PP_SERVER(PR_OPTIONS,PR_REQUEST_PATH)

function PP_SERVER(PR_OPTIONS,PR_REQUEST_PATH)
%PP_SERVER(PR_OPTIONS,PR_REQUEST_PATH)
%
%   This function starts a Parallel Processing server session
%   which handles requests posted in the directory PR_REQUEST_PATH..
%   Behavior of this function can be customized via the
%   parameter PR_OPTIONS which is a text string of the
%   form "opt1=val1&opt2=val2&...." The options allowed are:
%
%   NAME - A text string to identify this server session.
%      The default is 'PP_SERVER_computer'.
%   PAUSE - When equal to a positive value,
%      the function will pause the indicated number of seconds
%      between checks for additional requests to process.
%      Otherwise, this function will return as soon as all
%      outstanding requests have been processed..

% This file and the DistributePP software package were created and
% are maintained by Michael D. DeVore. The package originated in
% November, 1999. Permission is granted by the author for anyone
% to use or modify this software provided that:
% (1) any modified files are documented internally to clearly indicate
%     that they have been modified from the original release; and
% (2) it is recognized that neigher Michael D. DeVore nor Washington
%     University assumes any liability for the use or misuse of the software.

% Default option values...

LV_PAUSE = 0;
LV_SERVER_NAME = ['PP_SERVER_' computer];

% Extract options...

LV_OPTION_TAIL = PR_OPTIONS;
while length(LV_OPTION_TAIL) > 0
   [LV_OPT,LV_OPTION_TAIL] = strtok(LV_OPTION_TAIL,'=');
   LV_OPT = deblank(strrep(LV_OPT,'&',''));
   [LV_VAL,LV_OPTION_TAIL] = strtok(LV_OPTION_TAIL,'&');
   LV_VAL = strrep(LV_VAL,'=','');
   
   if strcmp('PAUSE',upper(LV_OPT)) == 1
      LV_PAUSE = str2num(LV_VAL);
   end

   if strcmp('NAME',upper(LV_OPT)) == 1
      LV_SERVER_NAME = LV_VAL;
   end
end

% Generate a unique name for this server based upon the third parameter...

LV_SERVER_NAME = [LV_SERVER_NAME '_' num2str(PP_SEQUENCE([PR_REQUEST_PATH LV_SERVER_NAME '.seq']))];

% We will log all operations to this file...

LV_LOG_FILE = fopen([PR_REQUEST_PATH LV_SERVER_NAME '.log'],'w');
fprintf(LV_LOG_FILE,'PP Server %s commencing processing at %s...',LV_SERVER_NAME,datestr(now));

% Capture the path and working directory so we can set them back after each operation...

LV_DEFAULT_PATH = path;
LV_WORKING_DIR  = pwd;
LV_STOP_FLAG = 0;

while ~LV_STOP_FLAG
   [LV_STOP_FLAG,LV_REQUEST,LV_FID] = GET_NEXT_REQUEST(PR_REQUEST_PATH,LV_SERVER_NAME);

   if LV_FID >= 0
      fprintf(LV_LOG_FILE,'\n\nProcessing request %s at %s...',LV_REQUEST,datestr(now));
      
      load(LV_REQUEST);
      addpath(LV_PROC_SPEC.Path);
      cd(LV_PROC_SPEC.WorkingDir);
      lasterr('');
      
%     Matlab 5.0 does not have try...catch...end blocks, so we resort to this for compatibility...
      
