--- loncom/lonsql 2002/08/06 13:48:47 1.51 +++ loncom/lonsql 2004/08/26 19:29:09 1.65 @@ -3,7 +3,7 @@ # The LearningOnline Network # lonsql - LON TCP-MySQL-Server Daemon for handling database requests. # -# $Id: lonsql,v 1.51 2002/08/06 13:48:47 matthew Exp $ +# $Id: lonsql,v 1.65 2004/08/26 19:29:09 albertel Exp $ # # Copyright Michigan State University Board of Trustees # @@ -39,10 +39,59 @@ lonsql - LON TCP-MySQL-Server Daemon for This script should be run as user=www. 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 -of documentation. +=head2 Purpose within LON-CAPA + +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 @@ -54,6 +103,7 @@ use strict; use lib '/home/httpd/lib/perl/'; use LONCAPA::Configuration; +use LONCAPA::lonmetadata(); use IO::Socket; use Symbol; @@ -65,6 +115,7 @@ use Fcntl; use Tie::RefHash; use DBI; use File::Find; +use localenroll; ######################################################## ######################################################## @@ -116,76 +167,6 @@ my $MAX_CLIENTS_PER_CHILD = 5; # numb my %children = (); # keys are current child process IDs my $children = 0; # current number of children -######################################################## -######################################################## - -=pod - -=item Functions required for forking - -=over 4 - -=item REAPER - -REAPER takes care of dead children. - -=item HUNTSMAN - -Signal handler for SIGINT. - -=item HUPSMAN - -Signal handler for SIGHUP - -=item DISCONNECT - -Disconnects from database. - -=back - -=cut - -######################################################## -######################################################## -sub REAPER { # takes care of dead children - $SIG{CHLD} = \&REAPER; - my $pid = wait; - $children --; - &logthis("Child $pid died"); - delete $children{$pid}; -} - -sub HUNTSMAN { # signal handler for SIGINT - local($SIG{CHLD}) = 'IGNORE'; # we're going to kill our children - kill 'INT' => keys %children; - my $execdir=$perlvar{'lonDaemons'}; - unlink("$execdir/logs/lonsql.pid"); - &logthis("CRITICAL: Shutting down"); - $unixsock = "mysqlsock"; - my $port="$perlvar{'lonSockDir'}/$unixsock"; - unlink($port); - exit; # clean up with dignity -} - -sub HUPSMAN { # signal handler for SIGHUP - local($SIG{CHLD}) = 'IGNORE'; # we're going to kill our children - kill 'INT' => keys %children; - close($server); # free up socket - &logthis("CRITICAL: Restarting"); - my $execdir=$perlvar{'lonDaemons'}; - $unixsock = "mysqlsock"; - my $port="$perlvar{'lonSockDir'}/$unixsock"; - unlink($port); - exec("$execdir/lonsql"); # here we go again -} - -sub DISCONNECT { - $dbh->disconnect or - &logthis("WARNING: Couldn't disconnect from database ". - " $DBI::errstr : $@"); - exit; -} - ################################################################### ################################################################### @@ -222,10 +203,26 @@ my $run =0; # running count # # Read loncapa_apache.conf and loncapa.conf # -my $perlvarref=LONCAPA::Configuration::read_conf('loncapa_apache.conf', - 'loncapa.conf'); +my $perlvarref=LONCAPA::Configuration::read_conf('loncapa.conf'); my %perlvar=%{$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 # my $dbh; @@ -237,10 +234,16 @@ unless ($dbh = DBI->connect("DBI:mysql:l my $subj="LON: $perlvar{'lonHostID'} Cannot connect to database!"; system("echo 'Cannot connect to MySQL database!' |". " 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; } else { $dbh->disconnect; } + # # Check if other instance running # @@ -251,6 +254,7 @@ if (-e $pidfile) { chomp($pide); if (kill 0 => $pide) { die "already running"; } } + # # Read hosts file # @@ -263,11 +267,12 @@ while (my $configline=) { chomp($ip); $hostip{$ip}=$id; $thisserver=$name if ($id eq $perlvar{'lonHostID'}); - $PREFORK++; + #$PREFORK++; } close(CONFIG); # -$PREFORK=int($PREFORK/4); +#$PREFORK=int($PREFORK/4); + # # Create a socket to talk to lond # @@ -280,21 +285,23 @@ unless ($server=IO::Socket::UNIX->new(Lo Listen => 10)) { print "in socket error:$@\n"; } -######################################################## -######################################################## + # # Fork once and dissociate +# my $fpid=fork; exit if $fpid; die "Couldn't fork: $!" unless defined ($fpid); POSIX::setsid() or die "Can't start new session: $!"; + # # Write our PID on disk my $execdir=$perlvar{'lonDaemons'}; open (PIDSAVE,">$execdir/logs/lonsql.pid"); print