationEndClock = clock;
		curWarnTime = startWarnTime;
		curWaitTime = startWaitTime;

		% remove variables before next run
		clear argumentCell objFctHandle
		
	else
		% display message if idle for long time
		timeSinceLastEvaluation = etime(clock, lastEvaluationEndClock);
		if min(timeSinceLastEvaluation, etime(clock, lastWarnClock)) > curWarnTime
			if timeSinceLastEvaluation >= 10*60
				% round to minutes
				timeSinceLastEvaluation = 60 * round(timeSinceLastEvaluation / 60);
			end
			disp(sprintf('Warning: No slave files found in last %s (%s).', formattime(timeSinceLastEvaluation), datestr(clock, 'mmm dd, HH:MM')));
			lastWarnClock = clock;
			if firstRun
				curWarnTime = startWarnTime;
			else
				curWarnTime = min(curWarnTime * 2, maxWarnTime);
			end
			curWaitTime = min(curWaitTime + 1, maxWaitTime);
		end

		% wait before next check
		pause(curWaitTime);
	
	end
end