      eval('LV_PROC_RESULT = feval(LV_PROC_SPEC.Command,LV_PROC_SPEC.Arguments{:}); LV_LAST_ERR = '''';',...
           'LV_LAST_ERR = lasterr; LV_PROC_RESULT = '''';');
      
      if isempty(findstr(LV_LAST_ERR,'Out of memory'))
         save(LV_REQUEST,'LV_PROC_RESULT','LV_LAST_ERR','-append')
         delete([LV_REQUEST '.req']);
         fprintf(LV_LOG_FILE,'\n  Completed request %s at %s. %s',LV_REQUEST,datestr(now),...
            strrep(LV_LAST_ERR,sprintf('\n'),': '));
      else
         fprintf(LV_LOG_FILE,'\n  Out of memory failure on request %s at %s.',LV_REQUEST,datestr(now));
      end
      
      clear global;
      path(LV_DEFAULT_PATH);
      cd(LV_WORKING_DIR);
      PP_CLOSE_LOCK(LV_FID);
   else
      if (LV_PAUSE > 0) & (~LV_STOP_FLAG)
         pause(LV_PAUSE);
      else
         LV_STOP_FLAG = 1;
      end
   end
end

fprintf(LV_LOG_FILE,'\n\nServer termination at %s.\n',datestr(now));
fclose(LV_LOG_FILE);



%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% End of PP_SERVER %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function [RT_STOP_FLAG,RT_REQUEST,RT_FID] = GET_NEXT_REQUEST(PR_REQUEST_PATH,PR_SERVER_NAME)

% This function locks the next indicator file in the given path, creates a flag file
% indicating that processing has begun, and returns the request and file id of a path
% to that indicator.

RT_STOP_FLAG = 0;
RT_REQUEST = '';
RT_FID = -1;

if exist([PR_REQUEST_PATH 'STOP_ALL.ind'],'file') | exist([PR_REQUEST_PATH 'STOP_' PR_SERVER_NAME '.ind'],'file')
   RT_STOP_FLAG = 1;
else
%  Get a list of request files and sort them by date...
   LV_DIR = dir([PR_REQUEST_PATH '*.req']);

   if length(LV_DIR) ~= 0
      LV_TIMESTAMP = [];
      for LV_INDX =1:length(LV_DIR)
         LV_TIMESTAMP(LV_INDX)=datenum(LV_DIR(LV_INDX).date);
      end
      [LV_TIMESTAMP,LV_INDX] = sort(LV_TIMESTAMP);
      LV_DIR = LV_DIR(LV_INDX);

      LV_IND_LIST = cell(length(LV_DIR),1);
      [LV_IND_LIST{:}] = deal(LV_DIR.name);

      LV_INDX = 0;
      while (LV_INDX < length(LV_IND_LIST)) & (RT_FID < 0)
         LV_INDX = LV_INDX + 1;
         RT_FID = PP_OPEN_LOCK([PR_REQUEST_PATH LV_IND_LIST{LV_INDX}]);
         
%        Ensure that we don't attempt to re-try a computation we've already failed at...
         LV_PRC_FILE = [PR_REQUEST_PATH strrep(LV_IND_LIST{LV_INDX},'.req','') '.prc'];
         if exist(LV_PRC_FILE,'file') & (RT_FID >= 0)
            LV_ALREADY_TRIED = 0;
            LV_PRC_FILE = fopen(LV_PRC_FILE,'rt');

            while (~feof(LV_PRC_FILE)) & (~LV_ALREADY_TRIED)
               LV_RECORD = fgetl(LV_PRC_FILE);
               LV_ALREADY_TRIED = strcmp(PR_SERVER_NAME,strtok(LV_RECORD,','));
            end
            fclose(LV_PRC_FILE);
            
            if LV_ALREADY_TRIED
               PP_CLOSE_LOCK(RT_FID);
               RT_FID = -1;
            end
         end
      end
   
      if RT_FID >=0
         RT_REQUEST = [PR_REQUEST_PATH strrep(LV_IND_LIST{LV_INDX},'.req','')];
         LV_PRC_FILE = fopen([RT_REQUEST '.prc'],'at');
         fprintf(LV_PRC_FILE,'\n%s, %s',PR_SERVER_NAME,datestr(now));
         fclose(LV_PRC_FILE);
      end
   end
end