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Diff for /loncom/lonsql between versions 1.52 and 1.64

version 1.52, 2002/08/13 19:40:57 version 1.64, 2004/08/20 16:42:41
Line 39  lonsql - LON TCP-MySQL-Server Daemon for Line 39  lonsql - LON TCP-MySQL-Server Daemon for
 This script should be run as user=www.    This script should be run as user=www.  
 Note that a lonsql.pid file contains the pid of the parent process.  Note that a lonsql.pid file contains the pid of the parent process.
   
 =head1 DESCRIPTION  =head1 OVERVIEW
   
 lonsql is many things to many people.  To me, it is a source file in need  =head2 Purpose within LON-CAPA
 of documentation.  
   LON-CAPA is meant to distribute A LOT of educational content to A LOT
   of people. It is ineffective to directly rely on contents within the
   ext2 filesystem to be speedily scanned for on-the-fly searches of
   content descriptions. (Simply put, it takes a cumbersome amount of
   time to open, read, analyze, and close thousands of files.)
   
   The solution is to index various data fields that are descriptive of
   the educational resources on a LON-CAPA server machine in a
   database. Descriptive data fields are referred to as "metadata". The
   question then arises as to how this metadata is handled in terms of
   the rest of the LON-CAPA network without burdening client and daemon
   processes.
   
   The obvious solution, using lonc to send a query to a lond process,
   doesn't work so well in general as you can see in the following
   example:
   
       lonc= loncapa client process    A-lonc= a lonc process on Server A
       lond= loncapa daemon process
   
                    database command
       A-lonc  --------TCP/IP----------------> B-lond
   
   The problem emerges that A-lonc and B-lond are kept waiting for the
   MySQL server to "do its stuff", or in other words, perform the
   conceivably sophisticated, data-intensive, time-sucking database
   transaction.  By tying up a lonc and lond process, this significantly
   cripples the capabilities of LON-CAPA servers.
   
   The solution is to offload the work onto another process, and use
   lonc and lond just for requests and notifications of completed
   processing:
   
                   database command
   
     A-lonc  ---------TCP/IP-----------------> B-lond =====> B-lonsql
            <---------------------------------/                |
              "ok, I'll get back to you..."                    |
                                                               |
                                                               /
     A-lond  <-------------------------------  B-lonc   <======
              "Guess what? I have the result!"
   
   Of course, depending on success or failure, the messages may vary, but
   the principle remains the same where a separate pool of children
   processes (lonsql's) handle the MySQL database manipulations.
   
   Thus, lonc and lond spend effectively no time waiting on results from
   the database.
   
 =head1 Internals  =head1 Internals
   
Line 54  use strict; Line 103  use strict;
   
 use lib '/home/httpd/lib/perl/';  use lib '/home/httpd/lib/perl/';
 use LONCAPA::Configuration;  use LONCAPA::Configuration;
   use LONCAPA::lonmetadata();
   
 use IO::Socket;  use IO::Socket;
 use Symbol;  use Symbol;
Line 65  use Fcntl; Line 115  use Fcntl;
 use Tie::RefHash;  use Tie::RefHash;
 use DBI;  use DBI;
 use File::Find;  use File::Find;
   use localenroll;
   
 ########################################################  ########################################################
 ########################################################  ########################################################
Line 152  my $run =0;              # running count Line 203  my $run =0;              # running count
 #  #
 # Read loncapa_apache.conf and loncapa.conf  # Read loncapa_apache.conf and loncapa.conf
 #  #
 my $perlvarref=LONCAPA::Configuration::read_conf('loncapa_apache.conf',  my $perlvarref=LONCAPA::Configuration::read_conf('loncapa.conf');
                                                  'loncapa.conf');  
 my %perlvar=%{$perlvarref};  my %perlvar=%{$perlvarref};
 #  #
   # Write the /home/www/.my.cnf file 
   my $conf_file = '/home/www/.my.cnf';
   if (! -e $conf_file) {
       if (open MYCNF, ">$conf_file") {
           print MYCNF <<"ENDMYCNF";
   [client]
   user=www
   password=$perlvar{'lonSqlAccess'}
   ENDMYCNF
           close MYCNF;
       } else {
           warn "Unable to write $conf_file, continuing";
       }
   }
   
