--- loncom/lonsql 2002/08/06 13:48:47 1.51
+++ loncom/lonsql 2006/02/10 09:50:50 1.71.2.1
@@ -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 1.71.2.1 2006/02/10 09:50:50 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("<font color=red>CRITICAL: Shutting down</font>");
- $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("<font color=red>CRITICAL: Restarting</font>");
- 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("<font color=blue>WARNING: Couldn't disconnect from database ".
- " $DBI::errstr : $@</font>");
- 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 $dbh;
@@ -237,10 +234,17 @@ unless ($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 {
+ unlink('/home/httpd/html/lon-status/mysql.txt');
$dbh->disconnect;
}
+
#
# Check if other instance running
#
@@ -251,23 +255,23 @@ if (-e $pidfile) {
chomp($pide);
if (kill 0 => $pide) { die "already running"; }
}
+
#
# Read hosts file
#
-my %hostip;
my $thisserver;
my $PREFORK=4; # number of children to maintain, at least four spare
open (CONFIG,"$perlvar{'lonTabDir'}/hosts.tab") || die "Can't read host file";
while (my $configline=<CONFIG>) {
- my ($id,$domain,$role,$name,$ip)=split(/:/,$configline);
- chomp($ip);
- $hostip{$ip}=$id;
+ my ($id,$domain,$role,$name)=split(/:/,$configline);
+ $name=~s/\s//g;
$thisserver=$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 +284,23 @@ 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("<font color=red>CRITICAL: ---------- Starting ----------</font>");
+&logthis("<font color='red'>CRITICAL: ---------- Starting ----------</font>");
+
#
# Ignore signals generated during initial startup
$SIG{HUP}=$SIG{USR1}='IGNORE';
@@ -303,11 +309,13 @@ $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 +370,7 @@ sub make_new_child {
$perlvar{'lonSqlAccess'},
{ RaiseError =>0,PrintError=>0})) {
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>");
# "($st secs): $@</font>");
print "database handle error\n";
@@ -390,7 +398,7 @@ 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 +423,49 @@ sub make_new_child {
$result='no_such_file';
}
# end of log query
+ } elsif (($query eq 'fetchenrollment') ||
+ ($query eq 'institutionalphotos')) {
+ # retrieve institutional class lists
+ my $dom = &unescape($arg1);
+ my %affiliates = ();
+ my %replies = ();
+ my $locresult = '';
+ my $querystr = &unescape($arg3);
+ foreach (split/%%/,$querystr) {
+ if (/^([^=]+)=([^=]+)$/) {
+ @{$affiliates{$1}} = split/,/,$2;
+ }
+ }
+ if ($query eq 'fetchenrollment') {
+ $locresult = &localenroll::fetch_enrollment($dom,\%affiliates,\%replies);
+ } elsif ($query eq 'institutionalphotos') {
+ my $crs = &unescape($arg2);
+ eval {
+ local($SIG{__DIE__})='DEFAULT';
+ $locresult = &localenroll::institutional_photos($dom,$crs,\%affiliates,\%replies,'update');
+ };
+ if ($@) {
+ $locresult = 'error';
+ }
+ }
+ $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 +473,13 @@ 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("<font color=blue>WARNING: Couldn't disconnect".
+ or &logthis("<font color='blue'>WARNING: Couldn't disconnect".
" from database $DBI::errstr : $@</font>");
# this exit is VERY important, otherwise the child will become
# a producer of more and more children, forking yourself into
@@ -471,6 +520,7 @@ sub process_file {
sub do_sql_query {
my ($query,$custom,$customshow) = @_;
+# &logthis('doing query '.$query);
$custom = &unescape($custom);
$customshow = &unescape($customshow);
#
@@ -485,8 +535,9 @@ sub do_sql_query {
#prepare and execute the query
my $sth = $dbh->prepare($query);
unless ($sth->execute()) {
- &logthis("<font color=blue>WARNING: ".
- "Could not retrieve from database: $@</font>");
+ &logthis('<font color="blue">'.
+ 'WARNING: Could not retrieve from database:'.
+ $sth->errstr().'</font>');
} else {
my $aref=$sth->fetchall_arrayref;
foreach my $row (@$aref) {
@@ -586,7 +637,7 @@ 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 +925,76 @@ 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("<font color='red'>CRITICAL: Shutting down</font>");
+ $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("<font color='red'>CRITICAL: Restarting</font>");
+ 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("<font color='blue'>WARNING: Couldn't disconnect from database ".
+ " $DBI::errstr : $@</font>");
+ exit;
+}
-# ----------------------------------- POD (plain old documentation, CPAN style)
=pod