PIDSAVE "$$\n"; close(PIDSAVE); -&logthis("CRITICAL: ---------- Starting ----------"); +&logthis("CRITICAL: ---------- Starting ----------"); + # # Ignore signals generated during initial startup $SIG{HUP}=$SIG{USR1}='IGNORE'; @@ -303,11 +310,13 @@ $SIG{HUP}=$SIG{USR1}='IGNORE'; for (1 .. $PREFORK) { make_new_child(); } + # # Install signal handlers. $SIG{CHLD} = \&REAPER; $SIG{INT} = $SIG{TERM} = \&HUNTSMAN; $SIG{HUP} = \&HUPSMAN; + # # And maintain the population. while (1) { @@ -362,7 +371,7 @@ sub make_new_child { $perlvar{'lonSqlAccess'}, { RaiseError =>0,PrintError=>0})) { sleep(10+int(rand(20))); - &logthis("WARNING: Couldn't connect to database". + &logthis("WARNING: Couldn't connect to database". ": $@"); # "($st secs): $@"); print "database handle error\n"; @@ -390,7 +399,7 @@ sub make_new_child { $queryid .= $run; print $client "$queryid\n"; # - &logthis("QUERY: $query - $arg1 - $arg2 - $arg3"); + # &logthis("QUERY: $query - $arg1 - $arg2 - $arg3"); sleep 1; # my $result=''; @@ -415,6 +424,37 @@ sub make_new_child { $result='no_such_file'; } # 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 { # Do an sql query $result = &do_sql_query($query,$arg1,$arg2); @@ -422,15 +462,13 @@ sub make_new_child { # result does not need to be escaped because it has already been # escaped. #$result=&escape($result); - # reply with result, append \n unless already there - $result.="\n" unless ($result=~/\n$/); &reply("queryreply:$queryid:$result",$conserver); } # tidy up gracefully and finish # # close the database handle $dbh->disconnect - or &logthis("WARNING: Couldn't disconnect". + or &logthis("WARNING: Couldn't disconnect". " from database $DBI::errstr : $@"); # this exit is VERY important, otherwise the child will become # a producer of more and more children, forking yourself into @@ -471,6 +509,7 @@ sub process_file { sub do_sql_query { my ($query,$custom,$customshow) = @_; + &logthis('doing query '.$query); $custom = &unescape($custom); $customshow = &unescape($customshow); # @@ -485,8 +524,9 @@ sub do_sql_query { #prepare and execute the query my $sth = $dbh->prepare($query); unless ($sth->execute()) { - &logthis("WARNING: ". - "Could not retrieve from database: $@"); + &logthis(''. + 'WARNING: Could not retrieve from database:'. + $sth->errstr().''); } else { my $aref=$sth->fetchall_arrayref; foreach my $row (@$aref) { @@ -586,7 +626,7 @@ Writes $message to the logfile. sub logthis { my $message=shift; my $execdir=$perlvar{'lonDaemons'}; - my $fh=IO::File->new(">>$execdir/logs/lonsqlfinal.log"); + my $fh=IO::File->new(">>$execdir/logs/lonsql.log"); my $now=time; my $local=localtime($now); print $fh "$local ($$): $message\n"; @@ -874,17 +914,76 @@ sub userlog { return join('&',sort(@results)); } +######################################################## +######################################################## + +=pod +=item Functions required for forking +=over 4 +=item REAPER +REAPER takes care of dead children. +=item HUNTSMAN +Signal handler for SIGINT. +=item HUPSMAN +Signal handler for SIGHUP + +=item DISCONNECT + +Disconnects from database. + +=back + +=cut +######################################################## +######################################################## +sub REAPER { # takes care of dead children + $SIG{CHLD} = \&REAPER; + my $pid = wait; + $children --; + &logthis("Child $pid died"); + delete $children{$pid}; +} + +sub HUNTSMAN { # signal handler for SIGINT + local($SIG{CHLD}) = 'IGNORE'; # we're going to kill our children + kill 'INT' => keys %children; + my $execdir=$perlvar{'lonDaemons'}; + unlink("$execdir/logs/lonsql.pid"); + &logthis("CRITICAL: Shutting down"); + $unixsock = "mysqlsock"; + my $port="$perlvar{'lonSockDir'}/$unixsock"; + unlink($port); + exit; # clean up with dignity +} + +sub HUPSMAN { # signal handler for SIGHUP + local($SIG{CHLD}) = 'IGNORE'; # we're going to kill our children + kill 'INT' => keys %children; + close($server); # free up socket + &logthis("CRITICAL: Restarting"); + my $execdir=$perlvar{'lonDaemons'}; + $unixsock = "mysqlsock"; + my $port="$perlvar{'lonSockDir'}/$unixsock"; + unlink($port); + exec("$execdir/lonsql"); # here we go again +} + +sub DISCONNECT { + $dbh->disconnect or + &logthis("WARNING: Couldn't disconnect from database ". + " $DBI::errstr : $@"); + exit; +} -# ----------------------------------- POD (plain old documentation, CPAN style) =pod