   
   #
 # Make sure that database can be accessed  # Make sure that database can be accessed
 #  #
 my $dbh;  my $dbh;
Line 167  unless ($dbh = DBI->connect("DBI:mysql:l Line 234  unless ($dbh = DBI->connect("DBI:mysql:l
     my $subj="LON: $perlvar{'lonHostID'} Cannot connect to database!";      my $subj="LON: $perlvar{'lonHostID'} Cannot connect to database!";
     system("echo 'Cannot connect to MySQL database!' |".      system("echo 'Cannot connect to MySQL database!' |".
            " mailto $emailto -s '$subj' > /dev/null");             " mailto $emailto -s '$subj' > /dev/null");
   
       open(SMP,'>/home/httpd/html/lon-status/mysql.txt');
       print SMP 'time='.time.'&mysql=defunct'."\n";
       close(SMP);
   
     exit 1;      exit 1;
 } else {  } else {
     $dbh->disconnect;      $dbh->disconnect;
Line 228  my $execdir=$perlvar{'lonDaemons'}; Line 300  my $execdir=$perlvar{'lonDaemons'};
 open (PIDSAVE,">$execdir/logs/lonsql.pid");  open (PIDSAVE,">$execdir/logs/lonsql.pid");
 print PIDSAVE "$$\n";  print PIDSAVE "$$\n";
 close(PIDSAVE);  close(PIDSAVE);
 &logthis("<font color=red>CRITICAL: ---------- Starting ----------</font>");  &logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
   
 #  #
 # Ignore signals generated during initial startup  # Ignore signals generated during initial startup
Line 299  sub make_new_child { Line 371  sub make_new_child {
                                     $perlvar{'lonSqlAccess'},                                      $perlvar{'lonSqlAccess'},
                                     { RaiseError =>0,PrintError=>0})) {                                       { RaiseError =>0,PrintError=>0})) { 
             sleep(10+int(rand(20)));              sleep(10+int(rand(20)));
             &logthis("<font color=blue>WARNING: Couldn't connect to database".              &logthis("<font color='blue'>WARNING: Couldn't connect to database".
                      ": $@</font>");                       ": $@</font>");
                      #  "($st secs): $@</font>");                       #  "($st secs): $@</font>");
             print "database handle error\n";              print "database handle error\n";
Line 327  sub make_new_child { Line 399  sub make_new_child {
     $queryid .= $run;      $queryid .= $run;
     print $client "$queryid\n";      print $client "$queryid\n";
     #      #
     &logthis("QUERY: $query - $arg1 - $arg2 - $arg3");      # &logthis("QUERY: $query - $arg1 - $arg2 - $arg3");
     sleep 1;      sleep 1;
             #              #
             my $result='';              my $result='';
Line 352  sub make_new_child { Line 424  sub make_new_child {
                     $result='no_such_file';                      $result='no_such_file';
                 }                  }
                 # end of log query                  # end of log query
               } elsif ($query eq 'fetchenrollment') {
                   # retrieve institutional class lists
                   my $dom = &unescape($arg1);
                   my %affiliates = ();
                   my %replies = ();
                   my $locresult = '';
                   my $querystr = &unescape($arg3);
                   foreach (split/%%/,$querystr) {
                       if (/^(\w+)=([^=]+)$/) {
                           @{$affiliates{$1}} = split/,/,$2;
                       }
                   }
                   $locresult = &localenroll::fetch_enrollment($dom,\%affiliates,\%replies);
                   $result = &escape($locresult.':');
                   if ($locresult) {
                       $result .= &escape(join(':',map{$_.'='.$replies{$_}} keys %replies));
                   }
               } elsif ($query eq 'prepare activity log') {
                   my ($cid,$domain) = map {&unescape($_);} ($arg1,$arg2);
                   &logthis('preparing activity log tables for '.$cid);
                   my $command = 
                       qq{$perlvar{'lonDaemons'}/parse_activity_log.pl -course=$cid -domain=$domain};
                   system($command);
                   &logthis($command);
                   my $returnvalue = $?>>8;
                   if ($returnvalue) {
                       $result = 'error: parse_activity_log.pl returned '.
                           $returnvalue;
                   } else {
                       $result = 'success';
                   }
             } else {              } else {
                 # Do an sql query                  # Do an sql query
                 $result = &do_sql_query($query,$arg1,$arg2);                  $result = &do_sql_query($query,$arg1,$arg2);
Line 359  sub make_new_child { Line 462  sub make_new_child {
             # result does not need to be escaped because it has already been              # result does not need to be escaped because it has already been
             # escaped.              # escaped.
             #$result=&escape($result);              #$result=&escape($result);
             # reply with result, append \n unless already there  
     $result.="\n" unless ($result=~/\n$/);  
             &reply("queryreply:$queryid:$result",$conserver);              &reply("queryreply:$queryid:$result",$conserver);
         }          }
         # tidy up gracefully and finish          # tidy up gracefully and finish
         #          #
         # close the database handle          # close the database handle
  $dbh->disconnect   $dbh->disconnect
             or &logthis("<font color=blue>WARNING: Couldn't disconnect".              or &logthis("<font color='blue'>WARNING: Couldn't disconnect".
                         " from database  $DBI::errstr : $@</font>");                          " from database  $DBI::errstr : $@</font>");
         # this exit is VERY important, otherwise the child will become          # this exit is VERY important, otherwise the child will become
         # a producer of more and more children, forking yourself into          # a producer of more and more children, forking yourself into
Line 408  sub process_file { Line 509  sub process_file {
   
 sub do_sql_query {  sub do_sql_query {
     my ($query,$custom,$customshow) = @_;      my ($query,$custom,$customshow) = @_;
       &logthis('doing query '.$query);
     $custom     = &unescape($custom);      $custom     = &unescape($custom);
     $customshow = &unescape($customshow);      $customshow = &unescape($customshow);
     #      #
Line 422  sub do_sql_query { Line 524  sub do_sql_query {
         #prepare and execute the query          #prepare and execute the query
         my $sth = $dbh->prepare($query);          my $sth = $dbh->prepare($query);
         unless ($sth->execute()) {          unless ($sth->execute()) {
             &logthis("<font color=blue>WARNING: ".              &logthis('<font color="blue">'.
                      "Could not retrieve from database: $@</font>");                       'WARNING: Could not retrieve from database:'.
                        $sth->errstr().'</font>');
         } else {          } else {
             my $aref=$sth->fetchall_arrayref;              my $aref=$sth->fetchall_arrayref;
             foreach my $row (@$aref) {              foreach my $row (@$aref) {
Line 855  sub HUNTSMAN {                      # si Line 958  sub HUNTSMAN {                      # si
     kill 'INT' => keys %children;      kill 'INT' => keys %children;
     my $execdir=$perlvar{'lonDaemons'};      my $execdir=$perlvar{'lonDaemons'};
     unlink("$execdir/logs/lonsql.pid");      unlink("$execdir/logs/lonsql.pid");
     &logthis("<font color=red>CRITICAL: Shutting down</font>");      &logthis("<font color='red'>CRITICAL: Shutting down</font>");
     $unixsock = "mysqlsock";      $unixsock = "mysqlsock";
     my $port="$perlvar{'lonSockDir'}/$unixsock";      my $port="$perlvar{'lonSockDir'}/$unixsock";
     unlink($port);      unlink($port);
Line 866  sub HUPSMAN {                      # sig Line 969  sub HUPSMAN {                      # sig
     local($SIG{CHLD}) = 'IGNORE';  # we're going to kill our children      local($SIG{CHLD}) = 'IGNORE';  # we're going to kill our children
     kill 'INT' => keys %children;      kill 'INT' => keys %children;
     close($server);                # free up socket      close($server);                # free up socket
     &logthis("<font color=red>CRITICAL: Restarting</font>");      &logthis("<font color='red'>CRITICAL: Restarting</font>");
     my $execdir=$perlvar{'lonDaemons'};      my $execdir=$perlvar{'lonDaemons'};
     $unixsock = "mysqlsock";      $unixsock = "mysqlsock";
     my $port="$perlvar{'lonSockDir'}/$unixsock";      my $port="$perlvar{'lonSockDir'}/$unixsock";
Line 876  sub HUPSMAN {                      # sig Line 979  sub HUPSMAN {                      # sig
   
 sub DISCONNECT {  sub DISCONNECT {
     $dbh->disconnect or       $dbh->disconnect or 
     &logthis("<font color=blue>WARNING: Couldn't disconnect from database ".      &logthis("<font color='blue'>WARNING: Couldn't disconnect from database ".
              " $DBI::errstr : $@</font>");               " $DBI::errstr : $@</font>");
     exit;      exit;
 }  }
   
   
   
   
   
   
   
   
   
   
   
 # ----------------------------------- POD (plain old documentation, CPAN style)  
   
 =pod  =pod
   
 =back  =back
Removed from v.1.52  
changed lines
  Added in v.1.64

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